[Federal Register Volume 68, Number 131 (Wednesday, July 9, 2003)]
[Notices]
[Pages 40939-40944]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-17104]


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ENVIRONMENTAL PROTECTION AGENCY

[OPP-2003-0204; FRL-7314-1]


Zinc Phosphide; Notice of Filing a Pesticide Petition to 
Establish a Tolerance for a Certain Pesticide Chemical in or on Food

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: This notice announces the initial filing of a pesticide 
petition proposing the establishment of regulations for residues of a 
certain pesticide chemical in or on various food commodities.

DATES: Comments, identified by docket ID number OPP-2003-0204, must be 
received on or before August 8, 2003.

ADDRESSES: Comments may be submitted electronically, by mail, or 
through hand delivery/courier. Follow the detailed instructions as 
provided in Unit I. of the SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT: Sidney Jackson, Registration Division 
(7505C), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 305-7610; e-mail address: [email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    You may be potentially affected by this action if you are an 
agricultural producer, food manufacturer, or pesticide manufacturer. 
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. Potentially affected entities 
may include, but are not limited to:
    [sbull] Crop production (NAICS 111)
    [sbull] Animal production (NAICS 112)
    [sbull] Food manufacturing (NAICS 311)
    [sbull] Pesticide manufacturing (NAICS 32532)
    This listing is not intended to be exhaustive, but rather provides 
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. 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 Get Copies of this Document and Other Related Information?

    1. Docket. EPA has established an official public docket for this 
action under docket identification (ID) number OPP-2003-0204. The 
official public docket consists of the documents specifically 
referenced in this action, any public comments received, and other 
information related to this action. Although a part of the official 
docket, the public docket does not include Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. The official public docket is the collection of materials 
that is available for public viewing at the Public Information and 
Records Integrity Branch (PIRIB), Rm. 119, Crystal Mall 2, 
1921 Jefferson Davis Hwy., Arlington, VA. This docket facility is open 
from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal 
holidays. The docket telephone number is (703) 305-5805.
    2. Electronic access. You may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr/.
    An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets. You may 
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public 
comments, access the index listing of the contents of the official 
public docket, and to access those documents in the public docket that 
are available electronically.

[[Page 40940]]

Although not all docket materials may be available electronically, you 
may still access any of the publicly available docket materials through 
the docket facility identified in Unit I.B.1. Once in the system, 
select ``search,'' then key in the appropriate docket ID number.
    Certain types of information will not be placed in the EPA Dockets. 
Information claimed as CBI and other information whose disclosure is 
restricted by statute, which is not included in the official public 
docket, will not be available for public viewing in EPA's electronic 
public docket. EPA's policy is that copyrighted material will not be 
placed in EPA's electronic public docket but will be available only in 
printed, paper form in the official public docket. To the extent 
feasible, publicly available docket materials will be made available in 
EPA's electronic public docket. When a document is selected from the 
index list in EPA Dockets, the system will identify whether the 
document is available for viewing in EPA's electronic public docket. 
Although not all docket materials may be available electronically, you 
may still access any of the publicly available docket materials through 
the docket facility identified in Unit I.B. EPA intends to work towards 
providing electronic access to all of the publicly available docket 
materials through EPA's electronic public docket.
    For public commenters, it is important to note that EPA's policy is 
that public comments, whether submitted electronically or in paper, 
will be made available for public viewing in EPA's electronic public 
docket as EPA receives them and without change, unless the comment 
contains copyrighted material, CBI, or other information whose 
disclosure is restricted by statute. When EPA identifies a comment 
containing copyrighted material, EPA will provide a reference to that 
material in the version of the comment that is placed in EPA's 
electronic public docket. The entire printed comment, including the 
copyrighted material, will be available in the public docket.
    Public comments submitted on computer disks that are mailed or 
delivered to the docket will be transferred to EPA's electronic public 
docket. Public comments that are mailed or delivered to the docket will 
be scanned and placed in EPA's electronic public docket. Where 
practical, physical objects will be photographed, and the photograph 
will be placed in EPA's electronic public docket along with a brief 
description written by the docket staff.

