[Federal Register Volume 73, Number 210 (Wednesday, October 29, 2008)]
[Rules and Regulations]
[Pages 64229-64246]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-25693]



[[Page 64229]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2008-0347; FRL-8388-1]


Carbaryl; Order Denying NRDC's Petition to Revoke Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Order.

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SUMMARY: In this Order, EPA denies a petition requesting that EPA 
revoke all pesticide tolerances for carbaryl under section 408(d) of 
the Federal Food, Drug, and Cosmetic Act (FFDCA). The petition was 
filed on January 10, 2005, by the Natural Resources Defense Council 
(NRDC).

DATES: This Order is effective October 29, 2008. Objections and 
requests for hearings must be received on or before December 29, 2008, 
and must be filed in accordance with the instructions provided in 40 
CFR part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).

ADDRESSES: EPA has established a docket for this action under docket 
identification (ID) number EPA-HQ-OPP-2008-0347. To access the 
electronic docket, go to http://www.regulations.gov, select ``Advanced 
Search,'' then ``Docket Search.'' Insert the docket ID number where 
indicated and select the ``Submit'' button. Follow the instructions on 
the regulations.gov website to view the docket index or access 
available documents. All documents in the docket are listed in the 
docket index available in regulations.gov. Although listed in the 
index, some information is not publicly available, e.g., Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Certain other material, such as copyrighted 
material, is not placed on the Internet and will be publicly available 
only in hard copy form. Publicly available docket materials are 
available in the electronic docket at http://www.regulations.gov, or, 
if only available in hard copy, at the OPP Regulatory Public Docket in 
Rm. S-4400, One Potomac Yard (South Bldg.), 2777 S. Crystal Dr., 
Arlington, VA. The Docket Facility is open from 8:30 a.m. to 4 p.m., 
Monday through Friday, excluding legal holidays. The Docket Facility 
telephone number is (703) 305-5805.

FOR FURTHER INFORMATION CONTACT: Christina Scheltema, Special Review 
and Reregistration Division (7508P), Office of Pesticide Programs, 
Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 
Washington, DC 20460-0001; telephone number: 703-308-2201; e-mail 
address: [email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    In this document, EPA denies a petition by the NRDC to revoke 
pesticide tolerances. This action may be of interest to agricultural 
producers, food manufacturers, or pesticide manufacturers. Potentially 
affected entities may include, but are not limited to those engaged in 
the following activities:
     Crop production (NAICS code 111), e.g., agricultural 
workers; greenhouse, nursery, and floriculture workers; farmers.
     Animal production (NAICS code 112), e.g., cattle ranchers 
and farmers, dairy cattle farmers, livestock farmers.
     Food manufacturing (NAICS code 311), e.g., agricultural 
workers; farmers; greenhouse, nursery, and floriculture workers; 
ranchers; pesticide applicators.
     Pesticide manufacturing (NAICS code 32532), e.g., 
agricultural workers; commercial applicators; farmers; greenhouse, 
nursery, and floriculture workers; residential users.
    This listing is not intended to be exhaustive, but rather to 
provide a guide for readers regarding entities likely to be affected by 
this action. Other types of entities not listed in this unit could also 
be affected. The North American Industrial Classification System 
(NAICS) codes have been provided to assist you and others in 
determining whether this action might apply to certain entities. If you 
have any questions regarding the applicability of this action to a 
particular entity, consult the person listed under FOR FURTHER 
INFORMATION CONTACT.

B. How Can I Access Electronic Copies of this Document?

    In addition to accessing an electronic copy of this Federal 
Register document through the electronic docket at http://www.regulations.gov, you may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr. You may also access a 
frequently updated electronic version of EPA's tolerance regulations at 
40 CFR part 180 through the Government Printing Office's pilot e-CFR 
site at http://www.gpoaccess.gov/ecfr.

C. Can I File an Objection or Hearing Request?

    Under section 408(g) of FFDCA, any person may file an objection to 
any aspect of this regulation and may also request a hearing on those 
objections. You must file your objection or request a hearing on this 
regulation in accordance with the instructions provided in 40 CFR part 
178. To ensure proper receipt by EPA, you must identify docket ID 
number EPA-HQ-OPP-2008-0347 in the subject line on the first page of 
your submission. All requests must be in writing, and must be mailed or 
delivered to the Hearing Clerk as required by 40 CFR part 178 on or 
before December 29, 2008.
    In addition to filing an objection or hearing request with the 
Hearing Clerk as described in 40 CFR part 178, please submit a copy of 
the filing that does not contain any CBI for inclusion in the public 
docket that is described in ADDRESSES. Information not marked 
confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA 
without prior notice. Submit this copy, identified by docket ID number 
EPA-HQ-OPP-2008-0347, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
     Mail: Office of Pesticide Programs (OPP) Regulatory Public 
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460-0001.
     Delivery: OPP Regulatory Public Docket (7502P), 
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South 
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only 
accepted during the Docket's normal hours of operation (8:30 a.m. to 4 
p.m., Monday through Friday, excluding legal holidays). Special 
arrangements should be made for deliveries of boxed information. The 
Docket Facility telephone number is (703) 305-5805.

II. Introduction

A. What Action Is the Agency Taking?

    The NRDC filed a petition dated January 10, 2005 with EPA which, 
among other things, requested that EPA revoke all tolerances for the 
pesticide carbaryl established under section 408 of the FFDCA, 21 
U.S.C. 346a (Ref. 1) This Order denies that aspect of the petition that 
sought the revocation of the carbaryl tolerances. This Order also 
denies NRDC's petition to cancel carbaryl pet collar registrations 
submitted as part of NRDC's comments on the N-methyl carbamate (NMC)

[[Page 64230]]

cumulative assessment and dated November 26, 2007, because NRDC is 
arguing that exposure to carbaryl pet collars makes the cumulative 
risks presented by carbaryl unsafe (Ref. 2).

B. What Is the Agency's Authority for Taking This Action?

    Under section 408(d)(4) of the FFDCA, EPA is authorized to respond 
to a section 408(d) petition to revoke tolerances either by issuing a 
final rule revoking the tolerances, issuing a proposed rule, or issuing 
an order denying the petition. (21 U.S.C. 346a(d)(4)).

III. Statutory and Regulatory Background

A. FFDCA/FIFRA and Applicable Regulations

    1. In general. EPA establishes maximum residue limits, or 
``tolerances,'' for pesticide residues in food and feed commodities 
under section 408 of the FFDCA. (21 U.S.C. 346a). Without such a 
tolerance or an exemption from the requirement of a tolerance, a food 
containing a pesticide residue is ``adulterated'' under section 402 of 
the FFDCA and may not be legally moved in interstate commerce. (21 
U.S.C. 331, 342). Monitoring and enforcement of pesticide tolerances 
are carried out by the U.S. Food and Drug Administration (FDA) and the 
U.S. Department of Agriculture (USDA). Section 408 was substantially 
rewritten by the Food Quality Protection Act of 1996 (FQPA), which 
added the provisions discussed below establishing a detailed safety 
standard for pesticides, additional protections for infants and 
children, and the estrogenic substances screening program. (Public Law 
104-170, 110 Stat. 1489 (1996)).
    EPA also regulates pesticides under the Federal Insecticide, 
Fungicide, and Rodenticide Act (FIFRA), (7 U.S.C. 136 et seq). While 
the FFDCA authorizes the establishment of legal limits for pesticide 
residues in food, FIFRA requires the approval of pesticides prior to 
their sale and distribution, (7 U.S.C. 136a(a)), and establishes a 
registration regime for regulating the use of pesticides. FIFRA 
regulates pesticide use in conjunction with its registration scheme by 
requiring EPA review and approval of pesticide labels and specifying 
that use of a pesticide inconsistent with its label is a violation of 
federal law. (7 U.S.C. 136j(a)(2)(G)). In the FQPA, Congress integrated 
action under the two statutes by requiring that the safety standard 
under the FFDCA be used as a criterion in FIFRA registration actions as 
to pesticide uses which result in dietary risk from residues in or on 
food, (7 U.S.C. 136(bb)), and directing that EPA coordinate, to the 
extent practicable, revocations of tolerances with pesticide 
cancellations under FIFRA. (21 U.S.C. 346a(l)(1)).
    2. Safety standard for pesticide tolerances. A pesticide tolerance 
may only be promulgated or left in effect by EPA if the tolerance is 
``safe.'' (21 U.S.C. 346a(b)(2)(A)(i)). This standard applies both to 
petitions to establish and petitions to revoke tolerances. ``Safe'' is 
defined by the statute to mean that ``there is a reasonable certainty 
that no harm will result from aggregate exposure to the pesticide 
chemical residue, including all anticipated dietary exposures and all 
other exposures for which there is reliable information.'' (21 U.S.C. 
346a(b)(2)(A)(ii)). Section 408(b)(2)(D) directs EPA, in making a 
safety determination, to:
    consider, among other relevant factors--...
    (v) available information concerning the cumulative effects of 
such residues and other substances that have a common mechanism of 
toxicity; and
    (vi) available information concerning the aggregate exposure 
levels of consumers (and major identifiable subgroups of consumers) 
to the pesticide chemical residue and to other related substances, 
including dietary exposure under the tolerance and all other 
tolerances in effect for the pesticide chemical residue, and 
exposure from other non-occupational sources;

(21 U.S.C. 346a(b)(2)(D)(v), (vi) and (viii)).

    EPA must also consider, in evaluating the safety of tolerances, 
``safety factors which . . . are generally recognized as appropriate 
for the use of animal experimentation data.'' (21 U.S.C. 
346a(b)(2)(D)(ix).
    Risks to infants and children are given special consideration. 
Specifically, section 408(b)(2)(C) states that EPA:
    shall assess the risk of the pesticide chemical based on--
    (II) available information concerning the special susceptibility 
of infants and children to the pesticide chemical residues, 
including neurological differences between infants and children and 
adults, and effects of in utero exposure to pesticide chemicals; and
    (III) available information concerning the cumulative effects on 
infants and children of such residues and other substances that have 
a common mechanism of toxicity. ...

 (21 U.S.C. 346a(b)(2)(C)(i)(II) and (III)).

    This provision also creates a presumptive additional safety factor 
for the protection of infants and children. Specifically, it directs 
that ``[i]n the case of threshold effects, ... an additional tenfold 
margin of safety for the pesticide chemical residue and other sources 
of exposure shall be applied for infants and children to take into 
account potential pre- and post-natal toxicity and completeness of the 
data with respect to exposure and toxicity to infants and children.'' 
(21 U.S.C. 346a(b)(2)(C)). EPA is permitted to ``use a different margin 
of safety for the pesticide chemical residue only if, on the basis of 
reliable data, such margin will be safe for infants and children.'' 
(Id.). The additional safety margin for infants and children is 
referred to throughout this Order as the ``FQPA Safety Factor.''
    3. Procedures for establishing, amending, or revoking tolerances. 
Tolerances are established, amended, or revoked by rulemaking under the 
unique procedural framework set forth in the FFDCA. Generally, a 
tolerance rulemaking is initiated by the party seeking to establish, 
amend, or revoke a tolerance by means of filing a petition with EPA. 
(See 21 U.S.C. 346a(d)(1)). EPA publishes in the Federal Register a 
notice of the petition filing and requests public comment. (21 U.S.C. 
346a(d)(3)). After reviewing the petition, and any comments received on 
it, EPA may issue a final rule establishing, amending, or revoking the 
tolerance, issue a proposed rule to do the same, or deny the petition. 
(21 U.S.C. 346a(d)(4)).
    Once EPA takes final action on the petition by establishing, 
amending, or revoking the tolerance or denying the petition, any party 
may file objections with EPA and seek an evidentiary hearing on those 
objections. (21 U.S.C. 346a(g)(2)). Objections and hearing requests 
must be filed within 60 days. (Id.). The statute provides that EPA 
shall ``hold a public evidentiary hearing if and to the extent the 
Administrator determines that such a public hearing is necessary to 
receive factual evidence relevant to material issues of fact raised by 
the objections.'' (21 U.S.C. 346a(g)(2)(B). EPA regulations make clear 
that hearings will only be granted where it is shown that there is ``a 
genuine and substantial issue of fact,'' the requestor has identified 
evidence ``which, if established, resolve one or more of such issues in 
favor of the requestor,'' and the issue is ``determinative'' with 
regard to the relief requested. (40 CFR 178.32(b)). EPA's final order 
on the objections is subject to judicial review. (21 U.S.C. 
346a(h)(1)).
    4. Tolerance reassessment and FIFRA reregistration. The FQPA 
required that EPA reassess the safety of all pesticide tolerances 
existing at the time of its enactment. (21 U.S.C. 346a(q)). EPA was 
given 10 years to reassess the

[[Page 64231]]

approximately 10,000 tolerances in existence in 1996. In this 
reassessment, EPA was required to review existing pesticide tolerances 
under the new ``reasonable certainty that no harm will result'' 
standard set forth in section 408(b)(2)(A)(i). (21 U.S.C. 
346a(b)(2)(A)(i)). This reassessment was substantially completed by the 
August 3, 2006 deadline. Tolerance reassessment was generally handled 
in conjunction with a similar program involving reregistration of 
pesticides under FIFRA. (7 U.S.C. 136a-1). Reassessment and 
reregistration decisions were generally combined in a document labeled 
a Reregistration Eligibility Decision (``RED'').

