[Federal Register Volume 62, Number 131 (Wednesday, July 9, 1997)]
[Rules and Regulations]
[Pages 36691-36698]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-17930]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300511; FRL-5729-4]
RIN 2070-AB78


Imidacloprid; Pesticide Tolerances for Emergency Exemptions

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This regulation establishes time-limited tolerances for 
combined residues of imidacloprid in or on the crop group citrus fruits 
and processed commodity dried citrus pulp. This action is in response 
to EPA's granting of an emergency exemption under section 18 of the 
Federal Insecticide, Fungicide, and Rodenticide Act authorizing use of 
the pesticide on citrus. This regulation establishes a maximum 
permissible level for residues of imidacloprid in this food commodity 
pursuant to section 408(l)(6) of the Federal Food, Drug, and Cosmetic 
Act, as amended by the Food Quality Protection Act of 1996. These 
tolerances will expire and are revoked on December 31, 1998.

DATES: This regulation is effective July 9, 1997. Objections and 
requests for hearings must be received by EPA on or before September 8, 
1997.

ADDRESSES: Written objections and hearing requests, identified by the 
docket control number, [OPP-300511], must be submitted to: Hearing 
Clerk (1900), Environmental Protection Agency, Rm. M3708, 401 M St., 
SW., Washington, DC 20460. Fees accompanying objections and hearing 
requests shall be labeled ``Tolerance Petition Fees'' and forwarded to: 
EPA Headquarters Accounting Operations Branch, OPP (Tolerance Fees), 
P.O. Box 360277M, Pittsburgh, PA 15251. A copy of any objections and 
hearing requests filed with the Hearing Clerk identified by the docket 
control number, [OPP-300511], must also be submitted to: Public 
Information and Records Integrity Branch, Information Resources and 
Services Division (7506C), Office of Pesticide Programs, Environmental 
Protection Agency, 401 M St., SW., Washington, DC 20460. In person, 
bring a copy of objections and hearing requests to Rm. 1132, CM #2, 
1921 Jefferson Davis Hwy., Arlington, VA.
    A copy of objections and hearing requests filed with the Hearing 
Clerk may also be submitted electronically by sending electronic mail 
(e-mail) to: [email protected]. Copies of objections and 
hearing requests must be submitted as an ASCII file avoiding the use of 
special characters and any form of encryption. Copies of objections and 
hearing requests will also be accepted on disks in WordPerfect 5.1 file 
format or ASCII file format. All copies of objections and hearing 
requests in electronic form must be identified by the docket control 
number [OPP-300511]. No Confidential Business Information (CBI) should 
be submitted through e-mail. Electronic copies of objections and 
hearing requests on this rule may be filed online at many Federal 
Depository Libraries.

FOR FURTHER INFORMATION CONTACT: By mail: Andrew Ertman, Registration 
Division 7505C, Office of Pesticide Programs, Environmental Protection 
Agency, 401 M St., SW., Washington, DC 20460. Office location, 
telephone number, and e-mail address: Crystal Mall #2, 1921 Jefferson 
Davis Hwy., Arlington, VA, (703) 308-9367, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: EPA, on its own initiative, pursuant to 
section 408(e) and (l)(6) of the Federal Food, Drug, and Cosmetic Act 
(FFDCA), 21 U.S.C. 346a(e) and (l)(6), is establishing tolerances for 
combined residues of the insecticide imidacloprid, in or on the crop 
group citrus fruits at 1 part per million (ppm) and the processed 
commodity dried citrus pulp at 5 ppm. These tolerances will expire and 
are revoked on December 31, 1998. EPA will publish a document in the 
Federal Register to remove the revoked tolerances from the Code of 
Federal Regulations.

I. Background and Statutory Authority

    The Food Quality Protection Act of 1996 (FQPA) (Pub. L. 104-170) 
was signed into law August 3, 1996. FQPA amends both the Federal Food, 
Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 301 et seq., and the Federal 
Insecticide, Fungicide, and Rodenticide Act (FIFRA), 7 U.S.C. 136 et 
seq . The FQPA amendments went into effect immediately. Among other 
things, FQPA amends FFDCA to bring all EPA pesticide tolerance-setting 
activities under a new section 408 with a new safety standard and new 
procedures. These activities are described below and discussed in 
greater detail in the final rule establishing the time-limited 
tolerance associated with the emergency exemption for use of 
propiconazole on sorghum (61 FR 58135, November 13, 1996)(FRL-5572-9).
    New section 408(b)(2)(A)(I) of the FFDCA allows EPA to establish a 
tolerance (the legal limit for a pesticide chemical residue in or on a 
food) only if EPA determines that the tolerance is ``safe.'' Section 
408(b)(2)(A)(ii) defines ``safe'' 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.'' This 
includes exposure through drinking water and in residential settings, 
but does not include occupational exposure. Section 408(b)(2)(C) 
requires EPA to give special consideration to exposure of infants and 
children to the pesticide chemical residue in establishing a tolerance 
and to ``ensure that there is a reasonable certainty that no harm will 
result to infants and children from aggregate exposure to the pesticide 
chemical residue. . . .''
    Section 18 of FIFRA authorizes EPA to exempt any Federal or State 
agency from any provision of FIFRA, if EPA determines that ``emergency 
conditions exist which require such exemption.'' This provision was not 
amended by FQPA. EPA has established regulations governing such 
emergency exemptions in 40 CFR part 166.
    Section 408(l)(6) of the FFDCA requires EPA to establish a time-
limited tolerance or exemption from the requirement for a tolerance for 
pesticide chemical residues in food that will result from the use of a 
pesticide under an emergency exemption granted by EPA under section 18 
of FIFRA. Such tolerances can be established without providing notice 
or period for public comment.
    Because decisions on section 18-related tolerances must proceed 
before EPA reaches closure on several policy issues relating to 
interpretation and implementation of the FQPA, EPA does not intend for 
its actions on such tolerance to set binding precedents for the 
application of section 408 and the new safety standard to other 
tolerances and exemptions.