C. How and to Whom Do I Submit Comments?

    You may submit comments electronically, by mail, or through hand 
delivery/courier. To ensure proper receipt by EPA, identify the 
appropriate docket ID number in the subject line on the first page of 
your comment. Please ensure that your comments are submitted within the 
specified comment period. Comments received after the close of the 
comment period will be marked ``late.'' EPA is not required to consider 
these late comments. If you wish to submit CBI or information that is 
otherwise protected by statute, please follow the instructions in Unit 
I.D. Do not use EPA Dockets or e-mail to submit CBI or information 
protected by statute.
    1. Electronically. If you submit an electronic comment as 
prescribed in this unit, EPA recommends that you include your name, 
mailing address, and an e-mail address or other contact information in 
the body of your comment. Also include this contact information on the 
outside of any disk or CD ROM you submit, and in any cover letter 
accompanying the disk or CD ROM. This ensures that you can be 
identified as the submitter of the comment and allows EPA to contact 
you in case EPA cannot read your comment due to technical difficulties 
or needs further information on the substance of your comment. EPA's 
policy is that EPA will not edit your comment, and any identifying or 
contact information provided in the body of a comment will be included 
as part of the comment that is placed in the official public docket, 
and made available in EPA's electronic public docket. If EPA cannot 
read your comment due to technical difficulties and cannot contact you 
for clarification, EPA may not be able to consider your comment.
    i. EPA Dockets. Your use of EPA's electronic public docket to 
submit comments to EPA electronically is EPA's preferred method for 
receiving comments. Go directly to EPA Dockets at http://www.epa.gov/edocket, and follow the online instructions for submitting comments. 
Once in the system, select ``search,'' and then key in docket ID number 
OPP-2003-0204. The system is an ``anonymous access'' system, which 
means EPA will not know your identity, e-mail address, or other contact 
information unless you provide it in the body of your comment.
    ii. E-mail. Comments may be sent by e-mail to [email protected], 
Attention: Docket ID Number OPP-2003-0204. In contrast to EPA's 
electronic public docket, EPA's e-mail system is not an ``anonymous 
access'' system. If you send an e-mail comment directly to the docket 
without going through EPA's electronic public docket, EPA's e-mail 
system automatically captures your e-mail address. E-mail addresses 
that are automatically captured by EPA's e-mail system are included as 
part of the comment that is placed in the official public docket, and 
made available in EPA's electronic public docket.
    iii. Disk or CD ROM. You may submit comments on a disk or CD ROM 
that you mail to the mailing address identified in Unit I.C.2. These 
electronic submissions will be accepted in WordPerfect or ASCII file 
format. Avoid the use of special characters and any form of encryption.
    2. By mail. Send your comments to: Public Information and Records 
Integrity Branch (PIRIB) (7502C), Office of Pesticide Programs (OPP), 
Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 
Washington, DC 20460-0001, Attention: Docket ID Number OPP-2003-0204.
    3. By hand delivery or courier. Deliver your comments to: Public 
Information and Records Integrity Branch (PIRIB), Office of Pesticide 
Programs (OPP), Environmental Protection Agency, Rm. 119, Crystal Mall 
2, 1921 Jefferson Davis Hwy., Arlington, VA, Attention: Docket 
ID Number OPP-2003-0204. Such deliveries are only accepted during the 
docket's normal hours of operation as identified in Unit I.B.1.

 D. How Should I Submit CBI to the Agency?

    Do not submit information that you consider to be CBI 
electronically through EPA's electronic public docket or by e-mail. You 
may claim information that you submit to EPA as CBI by marking any part 
or all of that information as CBI (if you submit CBI on disk or CD ROM, 
mark the outside of the disk or CD ROM as CBI and then identify 
electronically within the disk or CD ROM the specific information that 
is CBI). Information so marked will not be disclosed except in 
accordance with procedures set forth in 40 CFR part 2.
    In addition to one complete version of the comment that includes 
any information claimed as CBI, a copy of the comment that does not 
contain the information claimed as CBI must be submitted for inclusion 
in the public docket and EPA's electronic public docket. If you submit 
the copy that does not contain CBI on disk or CD ROM, mark the outside 
of the disk or CD ROM clearly that it does not contain CBI. Information 
not marked as CBI will be included in the public docket and EPA's 
electronic public docket without prior

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notice. If you have any questions about CBI or the procedures for 
claiming CBI, please consult the person listed under FOR FURTHER 
INFORMATION CONTACT.