B. EPA's Approach to Dietary Risk Assessment

    EPA performs a number of analyses to determine the risks from 
aggregate exposure to pesticide residues. A short summary is provided 
below to aid the reader. For further discussion of the regulatory 
requirements of section 408 of the FFDCA and a complete description of 
the risk assessment process, see http://www.epa.gov/fedrgstr/EPA-PEST/1999/January/Day-04/p34736.htm.(64 FR 162)
    To assess the risk of a pesticide tolerance, EPA combines 
information on pesticide toxicity with information regarding the route, 
magnitude, and duration of exposure to the pesticide. The risk 
assessment process involves three distinct steps: (1) identification of 
the toxicological hazards posed by a pesticide and determination of the 
exposure ``level of concern'' for humans; (2) estimation of human 
exposure; and (3) characterization of human risk based on comparison of 
human exposure to the level of concern.
    1. Hazard identification and determination of the level of concern. 
Any risk assessment begins with an evaluation of a chemical's inherent 
properties, and whether those properties have the potential to cause 
adverse effects (i.e., hazard identification). EPA then evaluates the 
hazards to determine the most sensitive and appropriate adverse effect 
of concern, based on factors such as the effect's relevance to humans 
and the likely routes of exposure. Once a pesticide's potential hazards 
are identified, EPA determines a toxicological level of concern for 
evaluating the risk posed by human exposure to the pesticide. In this 
step of the risk assessment process, EPA essentially evaluates the 
levels of exposure to the pesticide at which effects might occur. An 
important aspect of this determination is assessing the relationship 
between exposure (dose) and response (often referred to as the dose-
response analysis). Another aspect is the determination of whether the 
effect is associated with a threshold dose (i.e., the effect is seen 
only at or above a certain dose) or whether the effect can occur at any 
dose (such as some tumors).
    In evaluating a chemical's dietary risks for threshold effects, EPA 
uses a reference dose (RfD) approach, which involves a number of 
considerations including:
     A 'point of departure'(PoD) - the value from a dose-
response curve that is at the low end of the observable data (the no 
observed adverse effect level, or NOAEL, the lowest-observed adverse 
effect level or LOAEL, or an extrapolated benchmark dose) and that is 
the dose serving as the 'starting point' in extrapolating a risk to the 
human population;
     An uncertainty factor to address the potential for a 
difference in toxic response between humans and animals used in 
toxicity tests (i.e., interspecies extrapolation);
     An uncertainty factor to address the potential for 
differences in sensitivity in the toxic response across the human 
population (for intraspecies extrapolation); and
     The need for an additional safety factor to protect 
infants and children, as specified in FFDCA section 408(b)(2)(C).
    EPA uses the chosen PoD to calculate a safe dose or RfD. The RfD is 
calculated by dividing the chosen PoD by all applicable safety or 
uncertainty factors. Typically in EPA risk assessments, a combination 
of safety or uncertainty factors providing at least a hundredfold 
(100X) margin of safety is used: 10X to account for interspecies 
extrapolation and 10X to account for intraspecies extrapolation. 
Further, in evaluating the dietary risks for pesticide chemicals, an 
additional safety factor of 10X is presumptively applied to protect 
infants and children, unless reliable data support selection of a 
different factor. In implementing FFDCA section 408, EPA also 
calculates a variant of the RfD referred to as a population adjusted 
dose (PAD). The PAD is the RfD divided by any portion of the children's 
safety factor that does not correspond to one of the traditional 
additional uncertainty/safety factors used in general Agency risk 
assessment. The reason for calculating PADs is so that other parts of 
the Agency, which are not governed by FFDCA section 408, can, when 
evaluating the same or similar substances, easily identify which 
aspects of a pesticide risk assessment are a function of the particular 
statutory commands in FFDCA section 408. For acute assessments, the 
risk is expressed as a percentage of a maximum acceptable dose or the 
acute PAD (i.e., the acute dose which EPA has concluded will be 
``safe''). As discussed below in Unit V.C., dietary exposures greater 
than 100 percent of the acute PAD are generally cause for concern and 
would be considered ``unsafe'' within the meaning of FFDCA section 
408(b)(2)(B). Throughout this document general references to EPA's 
calculated safe dose are denoted as an acute PAD, or aPAD, because the 
relevant point of departure for carbaryl is based on an acute risk 
endpoint.
    In evaluating a chemical's dietary risk for non-threshold effects, 
such as cancer; EPA's default approach is to extrapolate a Q1* from the 
dose-response curve as a measure of cancer potency, and then to use 
this Q1* value in conjunction with estimated dietary exposure to 
estimate the probability of occurrence of additional adverse effects. 
The Q1*is the 95th percentile upper confidence limit from a tumor dose 
response curve extrapolated using a linear low-dose model. For non-
threshold dietary cancer risks, EPA generally considers cancer risk to 
be negligible if the probability of increased cancer cases falls within 
the range of 1 in 1 million.
    Animal studies show that carbaryl, like other NMC pesticides, 
causes transient, reversible inhibition of cholinesterase activity in 
brain, red blood cells, and plasma across all tested routes of 
exposure. Developmental toxicity was seen in rats and rabbits treated 
with carbaryl during gestation; effects included decreased fetal weight 
and incomplete ossification (bone formation). A carbaryl rat 
reproductive toxicity study showed decreased pup survival, and a rat 
developmental neurotoxicity study showed changes in fetal brain 
morphometry. In addition, a comparative cholinesterase study shows that 
young animals had increased sensitivity, compared with adults, to 
inhibition of brain cholinesterase from carbaryl. EPA used endpoints 
from the comparative cholinesterase study to assess human health risk 
in both the single chemical risk assessment for carbaryl and in the 
cumulative risk assessment for the NMC pesticides. Carbaryl is 
considered to be ``likely to be carcinogenic in humans'' based on 
tumors in male mice and EPA utilized the Agency default low-dose linear 
extrapolation (Q1*) approach to quantify cancer risk.
    2. Estimating human exposure levels. Pursuant to section 408(b) of 
the FFDCA, EPA has evaluated carbaryl dietary risks based on 
``aggregate

[[Page 64232]]

exposure'' to carbaryl. By ``aggregate exposure,'' EPA is referring to 
exposure to carbaryl alone by multiple pathways of exposure, including 
residues in food and water and exposure from use of carbaryl products 
in residential settings. EPA uses available data, together with 
assumptions designed to be protective of public health and standard 
analytical methods, to produce separate estimates of exposure for a 
highly exposed subgroup of the general population, for each potential 
pathway and route of exposure. For acute risks, EPA then calculates 
potential aggregate exposure and risk by using probabilistic techniques 
to combine distributions of potential exposures in the population for 
the dietary pathway, and uses single point estimates for the 
residential component in calculating aggregate exposure. For dietary 
analyses, the relevant sources of potential exposure to carbaryl are 
from the ingestion of residues in food and drinking water.
    The Agency uses a combination of monitoring data and predictive 
models to evaluate environmental exposure of humans to carbaryl, which 
may occur from ingesting carbaryl residues in food or drinking water, 
or from using products containing carbaryl in residential settings. 
These are described below.
    a. Exposure from food. Data on the residues of carbaryl in foods 
are available from a variety of sources. One of the primary sources of 
the data comes from federally-conducted surveys, including the 
Pesticide Data Program (PDP) conducted by the USDA. Further, market 
basket studies, which are typically performed by registrants, can 
provide additional residue data. These data generally provide a 
characterization of pesticide residues in or on foods consumed by the 
U.S. population that closely approximates real world exposures because 
they are sampled closer to the point of consumption in the chain of 
commerce than field trial data, which are generated to establish the 
maximum level of legal residues that could result from maximum 
permissible use of the pesticide. In certain circumstances, EPA will 
rely on field trial data, as it can provide more accurate exposure 
estimates. EPA estimated dietary exposure to carbaryl using residue 
data from a variety of sources, including USDA and FDA monitoring and 
crop field trial studies. These residue data were refined based on 
relevant processing factors. EPA also took into account information on 
the extent to which crops which may be treated with carbaryl are 
actually so treated.
    EPA uses a computer program, the Dietary Exposure Evaluation Model 
(DEEM), and the USDA Food Commodity Intake database (FCID), to estimate 
exposure by combining data on human consumption amounts with residue 
values in food commodities. DEEM-FCIDTM also compares 
exposure estimates to appropriate RfD or PAD values to estimate risk. 
EPA uses DEEM-FCIDTM to estimate exposure for the general 
U.S. population as well as for 32 subgroups based on age, sex, 
ethnicity, and region. DEEM-FCIDTM allows EPA to process 
extensive volumes of data on human consumption amounts and residue 
levels in making risk estimates. Matching consumption and residue data, 
as well as managing the thousands of repeated analyses of the 
consumption database conducted under probabilistic risk assessment 
techniques, requires the use of a computer.
    DEEM-FCIDTM contains consumption and demographic 
information on the individuals who participated in the USDA's Combined 
Survey of Food Intake by Individuals (CSFII) in 1994-1996 and 1998. The 
1998 survey was a special survey required by the FQPA to supplement the 
number of children survey participants. DEEM-FCIDTM also 
contains ``recipes'' that convert foods as consumed (e.g., pizza) back 
into their component raw agricultural commodities (e.g., wheat from 
flour, or tomatoes from sauce, etc.). This is necessary because residue 
data are generally gathered on raw agricultural commodities rather than 
on finished ready-to-eat food. Data on residue values for a particular 
pesticide and the RfD or PADs for that pesticide are inputs to the 
DEEM-FCIDTM program to estimate exposure and risk.
    For carbaryl's assessment, EPA used DEEM-FCIDTM to 
calculate risk estimates based on a probabilistic distribution. DEEM-
FCIDTM combines the full range of residue values for each 
food with the full range of data on individual consumption amounts to 
create a distribution of exposure and risk levels. More specifically, 
DEEM-FCIDTM creates this distribution by calculating an 
exposure value for each reported day of consumption per person 
(``person/day'') in USDA's CSFII, assuming that all foods potentially 
bearing the pesticide residue contain such residue at the chosen value. 
The exposure amounts for the thousands of person/days in the CSFII are 
then collected in a frequency distribution. EPA also uses DEEM-
FCIDTM to compute a distribution taking into account both 
the full range of data on consumption levels and the full range of data 
on potential residue levels in food. Combining consumption and residue 
levels into a distribution of potential exposures and risk requires use 
of probabilistic techniques.
    Probabilistic analysis is used to predict the frequency with which 
variations of a given event will occur. By taking into account the 
actual distribution of possible consumption and pesticide residue 
values, probabilistic analysis for pesticide exposure assessments 
``provides more accurate information on the range and probability of 
possible exposure and their associated risk values'' (Ref. 3). In 
capsule, a probabilistic pesticide exposure analysis constructs a 
distribution of potential exposures based on data on consumption 
patterns and residue levels and provides a ranking of the probability 
that each potential exposure will occur. People consume differing 
amounts of the same foods, including none at all, and a food will 
contain differing amounts of a pesticide residue, including none at 
all.
    The probabilistic technique that DEEM-FCIDTM uses to 
combine differing levels of consumption and residues involves the 
following steps:
    (1) Identification of any food(s) that could bear the residue in 
question for each person/day in the CSFII;
    (2) Calculation of an exposure level for each of the thousands of 
person/days in the CSFII database, based on the foods identified in 
Step 1 by randomly selecting residue values for the foods from 
the residue database;
    (3) Repetition of Step 2 up to one thousand times for each 
person/day; and
    (4) Collection of all of the hundreds of thousands of potential 
exposures estimated in Steps  2 and 3 in a frequency 
distribution.
    The resulting probabilistic assessment presents a range of 
exposure/risk estimates.
    b. Exposure from water. EPA may use field monitoring data and/or 
simulation water exposure models to generate pesticide concentration 
estimates in drinking water. Monitoring and modeling are both important 
tools for estimating pesticide concentrations in water and can provide 
different types of information. Monitoring data can provide estimates 
of pesticide concentrations in water that are representative of the 
specific agricultural or residential pesticide practices in specific 
locations, under the environmental conditions associated with a 
sampling design (i.e., the locations of sampling, the times of the year 
samples were taken, and the frequency by which samples were collected). 
Although monitoring data

[[Page 64233]]

can provide a direct measure of the concentration of a pesticide in 
water, it does not always provide a reliable basis for estimating 
spatial and temporal variability in exposures because sampling may not 
occur in areas with the highest pesticide use, and/or when the 
pesticides are being used and/or at an appropriate sampling frequency 
to detect high concentrations of a pesticide that occur over the period 
of a day to several days.
    Because of the limitations in most monitoring studies, EPA's 
standard approach is to use simulation water exposure models as the 
primary means to estimate pesticide exposure levels in drinking water. 
EPA's computer models use detailed information on soil properties, crop 
characteristics, and weather patterns to estimate water concentrations 
in vulnerable locations where the pesticide could be used according to 
its label. (69 FR 30042, May 26, 2004). These models calculate 
estimated water concentrations of pesticides using laboratory data that 
describe how fast the pesticide breaks down to other chemicals and how 
it moves in the environment at these vulnerable locations. The modeling 
provides an estimate of pesticide concentrations in ground and surface 
water. Daily concentrations can be estimated continuously over long 
periods of time, and for places that are of most interest for any 
particular pesticide.
    EPA relies on models it has developed for estimating pesticide 
concentrations in both surface water and ground water. Typically EPA 
uses a two-tiered approach to modeling pesticide concentrations in 
surface and ground water. If the first tier model suggests that 
pesticide levels in water may be unacceptably high, a more ined model 
is used as a second tier assessment. For surface water assessments, the 
second tier model is actually a combination of two models: The 
Pesticide Root Zone Model (PRZM) and the Exposure Analysis Model System 
(EXAMS).
    A detailed description of the models routinely used for exposure 
assessment is available from the EPA web site: http://www.epa.gov/oppefed1/models/water/index.htm. These models provide a means for EPA 
to estimate daily pesticide concentrations in surface water sources of 
drinking water (a reservoir) using local soil, site, hydrology, and 
weather characteristics along with pesticide application and 
agricultural management practices, and pesticide environmental fate and 
transport properties. Consistent with the recommendations of the FIFRA 
Science Advisory Panel (SAP), EPA also considers percent cropped area 
factors (PCA) which takes into account the potential extent of cropped 
areas that could be treated with pesticides in a particular area. The 
PRZM and EXAMS models used by EPA were developed by EPA's Office of 
Research and Development (ORD), and are used by many international 
pesticide regulatory agencies to estimate pesticide exposure in surface 
water. EPA's use of the percent cropped area factors and the Index 
Reservoir scenario was reviewed by the FIFRA SAP in 1999 and 1998, 
respectively (Refs. 4 and 5).
    In modeling potential surface water concentrations, EPA attempts to 
model areas of the country that are highly vulnerable to surface water 
contamination rather than simply model ``typical'' locations occurring 
across the nation. Consequently, EPA models exposures occurring in 
small highly agricultural watersheds in different growing areas 
throughout the country. The scenarios are designed to capture residue 
levels in drinking water from reservoirs with small watersheds with a 
large percentage of land use in agricultural production. EPA believes 
these assessments are likely reflective of a small subset of the 
watersheds across the country that maintain drinking water reservoirs, 
representing a drinking water source generally considered to be more 
vulnerable to frequent high concentrations of pesticides than most 
locations that could be used for crop production.
    When EPA completed the carbaryl Interim Reregistration Eligibility 
Decision (IRED)\1\ in June 2003, EPA compared the estimated drinking 
water concentrations (EDWCs) of pesticides, from the PRZM/EXAMS model, 
with a drinking water level of concern (DWLOC), a value representing 
the concentration of a pesticide in drinking water that would represent 
the upper limit in light of total aggregate exposure to that pesticide 
from food, water, and residential uses of that pesticide. The DWLOC 
approach was developed in the mid 1990s as part of EPA's review of 
pesticides under FQPA, before the current risk assessment methodologies 
became available. EPA now uses the output of daily concentration values 
from tier two modeling as an input to DEEM-FCIDTM, which 
combines water concentrations with drinking water consumption 
information in the daily diet to generate a distribution of exposures 
from consumption of drinking water containing pesticide residues. These 
results are then used to calculate a probabilistic assessment of the 
aggregate human exposure and risk from residues in food and drinking 
water.
---------------------------------------------------------------------------

    \1\ Because carbaryl is a member of the NMC group of pesticides, 
which share a common mechanism of toxicity, EPA was unable to 
complete the carbaryl Reregistration Eligibility Decision (RED) 
before completion of the NMC cumulative risk assessment in September 
2007.
---------------------------------------------------------------------------