II. Emergency Exemption for Imidacloprid on Citrus and FFDCA 
Tolerances

    The State of Florida has requested a specific exemption for the use 
of imidacloprid on citrus for the control of

[[Page 36692]]

the brown citrus aphid (BrCA) and the citrus leafminer (CLM). The BrCA 
is a potentially devastating pest that impacts citrus by feeding on 
newly developing foliage and by transmitting citrus tristeza virus 
(CTV). The citrus leafminer, since its initial discovery in May 1993, 
has become a major economic pest to citrus nurseries and young citrus 
groves by feeding on newly developing foliage.
    The Applicant asserts that CTV could potentially affect citrus 
yield in the following three ways: (1) threatened losses of $500 
million for sweet orange and grapefruit trees budded on sour orange 
rootstock; (2) if CTV stem pitting strains became endemic throughout 
the Florida grapefruit industry, yields from grapefruit trees on CTV 
tolerant rootstock could be reduced by 45% on a continuing basis, fruit 
size would be reduced, and production costs increased; and (3) if CTV 
became endemic throughout Florida, yields of sweet orange would be 
reduced by 5-20%, and production costs increased.
    As for yield losses caused by the CLM, the Applicant indicates that 
defoliation caused by CLM could result in up to a 44% reduction in 
yield, translating into a net loss of approximately $145/acre.
    For the BrCA, the registered alternatives are either ineffective 
due to labeled use restrictions and length of efficacy or are broad 
spectrum insecticides that, if used as needed to control the BrCA, 
would dramatically upset established populations of beneficials. The 
registered alternatives for the CLM have not provided adequate control 
of this pest, with the most effective alternatives demonstrating a 14-
day suppression of the CLM. Additionally, the CLM is difficult to 
control with foliar sprays because it is protected from foliar-applied 
insecticides by the mined leaf cuticle, and leaf margins role inward 
over the pupae, protecting it. Florida indicated that imidacloprid had 
demonstrated as much as 15 weeks of control, and since it is a systemic 
insecticide, would be particularly effective against these type of 
pests, due to their feeding habits.
    EPA has authorized under FIFRA section 18 the use of imidacloprid 
on citrus for control of the brown citrus aphid and citrus leafminer in 
Florida. After having reviewed the submission, EPA concurs that 
emergency conditions exist for this state.
    As part of its assessment of this emergency exemption, EPA assessed 
the potential risks presented by residues of imidacloprid in or on 
citrus fruits and dried citrus pulp. In doing so, EPA considered the 
new safety standard in FFDCA section 408(b)(2), and EPA decided that 
the necessary tolerance under FFDCA section 408(l)(6) would be 
consistent with the new safety standard and with FIFRA section 18. 
Consistent with the need to move quickly on the emergency exemption in 
order to address an urgent non-routine situation and to ensure that the 
resulting food is safe and lawful, EPA is issuing these tolerances 
without notice and opportunity for public comment under section 408(e), 
as provided in section 408(l)(6). Although these tolerances will expire 
and are revoked on December 31, 1998, under FFDCA section 408(l)(5), 
residues of the pesticide not in excess of the amounts specified in the 
tolerances remaining in or on citrus fruits and dried citrus pulp after 
that date will not be unlawful, provided the pesticide is applied in a 
manner that was lawful under FIFRA. EPA will take action to revoke 
these tolerances earlier if any experience with, scientific data on, or 
other relevant information on this pesticide indicate that the residues 
are not safe.
    Because these tolerances are being approved under emergency 
conditions EPA has not made any decisions about whether imidacloprid 
meets EPA's registration requirements for use on citrus or whether 
permanent tolerances for this use would be appropriate. Under these 
circumstances, EPA does not believe that these tolerance serve as a 
basis for registration of imidacloprid by a State for special local 
needs under FIFRA section 24(c). Nor do these tolerances serve as the 
basis for any State other than Florida to use this pesticide on this 
crop under section 18 of FIFRA without following all provisions of 
section 18 as identified in 40 CFR part 166. For additional information 
regarding the emergency exemption for imidacloprid, contact the 
Agency's Registration Division at the address provided above.

III. Risk Assessment and Statutory Findings

    EPA performs a number of analyses to determine the risks from 
aggregate exposure to pesticide residues. First, EPA determines the 
toxicity of pesticides based primarily on toxicological studies using 
laboratory animals. These studies address many adverse health effects, 
including (but not limited to) reproductive effects, developmental 
toxicity, toxicity to the nervous system, and carcinogenicity. Second, 
EPA examines exposure to the pesticide through the diet (e.g., food and 
drinking water) and through exposures that occur as a result of 
pesticide use in residential settings.