E. What Should I Consider as I Prepare My Comments for EPA?

    You may find the following suggestions helpful for preparing your 
comments:
    1. Explain your views as clearly as possible.
     2. Describe any assumptions that you used.
     3. Provide copies of any technical information and/or data you 
used that support your views.
     4. If you estimate potential burden or costs, explain how you 
arrived at the estimate that you provide.
     5. Provide specific examples to illustrate your concerns.
     6. Make sure to submit your comments by the deadline in this 
notice.
     7. To ensure proper receipt by EPA, be sure to identify the docket 
ID number assigned to this action in the subject line on the first page 
of your response. You may also provide the name, date, and Federal 
Register citation.

II. What Action is the Agency Taking?

     EPA has received pesticide petitions as follow proposing the 
establishment and/or amendment of regulations for residues of a certain 
pesticide chemical in or on various food commodities under section 408 
of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a. 
EPA has determined that these petitions contain data or information 
regarding the elements set forth in FFDCA section 408(d)(2); however, 
EPA has not fully evaluated the sufficiency of the submitted data at 
this time or whether the data support granting of the petitions. 
Additional data may be needed before EPA rules on the petitions.

List of Subjects

    Environmental protection, Agricultural commodities, Feed additives, 
Food additives, Pesticides and pests, Reporting and recordkeeping 
requirements.


    Dated: June 24, 2003.
Debra Edwards,
Director, Registration Division, Office of Pesticide Programs.

Summary of Petitions

    The petitioner's summary of the pesticide petitions is printed 
below as required by FFDCA section 408(d)(3). The summary of the 
petitions was prepared by the petitioner and represents the view of the 
petitioner. The petitions summary announces the availability of a 
description of the analytical methods available to EPA for the 
detection and measurement of the pesticide chemical residues or an 
explanation of why no such method is needed.

Interregional Research Project Number 4 (IR-4)

PP 2E6419, 1E6306, 1E6270, 1E6337, 9E5082, 0E6199, and 1E6292

    EPA has received pesticide petitions (2E6419, 1E6306, 1E6270, 
1E6337, 9E5082, 0E6199, 1E6292) from the IR-4 Project, Center for Minor 
Crop Pest Management, Rutgers, The State University of New Jersey, 681 
U.S. Highway 1 South, North Brunswick, NJ 08902-3390 
proposing, pursuant to section 408(d) of the Federal Food, Drug, and 
Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR 180.284 by 
establishing tolerances for residues of the rodenticide zinc phosphide 
in or on the following raw agricultural commodities:
    [sbull] PP 2E6419 proposes to establish a tolerance in or on 
alfalfa, forage and alfalfa, hay at 0.1 parts per million (ppm).
    [sbull] PP 1E6306 proposes a tolerance in or on barley, grain and 
barley, hay at 0.05 ppm, and barley, straw at 0.2 ppm.
    [sbull] PP 1E6270 proposes a tolerance in or on bean, dry, seed at 
0.05 ppm.
    [sbull] PP 1E6337 proposes tolerances in or on beet, sugar, roots 
at 0.05 ppm and beet, sugar, tops at 0.2 ppm.
    [sbull] PP 9E5082 proposes a tolerance in or on potato at 0.05 ppm.
    [sbull] PP 0E6199 proposes a tolerance in or on timothy hay and 
timothy forage at 0.05 ppm.
    [sbull] PP 1E6292 proposes a tolerance in or on wheat grain; wheat, 
hay; and wheat, straw at 0.05 ppm.
EPA has determined that these petitions contain data or information 
regarding the elements set forth in section 408(d)(2) of the FFDCA; 
however, EPA has not fully evaluated the sufficiency of the submitted 
data at this time or whether the data support granting of the requests. 
Additional data may be needed before EPA rules on the petitions.