    EPA also considers available surface water monitoring data, 
including data from the US Geological Survey (USGS) National Water 
Quality Assessment Program (NAWQA), in conducting drinking water 
assessments. For the 2007 carbaryl RED, EPA considered data from a 
variety of sources, including NAWQA, the joint USGS-EPA Mini Pilot 
Monitoring Program, Washington and California state monitoring data, 
and registrant voluntary water monitoring study measuring carbaryl in 
targeted community water systems associated with watersheds having high 
carbaryl use.
    c. Residential exposures. Generally, in assessing residential 
exposure to pesticides EPA relies on its Standard Operating Procedures 
(SOPs) for Residential Exposure Assessment and subsequent amendments 
(Refs. 6, 7, and 8). The Residential SOPs establish the approaches used 
for estimating application and post-application exposures in a 
residential setting. SOPs have been developed for many common exposure 
scenarios including pesticide treatment of lawns, garden plants, trees, 
swimming pools, pets, and indoor surfaces including crack and crevice 
treatments. The SOPs are based on existing monitoring and survey data 
including information on activity patterns, particularly for children. 
Where available, EPA relies on pesticide-specific data in estimating 
residential exposures. Although limited carbaryl specific data were 
available at the time the carbaryl IRED was completed, additional data 
were submitted in response to the 2005 Data Call-In (DCI) for carbaryl. 
These data were reviewed and incorporated into the revised residential 
risk assessment used to support the final carbaryl RED. Residential 
exposure from carbaryl was estimated using EPA's Residential SOPs (as 
amended) as well as a turf dissipation study for carbaryl which 
quantified turf transferable residues after carbaryl application to 
turf and other monitoring data available to the Agency (e.g., residue 
decline studies on garden crops).
    3. Risk characterization. The final step in the risk assessment is 
risk characterization. In this step, EPA combines information from the 
first three steps (hazard identification, level of concern/dose-
response analysis, and human exposure assessment) to

[[Page 64234]]

quantitatively estimate the risks posed by a pesticide. Separate 
characterizations of risk are conducted for different durations of 
exposure. Additionally, separate and, where appropriate, aggregate 
characterizations of risk are conducted for the different routes of 
exposure (dietary and non-dietary).
    For threshold risks, EPA estimates risk in one of two ways. Where 
EPA has calculated an RfD/PAD, risk is estimated by expressing human 
exposure as a percentage of the RfD/PAD. Exposures lower than 100 
percent of the RfD/PAD are generally not of concern. Alternatively, EPA 
may express risk by dividing the estimated human exposure into the PoD 
to derive a margin of exposure (MOE). The MOE is compared with a level 
of concern, which is the product of all applicable uncertainty/safety 
factors. In contrast to the RfD/PAD approach, the higher the MOE, the 
lower the risk concern for the pesticide. Accordingly, if the level of 
concern is 100, MOEs equal to or exceeding 100 would generally not be 
of concern.
    As a conceptual matter, the RfD/PAD and MOE approaches are 
fundamentally equivalent. For a given risk and given exposure of a 
pesticide, if exposure to a pesticide were found to be acceptable under 
an RfD/PAD analysis it would also pass under the MOE approach, and 
vice-versa. However, for any specific pesticide, risk assessments for 
different exposure durations or routes may yield different results. 
This is a function not of the choice of the RfD/PAD or MOE approach but 
of the fact that the levels of concern and the levels of exposure may 
differ depending on the duration and route of exposure.
    For non-threshold risks (generally, cancer risks), EPA uses the 
slope of the dose-response curve for a pesticide in conjunction with an 
estimation of human exposure to that pesticide to estimate the 
probability of occurrence of additional adverse effects. For non-
threshold cancer risks, EPA generally considers cancer risk to be 
negligible if the probability of increased cancer cases falls within 
the range of 1 in 1 million. Risks exceeding values within that range 
would raise a risk concern.

C. Science Policy Considerations

    1. EPA policy on the children's safety factor. As the above brief 
summary of EPA's risk assessment practice indicates, the use of safety 
factors plays a critical role in the process. This is true for 
traditional 10X safety factors to account for potential differences 
between animals and humans when relying on studies in animals (inter-
species safety factor) and potential differences among humans (intra-
species safety factor) as well as the FQPA's additional 10X children's 
safety factor.
    In general, Section 408 of FFDCA provides that EPA shall apply an 
additional tenfold margin of safety for infants and children in the 
case of threshold effects to account for prenatal and postnatal 
toxicity and the completeness of the data base on toxicity and exposure 
unless EPA determines that a different margin of safety will be safe 
for infants and children. Margins of safety are incorporated into EPA 
assessments either directly through use of a margin of exposure 
analysis or through using uncertainty (safety) factors in calculating a 
dose level that poses acceptable risk to humans.
    In applying the children's safety factor provision, EPA has 
interpreted the statutory language as imposing a presumption in favor 
of applying an additional 10X safety factor (Ref. 9). Thus, EPA 
generally refers to the additional 10X factor as a presumptive or 
default 10X factor. EPA has also made clear, however, that the 
presumption can be overcome if reliable data demonstrate that a 
different factor is safe for children (Id.). In determining whether a 
different factor is safe for children, EPA focuses on the three factors 
listed in section 408(b)(2)(C) - the completeness of the toxicity 
database, the completeness of the exposure database, and potential pre- 
and post-natal toxicity. In examining these factors, EPA strives to 
make sure that its choice of a safety factor, based on a weight-of-the-
evidence evaluation, does not understate the risk to children. (Id.).
    When EPA evaluated the carbaryl toxicological database in 2003 to 
determine the appropriate FQPA Safety Factor for use in the IRED, 
available studies included rat and rabbit teratology (developmental 
toxicity) studies, a rat developmental neurotoxicity study, a rat 
reproductive toxicity study, a 4-week dermal rat study, acute and 
subchronic neurotoxicity screening studies, and a chronic oral dog 
study (Ref. 10). Based on the weight of the evidence as evaluated in 
2003, the FQPA Safety Factor was determined to be 3X due to the lack of 
a NOAEL in the chronic dog study. This was what the weight of the 
evidence showed in 2003.
    The science has advanced since 2003; additional information on 
pharmacokinetics as well as additional acute cholinesterase data have 
become available for carbaryl and other NMCs. Due to the rapid recovery 
of cholinesterase activity, chronic exposure is no longer considered to 
be a concern for carbaryl. As the science has advanced, science policy 
has also evolved. As EPA acquired developmental neurotoxicity and 
comparative cholinesterase data on the NMCs, it became apparent that 
comparative cholinesterase studies measuring red blood cell (RBC) and 
brain cholinesterase inhibition in both maternal and young animals 
(postnatal day 11 (PND11) and postnatal day 17 (PND17)) were a more 
accurate predictor of age-related sensitivity than developmental 
neurotoxicity studies measuring behavioral and histopathological 
changes. Therefore, EPA informed registrants that, in the absence of 
comparative cholinesterase data for each pesticide, a 10X FQPA Safety 
Factor would be applied to that pesticide in the NMC cumulative risk 
assessment. If comparative cholinesterase data were available, EPA used 
a data derived approach for the FQPA Safety Factor by comparing the 
benchmark dose (BMD) at the 10% inhibition level for either brain or 
RBC acetyl cholinesterase inhibition between maternal animals and the 
juvenile animals (typically PND11).
    2. EPA Policy on cholinesterase inhibition as a regulatory 
endpoint. Cholinesterase inhibition is a disruption of the normal 
process in the body by which the nervous system chemically communicates 
with muscles and glands. Communication between nerve cells and a target 
cell (i.e., another nerve cell, a muscle fiber, or a gland) is 
facilitated by the chemical, acetylcholine. When a nerve cell is 
stimulated it releases acetylcholine into the synapse (or space) 
between the nerve cell and the target cell. The released acetylcholine 
binds to receptors in the target cell, stimulating the target cell in 
turn. As EPA has explained, ``the end result of the stimulation of 
cholinergic pathway(s) includes, for example, the contraction of smooth 
(e.g., in the gastrointestinal tract) or skeletal muscle, changes in 
heart rate or glandular secretion (e.g., sweat glands) or communication 
between nerve cells in the brain or in the autonomic ganglia of the 
peripheral nervous system.'' (Ref. 11 at 10).
    Acetylcholinesterase (AChE) is an enzyme that breaks down 
acetylcholine and terminates its stimulating action in the synapse 
between nerve cells and target cells. When AChE is inhibited, 
acetylcholine builds up prolonging the stimulation of the target cell. 
This excessive stimulation potentially results in a broad range of 
adverse effects on many bodily functions. Depending on

[[Page 64235]]

the degree of inhibition these effects can be serious, even fatal.
    EPA's cholinesterase inhibition policy statement explains EPA's 
approach to evaluating the risks posed by cholinesterase-inhibiting 
pesticides such as carbaryl. (Id). The policy focuses on three types of 
effects associated with cholinesterase-inhibiting pesticides that may 
be assessed in animal and human toxicological studies: (1) 
physiological and behavioral/functional effects; (2) cholinesterase 
inhibition in the central and peripheral nervous system; and (3) 
cholinesterase inhibition in red blood cells and blood plasma. The 
policy discusses how such data should be integrated in deriving an 
acceptable dose (RfD/PAD) for a cholinesterase-inhibiting pesticide.
    Clinical signs or symptoms of cholinesterase inhibition in humans, 
the policy concludes, provide the most direct evidence of the adverse 
consequences of exposure to cholinesterase-inhibiting pesticides. 
Nonetheless, as the policy notes, due to strict ethical limitations, 
studies in humans are ``quite limited.'' (Id. at 19). Although animal 
studies can also provide direct evidence of cholinesterase inhibition 
effects, animal studies cannot easily measure cognitive effects of 
cholinesterase inhibition such as effects on perception, learning, and 
memory. For these reasons, the policy recommends that ``functional data 
obtained from human and animal studies should not be relied on solely, 
to the exclusion of other kinds of pertinent information, when weighing 
the evidence for selection of the critical effect(s) that will be used 
as the basis of the RfD or RfC.'' (Id. at 20).
    After clinical signs or symptoms, cholinesterase inhibition in the 
nervous system provides the next most important endpoint for evaluating 
cholinesterase-inhibiting pesticides. Although cholinesterase 
inhibition in the nervous system is not itself regarded as a direct 
adverse effect, it is ``generally accepted as a key component of the 
mechanism of toxicity leading to adverse cholinergic effects.'' (Id. at 
25). As such, the policy states that it should be treated as ``direct 
evidence of potential adverse effects'' and ``data showing this 
response provide valuable information in assessing potential hazards 
posed by anticholinesterase pesticides.'' (Id.). AChE inhibition in 
brain and the peripheral nervous system is the initial adverse 
biological event which results from exposure to NMC pesticides, such as 
carbaryl, and with sufficient levels of inhibition leads to other 
effects. Thus, AChE inhibition provides the most appropriate effect to 
use in risk extrapolation for derivation of RfDs and PADs. Protecting 
against AChE inhibition ensures that the other adverse effects 
mentioned above do not occur.
    In summary, EPA uses a weight of evidence approach to determine the 
toxic effect that will serve as the appropriate PoD for a risk 
assessment for AChE inhibiting pesticides, such as carbaryl (Id). The 
neurotoxicity that is associated with these pesticides can occur in 
both the central (brain) and the peripheral nervous system. In its 
weight of the evidence analysis, EPA reviews data, such as AChE 
inhibition data from the brain, peripheral tissues and blood (e.g., RBC 
or plasma), in addition to data on clinical signs and other functional 
effects related to AChE inhibition. Based on these data, EPA selects 
the most appropriate effect on which to regulate; such effects can 
include clinical signs of AChE inhibition, central or peripheral 
nervous tissue measurements of AChE inhibition or RBC AChE measures 
(Id). Although RBC AChE inhibition is not adverse in itself, it is a 
surrogate for inhibition in peripheral tissues when peripheral data are 
not available. As such, RBC AChE inhibition provides an indirect 
indication of adverse effects on the nervous system (Id.). Due to 
technical difficulties regarding dissection of peripheral nerves and 
the rapid nature of carbaryl toxicity, measures of AChE inhibition in 
the peripheral nervous system are very rare for NMC pesticides. For 
these reasons, other state and national agencies such as California, 
Washington, Canada, the European Union, as well as the World Health 
Organization (WHO), all use blood measures in human health risk 
assessment and/or worker safety monitoring programs.
    3. Benchmark dose. EPA has relied on a benchmark dose approach for 
deriving the PoD from the available rat toxicity studies (Ref. 12). A 
benchmark dose, or BMD, is a point estimate along a dose-response curve 
that corresponds to a specific response level. For example, a 
BMD10 represents a 10% change from the background or typical 
value for the response of concern. Generically, the direction of change 
from background can be an increase or a decrease depending on the 
biological parameter and the chemical of interest. In the case of 
carbaryl, inhibition of AChE is the toxic effect of concern. Following 
exposure to carbaryl, the normal biological activity of the AChE enzyme 
is decreased (i.e., the enzyme is inhibited). Thus, when evaluating 
BMDs for carbaryl, the Agency is interested in a decrease in AChE 
activity compared to normal activity levels, which are also termed 
``background'' levels. Measurements of ``background'' AChE activity 
levels are usually obtained from animals in experimental studies that 
are not treated with the pesticide of interest (i.e., ``negative 
control'' animals).
    In addition to the BMD, a ``confidence limit'' was also calculated. 
Confidence limits express the uncertainty in a BMD that may be due to 
sampling and/or experimental error. The lower confidence limit on the 
dose used as the BMD is termed the BMDL, which the Agency uses as the 
PoD. Use of the BMDL for deriving the PoD rewards better experimental 
design and procedures that provide more precise estimates of the BMD, 
resulting in tighter confidence intervals. Use of the BMDL also helps 
ensure with high confidence (e.g., 95% confidence) that the selected 
percentage of AChE inhibition is not exceeded. From the PoD, EPA 
calculates the RfD and aPAD.
    Numerous scientific peer review panels over the last decade have 
supported the Agency's application of the BMD approach as a 
scientifically supportable method for deriving PoDs in human health 
risk assessment, and as an improvement over the historically applied 
approach of using NOAELs or LOAELs. The NOAEL/LOAEL approach does not 
account for the variability and uncertainty in the experimental 
results, which are due to characteristics of the study design, such as 
dose selection, dose spacing, and sample size. With the BMD approach, 
all the dose response data are used to derive a PoD. Moreover, the 
response level used for setting regulatory limits can vary based on the 
chemical and/or type of toxic effect (Refs. 12, 13, 14, and 15). 
Specific to carbaryl and other NMCs, the FIFRA SAP has reviewed and 
supported the statistical methods used by the Agency to derive BMDs and 
BMDLs on two occasions, February 2005 and August 2005 (Refs. 14 and 
15).

