[Federal Register Volume 62, Number 228 (Wednesday, November 26, 1997)]
[Rules and Regulations]
[Pages 62986-62993]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31104]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300568; FRL-5750-9]
RIN 2070-AB78


Hexythiazox; Pesticide Tolerances for Emergency Exemptions

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes a time-limited tolerance for 
combined residues of hexythiazox (trans-5-(4-chlorophenyl) -N-
cyclohexyl-4-methyl-2- oxothiazolidine-3-carboxamide) and its 
metabolites containing the (4-chlorophenyl)-4-methyl in or on cotton, 
undelinted seed, and cotton gin byproducts. 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 cotton in California. This regulation establishes a 
maximum permissible level for residues of hexythiazox 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. 
The tolerance will expire and be revoked on October 1, 1998.

DATES: This regulation is effective November 26, 1997. Objections and 
requests for hearings must be received by EPA on or before January 26, 
1998.

ADDRESSES: Written objections and hearing requests, identified by the 
docket control number, [OPP-300568], 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-300568], must also be submitted to: Public 
Information and Records Integrity Branch, Information Resources and 
Services Division (7502C), 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: <a href="/cdn-cgi/l/email-protection#96f9e6e6bbf2f9f5fdf3e2d6f3e6f7fbf7fffab8f3e6f7b8f1f9e0"><span class="__cf_email__" data-cfemail="79160909541d161a121c0d391c091814181015571c0918571e160f">[email protected]</span></a>. 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 5.1/6.1 
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-300568]. 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: David Deegan, 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) 308-9358, e-mail: 
<a href="/cdn-cgi/l/email-protection#1d7978787a7c7333797c6b785d786d7c707c747133786d7c337a726b"><span class="__cf_email__" data-cfemail="5034353537313e7e34312635103520313d31393c7e3520317e373f26">[email protected]</span></a>.

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 a tolerance for 
combined residues of the insecticide hexythiazox (trans-5- (4-
chlorophenyl) -N-cyclohexyl-4-methyl-2- oxothiazolidine-3-carboxamide) 
and its metabolites containing the (4-chlorophenyl)-4-methyl, in or on 
cotton, undelinted seed at 0.1 part per million; and on cotton gin 
byproducts at 2.0 part per million (ppm). This tolerance will expire 
and be revoked on October 1, 1998. EPA will publish a document in the 
Federal Register to remove the revoked tolerance 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

[[Page 62987]]

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 tolerances to set binding precedents for the 
application of section 408 and the new safety standard to other 
tolerances and exemptions.

II. Emergency Exemption for hexythiazox on Cotton and FFDCA 
Tolerances

    The state of California submitted a request to EPA on April 1, 1997 
for a specific exemption from the requirements of FIFRA, allowed under 
provisions of section 18 of FIFRA, for the emergency use of hexythiazox 
on cotton to control various spider mites (strawberry spider mite 
Tetranychus turkestani, twospotted spider mite T. urticae, Pacific 
spider mite T. pacificus, carmine spider mite T. cinabarinus). The 
state contended that an emergency condition was likely to develop 
during the 1997 growing season, due to conditions which have developed 
over the past several years favoring spider mite infestations on 
cotton. The state's request detailed the lack of effective non-chemical 
control measures for this pest. Additionally, three of the four mite 
species have been shown to have developed resistance to alternative 
registered chemicals. Spider mites attack plants primarily as foliage 
feeders. This action reduces plant vigor and growth, which can lead to 
reduced yields and/or nonproductive crops. During the last several 
years, wetter than normal conditions have resulted in more vegetation 
outside the irrigated cotton fields. This habitat has supported larger 
numbers of plant bugs, including mites, which have inflicted increased 
losses on cotton fields. On May 29, 1997 EPA allowed the state to 
invoke it's crisis authority under FIFRA section 18 for the use of 
hexythiazox on cotton for control of spider mites in California. 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 hexythiazox in or on 
cotton. 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 this tolerance without notice and opportunity 
for public comment under section 408(e), as provided in section 
408(l)(6). Although this tolerance will expire and be revoked on 
October 1, 1998, under FFDCA section 408(l)(5), residues of the 
pesticide not in excess of the amounts specified in the tolerance 
remaining in or on cotton, undelinted seed, and cotton gin byproducts 
after that date will not be unlawful, provided the pesticide was 
applied in a manner that was lawful under FIFRA while these tolerances 
were in effect. EPA will take action to revoke this tolerance earlier 
if any experience with, scientific data on, or other relevant 
information on this pesticide indicate that the residues are not safe.
    Because this tolerance is being approved under emergency conditions 
EPA has not made any decisions about whether hexythiazox meets EPA's 
registration requirements for use on cotton or whether a permanent 
tolerance for this use would be appropriate. Under these circumstances, 
EPA does not believe that this tolerance serves as a basis for 
registration of hexythiazox by a State for special local needs under 
FIFRA section 24(c). Nor does this tolerance serve as the basis for any 
State other than California 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 hexythiazox, 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 percent 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