A. Toxicological Profile

    1. Acute toxicity. The rat acute oral lethal dose (LD)50 
values for zinc phosphide technical (89% active ingredient (a.i.) 
ranged from 13-35 milligrams/kilogram (mg/kg) body weight (bwt) and 
averaged 21 mg/kg. The acute dermal LD50 was greater than 
2,000 mg/kg for zinc phosphide technical (94% a.i.) in rabbits. The 4-
hour inhalation lethal concentration (LC)50 on end-use 
product was less than 69 mg/cubic meter(m3) air (aerosol). 
Zinc phosphide was not irritating dermally to rabbit skin (94% a.i.) 
and caused only slight conjunctival redness, chemosis, and discharge in 
the rabbit's eyes. Zinc phosphide end-use product did not cause skin 
sensitization in guinea pigs. No toxicology studies were identified by 
EPA which demonstrated the need for an acute dietary risk assessment 
(65 FR 49936).
    2. Genotoxicity. Salmonella TA-strains of bacteria were exposed to 
zinc phosphide (97% a.i.) suspended in dimethyl sulfoxide (DMSO), at 
doses up to 5,000 [mu]g/plate, with and without metabolic activation 
(S9). Zinc phosphide was negative for gene mutation in the Ames test. 
Mouse lymphoma cells were exposed to zinc phosphide (97% a.i.) with and 
without mammalian metabolic activation (S9). Increased mutants at the 
thymidine kinase locus (TK) were induced in a dose-dependent manner at 
doses of 10 through 80 [mu]g/mL (+/- S9). Zinc phosphide was positive 
for gene mutation in this mouse lymphoma assay. Mice were treated with 
zinc phosphide (97% a.i.) suspended in corn oil up to severely toxic 
levels (150 mg/kg). No increased aberrations (micronuclei) were 
induced. Zinc phosphide was negative for mutagenicity in this 
micronucleus test.
    3. Reproductive and developmental toxicity. The requirements for a 
two-generation reproductive toxicity study in rats and a developmental 
study on a non-rodent species were waived in the Reregistration 
Eligibility Decision (RED Zinc Phosphide, EPA 738-R-98-006, July 1998). 
In a developmental toxicity study, the maternal no observed adverse 
effect level (NOAEL) was determined to be 2.0 mg/kg and the lowest 
effect level (LEL) was 4.0 mg/kg based on mortality. The developmental 
NOAEL was at or above 4.0 mg/kg, which was the highest dose tested.
    4. Short- and intermediate-term toxicity. Based on the acute dermal 
LD50 study in rabbits, no appropriate toxic effects were 
identified for risk assessment. In that study no mortalities were 
observed at 5,000 mg/kg. At the lowest observed adverse effect level 
(LOAEL) of 2,000 mg/kg, there was a decrease in body weight. Based on 
the physical properties of the chemical, dermal absorption is expected 
to be very low, since zinc phosphide reacts with water and stomach acid 
to produce the toxic gas phosphine from oral, but not dermal exposure. 
As no endpoint of toxicological concern for dermal

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exposure has been identified, no dermal penetration data were required. 
The requirement for an acute inhalation study has been waived; thus, 
zinc phosphide has been placed in Toxicity Category I for acute 
inhalation exposure.
    5. Chronic toxicity. EPA has established the Reference Dose (RfD) 
for zinc phosphide at 0.0001 mg/kg/day. This RfD is based on a 
subchronic oral study in rats with a NOAEL of 0.1 mg/kg/day and an 
uncertainty factor (UF) of 1,000 based on increased mortality, increase 
in absolute and relative liver weight and hematological changes at the 
LOAEL of 1 mg/kg/day. An uncertainty factor of 100 was applied to 
account for both the interspecies extrapolation and intraspecies 
variability. An additional UF of 10 was applied to account for the lack 
of reproductive data, and the lack of chronic toxicity data in a non-
rodent species (65 FR 49936).
    6. Animal metabolism. Since residues are expected to be minimal or 
nonexistent, the requirement for a metabolism study with zinc phosphide 
has been waived. If new uses result in detectable residues, then this 
requirement will be reinstated.
    7. Metabolite toxicity. Since residues are expected to be minimal 
or nonexistent, the requirement for a metabolism study with zinc 
phosphide has been waived.
    8. Carcinogenicity. The requirement for carcinogenicity studies has 
been waived for zinc phosphide because chronic exposure is expected to 
be negligible.
    9. Endocrine disruption. There are no data available to suggest 
that zinc phosphide will adversely affect the immune or endocrine 
systems.