IV. Carbaryl Tolerances

A. Regulatory Background

    Carbaryl is a carbamate insecticide and molluscide that was first 
registered in 1959 for use on cotton. Carbaryl has many trade names, 
but is most commonly known as Sevin[reg]. In 1980, the Agency published 
a position document summarizing its conclusions from a Special Review 
of carbaryl, and concluded that risk concerns, particularly those 
related to teratogenicity, did not warrant cancellation of the 
registration for carbaryl. A Registration Standard, issued for carbaryl 
in 1984 and revised

[[Page 64236]]

in 1988, described the terms and conditions for continued registration 
of carbaryl. At the time carbaryl was assessed for purposes of 
reregistration, carbaryl was registered for use on over 400 
agricultural and non-agricultural use sites, and there were more than 
140 tolerances for carbaryl in the Code of Federal Regulations (40 CFR 
180.169). For example, carbaryl was registered for domestic outdoor 
uses on lawns and gardens, and indoors in kennels and on pet sleeping 
quarters. It was also registered for direct application to cats and 
dogs (collar, powder, and dip) to control fleas and ticks.
    EPA completed an IRED for carbaryl on June 30, 2003 (2003 IRED). 
The Agency amended the IRED on October 22, 2004 (2004 Amended IRED), 
and published a formal Notice of Availability for the document, which 
provided for a 60-day public comment period (Ref. 16). EPA received 
numerous comments on the carbaryl IRED, including the NRDC petition 
requesting that EPA cancel all carbaryl registrations and revoke all 
tolerances. The Agency published a Notice of Receipt for the petition 
in the Federal Register, which provided a public comment period. 
Petition to Revoke or Modify Tolerances Established for Carbaryl; 
Notice of Availability, 70 FR 16281 (March 30, 2005). The mitigation 
detailed in the 2004 Amended IRED for residential uses included: 
canceling liquid broadcast applications to home lawns pending EPA 
review of pharmacokinetic data to refine post-application risk 
estimates; home garden/ornamental dust products must be packaged in 
ready-to-use shaker can containers, with no more than 0.05 lbs. active 
ingredient per container; cancellation of the following uses and 
application methods: all pet uses (dusts and liquids) except collars, 
aerosol products for various uses, belly grinder applications of 
granular and bait products for lawns, hand applications of granular and 
bait products for ornamentals and gardens.
    On March 9, 2005, EPA issued a cancellation order for the liquid 
broadcast use of carbaryl on residential turf to address post-
application risk to toddlers (Ref. 17). In March 2005, EPA also issued 
generic and product-specific DCIs for carbaryl. The carbaryl generic 
DCI required several studies of the active ingredient carbaryl, 
including additional toxicology, worker exposure monitoring, and 
environmental fate data. The product-specific DCI required acute 
toxicity and product chemistry data for all pesticide products 
containing carbaryl; these data are being used for product labeling. 
EPA has received numerous studies in response to these DCIs, and, where 
appropriate, these studies were considered in the tolerance 
reassessment.
    In response to the DCIs, many carbaryl registrants chose to 
voluntarily cancel their carbaryl products, rather than revise their 
labels or conduct studies to support these products. EPA published a 
notice of receipt of this request in the Federal Register on October 
28, 2005 (70 FR 62112), followed by a cancellation order issued on July 
3, 2006. One technical registrant, Burlington Scientific, chose to 
cancel their technical product, leaving Bayer CropScience (Bayer) as 
the sole technical registrant for carbaryl. Approximately two-thirds of 
all of the carbaryl products registered at the time of the 2003 IRED 
have been canceled through this process.
    In addition, Bayer, the sole remaining technical registrant 
responsible for developing data, requested waivers of required exposure 
monitoring or residue studies because these use scenarios are not on 
any Bayer technical or product labels or were to be deleted from Bayer 
labels: carbaryl use in or on pea and bean, succulent shelled (subgroup 
6B); millet; wheat; pre-plant root dip for sweet potato; pre-plant root 
dip/drench fpr nursery stocks, vegetable transplants, bedding plants, 
and foliage plants; use of granular formulations on leafy vegetables 
(except Brassica); ultra low volume (ULV) application for adult 
mosquito control; and dust applications in agriculture.
    Bayer subsequently requested that all of their carbaryl 
registrations bearing any of these uses be amended to delete these 
uses; EPA published a Notice of receipt of this request in the Federal 
Register on August 20, 2008 (73 FR 49184), and plans to approve Bayer's 
request and issue a final order amending these registrations at the end 
of the comment period for the Notice. As a consequence, EPA has 
notified all affected registrants that these uses and application 
methods must be deleted from their carbaryl product labels. EPA has 
identified thirty four (34) product labels from 14 registrants (other 
than Bayer) bearing these end uses. All of these registrants have 
requested that their affected carbaryl product registrations be amended 
to delete these uses. EPA published a Notice of receipt of these 
requests in the Federal Register on August 20, 2008 and will publish a 
second Notice of Receipt of these requests on or about October 8, 2008.
    In June 2006, EPA determined that the uses associated with 120 of 
the existing carbaryl tolerances are not significant contributors to 
the overall NMC cumulative risk and as a result these tolerances will 
have no effect on the retention or revocation of other NMC tolerances. 
Therefore, EPA considered these 120 tolerances for carbaryl as 
reassessed on June 29, 2006, and posted this decision on the internet 
site. (See http://www.epa.gov/pesticides/cumulative/carbamates_commodity.pdf).
    Carbaryl is a member of the NMC class of pesticides which share a 
common mechanism of toxicity by affecting the nervous system via 
cholinesterase inhibition. Specifically, carbaryl is a reversible 
inhibitor of AChE. A cumulative risk assessment, which evaluates 
exposures based on a common mechanism of toxicity, was conducted to 
evaluate risk from food, drinking water, residential use, and other 
non-occupational exposures resulting from registered uses of NMC 
pesticides, including carbaryl.
    In late November 2006, EPA received data from a carbaryl 
comparative cholinesterase study, conducted to determine the 
comparative sensitivity of adults and offspring to cholinesterase 
inhibition by carbaryl. These data were used to revise the FQPA Safety 
Factor for carbaryl for the NMC cumulative risk assessment and to 
select new toxicology endpoints (PoDs) for the risk assessment. The 
Agency determined that it was appropriate to use the new FQPA Safety 
Factor and revised PoDs in both the NMC cumulative risk assessment and 
the carbaryl-specific human health risk assessment. Because this 
necessitated a revision of the carbaryl human health aggregate risk 
assessment, EPA also considered additional new data generated in 
response to the DCI, new methodologies, and other new information in 
performing its most recent assessment of carbaryl and in responding to 
this Petition. EPA has thus, in effect, revised the carbaryl single 
chemical assessment in response to the issues raised during the public 
comment process as well as based upon more recent data and analytical 
methods.
    On September 26, 2007, EPA issued the NMC cumulative risk 
assessment. EPA concluded that the cumulative risks associated with the 
NMC pesticides meet the safety standard set forth in section 408(b)(2) 
of the FFDCA, provided that the mitigation specified in the NMC 
cumulative risk assessment is implemented, such as cancellation of all 
uses of carbofuran, termination of methomyl use on grapes, etc. EPA has 
therefore terminated the tolerance reassessment process under 408(q) of

[[Page 64237]]

the FFDCA. (See Ref. 18 for additional information).
    In conjunction with the NMC cumulative risk assessment, EPA 
completed a RED for carbaryl on September 24, 2007 and issued this RED 
on October 17, 2007 with a formal Notice of Availability in the Federal 
Register (72 FR 58844). In addition to relying on the NMC cumulative 
risk assessment to determine that the cumulative effects from exposure 
to all NMC residues, including carbaryl, was safe, the carbaryl RED 
relied upon the revised assessments and the mitigation that had already 
been implemented (e.g., cancellation of pet uses except for collars). 
In addition, the RED included additional mitigation with respect to 
granular turf products for residential use; namely, that product labels 
direct users to water the product in immediately after application. 
Subsequently, on August 25, 2008, EPA completed an addendum to the 
Carbaryl RED incorporating the results of a revised occupational risk 
assessment and modified mitigation measures for the protection of 
workers. Elsewhere in this issue of the Federal Register EPA is 
announcing the availability of the amendments to the Carbaryl RED.

B. FFDCA Tolerance Reassessment and FIFRA Pesticide Reregistration

    As required by the Food Quality Protection Act of 1996, EPA 
reassessed the safety of the carbaryl tolerances under the safety 
standard established in the FQPA. In the September 2007 RED for 
carbaryl, EPA evaluated the human health risks associated with all 
currently registered uses of carbaryl and determined that there is a 
reasonable certainty that no harm will result from aggregate non-
occupational exposure to the pesticide chemical residue. In making this 
determination, EPA considered dietary exposure from food and drinking 
water and all other non-occupational sources of pesticide exposure for 
which there is reliable information (Ref. 18). The Agency has concluded 
that with the adoption of the risk mitigation measures identified in 
the NMC cumulative risk assessment, all of the tolerances for carbaryl 
meet the safety standard as set forth in section 408(b)(2)(D) of the 
FFDCA. Therefore, the tolerances established for residues of carbaryl 
in/on raw agricultural commodities were considered reassessed as safe 
under section 408(q) of FFDCA, as amended by FQPA, in September 2007. 
These findings satisfied EPA's obligation to review the carbaryl 
tolerances under the FQPA safety standard.
    To implement the carbaryl tolerance reassessment, EPA commenced 
with rulemaking in 2008. The Agency published a Notice of proposed 
tolerance actions in the May 21, 2008 Federal Register (73 FR 29456). 
This proposed rule provided for a 60 day public comment period. No 
comments relevant to carbaryl tolerances were received and EPA 
published a Notice of final tolerance actions in the September 10, 2008 
Federal Register (73 FR 52607). This rule codifies the carbaryl 
tolerances in 40 CFR 180.169.

V. The Petition to Revoke Tolerances

    NRDC filed a petition dated January 10, 2005 (Petition), 
requesting, among other things, that EPA cancel all carbaryl 
registrations and revoke all carbaryl tolerances (Ref. 1). In response 
to EPA's publication of the Petition pursuant to section 408(d) of the 
FFDCA, NRDC resubmitted its Petition and earlier comments in support of 
its Petition. (See Docket ID EPA-HQ-OPP-2005-0077-0066).
    It should be noted that NRDC's January 10, 2005 submission is in 
the form of comments on and requests for changes to the Carbaryl 
Interim Reregistration Eligibility Decision published in the Federal 
Register on October 27, 2004, 70 FR 62663; (Ref. 16). Nonetheless, in 
the introduction to the comments, NRDC included a statement that NRDC 
is also petitioning the Agency to revoke all carbaryl tolerances. Among 
other things, NRDC raises issues with the dietary assessment and in 
particular its drinking water assessment that supported the 2004 IRED 
decision. NRDC also raises concerns about the data surrounding EPA's 
selection of a children's safety factor. NRDC's petition also includes 
some generic disagreements with how EPA conducts its assessments.

VI. Public Comment

    In response to that portion of NRDC's petition seeking revocation 
of the carbaryl tolerances, EPA published notice of the Petition for 
comment on March 30, 2005 (70 FR 16281). EPA received approximately 
5,230 comments in support of the Petition. The vast majority of these 
comments followed an identical or similar format expressing the 
commenters support for the Petition in general terms. These commenters 
uniformly protested the Agency's decision to continue allowing the use 
of carbaryl ``a chemical [EPA] consider[s] likely to cause cancer.'' As 
a preliminary note, although the Agency considers carbaryl to have the 
potential to cause cancer, exposure to carbaryl residues is so low that 
the actual risk of cancer from carbaryl is negligible. EPA is generally 
not concerned about cancer risks at or below the range of 1 x 
10-6, or 1 in a million. For carbaryl, the dietary cancer 
risk from residues in food and drinking water is estimated to be 3 x 
10-8, or 3 in 10 million. The estimated cancer risk from 
exposure to carbaryl in products used in a residential setting range 
from 1 x 10-8 to 10-13 (from 1 in 10 million to 1 
in 10 trillion). Because EPA considers carbaryl to be a non-threshold 
carcinogen, the Agency uses the conservative, default linear low-dose 
linear method to quantify cancer risk. Even using this conservative 
approach to evaluate potential cancer risk from food, drinking water, 
and residential uses of carbaryl, EPA has not identified any cancer 
risks of concern.
    Of the subset of comments not based upon a form letter, most 
related to ecological issues and in particular toxicity to bees and 
apple thinning uses. These comments are not relevant to the requested 
revocation of pesticide tolerances. EPA is responding to the Petition 
insofar as it seeks the cancellation of all carbaryl registrations 
separately and, therefore, these comments are not directly relevant 
here. One commenter, Bayer, the sole technical product registrant, 
submitted comments that purport to address all of the issues raised by 
NRDC (Ref. 19). In any event, these comments as a whole did not add any 
new information pertaining to whether the tolerances were in compliance 
with the FFDCA. Comments on the specific claims by NRDC are summarized 
in Unit VII immediately following the summary of NRDC's claim but prior 
to EPA's response to the claim.

VII. Ruling on Petition

    This Order addresses NRDC's petition to revoke carbaryl tolerances. 
As noted above, this ``Petition'' was included as part of NRDC's 
comments on the carbaryl IRED. Thus, the Petition contains a number of 
comments that are just that, comments, and that do not provide a basis 
upon which to either cancel all carbaryl registrations or revoke all 
carbaryl tolerances. Where those comments are directly related to 
suggestions that the carbaryl tolerances do not meet the safety 
standard in section 408 of the FFDCA, the Agency has tried to address 
those comments in this petition response. However, EPA has not 
attempted to respond to every comment or suggestion for improvement 
made in NRDC's filing.
    EPA has, to the extent possible, construed NRDC's comments as 
asserting various grounds as to why the carbaryl tolerances do not meet 
the

[[Page 64238]]

FQPA safety standard and should be revoked. EPA has divided NRDC's 
grounds for revocation into four categories - toxicology; dietary 
exposure; residential exposure; and risk characterization - and 
addressed separately each claim under these categories. Each specific 
claim of NRDC is summarized in Unit VII immediately prior to EPA's 
response to the claim.
    This Order also constitutes a response to a petition dated November 
26, 2007, to cancel carbaryl pet collar registrations submitted as part 
of NRDC's comments on the NMC cumulative assessment (NMC Petition) 
(Ref. 2). EPA's response to NRDC's petition to cancel pet collar 
registrations is addressed here because the basis for the petition to 
cancel pet collars rests on issues related to EPA's assessment of 
cumulative effects under the FFDCA.
    EPA has not addressed claims that concern carbaryl uses that have 
been canceled, or application methods that have been discontinued since 
the time of the Petition. Nor is EPA addressing claims that concern 
carbaryl uses for which the registrant(s) has requested that the use be 
deleted or registration cancelled pursuant to section 6(f) of FIFRA. 
These include the liquid broadcast use of carbaryl on residential lawns 
and turf, cancelled in March 2005 (Ref. 17), and several other uses and 
application methods which have been or are in the process of 
cancellation because the registrants are not supporting these uses and 
application methods with the necessary data (73 FR 49184, August 20, 
2008). The following carbaryl uses are in the process of being 
cancelled: wheat, millet, and fresh/succulent beans and peas (crop 
subgroup 6B); use of carbaryl drench or dip treatments of seedlings or 
seed pieces, dust formulations in agricultural crops, granular 
applications to leafy vegetables (except Brassica), direct applications 
of carbaryl (except for flea collars) to domestic animals (including 
dogs, cats, and other pets), and all indoor applications. Carbaryl 
registrations are also being amended to discontinue the following 
application methods: drenching dipping, hand held fogger, mosquito 
adulticide ULV, power backpack sprayer, and tree injection.