A. Toxicity

    1. Threshold and non-threshold effects. For many animal studies, a 
dose response relationship can be determined, which provides a dose 
that causes adverse effects (threshold effects) and doses causing no 
observed effects (the ``no-observed effect level'' or ``NOEL'').
    Once a study has been evaluated and the observed effects have been 
determined to be threshold effects, EPA generally divides the NOEL from 
the study with the lowest NOEL by an uncertainty factor (usually 100 or 
more) to determine the Reference Dose (RfD). The RfD is a level at or 
below which daily aggregate exposure over a lifetime will not pose 
appreciable risks to human health. An uncertainty factor (sometimes 
called a ``safety factor'') of 100 is commonly used since it is assumed 
that people may be up to 10 times more sensitive to pesticides than the 
test animals, and that one person or subgroup of the population (such 
as infants and children) could be up to 10 times more sensitive to a 
pesticide than another. In addition, EPA assesses the potential risks 
to infants and children based on the weight of the evidence of the 
toxicology studies and determines whether an additional uncertainty 
factor is warranted. Thus, an aggregate daily exposure to a pesticide 
residue at or below the RfD (expressed as 100% or less of the RfD) is 
generally considered acceptable by EPA. EPA generally uses the RfD to 
evaluate the chronic risks posed by pesticide exposure. For shorter 
term risks, EPA calculates a margin of exposure (MOE) by dividing the 
estimated human exposure into the NOEL from the appropriate animal 
study. Commonly, EPA finds MOEs lower than 100 to be unacceptable. This 
100-fold MOE is based on the same rationale as the 100-fold uncertainty 
factor.
    Lifetime feeding studies in two species of laboratory animals are 
conducted to screen pesticides for cancer effects. When evidence of 
increased cancer is noted in these studies, the Agency conducts a 
weight of the evidence review of all relevant toxicological data 
including short-term and mutagenicity studies and structure activity 
relationship. Once a pesticide has been classified as a potential human 
carcinogen, different types of risk assessments (e.g., linear low dose 
extrapolations or MOE calculation based on the appropriate NOEL) will 
be carried out based on the nature of the carcinogenic response and the 
Agency's knowledge of its mode of action.

[[Page 36693]]

    2. Differences in toxic effect due to exposure duration. The 
toxicological effects of a pesticide can vary with different exposure 
durations. EPA considers the entire toxicity data base, and based on 
the effects seen for different durations and routes of exposure, 
determines which risk assessments should be done to assure that the 
public is adequately protected from any pesticide exposure scenario. 
Both short and long durations of exposure are always considered. 
Typically, risk assessments include ``acute'', ``short-term'', 
``intermediate term'', and ``chronic'' risks. These assessments are 
defined by the Agency as follows.
    Acute risk, by the Agency's definition, results from 1-day 
consumption of food and water, and reflects toxicity which could be 
expressed following a single oral exposure to the pesticide residues. 
High-end exposure to food and water residues are typically assumed.
    Short-term risk results from exposure to the pesticide for a period 
of 1-7 days, and therefore overlaps with the acute risk assessment. 
Historically, this risk assessment was intended to address primarily 
dermal and inhalation exposure which could result, for example, from 
residential pesticide applications. However, since enaction of FQPA, 
this assessment has been expanded to include both dietary and non-
dietary sources of exposure, and will typically consider exposure from 
food, water, and residential uses when reliable data are available. In 
this assessment, risks from average food and water exposure, and high-
end residential exposure, are aggregated. High-end exposures from all 3 
sources are not typically added because of the very low probability of 
this occurring in most cases, and because the other conservative 
assumptions built into the assessment assure adequate protection of 
public health. However, for cases in which high-end exposure can 
reasonably be expected from multiple sources (e.g. frequent and 
widespread homeowner use in a specific geographical area), multiple 
high-end risks will be aggregated and presented as part of the 
comprehensive risk assessment/characterization. Since the toxicological 
endpoint considered in this assessment reflects exposure over a period 
of at least 7 days, an additional degree of conservatism is built into 
the assessment; i.e., the risk assessment nominally covers 1-7 days 
exposure, and the toxicological endpoint/NOEL is selected to be 
adequate for at least 7 days of exposure. (Toxicity results at lower 
levels when the dosing duration is increased.)
    Intermediate-term risk results from exposure for 7 days to several 
months. This assessment is handled in a manner similar to the short-
term risk assessment.
    Chronic risk assessment describes risk which could result from 
several months to a lifetime of exposure. For this assessment, risks 
are aggregated considering average exposure from all sources for 
representative population subgroups including infants and children.

B. Aggregate Exposure

    In examining aggregate exposure, FFDCA section 408 requires that 
EPA take into account available and reliable information concerning 
exposure from the pesticide residue in the food in question, residues 
in other foods for which there are tolerances, residues in groundwater 
or surface water that is consumed as drinking water, and other non-
occupational exposures through pesticide use in gardens, lawns, or 
buildings (residential and other indoor uses). Dietary exposure to 
residues of a pesticide in a food commodity are estimated by 
multiplying the average daily consumption of the food forms of that 
commodity by the tolerance level or the anticipated pesticide residue 
level. The Theoretical Maximum Residue Contribution (TMRC) is an 
estimate of the level of residues consumed daily if each food item 
contained pesticide residues equal to the tolerance. In evaluating food 
exposures, EPA takes into account varying consumption patterns of major 
identifiable subgroups of consumers, including infants and children. 
The TMRC is a ``worst case'' estimate since it is based on the 
assumptions that food contains pesticide residues at the tolerance 
level and that 100% of the crop is treated by pesticides that have 
established tolerances. If the TMRC exceeds the RfD or poses a lifetime 
cancer risk that is greater than approximately one in a million, EPA 
attempts to derive a more accurate exposure estimate for the pesticide 
by evaluating additional types of information (anticipated residue data 
and/or percent of crop treated data) which show, generally, that 
pesticide residues in most foods when they are eaten are well below 
established tolerances.
    Percent of crop treated estimates are derived from federal and 
private market survey data. Typically, a range of estimates are 
supplied and the upper end of this range is assumed for the exposure 
assessment. By using this upper end estimate of percent of crop 
treated, the Agency is reasonably certain that exposure is not 
understated for any significant subpopulation group. Further, regional 
consumption information is taken into account through EPA's computer-
based model for evaluating the exposure of significant subpopulations 
including several regional groups, to pesticide residues. For this 
pesticide, the most highly exposed population subgroup (children 1-6 
years old) was not regionally based.