B. Exposures and Risks

    1. From food and feed uses. Tolerances have been established (40 
CFR 180.284) for the residues of phosphine resulting from the use of 
zinc phosphide, in or on a variety of raw agricultural commodities at 
levels ranging from 0.01 ppm in or on grapes to 0.1 ppm in or on 
grasses (rangeland). Zinc phosphide uses on grapes, pasture, and 
rangeland grasses, sugar beets, and sugar cane are classified as food 
uses. Currently registered uses on alfalfa, barley, wheat, and timothy 
are classified as non-food uses. The recently submitted petitions seek 
to amend the method of applications for these crops as follows:
    i. Alfalfa; from underground or in burrow builder, or bait box use 
to above ground broadcast application. The proposed application would 
limit the timing of application to the period during dormant season 
(Idaho), or following removal of all cut alfalfa and prior to new 
growth obtaining 2 to 3 inches (California and Idaho),
    ii. Barley and wheat; from dormant season use (underground or in 
burrow builders) to above ground broadcast application prior to grain 
head formation.
    iii. Timothy; from dormant season use, with no animal grazing, to 
use during crop dormancy but permitting livestock grazing after 158 
days. These types of applications are classified as food uses; 
therefore, a tolerance is required. There is no reasonable expectation 
of secondary residues in meat, milk, poultry, or eggs. Any residues of 
zinc phosphide ingested by livestock would be metabolized to naturally 
occurring phosphorous compounds. Risk assessments were conducted by EPA 
to assess dietary exposures and risks from zinc phosphide applied as 
non-food use as follows: Acute and chronic 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 1-day or single exposure. Currently, 
it is not known whether the proposed use of zinc phosphide on the 
subject crops will result in acute or chronic human dietary exposure to 
zinc phosphide.
    However, the petitioner notes the following:
    i. Zinc phosphide is not systemic (i.e., it will not move to other 
portions of the plant such as roots and affect a root crop such as 
potatoes or sugar beets).
    ii. Residues of phosphine are less than the limit of quantification 
(0.05) in wheat and barley grain, in dry beans, in potatoes, in sugar 
beet roots, and in timothy hay.
    iii. The grain and sugar beet roots will be processed prior to 
human consumption.
    iv. There is no expectation of secondary residues in meat, milk, 
poultry, and eggs as a result of the registered and proposed uses.
    2. From drinking water. Zinc phosphide degrades rapidly to 
phosphine and zinc ions both of which adsorb strongly to soil and are 
common nutrients in soil. Zinc phosphide and its degradation products 
appear to have low potential for ground water and surface water 
contamination. Therefore, dietary exposure is not expected from either 
ground water or surface water fed drinking water.
    3. From non-dietary exposure. Zinc phosphide is currently 
registered for use on residential non-food sites. A detailed 
residential exposure assessment is contained in the RED for zinc 
phosphide (RED Zinc Phosphide, EPA 738-R-98-006, July 1998). The 
residential exposure assessment evaluated exposure from accidental 
ingestion of zinc phosphide. No other residential exposure assessment 
was required. It is stated in the RED that the Agency believes that 
``accidental ingestion'' of zinc phosphide baits should not be included 
in the FQPA determination for tolerance setting.
    4. Cumulative exposure to substances with a common mechanism of 
toxicity. Section 408(b)(2)(D)(v) requires that, when considering 
whether to establish, modify, or revoke a tolerance, the Agency 
considers ``available information'' concerning the cumulative effects 
of a particular pesticide's residues and ``other substances that have a 
common mechanism of toxicity.'' Zinc phosphide, aluminum phosphide, and 
magnesium phosphide all generate phosphine gas. However, the toxicity 
from phosphine gas is an acute effect and is readily eliminated from 
the body. Aluminum and magnesium phosphide, unlike zinc phosphide which 
is a bait, are used in fumigations. Exposure to phosphine gas from both 
bait and fumigation treatments is highly unlikely. It is unclear 
whether zinc phosphide has a common mechanism of toxicity with other 
substances or how to include this pesticide in a cumulative risk 
assessment. Unlike other pesticides, where a cumulative risk approach 
is based on a common mechanism of toxicity, zinc phosphide does not 
appear to produce a toxic metabolite produced by other substances.