A. Dietary Exposure Issues

    1. Revised dietary exposure and risk assessment. NRDC's petition 
challenges some aspects of EPA's 2003 proposed dietary exposure and 
risk assessment of carbaryl (Ref. 1 at 16-20). EPA has since updated 
its dietary exposure and risk assessment. These revisions were 
incorporated in and provided the basis for the RED. The main changes in 
the revised assessment include: (1) Use of the half-life value for 
carbaryl from a study that measures how quickly carbaryl degrades in an 
aerobic aquatic environment; (2) inclusion of updated percent crop 
treated data for evaluation of dietary exposure from residues in food; 
(3) inclusion of a comprehensive review of recent surface water 
monitoring data, including an investigation into the high carbaryl 
detection in groundwater reported in the 2003 IRED; (4) incorporation 
of the most recent food residue data from USDA's PDP; and (5) inclusion 
of drinking water exposure modeling and monitoring data for 
agricultural and nonagricultural uses of carbaryl. In addition, in a 
change from the 2003 assessment, the revised risk assessment did not 
evaluate dietary risk for long term (> 6 months) and chronic exposure 
to carbaryl due to the rapid reversibility of cholinesterase 
inhibition, the toxicological endpoint of concern. Specifically, recent 
data for carbaryl and the other NMCs show that cholinesterase 
inhibition is reversible, with recovery in less than 24 hours. Because 
the acute exposure from carbaryl is the main duration of concern, EPA 
determined that a chronic assessment is not appropriate for carbaryl.
    These revisions effectively address NRDC's concerns and EPA is not 
reopening the issues here. Nonetheless, EPA is providing more specific 
information concerning the revised risk assessment in the context of 
the specific issues raised by NRDC.
    2. Drinking water assessment--a. NRDC's claims. NRDC criticizes the 
Agency's drinking water assessment because it only considered 
agricultural sources. NRDC urged EPA to include all available 
information in its surface water assessment, including non-agricultural 
sources (Ref. 1 at 16). NRDC further notes that the drinking water 
levels of comparison (DWLOCs) ``exceeds acceptable levels.'' (Ref. 1 at 
16). NRDC disagrees with EPA's conclusion that the DWLOC was 
nonetheless acceptable because the modeling is overly conservative and 
that actual concentrations of carbaryl in drinking water are likely to 
be ``much lower.'' NRDC faults the Agency for not defining the 
magnitude of ``much lower'' and not providing any support for this 
contention. In particular, NRDC argues that the modeling estimates are 
actually in agreement with some of the monitoring data, and therefore 
EPA should accept the modeling estimates as an accurate indicator of 
exposure. Specifically, NRDC argues that peak modeling estimates from 
Florida citrus use (646 ppb) match monitoring data from a well in New 
York (610 ppb), and therefore EPA should accept the modeling estimates 
as an accurate indicator of exposure. NRDC further argues that the 
Agency's rationale for concluding that the models overestimate actual 
concentrations in surface water is faulty.
    b. Public comments. In its comments, Bayer took issue with NRDC's 
characterization that the monitoring data are in agreement with the 
model calculations, based upon a detection of 610 ppb in a well in New 
York and a maximum concentration value of 6.5 ppb in the USGS NAWQA 
data. Bayer argues that comparing an isolated ground water finding with 
predicted concentrations in surface water is scientifically 
inappropriate because of the different transport processes in ground 
water as compared to surface water. Bayer characterizes the ground 
water detection in NY as anomalous and notes that it has not been 
investigated or confirmed, and argues that it is not likely to be the 
result of normal movement though the soil.
    Further, Bayer submitted a voluntary drinking water monitoring 
study for carbaryl, Surface Water Monitoring for Residue of Carbaryl in 
High Use Areas in the United States: Final Report (MRID 45788101). 
Bayer defends its drinking water study, stating that it was targeted to 
community water systems having watersheds with high carbaryl use and 
that showed lower concentrations than the NAWQA data. Bayer further 
argues that NRDC's assertion that monitoring can be spotty and is not 
designed to coincide with high use sites, seasonal application times, 
watershed characteristics, and urban and agricultural methods is 
misplaced. Bayer asserts that the monitoring program was targeted and 
did focus on high use sites, with a sampling program tailored to the 
application times, and covered both agricultural and non-agricultural 
uses.
    Bayer also argues that the modeling is a worst case scenario and 
gives several reasons why EPA's model can overestimate movement of 
surface water, including assumptions regarding use intensity (100% of 
field treated at maximum rates for the maximum number of times). Bayer 
then asserts that the worst-case predictions are not confirmed by 
monitoring data ``specifically designed to capture high use areas and 
application times.'' (Ref. 19 at 5).
    Another commenter from the Department of Entomology, Virginia Tech, 
notes that while NRDC complains that EPA makes assumptions in its risk

[[Page 64239]]

models, NRDC makes questionable assumptions of its own; namely, that 
EPA's model is more reliable than actual monitoring data. Similarly, 
NRDC emphasizes that most acreage is treated, implying that most acres 
received the full allowable rate. However, although carbaryl is allowed 
to be applied to apples during the growing season, apple growers use 
carbaryl mainly as a chemical thinner, which occurs early in the season 
and is much less likely to cause harvest residues. Other commenters 
(apple growers) submitted similar comments regarding the actual use and 
that the use of carbaryl for thinning is not likely to result in 
residues at harvest time as well as the importance of carbaryl for 
chemical thinning.
    Another commenter from the University of Florida asserts that the 
acute drinking water concern is driven by Florida modeling, based upon 
a 38% crop treated assumption. According to the commenter, actual use 
in Florida is ``probably closer'' to one tenth of that amount. Again, 
according to the commenter, the National Agricultural Statistics 
Service (NASS) 2003 fruit data report percent crop treated amounts of 
3% for Florida and 5% for grapefruit nationally. The commenter takes 
issue with NRDC's claim that the greater than 600 ppb spike in New York 
``conforms'' to the results from the modeling. In so doing, the 
commenter asserts that carbaryl in New York degrades much slower than 
in Florida. The commenter then implies that it is significant that 
there are no Florida monitoring values that were in the hundred parts 
per billion concentration range.
    c. EPA's response. EPA has addressed NRDC's concerns in the revised 
drinking water assessments supporting the carbaryl RED, which includes 
all available information including surface water monitoring data, new 
environmental fate data, and other new information and methodologies. 
EPA incorporated new half-life data from an aerobic aquatic metabolism 
study, regional percent cropped area factors, and the mitigation 
required in the carbaryl IRED into modeled estimates of carbaryl levels 
in surface water. In addition, the Agency used the PRZM-EXAMS model to 
generate a distribution of approximately 11,000 values, representing 
daily peak values over 30 years. This data set was used to create water 
residue data files for use in DEEM-FCIDTM. The range of 
annual peak water values was 13 to 108 parts per billion (ppb) over 30 
years (Ref. 20 for further details of EPA's refined drinking water 
modeling). EPA incorporated this distribution of drinking water values 
directly into the exposure component of the dietary assessment, using 
the DEEM-FCIDTM model. EPA also incorporated drinking water 
consumption data and reported body weights from the CSFII into the 
exposure assessment.
    As mentioned above, the carbaryl drinking water assessment is no 
longer based upon the DWLOC approach. EPA officially withdrew the 
science policy paper describing the DWLOC approach on August 1, 2007 
(72 FR 42082). In addition, EPA believes that the new approach is more 
protective of sensitive population subgroups, including infants and 
children, than the DWLOC approach used in the carbaryl IRED.
    Although EPA did not model nonagricultural use of carbaryl, the 
Agency considered these uses in the process of evaluating all available 
water monitoring data for carbaryl for the 2007 carbaryl RED. EPA 
reviewed the most recent surface water monitoring data for carbaryl in 
urban and suburban areas for both the carbaryl IRED and the RED. 
Specifically, EPA considered data from NAWQA, the joint USGS-EPA Mini 
Pilot Monitoring Program, Washington and California state monitoring 
data, and a registrant voluntary water monitoring study measuring 
carbaryl in targeted community water systems associated with watersheds 
having high carbaryl use. The Agency also considered California 
monitoring data targeted to urban use of pesticides (Ref. 21).
    EPA has also obtained additional information on the groundwater 
monitoring value of 610 micrograms/liter ([mu]g/L) from Suffolk County 
New York reported in the carbaryl IRED. Because this value was 
significantly higher than any other monitoring values from ground or 
surface water, EPA contacted the Suffolk County government for more 
information about this particular groundwater sample. The sample 
associated with that concentration (the actual concentration was 61,000 
[mu]g/L, not 610 [mu]g/L) was taken from a sump at a pesticide mixer/
loader site as part of a pesticide spill investigation, not from a 
groundwater monitoring well. Therefore, this value should not have been 
reported in the Suffolk County water quality database (Suffolk County 
Department of Health 2007, personal communication); EPA has removed it 
from the carbaryl drinking water assessment. There were a small number 
of detections of carbaryl reported to OPP as a result of a quality 
control check of the Suffolk County database, ranging from 0.1 to 13 
[mu]g/L. These values are more in line with other monitoring data for 
carbaryl reported in the EPA assessment.
    Finally, both the commenter from the University of Florida and NRDC 
are mistaken in their statements that that EPA's drinking water 
assessment relied on default percent crop treated assumptions. In 
particular, NRDC appears to have confused percent crop treated (PCT) 
data for the percentage of a food commodity treated with carbaryl with 
EPA's use of percent crop area (PCA) in the carbaryl drinking water 
assessment. The default PCA (87%) represents the largest fraction of a 
watershed that can be planted to any crop. This default PCA, which is 
based on Geographic Information Systems (GIS) analysis of fairly large 
watersheds\2\, is used in drinking water assessments to account for the 
fact that not all land in a watershed is agricultural land (planted 
with crops). Regional PCAs reflect the greatest fraction of a watershed 
used in agriculture in each of the major drainage basins in the United 
States. In either case, the drinking water assessment assumes that 
carbaryl is applied to 100% of the agricultural land in the watershed, 
regardless of the fraction of the watershed that is used in 
agriculture.
---------------------------------------------------------------------------

    \2\ Large watershed having an 8 digit hydrologic unit code (HUC-
8).
---------------------------------------------------------------------------

    In sum, the revised dietary risk assessment for food shows that 
acute dietary exposure and risk are below the Agency's level of concern 
for the general U.S. population and all population subgroups. The 
revised drinking water assessment also does not rely on the old 
methodology, using DWLOCs. The drinking water assessment was not 
limited to agriculture uses; EPA included the most recent available 
monitoring data for carbaryl in urban and suburban areas in the revised 
assessment. Last, estimated pesticide residues in drinking water were 
incorporated directly into the exposure component of the dietary 
assessment.
    3. CARES dietary exposure model--a. NRDC's claims. NRDC asserts 
that EPA improperly relied upon Cumulative and Aggregate Risk 
Evaluation System (CARES), a ``confidential'' industry model to assess 
human health risks. While NRDC acknowledges that EPA may rely on a 
proprietary model, it insists that EPA has not provided sufficient 
detail about the model's ``built-in assumptions and calculation 
methodologies.'' (Ref. 1 at 19).
    b. Public comments. Bayer asserts that during its development by 
industry, with input from EPA and USDA, CARES was ``freely'' available 
from CropLife

[[Page 64240]]