IV. Aggregate Risk Assessment and Determination of Safety

    Consistent with section 408(b)(2)(D), EPA has reviewed the 
available scientific data and other relevant information in support of 
this action. EPA has sufficient data to assess the hazards of 
imidacloprid and to make a determination on aggregate exposure, 
consistent with section 408(b)(2), for time-limited tolerances for 
combined residues of imidacloprid on the citrus fruits crop group at 1 
ppm and the processed commodity dried citrus pulp 5 ppm. EPA's 
assessment of the dietary exposures and risks associated with 
establishing these tolerances follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
children. The nature of the toxic effects caused by imidacloprid are 
discussed below.
    1. Acute toxicity. NOEL = 24 mg/kg/day. The Agency recommends use 
of the NOEL of 24 mg/kg/day, based on decreased body weight, increased 
resorptions, increased abortions, and increased skeletal abnormalities 
at the lowest effect level (LEL) of 72 mg/kg/day, from the 
developmental toxicity study in rabbits. This risk assessment should 
evaluate acute dietary risk to females 13+ years.
    2. Short - and intermediate - term toxicity. For short- and 
intermediate-term MOE calculations, the Agency determined that 
available data do not demonstrate that imidacloprid has dermal or 
inhalation toxicity potential. Therefore, short-or intermediate-term 
dermal and inhalation risk assessments are not required. This decision 
was based on the fact that no effects were observed at the highest dose 
level tested (0.191 mg/L) in a 28-day inhalation toxicity study in 
rats, and that no systemic toxicity was observed at dose

[[Page 36694]]

levels up to 1,000 mg/kg/day in a 21-day dermal toxicity study in 
rabbits.
    3. Chronic toxicity. EPA has established the RfD for imidacloprid 
at 0.057 milligrams/kilogram/day (mg/kg/day). This RfD is based on a 
NOEL of 5.7 mg/kg/day from a 2-year feeding/carcinogenicity study in 
rats. An uncertainty factor of 100 was applied to take into account 
inter-species sensitivity and intra-species variation. The lowest 
observed effect level (LOEL) of 16.9 mg/kg/day was based on increased 
thyroid lesions in males.
    4. Carcinogenicity. Imidacloprid has been classified as a Group E 
chemical, no evidence of carcinogenicity for humans, by the Agency.

B. Exposures and Risks

    1. From food and feed uses. Tolerances have been established (40 
CFR 180.472) for the combined residues of imidacloprid, in or on a 
variety of raw agricultural commodities. Tolerances range from 0.02 ppm 
in eggs to 6 ppm in cottonseed. Risk assessments were conducted by EPA 
to assess dietary exposures and risks from imidacloprid as follows:
    i.  Acute exposure and risk. Acute dietary risk assessments are 
performed for a food-use pesticide if a toxicological study has 
indicated the possibility of an effect of concern occurring as a result 
of a one day or single exposure. The acute dietary (food only) risk 
assessment used Theoretical Maximum Residue Contribution (TMRC). The 
resulting high-end exposure estimate of 0.1 mg/kg/day, which results in 
a dietary (food only) MOE of 240 for females 13+ years, should be 
viewed as a conservative risk estimate; refinement using anticipated 
residue values and percent crop-treated data in conjunction with Monte 
Carlo analysis would result in a lower acute dietary exposure estimate.
    ii. Chronic exposure and risk. In conducting this exposure 
assessment, the Agency has made very conservative assumptions -- 100% 
of citrus commodities and all other commodities having imidacloprid 
tolerances will contain imidacloprid residues and those residues would 
be at the level of the tolerance -- which result in an overestimate of 
human dietary exposure. This chronic dietary (food only) exposure 
should be viewed as a conservative risk estimate; refinement using 
anticipated residue levels and percent crop-treated values analysis 
would result in a lower dietary exposure estimate. Thus, in making a 
safety determination for this tolerance, EPA is taking into account 
this conservative exposure assessment. The existing imidacloprid 
tolerances (published, pending, and including the necessary Section 18 
tolerances) result in a Theoretical Maximum Residue Contribution (TMRC) 
that is equivalent to the following percentages of the RfD:

                                                                        
------------------------------------------------------------------------
          Subpopulation                  TMRC                %RfD       
------------------------------------------------------------------------
U.S. population.................  0.011276            20%               
Nursing infants.................  0.009403            17%               
Non-nursing infants (<1 year      0.022489            40%               
 old).                                                                  
Children (1-6 years old)........  0.024609            43%               
Children (7-12 years old).......  0.016932            30%               
U.S. population - winter........  0.011763            21%               
Northeast Region................  0.012362            22%               
Western Region..................  0.011992            21%               
Hispanics.......................  0.012485            22%               
Non-Hispanic others.............  0.013116            23%               
------------------------------------------------------------------------