C. Aggregate Exposure

    1. Acute and chronic risk. There are currently no drinking water, 
residential, or dietary components to acute and chronic aggregate 
exposure to zinc phosphide residues. Thus, acute and chronic aggregate 
exposure assessments were not required in the RED (Zinc Phosphide, EPA 
738-R-98-006, July 1998).
    2. 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. No short- or intermediate-term dermal, oral or 
inhalation toxicological endpoints were identified for zinc phosphide. 
Thus, no short- or intermediate-term risk assessments were required in 
the RED (Zinc Phosphide, EPA 738-R-98-006, July 1998).
    3. Aggregate cancer risk for U.S. population. Although zinc 
phosphide is registered for use on food crops, no chronic toxicity or 
carcinogenicity

[[Page 40943]]

studies were required because chronic exposure to zinc phosphide or its 
byproducts were considered to be negligible. Thus, data are not 
available to classify zinc phosphide in terms of carcinogenicity and a 
cancer risk assessment was not performed.

 D. Determination of Safety

    1. U.S. population. The RED set the RfD at 0.0001. EPA generally 
has no concerns for exposures below 100% of the RfD, because the RfD 
represents the level at or below which daily aggregate exposure over a 
lifetime will not pose appreciable risks to human health.
    2. Infants and children. The available data base for zinc phosphide 
does not indicate a potential for an increased sensitivity to infants 
or children; however it does not include a two-generation reproductive 
toxicity study in rats or a developmental toxicity study for a non-
rodent species. The available data provided no indication of increased 
sensitivity of fetal rats to in utero exposure to zinc phosphide. The 
prenatal exposure developmental toxicity study in rats demonstrated no 
developmental effects at the highest dose tested (4.0 mg/kg/day) which 
was maternally toxic. There was no assessment of in utero exposure to 
non-rodents (rabbits), nor was there an assessment of early postnatal 
exposure. The EPA did not require these studies because exposure from 
food sources is expected to be minimal to non-existent. The additional 
uncertainty factor (referred to in Section A.5.) will also accommodate 
the inability to assess the potential for increased sensitivity of 
infants and children, because of the lack of sufficient animal data on 
in utero and early postnatal exposure to zinc phosphide (a prenatal 
developmental toxicity study in rabbits and a two-generation 
reproductive toxicity study in rats). Although residue studies show 
there were quantifiable residues in sugarcane, sugar beets, and 
grasses, these commodities are not direct human foods and no dietary 
consumption is expected. EPA has determined that there is no likelihood 
of residues of zinc phosphide occurring in any processed commodities. 
Also, there is no likelihood of residues of zinc phosphide or phosphine 
being found through transfer of residues on grasses to meat and milk.
    Based upon the likelihood that residues of zinc phosphide will not 
occur in processed commodities, milk and meat, there is a reasonable 
certainty that no harm will result from aggregate exposure to zinc 
phosphide residues.