America by request. Bayer also notes that the model was reviewed at two 
FIFRA SAP meetings in 2002 and 2004 (US EPA, SAP April 30 to May 1, 
2002. CARES Model Review http://www.epa.gov/scipoly/sap; USEPA, SAP 
April 29 to 30, 2004. A Model Comparison: Dietary and Aggregate 
Exposure in Calendex, CARES and Lifeline. http://www.epa.gov/scipoly/sap). On completion of the model, it was donated to The International 
Life Sciences Institute (ILSI). CARES is now freely available from the 
ILSI web site (http://www.ilsi.org).
    c. EPA's Response. In the 2003 IRED, EPA used the DEEM- 
FCIDTM model to estimate dietary risks from carbaryl. The 
carbaryl registrant submitted an assessment derived from CARES, which 
EPA reviewed and compared with the Agency's results. However, the 
Agency did not rely upon the CARES model in the Carbaryl IRED. EPA 
relied upon the DEEM-FCIDTM model for both the 2003 human 
health risk assessment supporting the IRED and the revised 2007 dietary 
assessment supporting the carbaryl RED. Thus, any concerns regarding 
the public availability of the CARES model are irrelevant to EPA's risk 
assessment for the 2003 IRED.
    Nonetheless, it is worth noting that the CARES model has been 
transferred to the ILSI Research Foundation and the CARES program and 
source code is publicly available at no charge. In addition, in 2002, 
the FIFRA SAP reviewed the underlying science, computational approaches 
and ease of use of the CARES model. The FIFRA SAP's June 13, 2002 
report (Ref. 22) provides results of the panel's deliberations. The 
FIFRA SAP provided a series of recommendations designed to improve the 
technical basis of the model and software system. In any case, CARES 
meets OPP's criteria for use in regulatory decision making with respect 
to public availability, transparency, and compliance with Agency policy 
guidelines and NRDC's objection in this regard are without merit.
    4. Farmers' markets and roadside produce stands--a. NRDC's claims. 
NRDC asserts that EPA did not explicitly consider food purchased at 
farmer's markets, farm stands, ``U-PIK'' farms, or eaten from household 
gardens (Ref. 1 at 19-20). NRDC suggests that, in the absence of data 
to support EPA's belief that its exposure assessment adequately 
accounts for food purchased at such locals, EPA include an uncertainty 
factor to account for children who consume this source of food (Ref. 1 
at 20).
    b. Public comments. Bayer noted that EPA adequately responded to 
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk 
Assessment (Docket ID No. EPA-HQ-OPP-2003-0376-00008).
    c. EPA's response. In an Order responding to NRDC objections to 
tolerances for different pesticides, EPA has addressed NRDC's claims 
regarding pesticide exposure to persons who purchase food at roadside 
stands or farmers' markets. (70 FR 733; 72 FR 662, December 5, 2007). 
This is equally applicable to ``U-PIK'' farms and household gardens. As 
EPA explained there, whether EPA relies on data from crop field trials 
or monitoring data in estimating pesticide exposure, given the sampling 
methods in field trials and food monitoring residue levels identified 
from these sources are unlikely to understate residue levels at farm 
stands. Moreover, EPA does not believe it is reasonable to assume that 
farm stands sell food containing a significantly different residue 
profile than found in PDP monitoring data. Therefore, this factor 
introduces little to no uncertainty concerning the possibility of 
underestimation of residues into EPA's analysis. In any case, EPA 
hereby incorporates its prior response to these issues EPA relies on 
its prior response to this issue and finds NRDC's contentions without 
merit.
    5. Tolerances for cancelled uses--a. NRDC's claims. NRDC is 
concerned that EPA proposed to increase tolerances for 20 commodities 
and establish new tolerances for 7 commodities (Ref. 1 at 14-15). 
Specifically, NRDC urges EPA not to make any tolerance reassessment 
determination prior to completion of the carbamate cumulative risk 
assessment. NRDC also insists that EPA revoke tolerances for all uses 
of carbaryl that have been voluntarily cancelled. NRDC is particularly 
concerned about imported food and products entering the United States 
with carbaryl residues without triggering action by the FDA. NRDC is 
also concerned about the effect that the failure to ``ban'' products 
will have on the international community and in particular developing 
countries. Specifically, NRDC asserts that manufacturers voluntarily 
cancel the registration of high risk products to avoid Prior Informed 
Consent (PIC) listings.
    b. Public comments. Bayer asserts in its comments that in the 
carbaryl IRED EPA addressed NRDC's concern regarding the reassessment 
of tolerances prior to the completion of the NMC cumulative risk 
assessment. Bayer notes, however, that the IRED specifically provides 
that the establishment of new tolerances or raising tolerances will be 
deferred pending consideration of cumulative risk for the NMCs. The 
IRED further provides that, for purposes of that document, the term 
``reassessed'' does not imply that all of the tolerances for carbaryl 
have been reassessed as required by FQPA, since these tolerances may 
only be reassessed once the cumulative risk assessment of all carbamate 
pesticides is considered. Rather, the IRED provided reassessed 
tolerances for carbaryl in/on various commodities, supported by all of 
the submitted residue data, only for the single carbamate chemical 
carbaryl (Ref. 16 at 67).
    Bayer further expressed its belief that EPA's practice of revoking 
tolerances after a sufficient period of time that allows existing 
stocks bearing the use being cancelled to clear the channels of trade 
is in compliance with the requirements of the FQPA. Finally, Bayer 
argues that NRDC's concern about potential risk from new or increased 
tolerances being established for carbaryl are not justified because the 
tolerance reassessment process is not associated with labeling changes 
that increase the maximum application rates or frequency of application 
allowed by current labels. Bayer further notes that many of the 
labeling amendments required by the IRED serve to reduce potential 
human health and environmental risks. Bayer also notes that the 
pursuant to the IRED most tolerances will be either reduced, revoked, 
or left unchanged.
    c. EPA's response. Notwithstanding NRDC's insistence that EPA 
revoke tolerances for uses that have been voluntarily canceled, NRDC 
has not provided any basis for determining that tolerances for uses 
that have been voluntarily cancelled do not meet the FFDCA standard 
such that the tolerance must be revoked. Be that as it may, EPA has now 
completed and released the cumulative risk assessment for the NMCs and, 
therefore, all carbaryl tolerances are considered reassessed at this 
time. With respect to tolerances associated with uses that have been 
cancelled and/or deleted pursuant to section 6(f)(1) of FIFRA, EPA has 
revoked the associated tolerances, except for the wheat tolerance, 
which is still needed to cover imported wheat and any domestic wheat 
that may receive inadvertent residues of carbaryl resulting from 
carbaryl use to control grasshoppers and/or Mormon crickets on pasture 
and rangeland. The Agency included carbaryl residues on wheat in the 
cumulative risk assessment for the NMCs.
    The Agency has completed rulemaking proceedings to revoke and 
modify the existing carbaryl tolerances,

[[Page 64241]]

and correct commodity definitions. EPA published a proposed tolerance 
rule for carbaryl on May 21, 2008 (73 FR 29456) and a final tolerance 
rule on September 10, 2008 (73 FR 52607). The final carbaryl tolerance 
rule revokes tolerances associated with uses that have been cancelled 
and/or deleted to date pursuant to section 6(f)(1) of FIFRA, allowing 
sufficient time for existing stock to clear channels of trade, with the 
exception of the tolerance for wheat. As a result of the final 
tolerance rule, many existing carbaryl tolerances have been reassigned 
to crop groups, and old commodity specific tolerances have been revoked 
as new tolerances have been established for residues in/on various crop 
groups and subgroups. New tolerances were also established for carbaryl 
residues in/on the following raw agricultural commodities: aspirated 
grain fractions, proso millet hay, sorghum stover, and sugar beet 
roots. At the present time, sufficient data are available to determine 
an appropriate tolerance for residues in/on aspirated grain fractions 
(70 ppm), sugar beet roots (0.5 ppm), and sorghum stover (30.0 ppm). 
Separate tolerances have been established for residues in the following 
processed food/feed items: wet apple pomace (15.0 ppm), citrus fruit 
oil (20.0 ppm), raisins (12.0 ppm), and rice hulls (30.0 ppm).
    Finally, to the extent that NRDC argues that tolerances must be 
revoked simply because an active ingredient or use is not registered in 
the United States, EPA disagrees. Nothing in the FFDCA requires that 
tolerances be limited to pesticides that have a U.S. registration. In 
fact, FIFRA explicitly recognizes that EPA may set import tolerances 
under the FFDCA. See Section 33 of FIFRA (establishing fees and 
decision review times for import tolerance applications). While EPA 
often proposes to revoke tolerances after the cancellation of 
associated uses because EPA believes the tolerances may no longer be 
necessary, EPA has always recognized that a revocation can not proceed 
on such grounds if foreign growers wish to rely on the tolerance. In 
such circumstances, a tolerance can only be revoked if necessary data 
to support the tolerance are not provided or if EPA determines that the 
tolerance does not meet the safety standard.

B. Risk Characterization

    1. New data. In keeping with science policy developments for the 
NMCs, EPA used data from a comparative cholinesterase study comparing 
carbaryl-induced cholinesterase inhibition in adult and juvenile rats 
to calculate a revised FQPA Safety Factor for carbaryl and to derive 
the toxicology points of departure for risk assessment. Specifically, 
this study was conducted to determine whether young animals are more 
susceptible to the effects of carbaryl than adults. This oral study 
showed that juvenile 11-day-old (PND11) pups were more sensitive to 
inhibition of brain cholinesterase from carbaryl than adult rats.
    EPA conducted a benchmark dose analysis for the carbaryl 
comparative cholinesterase study, using the same modeling methodology 
used in the NMC cumulative risk assessment. A benchmark dose analysis 
models the dose-response relationship with a dose-response curve, which 
allows selection of doses corresponding to a specified level of 
response, called a benchmark response. This analysis allows EPA to 
determine a more appropriate point of departure from a toxicology study 
rather than using the study NOAEL or LOAEL. (See Refs. 12, 23, and 24 
for more information on benchmark dose modeling).
    The Agency estimated the 10% benchmark dose response 
(BMD10) and the BMDL10, or lower 95% confidence 
limit of the benchmark dose, for this study. The Agency also conducted 
a full benchmark dose analysis of all rat oral toxicity studies for 
adults; this analysis showed that the BMDL10 for pups is also 
protective for adults. Because the brain is the target tissue for 
carbaryl, and the brain BMDL10 of 1.1 milligrams/kilogram 
(mg/kg) is also protective of cholinesterase inhibition in blood, then 
the brain BMDL10 is the appropriate point of departure for 
both children and adults in the revised carbaryl risk assessment. (See 
Ref. 23 and Ref. 24 for additional details regarding the comparative 
cholinesterase study).
    2. Revised FQPA safety factor. To complete the carbaryl IRED in 
2003, EPA evaluated the potential for special sensitivity of infants 
and children to carbaryl and the need for an additional FQPA Safety 
Factor. After evaluating the entire toxicity database available for 
carbaryl at that time, the FQPA Safety Factor, to account for special 
susceptibility of infants and children, was reduced from 10X to 1X for 
all scenarios, except for the chronic dietary endpoint where a 3X FQPA 
SF was used to account for the lack of a NOAEL. This decision and 
rationale is described in detail in the technical support documents for 
the carbaryl IRED.
    As previously mentioned in Unit III.C.1. of this document, EPA has 
revised the FQPA Safety Factor for carbaryl using the most recent data 
on carbaryl age sensitivity. The new comparative cholinesterase study 
data was used to derive a new FQPA Safety Factor by comparing the 
BMD10 for brain cholinesterase inhibition between adults and 
pups at postnatal day 11. Pups were 1.8x more sensitive to brain 
cholinesterase inhibition than the adults; therefore, a 1.8X FQPA 
Safety Factor was applied to both the NMC cumulative and the carbaryl-
specific risk assessments. This safety factor of 1.8X is applied to the 
dermal endpoint because there are no comparative cholinesterase data in 
offspring from dermal exposure, and because juvenile rats are 1.8X more 
sensitive than adults based on the oral comparative cholinesterase 
study in rats. The FQPA Safety Factor is 1X for oral and inhalation 
endpoints because these endpoints are selected from the comparative 
cholinesterase data for the most sensitive population (PND11 pups).
    3. Issues raised by NRDC concerning the FQPA safety factor--a. 
NRDC's claims. NRDC objects to EPA's decision to reduce the FQPA Safety 
Factor to 1X in the IRED and repeats earlier arguments that a 
developmental neurotoxicity study (DNT) used by EPA in the 2004 IRED 
does not provide a basis for removing the FQPA Safety Factor because 
pups had effects at doses that did not produce effects in adults in the 
DNT study. (Ref. 1 at 17, 18) In addition, NRDC maintains that EPA 
should have applied an additional 3X uncertainty factor to account for 
the failure to identify a No Observable Adverse Effect Level (NOAEL) 
for brain morphometric changes in pups in the DNT study. Specifically, 
NRDC argues that the low and mid-dose samples were ``damaged and 
uninterpretable'' and thus this test did not produce a ``no observed 
adverse effect level.'' (Ref. 1 at 17-19).
    b. Public comments. Bayer noted that EPA adequately responded to 
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk 
Assessment (Docket ID No. 2003-0376-00008).
    c. EPA's response. Since the 2004 IRED, EPA has incorporated new 
data into its assessment of carbaryl. In the process of completing the 
carbaryl RED and the cumulative risk assessment for the NMCs, EPA re-
evaluated the toxicology database for carbaryl, which includes studies 
submitted since the completion of the IRED. EPA received 
pharmacokinetic data on the rapid reversibility of carbaryl effects 
(Ref. 25), a comparative cholinesterase study to inform age-related 
sensitivity to carbaryl (Ref. 23), and a dermal penetration study for 
carbaryl (Ref. 26). As a result, the Agency revised the FQPA Safety 
Factor in 2007 and selected new points

[[Page 64242]]

of departure using the new comparative cholinesterase data and 
benchmark dose modeling.
    The comparative cholinesterase study was conducted specifically to 
provide age-related sensitivity data for carbaryl to be used in the NMC 
cumulative risk assessment. Experience with other NMCs has shown that 
comparative cholinesterase studies provide a more accurate indication 
of comparative adult and offspring sensitivity than the behavioral and 
histopathological changes evaluated in the DNT study. The carbaryl 
comparative cholinesterase study involved oral dosing of three age 
groups of rats, adults (97 days old) and juveniles 11 or 17 days old 
(postnatal day, PND, 11 or 17), followed by measurement of both brain 
and blood cholinesterase. Based on a benchmark dose analysis of the 
results of this study, EPA identified a clear point of departure (the 
equivalent of a NOAEL) for brain cholinesterase effects in the young 
and thus the sensitivity in the young is well-characterized. In these 
circumstances, EPA finds that it has reliable data on pre- and post-
natal toxicity to remove (oral and inhalation) or reduce (dermal) the 
10X FQPA Safety Factor.
    Based on the results of the benchmark dose analysis from the 
comparative cholinesterase study, which provide the most sensitive data 
available to date on age related sensitivity to carbaryl, juvenile 
animals are 1.8X more sensitive to carbaryl induced cholinesterase 
inhibition than adults. EPA has thus derived an FQPA Safety Factor of 
1.8X. This safety factor of 1.8X is applied to the dermal endpoint 
because there are no comparative cholinesterase data in offspring from 
dermal exposure, and because juvenile rats are 1.8X more sensitive than 
adults based on the oral comparative cholinesterase study in rats. The 
FQPA Safety Factor is 1X for oral and inhalation endpoints because 
these endpoints are selected from the comparative cholinesterase data 
for the most sensitive population (PND11 pups).
    Moreover, NRDC's concern that EPA failed to apply an additional 3X 
uncertainty factor to account for the failure to detect a NOAEL in the 
DNT study is no longer relevant. Specifically, brain cholinesterase 
inhibition in the PND 11 animals in the comparative cholinesterase 
study was the most sensitive endpoint in this study; therefore, this 
endpoint of 1.1 mg/kg/day was used as the point of departure for the 
2007 carbaryl risk assessment. This new endpoint occurs at a lower dose 
than NRDC's suggested extrapolated NOAEL (i.e., including a 3X 
uncertainty factor) of 3.3 mg/kg/day for brain morphometry from the DNT 
study. Because EPA's assessment is now based upon a lower endpoint, 
NRDC's contention that EPA failed to apply an additional 3X uncertainty 
factor to the point of departure derived from the DNT study is no 
longer relevant.