    The subgroups listed above are: (1) the U.S. population (48 
states); (2) those for infants and children; and, (3) the other 
subgroups for which the percentage of the RfD occupied is greater than 
that occupied by the subgroup U.S. population (48 states).
    2. From drinking water. Based on data available to the Agency, 
imidacloprid is persistent and could potentially leach into 
groundwater. There is no established Maximum Contamination Level (MCL) 
for residues of imidacloprid in drinking water. No health advisory 
levels for imidacloprid in drinking water have been established. The 
``Pesticides in Groundwater Database'' has no entry for imidacloprid.
     Chronic exposure and risk. Because the Agency lacks sufficient 
water-related exposure data to complete a comprehensive drinking water 
risk assessment for many pesticides, EPA has commenced and nearly 
completed a process to identify a reasonable yet conservative bounding 
figure for the potential contribution of water-related exposure to the 
aggregate risk posed by a pesticide. In developing the bounding figure, 
EPA estimated residue levels in water for a number of specific 
pesticides using various data sources. The Agency then applied the 
estimated residue levels, in conjunction with appropriate toxicological 
endpoints (RfDs or acute dietary NOELs) and assumptions about body 
weight and consumption, to calculate, for each pesticide, the increment 
of aggregate risk contributed by consumption of contaminated water. 
While EPA has not yet pinpointed the appropriate bounding figure for 
exposure from contaminated water, the ranges the Agency is continuing 
to examine are all below the level that would cause imidacloprid to 
exceed the RfD if the tolerance being considered in this document were 
granted. The Agency has therefore concluded that the potential 
exposures associated with imidacloprid in water, even at the higher 
levels the Agency is considering as a conservative upper bound, would 
not prevent the Agency from determining that there is a reasonable 
certainty of no harm if the tolerance is granted.
    3. From non-dietary exposure. Imidacloprid is currently registered 
for use on the following residential non-food sites: ornamental 
flowering plants, ornamental ground covers, ornamental woody plants, 
ornamental turf, ornamental lawns, household and domestic dwellings 
(indoor/outdoor), wood protection, and pets. Because the Agency has 
determined that imidacloprid has no dermal or inhalation toxicological 
potential and has not identified a chronic toxicological endpoint, EPA 
does not expect any harm from non-dietary exposure to imidacloprid.
    4. Cumulative exposure to substances with common mechanism of 
toxicity. Section 408(b)(2)(D)(v) requires that, when considering 
whether to establish, modify, or revoke a tolerance, the Agency 
consider ``available information'' concerning the cumulative effects of 
a particular pesticide's residues and ``other substances that have a 
common mechanism of toxicity.''

[[Page 36695]]

 The Agency believes that ``available information'' in this context 
might include not only toxicity, chemistry, and exposure data, but also 
scientific policies and methodologies for understanding common 
mechanisms of toxicity and conducting cumulative risk assessments. For 
most pesticides, although the Agency has some information in its files 
that may turn out to be helpful in eventually determining whether a 
pesticide shares a common mechanism of toxicity with any other 
substances, EPA does not at this time have the methodologies to resolve 
the complex scientific issues concerning common mechanism of toxicity 
in a meaningful way. EPA has begun a pilot process to study this issue 
further through the examination of particular classes of pesticides. 
The Agency hopes that the results of this pilot process will increase 
the Agency's scientific understanding of this question such that EPA 
will be able to develop and apply scientific principles for better 
determining which chemicals have a common mechanism of toxicity and 
evaluating the cumulative effects of such chemicals. The Agency 
anticipates, however, that even as its understanding of the science of 
common mechanisms increases, decisions on specific classes of chemicals 
will be heavily dependent on chemical specific data, much of which may 
not be presently available.
    Although at present the Agency does not know how to apply the 
information in its files concerning common mechanism issues to most 
risk assessments, there are pesticides as to which the common mechanism 
issues can be resolved. These pesticides include pesticides that are 
toxicologically dissimilar to existing chemical substances (in which 
case the Agency can conclude that it is unlikely that a pesticide 
shares a common mechanism of activity with other substances) and 
pesticides that produce a common toxic metabolite (in which case common 
mechanism of activity will be assumed).
    EPA does not have, at this time, available data to determine 
whether imidacloprid has a common mechanism of toxicity with other 
substances or how to include this pesticide in a cumulative risk 
assessment. Unlike other pesticides for which EPA has followed a 
cumulative risk approach based on a common mechanism of toxicity, 
imidacloprid does not appear to produce a toxic metabolite produced by 
other substances. For the purposes of this tolerance action, therefore, 
EPA has not assumed that imidacloprid has a common mechanism of 
toxicity with other substances.