[[Page 62988]]

carcinogenic response and the Agency's knowledge of its mode of action.
    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 nursing and non-
nursing infants, <1 year 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 
hexythiazox and to make a determination on aggregate exposure, 
consistent with section 408(b)(2), for a time-limited tolerance for 
combined residues of hexythiazox (trans-5-(4-chlorophenyl) -N-
cyclohexyl -4-methyl-2- oxothiazolidine-3-carboxamide) and its 
metabolites containing the (4-chlorophenyl)-4-methyl on cotton, 
undelinted seed at 0.1 ppm, and cotton gin byproducts at 2.0 ppm. EPA's 
assessment of the dietary exposures and risks associated with 
establishing the tolerance 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 hexythiazox are 
discussed below.
    1. Acute toxicity. An acute dietary risk assessment is not 
required, since EPA did not identify an acute toxicological endpoint.
    2. Short - and intermediate - term toxicity. For short and 
intermediate-term Margin of Exposure (MOE) calculations, EPA 
recommended use of the maternal NOEL of 240 mg/kg/day from the 
developmental toxicity study in rats. At the LEL of 740 mg/kg/day, 
there was decreased food consumption, decreased body weight and 
increased ovarian weights.
    3.  Chronic toxicity. EPA has established the RfD for hexythiazox 
at 0.025 milligrams/kilogram/day (mg/kg/day). This RfD is based on a 
one year feeding study in dogs with a NOEL of 2.5 mg/kg/day and an 
uncertainty factor

[[Page 62989]]

of 100. The LOEL of 12.5 mg/kg/day was based on hypertrophy of the 
adrenal cortex (both sexes).
    4. Carcinogenicity. Hexythiazox has been classified as a Group C 
chemical (possible human carcinogen) by the Cancer Peer Review 
Committee (CPRC), based on an increased incidence of female mouse liver 
tumors. The Committee recommended using the Q<INF>1</INF>* approach. 
The Q<INF>1</INF>* is 0.039 mg/kg/day<SUP>-1</SUP>.

B. Exposures and Risks

    1.  From food and feed uses. Tolerances have been established (40 
CFR 180.448) for the combined residues of hexythiazox (trans-5-(4-
chlorophenyl) -N-cyclohexyl-4-methyl-2-oxothiazolidine-3-carboxamide) 
and its metabolites containing the (4-chlorophenyl)-4-methyl, in or on 
a variety of raw agricultural commodities. Risk assessments were 
conducted by EPA to assess dietary exposures and risks from hexythiazox 
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 is not required for this pesticide use, as the EPA did not 
identify an acute dietary risk endpoint.
    ii. Chronic exposure and risk. In conducting this chronic dietary 
risk assessment, EPA has made conservative assumptions -- 100% of 
cotton seed commodities (oil and meal) and apple commodities will 
contain residues of hexythiazox and its metabolites and those residues 
will be at the level of the tolerance. Percent crop treated data were 
utilized for pear commodities. These conservative assumptions result in 
an overestimate of human dietary exposure. Thus, in making a safety 
determination for this tolerance, EPA is taking into account this 
conservative exposure assessment.
    The published tolerances for the regulated residue of hexythiazox, 
plus this proposed Section 18 use result in a Anticipated Residue 
Contribution (ARC) that is equivalent to the following percentages of 
the RfD:
    U.S. Population              <1%
    Nursing Infants              <1%
    Non-Nursing Infants (<1 year old)       <1%
    Children (1-6 years old)            <1%
    Children (7-12 years old)            <1%