C. Residential Exposure

    1. Aggregating exposures. The safety standard in FFDCA section 408 
for tolerances requires that there be a reasonable certainty of no harm 
from ``aggregate exposure to the pesticide chemical residue, including 
all dietary exposures and all other exposure for which there is 
reliable information.'' (21 U.S.C. 346a(b)(2)(A)(ii)). Further, in 
evaluating the safety of tolerances EPA is directed to ``consider . . . 
available information concerning the aggregate exposures of consumers . 
. . to the pesticide chemical residue . . . including dietary exposure 
under [all] tolerance[s] . . . in effect for the pesticide chemical 
residue and exposure from other non-occupational sources.'' (21 U.S.C. 
346a(b)(2)(D)(vi)).
    Unit VII.B. discusses EPA's assessment of aggregate dietary 
exposure to carbaryl from residues in foods and water. That assessment 
showed that the dietary exposure and risk are below the Agency's level 
of concern for the general U.S. population and all population 
subgroups; exposure to carbaryl residues in food comprises <100% of the 
aPAD at the 99.9th percentile of exposure. Estimated dietary exposure 
for the general U.S. population is 29% of the aPAD; exposure to 
children age 1 to 2 years, the most highly exposed population subgroup, 
comprises 60% of the aPAD. Although refined, these exposure estimates 
still are likely to overstate exposure and risk.
    Pesticide residues to which humans are exposed from residential 
uses of pesticides must be considered as part of section 408's 
aggregate exposure calculus. The concern, of course, is that pesticide 
tolerances should not be established or left in effect if dietary 
exposures when combined with other sources of exposure exceed safe 
levels.
    2. Residential exposure and risk assessment. Since the 2004 Amended 
IRED, the Agency has revised the residential risk assessment for 
carbaryl to incorporate the revised toxicology endpoints and FQPA 
Safety Factor, the mitigation specified in the IRED (as well as the 
mitigation specified in the RED for residential use of granular 
formulations; namely, that granular formulations must be watered in 
immediately), and confirmatory data received as a result of the generic 
DCI for carbaryl. EPA received turf transferable residue (TTR) data for 
granular formulations of carbaryl, as well as additional data to 
support the use of carbaryl in pet collars. The granular TTR data were 
incorporated into the revised risk assessment; however, the pet collar 
data were considered but not incorporated because of data quality 
issues. In addition, the Agency incorporated data from several studies 
for pesticides applied to turf to estimate the percent of carbaryl 
transferred from turf to a person's hand. (See Ref. 27 for details of 
the revised carbaryl residential risk assessment).
    3. Pet collars--a. NRDC's claims. In its Petition, NRDC expressed 
concern that EPA's assessment of pet collars significantly 
underestimates exposure. (Ref. 1 at 4). NRDC therefore requested that 
EPA provide information on the assumptions used to calculate flea 
collar exposures. In particular, NRDC is concerned that EPA's 
calculations do not take into account the possibility that pet sleep 
with children, share intimate spaces or share hugs/kisses with 
children. NRDC also contends that there are safer ``non-pesticide'' 
alternatives available.
    In addition, in a November 2007 petition to cancel all carbaryl pet 
collar registrations, NRDC asserts that changes in this algorithm made 
from the preliminary NMC cumulative assessment result in a repeated and 
additive bias towards reducing the exposure estimate so that it 
``appears'' that the pet collar uses do not exceed the Agency's level 
of concern. (Ref. 2 at 5-7). Specifically, NRDC takes issue with the 
following modifications made in the probabilistic assessment for 
carbaryl as part of the NMC cumulative risk assessment:
     Assuming a child mouths only one hand at a time, thereby 
dividing the hand-loading residues by 2X.
     Assuming the hand is fully replenished with residues from 
a contaminated surface on an hourly basis rather than assuming (as done 
previously with flea collar assessments) full replenishment between 
each mouthing event, which NRDC contends is a more likely scenario for 
children actively engaged with their pets.
     Assuming that the maximum time spent with a pet is 1.03 
hrs./day. NRDC contends that EPA's assumption in previous assessments 
of 2 hrs./day is a much more likely scenario for pre-schoolers who are 
home all day with their pets and for school age children lying with 
their pets watching TV.
     Assuming that only 1% of the surface area of a single hand 
is mouthed, which is approximately 1/75

[[Page 64243]]

cm2 surface area. NRDC contends that EPA's assumption in 
previous assessments of 20 cm2 is a more reasonable and 
realistic estimate of the surface area likely to contact a child's 
mouth repeatedly.
     Assuming that only 20 to 50% of the pesticide is removed 
per mouthing event (saliva extraction factor). NRDC contends that EPA's 
assumption in previous assessments that all of the pesticide is removed 
is more reasonable and realistic.

NRDC also criticizes the Agency for not including inhalation as an 
exposure route for residential post-application of flea collars. NRDC 
also points out that inhalation was the only route of exposure that EPA 
estimated in an earlier RED decision on another pesticide used in flea 
collars.
    NRDC argues that all of these modifications in the Agency's 
algorithm for calculating non-dietary hand-to-mouth exposures for 
children bias towards reducing the exposure estimate. NRDC also 
criticizes the Agency for stating that the modifications result from 
the recommendations from the August 2005 FIFRA SAP. To the contrary, 
NRDC contends that these modifications were never reviewed or 
recommended by the FIFRA SAP. NRDC therefore asserts that EPA cannot 
use this new method presented in the NMC cumulative assessment to 
``reduce protections for children from pet uses of [carbamate] 
pesticides''. (Ref. 2 at 7).
    b. Public comments. Bayer contends that NRDC is misinformed 
regarding ``non-pesticide'' alternatives. In particular, Bayer takes 
issue with NRDC's statement that ``[p]et products containing non-
pesticide growth regulators also can stop fleas from reproducing 
successfully''. (Ref. 19 at 7, citing Ref. 1 at 4). Bayer points out 
that by definition any product that controls pest growth is a pesticide 
and that making pesticidal claims without registration is a violation 
of federal law. Bayer further asserts that unspecified ``non-
pesticide'' alternatives have not been rigorously tested for efficacy 
or safety. Thus, Bayer asserts that NRDC offers no real alternative to 
the use of carbaryl-containing flea collars.
    c. EPA's response. NRDC is concerned that while EPA has determined 
that pet collar uses are safe (with MOEs of greater than 1 million), 
EPA's calculations significantly underestimate exposure\3\. NRDC 
therefore requested that EPA provide information on the assumptions 
used to calculate flea collar exposures. In particular, NRDC is 
concerned that EPA's calculations do not take into account the 
possibility that pets sleep with children, share intimate spaces or 
share hugs/kisses with children.
---------------------------------------------------------------------------

    \3\ NRDC asserts that a MOE of 1 million relates to residential 
postapplication exposures associated with pet collars. This is 
incorrect. The MOE referred to relates to residential handler 
(applicator) exposure as assessed in the 2003 carbaryl IRED.
---------------------------------------------------------------------------

    As a preliminary matter, it is important to note that EPA assessed 
pet collars both in the individual chemical assessment and as part of 
the NMC cumulative risk assessment. The single chemical assessment done 
for carbaryl was a deterministic assessment. For the NMC cumulative 
risk assessment, EPA performed a probabilistic assessment.
    With respect to the single chemical, deterministic assessment, the 
assumptions used are based upon Agency standard values for estimating 
exposure to pets as defined in the 1997 Draft SOPs for Residential 
Exposure Assessments and amendments. (Refs. 6, 7, and 8). Specifically, 
SOPs 9.2.1--Postapplication Dermal Dose from Pesticide Residues on Pets 
and 9.2.2 - Postapplication Potential Dose Among Toddlers from 
Incidental Nondietary Ingestion of Pesticide Residues on Pets from 
Hand-to-Mouth Transfer describe the algorithms that provided the basis 
for EPA's assessment. In addition, to the extent that EPA had chemical 
specific data (e.g., transferable residue data) or made chemical 
specific adjustments to the algorithms, they are explained in the 
Revised Phase 5, Occupational and Residential Exposure Assessment and 
Recommendations for the Reregistration Eligibility Decision Document 
(RED), dated February 20, 2003.
    In sum, for the single chemical assessment, exposures to children 
after contact with treated pets were addressed using the latest EPA 
methodology, as described below:
     Only toddlers are considered because their exposures are 
considered to be the most highly exposed population by the Agency;
     An equilibrium approach based on a single child ``hug'' of 
the treated animal is used to assess dermal exposure (i.e., the skin 
loads after a single contact with the treated animal and additional 
contacts don't proportionally add exposures) as described in the 
amendments to the residential SOPs (Ref. 6), the surface area of the 
dermal hug is based on a toddler's skin surface area and typical 
clothing;
     The Agency default for transferability of residues from 
fur is 20%; however, a pet collar transferable residue study (MRID 
45792201) was submitted and used in the assessment for comparative 
purposes with the Agency's standard approach. The data from this study 
were used to develop an alternative transferability factor of 2.6% for 
dusts and liquid applications;
     The active lifetime of a collar is expected to be 120 days 
based on label statements which were used by the Agency, a daily 
emission term from the collar of 0.000290 mg/cm/gram ai/day2 
is also based on measured data from Mississippi State University for a 
pet collar. Additionally, data from a pet collar transferable residue 
study (MRID 45792201) was submitted and used in the assessment for 
comparative purposes with the Agency's standard approach the data from 
this study were used to complete risk calculations using direct 
measurements of transferable residue concentration on dogs;
     Risks are based on an even loading of residues across the 
entire surface of a 30 lb dog which has been chosen as a representative 
animal. The animal surface area was calculated using (12.3 * Body 
Weight (g) 0.65) from the Agency's 1993 Wildlife Exposure Factors 
Handbook (i.e., dog surface area of 5986 cm2);
     The approach used to address the hand-to-mouth exposure 
pathway has been modified since the previous risk assessment. In the 
previous assessment, contact with dogs was based on 40 events per day, 
in each event, the palmar surface of the hands (i.e., 20 
cm2/event) is placed in the mouth of the child contributing 
to nondietary ingestion exposure. In the revised approach, the 
frequency term has been modified to an equilibrium approach analogous 
to the dermal exposure component (i.e., the frequency = 1) because the 
transferable residue concentrations are from measured concentrations on 
the hands following heavy rubbing/petting of a dog for 5 minutes. This 
would result in significantly higher concentrations on the hands than 
would be expected from a single contact.
    With respect to the single chemical assessment, NRDC asserts that 
the Agency failed to properly take into account children hugging and 
sleeping with pets. To the contrary, EPA's assessment is in fact based 
upon toddler exposure through hugging and petting. Indeed, for maximum 
exposure, EPA's assessment is based upon assumptions of hugging and 
petting followed by mouthing activity. Thus, NRDC's concerns about 
EPA's assessment not taking hugging into account are misplaced.
    The estimation of risk from dermal and oral exposures related to 
pet collars is best described by means of combining both routes of 
exposure. The Agency

[[Page 64244]]

combines risks resulting from total exposures to individual chemicals 
when it is likely that they can occur simultaneously based on the use 
pattern and the behavior associated with the exposure population. For 
carbaryl, the Agency combined risk values (i.e., MOEs) for different 
kinds of exposures associated with the pet collar scenario (dermal and 
hand-to-mouth). These represent the standard set of exposures that are 
typically added together when chemicals are used on pets because it is 
logical that they can co-occur. It should be noted that the dermal and 
hand-to-mouth assessments are considered conservative and that 
combining the assessments is expected to provide a highly conservative 
assessment of children's incidental oral exposure.
    EPA did not, however, separately assess exposure to toddlers while 
sleeping with (near or next to) pets wearing a pet collar impregnated 
with carbaryl. This is because EPA assumes that the ``hug'' or 
equilibrium approach is adequately protective for all activities in 
which a child engages that result in dermal exposure. EPA presented the 
concept of a pet hug to assess dermal exposure to the FIFRA SAP on 
September 21, 1999 (64 FR 48394, Ref. 28); this was considered to be a 
reasonable approach. (Ref. 26). As described in the 1999 Overview 
document presented to the SAP (Ref. 21), the residential pet SOP 
``assumes a one to one transfer to the skin of surface area 
representing both hands. This assumption suggests equilibrium is 
established between the transferable residues on the pet and the 
residues on the hand after contact. The concept of equilibrium ... has 
utility in constructing scenarios such as a child hugging a dog or a 
child sleeping with a dog. This is possible by assuming direct transfer 
or transferable residue estimates to human surface area values.'' (Ref. 
22 at 38 to 39).
    NRDC also criticizes the Agency for not including inhalation as an 
exposure route for residential post-application of flea collars. In so 
doing, NRDC points out that inhalation was the only route of exposure 
that EPA estimated in an earlier RED decision on another pesticide used 
in flea collars.
    EPA did not assess inhalation exposure to pet collars impregnated 
with carbaryl because EPA generally assumes that residential post-
application inhalation exposures are negligible due to the low vapor 
pressures associated with many pesticides. In the case of carbaryl, 
this assumption is warranted. The vapor pressure of carbaryl is 
sufficiently low (4.1 x 10-5 mmHg at 25 [deg]C) so that the 
inhalation route of exposure will contribute insignificantly to the 
overall estimated daily dose when compared to the combined exposures 
resulting from the combination of the dermal and oral (i.e., hand-to-
mouth) routes. In other cases, this assumption might not be warranted. 
For example, dichlorvos, another pesticide used in impregnated pet 
collars, has a vapor pressure of 1.2 x 10-3 at 20 [deg]C, 
which is considerably higher than that of carbaryl. The higher vapor 
pressure suggests rapid volatilization at room temperature; therefore, 
the Agency considered inhalation a potential route of exposure when 
assessing residential exposure to dischlorvos from impregnated pet 
collars. The Agency also considered dermal and hand-to-mouth routes of 
exposure, in addition to inhalation. All potential routes of exposure 
are considered for each pesticide on a case-by-case basis to determine 
which routes will be the most significant contributors to exposure and 
risk.
    In addition, as the basis for petitioning the Agency to cancel all 
carbaryl pet collar registrations (submitted as part of NRDC's comments 
on the NMC cumulative assessment), NRDC asserts that changes in this 
algorithm made from the preliminary NMC cumulative assessment result in 
a repeated and additive bias towards reducing the exposure estimate so 
that it ``appears'' that the pet collar uses do not exceed the Agency's 
level of concern. NRDC also criticizes the Agency for stating that the 
modifications result from the recommendations from the August 2005 
FIFRA SAP. To the contrary, NRDC contends that these modifications were 
never reviewed or recommended by the FIFRA SAP. NRDC then asserts that 
EPA cannot use this new method presented in the NMC cumulative 
assessment to ``reduce protections for children from pet uses of 
[carbamate] pesticides.'' (Ref. 2 at 7).
    EPA disagrees with NRDC's assertion that the techniques used in the 
NMC cumulative assessment for pet collars results in an additive bias 
towards reducing exposures and risks. The main difference between the 
approach used to assess exposure to carbaryl from pet collars in the 
2003 RED and the cumulative exposure assessment of the carbaryl pet 
collar is that the cumulative exposure assessment uses probabilistic 
techniques to estimate exposures and the single chemical assessment 
uses deterministic techniques to assess exposures. Probabilistic 
techniques have the advantage of using distributions of all available 
data to describe the myriad of potential combinations of residues and 
activity patterns that may occur as a child is interacting with a pet 
wearing a carbaryl-impregnated collar. These potential combinations of 
residues and activities provide a distribution of exposures for use in 
risk assessment. Deterministic techniques rely on point estimates of 
both residues and activity patterns. These point estimates may, for 
example, represent averages or absolute maximum values for residues and 
activity patterns.
    The specific modifications and the reasons for adopting the 
modification are provided below:
     Assuming a child mouths only one hand at a time, thereby 
dividing the hand-loading residues by 2X.
    This assumption is consistent with the way EPA has assessed hand-
to-mouth exposure in the past. Both the EPA Residential SOP methodology 
(deterministic) and the revised hand-to-mouth algorithm used in the 
Revised NMC cumulative risk assessment (probabilistic) are based upon 
the assumption that a child can only place one hand in his/her mouth at 
a time.
     Assuming the hand is fully replenished with residues from 
a contaminated surface on an hourly basis rather than assuming (as done 
previously with flea collar assessments) full replenishment between 
each mouthing event, which NRDC contends is a more likely scenario for 
kids actively engaged with their pets.
    As stated in the preliminary NMC cumulative risk assessment, 
previous assumptions regarding replenishment were overly conservative 
when used in a probabilistic model. These low MOEs were mainly due to 
the incorporation of micro-activity data into EPA's macro activity 
models (defined as human exposure models based on daily time step). The 
non-dietary ingestion pathway was the least refined of the residential 
exposure pathways modeled in the preliminary revised NMC cumulative 
risk assessment. This input is part of the revised approach that was 
developed in collaboration with ORD and is currently being used in the 
Stochastic Human Exposure and Dose Simulation (SHEDS) model. (For a 
full explanation of the implications of using microactivity data in a 
macro activity model, see Ref. 29 p. 91.) The data used in the revised 
assessment are based on a meta analysis provided by ORD. The meta 
analysis relies upon the best available observational data on 
children's mouthing frequency.
     Assuming that the maximum time spent with a pet is 1.03 
hours/day. NRDC contends that EPA's assumption in previous assessments 
of 2 hours/day is a much more likely scenario for pre-