C. Aggregate Risks and Determination of Safety for U.S. Population

    1. Acute risk. An acute aggregate risk assessment takes into 
account exposure from dietary food and water. For imidacloprid, no data 
were available to EPA from possible exposure to contaminated drinking 
water. Thus, this risk assessment is based on acute dietary risk from 
food only. For the population subgroup of concern, females 13+ years, 
the calculated MOE value is 240. This MOE does not exceed the Agency's 
level of concern for acute dietary exposure.
    2. Chronic risk. Using the conservative exposure assumptions 
described above, and taking into account the completeness and 
reliability of the toxicity data, EPA has concluded that aggregate 
dietary exposure to imidacloprid will utilize 20% of the RfD for the 
U.S. population. EPA generally has no concern for exposures below 100% 
of the RfD because the RfD represents the level at or below which daily 
aggregate dietary exposure over a lifetime will not pose appreciable 
risks to human health. Despite the potential for exposure to 
imidacloprid in drinking water, the Agency does not expect the 
aggregate dietary exposure to exceed 100% of the RfD. Since EPA has 
determined that there is no dermal or inhalation toxicity potential for 
imidacloprid, non-dietary, non-occupational exposure is not a concern. 
The Agency concludes that there is a reasonable certainty that no harm 
will result from chronic aggregate exposure to imidacloprid residues.
    3. Short- and intermediate-term risk. Short- and intermediate-term 
aggregate exposure takes into account chronic dietary food and water 
(considered to be a background exposure level) plus indoor and outdoor 
residential exposure. Because the Agency has determined that 
imidacloprid has no dermal or inhalation toxicity potential, short-term 
or intermediate-term dermal and inhalation risk assessments are not 
required.

D. Aggregate Cancer Risk for U.S. Population

    Since imidacloprid has been classified as a Group E chemical, no 
evidence of carcinogenicity for humans, a cancer risk assessment was 
not required.

E. Aggregate Risks and Determination of Safety for Infants and Children

    1. Safety factor for infants and children.--a. In general. In 
assessing the potential for additional sensitivity of infants and 
children to residues of imidacloprid, EPA considered data from 
developmental toxicity studies in the rat and rabbit and a two-
generation reproduction study in the rat. The developmental toxicity 
studies are designed to evaluate adverse effects on the developing 
organism resulting from pesticide exposure during prenatal development 
to one or both parents. Reproduction studies provide information 
relating to effects from exposure to the pesticide on the reproductive 
capability of mating animals and data on systemic toxicity.
    FFDCA section 408 provides that EPA shall apply an additional 
tenfold margin of safety for infants and children in the case of 
threshold effects to account for pre-and post-natal toxicity and the 
completeness of the database unless EPA determines that a different 
margin of safety will be safe for infants and children. Margins of 
safety are incorporated into EPA risk assessments either directly 
through use of a MOE analysis or through using uncertainty (safety) 
factors in calculating a dose level that poses no appreciable risk to 
humans. EPA believes that reliable data support using the standard MOE 
and uncertainty factor (usually 100 for combined inter- and intra-
species variability) and not the additional tenfold MOE/uncertainty 
factor when EPA has a complete data base under existing guidelines and 
when the severity of the effect in infants or children or the potency 
or unusual toxic properties of a compound do not raise concerns 
regarding the adequacy of the standard MOE/safety factor.
    b. Developmental toxicity studies. From the developmental toxicity 
study in rats, the maternal (systemic) NOEL was 30 mg/kg/day. The 
maternal (systemic) LOEL of 100 mg/kg/day was based on decreased weight 
gain. The developmental (fetal) NOEL was 30 mg/kg/day. The 
developmental (fetal) LEL of 100 mg/kg/day was based on increased wavy 
ribs.
    From the developmental toxicity study in rabbits, the maternal 
(systemic) NOEL was 24 mg/kg/day. The maternal (systemic) LOEL of 72 
mg/kg/day was based on decreased body weight, increased abortions, and 
death. The developmental (fetal) NOEL was 24 mg/kg/day. The 
developmental (fetal) LOEL of 72 mg/kg/day was based on decreased body 
weight and increased skeletal anomalies.
    c. Reproductive toxicity study. From the reproductive toxicity 
study in rats, the maternal (systemic) NOEL was 55 mg/kg/day at the 
highest dose tested (HDT). The reproductive/developmental (pup) NOEL 
was 8 mg/kg/day. The reproductive/developmental (pup)

[[Page 36696]]