E. Other Considerations

    1. Metabolism in plants and animals. The nature of the residue in 
plants is adequately understood. The residue of concern is zinc 
phosphide measured as phosphine. There is no expectation of secondary 
residues in meat, milk, poultry, and eggs as a result of the registered 
uses. Residues of zinc phosphide ingested by livestock would be 
immediately converted to phosphine and metabolized to naturally 
occurring phosphorous compounds.
    2. Analytical enforcement methodology. Adequate enforcement 
methodology (colorimetric and GLC/FPD) is available (Pesticide 
Analytical Method II under aluminum phosphide) to enforce the tolerance 
expression. Residues were less than the limit of quantification in all 
raw agricultural commodities except for sugar beet tops (0.05 ppm for 
alfalfa, barley, grain and hay, dry beans, potatoes, sugar beet roots, 
timothy and wheat; 0.1 for barley straw),
    i. Barley grown in the state of Idaho was treated with two 
applications of zinc phosphide at approximately 0.12 lb a.i./A per 
application, 23 to 28 days apart, and were harvested 50 or 60 days 
after the last application. Barley was also harvested 50 days following 
two applications at 0.96 lb a.i./A (8X the proposed application rate). 
Residues were less than the limit of quantification for barley grain 
and hay (0.05 ppm) and straw (0.1). Because no residues were found in 
samples treated at the 8X rate, no processing study is needed.
    ii. Dry beans grown in the state of Idaho were treated with one 
application of zinc phosphide at approximately 0.12 lb a.i./A, and were 
harvested 31 days after the application and allowed to dry in the 
field. Seven days after harvesting the beans were thrashed and samples 
taken. Residues were less than the limit of quantification (0.05 ppm) 
on this commodity.
    iii. Potatoes grown in the state of Idaho were treated with one 
application of zinc phosphide at approximately 0.2 lb a.i./A, and were 
harvested 28 to 31 days later. Potatoes were also harvested 28 to 31 
days later following an application at 1.0 lb a.i./A (5x the proposed 
application rate). Residues were less than the limit of quantification 
(0.05 ppm) on this commodity. Because no residues were found in samples 
treated at the 5X rate, no processing study is needed.
    iv. Sugar beets grown in the state of Idaho were harvested 27 to 29 
days following two treatments of zinc phosphide at approximately 0.2 lb 
a.i./A. Sugar beets were also harvested 27 to 29 days following two 
treatments of zinc phosphide at approximately 4 lb a.i./A (20X the 
proposed application rate). Residues were less than the limit of 
quantification (0.05 ppm) on sugar beet roots. Sugar beet tops 
contained some residue and a tolerance of 0.2 ppm is being proposed for 
sugar beet tops. Because no residues were found in roots treated at the 
exaggerated rate, there is no need for data from processed roots. 
(OPPTS Harmonized Guideline 860.1520(f)(3)(iii)).
    v. Timothy hay grown in the state of Washington was harvested 117 
days following two treatments of zinc phosphide. The first treatment 
was at approximately 0.2 lb a.i./A and the second treatment was at 
approximately 0.4 lb a.i./A (due to applicator error). The hay was 
allowed to dry in the field after harvest. Residues were less than the 
limit of quantification (0.05 ppm) on timothy hay and timothy forage at 
harvest.
    vi. Wheat grown in the state of Idaho was treated with two 
applications of zinc phosphide at approximately 0.12 lb a.i./A per 
application, 22 to 28 days apart, and were harvested 56 to 60 days 
after the last application. Wheat was also harvested 56 days following 
two applications at 0.96 lb a.i./A (8X the proposed application rate). 
Residues were less than the limit of quantification (0.05 ppm) for 
wheat grain, hay and straw. Because no residues were found in samples 
treated at the 8X rate, no processing study is needed.
    vii. Fresh alfalfa grown in the state of California was harvested 
32 days following one treatment of zinc phosphide at approximately 0.2 
lb a.i./A. Fresh alfalfa was also harvested 32 days following one 
treatment of zinc phosphide at approximate 0.4 lbs a.i./A (2X the 
proposed application rate). Residues were less than the limit of 
quantification (0.05 ppm) on fresh alfalfa.
    viii. Alfalfa hay and fresh alfalfa grown in the state of Nebraska 
were harvested 21 days following one treatment of zinc phosphide at 
approximately 0.2 lbs a.i./A. Residues were less than the limit of 
quantification (0.05 ppm) on alfalfa hay and fresh alfalfa.
    ix. Alfalfa hay and alfalfa forage grown in the state of Idaho were 
harvested three times: 28-32 days, 78-83 days, and 121-129 days 
following the second of two treatments of zinc phosphide at 
approximately 0.2 lbs a.i./A. Residues were less than the limit of 
quantification (0.05 ppm) on alfalfa hay and alfalfa forage. (Petition 
for residue tolerance for alfalfa use in Idaho soon to be submitted.)

[[Page 40944]]

F. International Residue Limits

    No CODEX, Canadian or Mexican maximum residue levels have been 
established for zinc phosphide.

G. Rotational Crop Restrictions

     Data for confined accumulation in rotational crops have been 
waived because the physical properties of zinc phosphide precludes 
transfer of residues to rotated crops (Zinc Phosphide RED, EPA 738-R-
98-006, July 1998). Thus, rotational crop restrictions are not 
required.
[FR Doc. 03-17104 Filed 7-8-03; 8:45 am]
BILLING CODE 6560-50-S