[[Page 64245]]

schoolers who are home all day with their pets and for school age kids 
lying with their pets watching TV.
    This assumption is based on data that involved videotaping 
children's time spent with pets. (Ref. 30). As stated in the NMC 
Cumulative Risk Assessment document, the duration of exposure is 
assumed to be continuous contact rather than the intermittent contact 
normally associated with pet care (e.g. walking, feeding). OPP is 
attempting to draw the distinction between direct contact with a 
treated pet and the time spent with a pet where there is limited 
contact. For example, time spent with pets in and around the house may 
not result in direct contact for the entire duration. The pet collar 
scenario assessed in the revised NMC Risk Assessment uses pet fur 
residues transferred to individuals at a rate found during a study of 
shampooing and grooming for a duration of approximately 1 hour. Use of 
these data to represent residential exposure to pets is likely to 
encompass all other potential exposure scenarios involving direct or 
indirect contact with treated pets.
     Assuming that only 1% of the surface area of a single hand 
is mouthed, which is approximately 1/75 cm2 surface area. 
NRDC contends that EPA's assumption in previous assessments of 20 cm2 
is a more reasonable and realistic estimate of the surface area likely 
to contact a child's mouth repeatedly.
    The Agency is unclear how NRDC determined that a surface area of 1% 
was used in the NMC cumulative risk assessment. It should be noted that 
the revised algorithm does not use a surface area (cm2), but 
rather a distribution of fraction of the hand mouthed (unitless). The 
distribution of fraction of surface area of hand mouthed ranged from a 
mean of 0.129 to a maximum of 0.305. This is equivalent to 
approximately 13 to 30.5 cm2, respectively (assuming a 100 
cm2 total palmar surface area of the hand). In addition, as 
a part of the algorithm used in SHEDS and CARES, the fraction of the 
surface area of the hand mouthed is based on the best available data. 
In some places in the revised NMC cumulative risk assessment, the 
fraction of hand mouthed is referred to as surface area mouthed in 
error.
     Assuming that only 20 to 50% of the pesticide is removed 
per mouthing event (saliva extraction factor). NRDC contends that EPA's 
assumption in previous assessments that all of the pesticide is removed 
is more reasonable and realistic.
    The assumptions used in the hand-to-mouth assessment are based upon 
data from several studies (Refs. 31, 32, and 33). The studies were 
conducted to address the removal efficiency of residues from the hands 
by saliva and other substances (e.g., ethanol) during mouthing events. 
The resulting range, 20-50% removal efficiency, is the same used for 
hand-to-mouth assessment in the Draft Residential SOPs and in the NMC 
cumulative risk assessment; however, the Residential SOPs rely upon the 
upper percentile of the range (50%) while the NMC cumulative risk 
assessment made use of all available data to better estimate exposure 
using a probabilistic approach.
    In sum, EPA made modifications in part because of the FIFRA SAP's 
comments with respect to the limitations of the approach used in the 
preliminary NMC cumulative risk assessment--most notable of which was 
that the approach used in the preliminary NMC cumulative risk 
assessment was likely to overestimate exposure and EPA should consider 
not assessing this exposure pathway at all until it has better data. 
EPA assessed this pathway (which the FIFRA SAP also suggested EPA) but 
modified the algorithm in an effort to further refine the assessment.
    Furthermore, the FIFRA SAP provides independent scientific advice 
to the EPA on health and safety related issues related to pesticides. 
Thus, whether the FIFRA SAP reviewed and offered its recommendations on 
the specifics of the modifications does not preclude EPA from making 
such modifications (especially where the FIFRA SAP recommends that EPA 
consider how the approach should be modified). Similarly, review by the 
FIFRA SAP is not required in order for EPA to make a safety finding. 
Accordingly, the issues raised by NRDC do not provide a basis for 
revoking all carbaryl tolerances or cancelling pet collar 
registrations.
    4. Farm children--a. NRDC's claims. Previously, NRDC had asserted 
that farm children are especially vulnerable to pesticide exposure and 
are not adequately considered. (Ref. 1. at 19). Notwithstanding EPA's 
previous response to this issue, NRDC maintains that the Agency still 
has not adequately addressed this issue.
    b. Public comments. Bayer noted that EPA adequately responded to 
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk 
Assessment (Docket ID No. 2003-0376-00008).
    c. EPA's response. Simply asserting that the Agency has not (in 
NRDC's opinion) adequately addressed an issue is not a basis upon which 
to revoke a tolerance. In particular, NRDC has not provided any 
additional information or data, nor has NRDC suggested in what respect 
it finds the Agency's previous analysis and response to this issue is 
inadequate. See Imidacloprid; Order Denying Objections to Issuance of 
Tolerance, Final Order, 69 FR 30042 (May 26, 2004). EPA hereby 
incorporates its prior response to this issue and finds NRDC's 
contention without merit.

D. Conclusion

    NRDC's petitions to revoke all carbaryl tolerances are denied. 
NRDC's arguments have not demonstrated that carbaryl tolerances are 
unsafe; to the contrary, EPA continues to believe that its risk 
assessments appropriately support its finding that the carbaryl 
tolerances pose a reasonable certainty of no harm.

VIII. Regulatory Assessment Requirements

    As indicated previously, this action announces the Agency's order 
denying a petition filed, in part, under section 408(d) of FFDCA. As 
such, this action is an adjudication and not a rule. The regulatory 
assessment requirements imposed on rulemaking do not, therefore, apply 
to this action.

IX. Submission to Congress and the Comptroller General

    The Congressional Review Act, (5 U.S.C. 801 et seq.), as added by 
the Small Business Regulatory Enforcement Fairness Act of 1996, does 
not apply because this action is not a rule for purposes of 5 U.S.C. 
804(3).

X. References

    1. NRDC comments to IRED and petition to cancel registrations dated 
January 10, 2005.
    2. NRDC petition to cancel carbaryl registrations submitted as part 
of NRDC's comments to N-methyl carbamate NMC cumulative dated September 
24, 2007.
    3. USEPA. 2000a. ``Choosing a Percentile of Acute Dietary Exposure 
as a Threshold of Regulatory Concern.'' March 16, 2000. Available at: 
http://www.epa.gov/pesticides/trac/science/trac2b054.pdf
    4. US EPA Office of Pesticide Programs. 1998. Proposed Methods for 
Basin-Scale Estimation of Pesticide Concentrations in Flowing Water and 
Reservoirs for Tolerance Reassessment. Presentation to the FIFRA SAP, 
July 29, 1998.
    5. US EPA Office of Pesticide Programs. 1999. Proposed Methods for 
Determining Watershed-derived Percent Crop Areas and Consideration for 
Applying Crop Area Adjustments to

[[Page 64246]]

Surface Water Screening Models. Presentation to the FIFRA SAP, May 27, 
1999.
    6. US EPA. Office of Pesticide Programs. 1997. Standard Operating 
Procedures (SOPs) for Residential Exposure Assessments (Draft December 
19, 1997).
    7. US EPA Office of Pesticide Programs. 2001. Science Advisory 
Council for Exposure (ExpoSAC) Policy 12: Recommended Revisions to the 
Standard Operating Procedures (SOPs) for Residential Exposure 
Assessments. February 2001.
    8. US EPA Office of Pesticide Programs. 2002a. ExpoSAC Policy 13: 
Postapplication Exposure Assessment for Children from Pet Treatments. 
January 2002.
    9. US EPA Office of Pesticide Programs. 2002b. Office of Pesticide 
Programs' Policy on the Determination of the Appropriate FQPA Safety 
Factor(s) for Use in Tolerance Assessment. Available at http://www.epa.gov/oppfead1/trac/science/determ.pdf.
    10. US EPA Office of Pesticide Programs. 2002c. Carbaryl: Updated 
Toxicology Chapter for RED. May 24, 2002. See docket ID EPA-HQ-OPP-
2002-0138.
    11. US EPA Office of Pesticide Programs. 2000b. The Use of Data on 
Cholinesterase Inhibition for Risk Assessments of Organophosphorous and 
Carbamate Pesticides (August 18, 2000).
    12. US EPA. Office of Research and Development. 2000. Benchmark 
Dose Technical Guidance Document. Draft report. Risk Assessment Forum, 
Office of Research and Development, U.S. Environmental Protection 
Agency. Washington, DC. EPA/630/R-00/001.
    13. FIFRA Science Advisory Panel. 2002. Methods Used to Conduct a 
Preliminary Cumulative Risk Assessment for Organophosphate Pesticides. 
Final Report from the FIFRA Scientific Advisory Panel Meeting of 
February 5-7, 2002 (Report dated March 19, 2002). FIFRA Scientific 
Advisory Panel, Office of Science Coordination and Policy, Office of 
Prevention, Pesticides and Toxic Substances, U.S. Environmental 
Protection Agency. Washington, DC. SAP Report 2002-01.
    14. FIFRA Science Advisory Panel. 2005a. Final report on N-Methyl 
Carbamate Cumulative Risk Assessment: Pilot Cumulative Analysis. Final 
Report from the FIFRA Scientific Advisory Panel Meeting of February , 
2005 (Report dated September 2, 1998). Available at: http://www.epa.gov/scipoly/sap/2005/february/minutes.pdf.
    15. FIFRA Science Advisory Panel. 2005b. Final report on 
Preliminary N-Methyl Carbamate Cumulative Risk Assessment. Final Report 
from the FIFRA Scientific Advisory Panel Meeting of July 29-30, 2005 
(Report dated September -, 2005). Available at: http://www.epa.gov/scipoly/sap/2005/august/minutes.pdf.
    16. US EPA Office of Pesticide Programs. 2004. Interim 
Reregistration Eligibility Decision for Carbaryl. (October 22, 2004).
    17. US EPA Office of Pesticide Programs. March 9, 2005 letter to 
Peg Cherney, Bayer Crop Science, Final Cancellation Order for Carbaryl 
Liquid Broadcast Application to Lawns/Turf; EPA Registration Numbers 
264-324, 264-325, and 264-328.
    18. US EPA Office of Pesticide Programs. 2007. Office of 
Prevention, Pesticides and Toxic Substances, EPA, Reregistration 
Eligibility Decision for Carbaryl (September 24, 2007).
    19. BayerCropScience, Comments of BayerCropScience on the Petition 
to Revoke or Modify Tolerances Established for Carbaryl. May 31, 2005.
    20. US EPA Office of Pesticide Programs. 2007. Carbaryl Refined 
Drinking Water Time Series Simulations Using Regional PCAs (March 13, 
2007).
    21. UP3 2007. Pesticides in Urban Surface Water. Urban Uses Trends 
Annual Report, available at http://www.up3project.org/documents/FInal_UP3_Use_Report_2007.pdf.
    22. USEPA Office of Pesticide Programs. Report of the FIFRA SAP 
Meeting held April 30 to May 1, 2002. A Set of Scientific Issues Being 
Considered by the EPA regarding CARES model review. June 13. 2002. EPA 
SAP 2002-02.
    23. US EPA. Office of Research and Development. 2007. Report on 
Comparative Cholinesterase Study of Carbaryl May 7, 2007).
    24. US EPA Office of Pesticide Programs. 2007. Carbaryl: Updated 
Endpoint Selection for Single Chemical Risk Assessment (June 29, 2007).
    25. Padilla S, Setzer W, Marshall RS, et al. 2007. Time Course of 
cholinesterase inhibition in adult rats treated acutely with carbaryl, 
carbofuran, formetanate, methonmy, methiocarb, oxamyl, or propoxur. 
Toxicology and Applied Pharmacology 219: 202-209.
    26. US EPA Office of Pesticide Programs. 2007. Carbaryl: Review of 
in vitro Dermal Absorption Study (MRID 47151902). June 28, 2007.
    27. US EPA Office of Pesticide Programs. 2007. Carbaryl: Revisions 
to Residential Exposure and Risk Assessment. June 29, 2007.
    28. US EPA Office of Pesticide Programs. 1999. Overview of Issues 
Related to the Standard Operating Proceedures for Residential Exposure 
Assessment. Presented to the FIFRA SAP on September 21, 1999.
    29. US EPA Office of Pesticide Programs. 2007. Revised N-methyl 
Carbamate Cumulative Risk Assessment. September 24, 2007. (EPA-HQ-OPP-
2007-0935-0003).
    30. Freeman, N. C. G., Jimenez, M., Reed, K. J., Gurunathan, S., 
Edwards, R. D., & Lioy, P. J. 2001. Quantitative Analysis of Children's 
Microactivity Patterns: The Minnesota Children's Pesticide Exposure 
Study. Journal of Exposure Analysis and Environmental Epidemiology. 
11(6): 501-509.
    31. Geno PW, Camann DE, Harding, HJ, Villalobos K, Lewis RG. 1995. 
Handwipe Sampling and Analysis Procedure for the Measurement of Dermal 
Contact with Pesticides. Arch Environ Contam Toxicol. 30:132-138.
    32. Fenske R. and C. Lu. 1994. Determination of Handwash Removal 
Efficiency: Incomplete Removal of the Pesticide Chlorpyrifos from Skin 
by Standard Handwash Techniques. American Industrial Hygiene 
Association Journal. 55(5): 425-432.
    33. Wester RC, and Maibach HI. 1989. Dermal Decontamination and 
Percutaneous Absorption. In: Percutaneous Absorption. 2nd ed. R. 
Bronaugh and H.I. Maibach, editors. New York: Marcel Dekker, pp 335-
342.

List of Subjects in 40 CFR Part 180

    Environmental protection, Carbaryl, Pesticides and pest.

    Dated: September 30, 2008.
Debra Edwards,
Director, Office of Pesticide Programs.

[FR Doc. E8-25693 Filed 10-28-08; 8:45 am]
BILLING CODE 6560-50-S