LOEL of 19 mg/kg/day was based on decreased pup body weight during 
lactation in both generations.
    d. Pre- and post-natal sensitivity. The toxicological database for 
evaluating pre- and post-natal toxicity for imidacloprid is complete. 
In the case of the developmental toxicity studies, the developmental 
and maternal NOELs for both rats and rabbits occur at the same dose 
level for each species (24 mg/kg/day for rabbits and 30 mg/kg/day for 
rats) which suggests that there is no extra sensitivity for unborn 
children in the absence of maternal toxicity. However, a detailed 
analysis of the developmental toxicity studies indicates that the 
skeletal findings (wavy ribs and other anomalies) in both the rat and 
rabbit fetuses are severe effects which occurred in the presence of 
slight maternal toxicity (decreases of body weight). Additionally, in 
rabbits, there were increases in resorptions and abortions which can be 
attributed to acute maternal exposure. This information has been 
interpreted by the Agency as indicating a potential acute dietary risk 
for pre-natally exposed infants. The acute dietary MOE for females 13+ 
years is 240. This large MOE, based on conservative exposure 
assumptions, demonstrates that pre-natal exposure to imidacloprid is 
not a toxicological concern at this time.
    In the case of the 2-generation reproductive toxicity study in 
rats, the parental NOEL is 55 mg/kg/day (HDT). The reproductive NOEL is 
8 mg/kg/day based on decreased pup body weight during lactation 
observed at the LOEL of 19 mg/kg/day. The results of this study 
indicate that adverse reactions to imidacloprid by the pups occurs at 
levels (19 mg/kg/day) which are lower than the NOEL for the parental 
animals (55 mg/kg/day). Therefore, the pups are more sensitive to the 
effects of imidacloprid than parental animals and for the purpose of 
this Section 18 an additional 3X safety factor should be added to the 
RfD.
    The aggregate risk estimate for the most highly exposed infant and 
children subgroup (children 1-6 years old) occupies 129% of the RfD 
(including the 3X additional safety factor). Both chronic and acute 
dietary exposure risk assessments assume 100% crop treated and use 
tolerance level residues for all commodities. Refinement of these 
dietary risk assessments by using percent crop treated information and 
anticipated residue data would reduce dietary exposure. Therefore, both 
of these risk assessments are over-estimates of dietary risk. 
Consideration of anticipated residues and percent crop treated would 
likely result in an anticipated residue contribution (ARC) which would 
occupy a percentage of the RfD that is likely to be significantly lower 
than the currently calculated TMRC value, and aggregate risk estimates. 
Therefore, EPA concludes that extension of this time-limited tolerance 
should not pose an unacceptable risk to infants and children.
    2. Acute risk. At present, the acute dietary MOE for females 13+ 
years (accounts for both maternal and fetal exposure) is 240. This risk 
assessment also assumed 100% crop-treated with tolerance level residues 
on all treated crops consumed, resulting in a significant over-estimate 
of dietary exposure. The Agency does not expect that aggregate exposure 
(food plus water) would result in an unacceptable acute dietary MOE. 
The large acute dietary MOE calculated for females 13+ years provides 
assurance that there is a reasonable certainty of no harm for both 
females 13+ years and the pre-natal development of infants from 
exposure to imidacloprid.
    3. Chronic risk. Using the conservative exposure assumptions 
described above, EPA has concluded that aggregate exposure to 
imidacloprid from food will utilize 48% of the RfD for nursing infants, 
and 129% of the RfD for children 1-6 years old (including the 
additional 3X safety factor). This chronic aggregate (food only) 
exposure should be viewed as a conservative risk estimate; refinement 
using anticipated residue levels and percent crop-treated values 
analysis would result in a lower aggregate exposure estimate. Despite 
the potential for exposure to imidacloprid in drinking water and from 
non-dietary, non-occupational exposure, EPA does not expect the 
aggregate exposure to exceed 100% of the RfD. Therefore, taking into 
account the completeness and reliability of the toxicity data and the 
conservative exposure assessment, EPA concludes that there is a 
reasonable certainty that no harm will result to infants and children 
from aggregate exposure to imidacloprid residues.

V. Other Considerations

A. Metabolism In Plants and Animals

    The nature of the residue in plants and animals, is adequately 
understood. The residue of concern is imidacloprid and its metabolites 
containing the 6-chloropyridinyl moiety, all expressed as parent as 
specified in 40 CFR 180.472.

B. Analytical Enforcement Methodology

    An adequate common moiety GC/MS enforcement method is available for 
the determination of the regulated imidacloprid residues in citrus 
commodities. Bayer Method 00200 has successfully completed an EPA 
Tolerance Method Validation. Copies of the method have been forwarded 
to FDA for publication in PAM Volume II.

C. Magnitude of Residues

    Combined residues of imidacloprid and its regulated metabolites are 
not expected to exceed 1.0 ppm in/on the citrus crop group or 5 ppm in/
on the processed commodity dried citrus pulp as a result of this 
Section 18 use. Secondary residues in animal commodities are not 
expected to exceed existing tolerances as a result of this Section 18 
use.

D. International Residue Limits

    There are no CODEX, Canadian, or Mexican residue limits, therefore 
harmonization is not an issue for this action.

E. Rotational Crop Restrictions

    Citrus crops are not rotated to other crops, thus rotational crop 
concerns are not germane to this action.

VI. Conclusion

    Therefore, tolerances are established for combined residues of 
imidacloprid on the citrus fruits crop group at 1 ppm and dried citrus 
pulp at 5 ppm.

VII. Objections and Hearing Requests

    The new FFDCA section 408(g) provides essentially the same process 
for persons to ``object'' to a tolerance regulation issued by EPA under 
new section 408(e) and (l)(6) as was provided in the old section 408 
and in section 409. However, the period for filing objections is 60 
days, rather than 30 days. EPA currently has procedural regulations 
which govern the submission of objections and hearing requests. These 
regulations will require some modification to reflect the new law. 
However, until those modifications can be made, EPA will continue to 
use those procedural regulations with appropriate adjustments to 
reflect the new law.
    Any person may, by September 8, 1997, file written objections to 
any aspect of this regulation and may also request a hearing on those 
objections. Objections and hearing requests must be filed with the 
Hearing Clerk, at the address given above (40 CFR 178.20). A copy of 
the objections and/or hearing requests filed with the Hearing Clerk 
should be submitted to the OPP docket for this rulemaking. The 
objections submitted must specify the provisions of the regulation 
deemed objectionable and the grounds for the objections (40

[[Page 36697]]

CFR 178.25). Each objection must be accompanied by the fee prescribed 
by 40 CFR 180.33(i). If a hearing is requested, the objections must 
include a statement of the factual issues on which a hearing is 
requested, the requestor's contentions on such issues, and a summary of 
any evidence relied upon by the requestor (40 CFR 178.27). A request 
for a hearing will be granted if the Administrator determines that the 
material submitted shows the following: There is genuine and 
substantial issue of fact; there is a reasonable possibility that 
available evidence identified by the requestor would, if established, 
resolve one or more of such issues in favor of the requestor, taking 
into account uncontested claims or facts to the contrary; and 
resolution of the factual issues in the manner sought by the requestor 
would be adequate to justify the action requested (40 CFR 178.32). 
Information submitted in connection with an objection or hearing 
request may be claimed confidential by marking any part or all of that 
information as Confidential Business Information (CBI). Information so 
marked will not be disclosed except in accordance with procedures set 
forth in 40 CFR part 2. A copy of the information that does not contain 
CBI must be submitted for inclusion in the public record. Information 
not marked confidential may be disclosed publicly by EPA without prior 
notice.

VIII. Public Docket

    EPA has established a record for this rulemaking under docket 
control number [OPP-300511] (including any comments and data submitted 
electronically). A public version of this record, including printed, 
paper versions of electronic comments, which does not include any 
information claimed as CBI, is available for inspection from 8:30 a.m. 
to 4 p.m., Monday through Friday, excluding legal holidays. The public 
record is located in Room 1132 of the Public Information and Records 
Integrity Branch, Information Resources and Services Division (7506C), 
Office of Pesticide Programs, Environmental Protection Agency, Crystal 
Mall #2, 1921 Jefferson Davis Highway, Arlington, VA.
    Electronic comments may be sent directly to EPA at:
    [email protected].


    Electronic comments must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption.
    The official record for this rulemaking, as well as the public 
version, as described above will be kept in paper form. Accordingly, 
EPA will transfer any copies of objections and hearing requests 
received electronically into printed, paper form as they are received 
and will place the paper copies in the official rulemaking record which 
will also include all comments submitted directly in writing. The 
official rulemaking record is the paper record maintained at the 
Virginia address in ``ADDRESSES'' at the beginning of this document.

IX. Regulatory Assessment Requirements

    This final rule establishes tolerances under FFDCA section 408(d) 
in response to a petition submitted to the Agency. The Office of 
Management and Budget (OMB) has exempted these types of actions from 
review under Executive Order 12866, entitled Regulatory Planning and 
Review (58 FR 51735, October 4, 1993). This final rule does not contain 
any information collections subject to OMB approval under the Paperwork 
Reduction Act (PRA), 44 U.S.C. 3501 et seq., or impose any enforceable 
duty or contain any unfunded mandate as described under Title II of the 
Unfunded Mandates Reform Act of 1995 (UMRA) (Pub. L. 104-4). Nor does 
it require any prior consultation as specified by Executive Order 
12875, entitled Enhancing the Intergovernmental Partnership (58 FR 
58093, October 28, 1993), or special considerations as required by 
Executive Order 12898, entitled Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations (59 FR 7629, February 16, 1994), or require OMB review in 
accordance with Executive Order 13045, entitled Protection of Children 
from Environmental Health Risks and Safety Risks (62 FR 19885, April 
23, 1997).
    In addition, since these tolerances and exemptions that are 
established on the basis of a petition under FFDCA section 408 (d), 
such as the tolerances in this final rule, do not require the issuance 
of a proposed rule, the requirements of the Regulatory Flexibility Act 
(RFA) (5 U.S.C. 601 et seq.) do not apply. Nevertheless, the Agency has 
previously assessed whether establishing tolerances, exemptions from 
tolerances, raising tolerance levels or expanding exemptions might 
adversely impact small entities and concluded, as a generic matter, 
that there is no adverse economic impact. The factual basis for the 
Agency's generic certification for tolerance actions published on May 
4, 1981 (46 FR 24950), and was provided to the Chief Counsel for 
Advocacy of the Small Business Administration.

X. Submission to Congress and the General Accounting Office

    Under 5 U.S.C. 801(a)(1)(A), as added by the Small Business 
Regulatory Enforcement Fairness Act of 1996, the Agency has submitted a 
report containing this rule and other required information to the U.S. 
Senate, the U.S. House of Representatives, and the Comptroller General 
of the General Accounting Office prior to publication of this rule in 
today's Federal Register. This is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

    Environmental protection, Administrative practice and procedure, 
Agricultural commodities, Pesticides and pests, Reporting and 
recordkeeping requirements.

    Dated: June 30, 1997.
James Jones,
Acting Director, Registration Division, Office of Pesticide Programs.
    Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

    1. The authority citation for part 180 continues to read as 
follows:

    Authority : 21 U.S.C. 346a and 371.

    2. In Sec. 180.472, by adding the text of paragraph (b) to read as 
follows:


Sec. 180.472 1-[(6-Chloro-3-pyridinyl)methyl]-N-nitro-2-
imidazolidinimine].

 * * * * *
    (b) Section 18 emergency exemptions. Time-limited tolerances are 
established for residues of the insecticide imidacloprid in connection 
with use of the pesticide under section 18 emergency exemptions granted 
by EPA. These tolerances will expire and are revoked on the dates 
specified in the following table.

                                                                        
------------------------------------------------------------------------
                                                          Expiration/   
            Commodity              Parts per million    Revocation Date 
------------------------------------------------------------------------
Citrus fruits crop group........  1.0                 December 31, 1998 

[[Page 36698]]

                                                                        
Dried citrus pulp...............  5.0                 December 31, 1998 
------------------------------------------------------------------------

*    *    *    *    *

[FR Doc. 97-17930 Filed 7-8-97; 8:45 am]
BILLING CODE 6560-50-F