    The subgroups listed above are: (1) the U.S. population (48 
states); and (2) those for infants and children.
    2. From drinking water. Based on information currently available to 
EPA, hexythiazox is considered persistent in soil. EPA's current data 
also indicates that hexythiazox and soil metabolites are not likely to 
leach to groundwater. There are no established Maximum Contaminant 
Levels for residues of hexythiazox in drinking water. No health 
advisory levels for hexythiazox in drinking water have been 
established.
    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 (RfD's or acute dietary NOEL's) 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 hexythiazox 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 hexythiazox 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. Hexythiazox is not currently 
registered for use on any residential non-food sites. The Agency does 
not expect there to be any meaningful non-dietary residential exposure 
to hexythiazox.
    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.'' 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 hexythiazox 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, 
hexythiazox does not appear to produce a toxic metabolite produced by 
other substances. According to information evaluated related to this 
action, hexythiazox is a member of the thiazolidinone class of 
pesticides and there are no other members of this class. For the 
purposes of this tolerance action, therefore, EPA has not assumed that 
hexythiazox has a common mechanism of toxicity with other substances.

[[Page 62990]]

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

    1. 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 dietary 
exposure (food only) to hexythiazox will utilize <1% of the RfD for the 
U.S. population. The major identifiable subgroup with the highest 
aggregate exposure is non-nursing infants. 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 hexythiazox in drinking water, EPA does not 
expect the aggregate exposure to exceed 100% of the RfD. EPA concludes 
that there is a reasonable certainty that no harm will result from 
aggregate exposure to hexythiazox residues.
    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. EPA believes that uses of hexythiazox may 
constitute a short- and/or intermediate-term exposure scenario. 
However, the Agency is not, at this time, able to complete a 
comprehensive residential risk assessment for many pesticides, 
including hexythiazox. Because there are no residential non-food uses 
registered for hexythiazox, and because there are no other chemicals 
that share its class, and based on the lack of an identified acute 
toxicological endpoint for hexythiazox, and the low percentage (<1%) of 
the RfD occupied by food and water, in the best scientific judgment of 
EPA, short- and intermediate-term aggregate risk will not exceed the 
Agency's level of concern.

D. Aggregate Cancer Risk for U.S. Population

    Based on published tolerances (none are currently pending) and this 
proposed section 18 use, an upper bound lifetime dietary (food only) 
cancer risk estimate of 5.9 x  10<SUP>-7</SUP> was calculated for the 
hexythiazox regulated residue. The calculation used the conservative 
exposure assumptions described above for generating ARC's and amortized 
the cancer risk over a 70-year lifetime (i.e., 5/70, for this first 
year section 18 use). This section 18 use contributes 8.0  x  
10<SUP>-8</SUP> to the upper bound lifetime dietary (food only) cancer 
risk and 5.7  x  10<SUP>-9</SUP> if the cancer risk is amortized over a 
70-year lifetime.
    The cancer risk estimate for the existing hexythiazox uses plus the 
amortized risk estimate for cottonseed commodities does not exceed 
EPA's level of concern. EPA believes the registered uses do not 
constitute a chronic exposure scenario. Thus, no non-dietary, non-
occupational chronic exposure to hexythiazox is expected, or is a 
factor in aggregate cancer risk.

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

    1. Safety factor for infants and children. --i. In general. In 
assessing the potential for additional sensitivity of infants and 
children to residues of hexythiazox, 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.
    ii. Developmental toxicity studies-- a. Rats. In the rat 
developmental study, the maternal (systemic) NOEL was 240 mg/kg/day. 
The maternal LOEL of 720 mg/kg/day was based on decreased food 
consumption and decreased body weight. The developmental (fetal) NOEL 
was 240 mg/kg/day. The developmental LOEL was based on slight delayed 
ossification.
    b. Rabbits. In the rabbit developmental toxicity study, the 
maternal (systemic) NOEL was 1,080 mg/kg/day at the highest dose tested 
(HDT). The developmental (fetal) NOEL was 1,080 mg/kg/day at the 
highest dose tested.
    iii. Reproductive toxicity study. Rats. In the 2-generation 
reproductive toxicity study in rats, the parental (systemic) NOEL was 
20 mg/kg/day. The LOEL of 120 mg/kg/day was based on decreased body 
weight and decreased food consumption. The developmental NOEL was 20 
mg/kg/day. The developmental LOEL of 120 mg/kg/day was based on 
decreased body weight and delayed maturation. The reproductive NOEL was 
120 mg/kg/day at the highest dose tested.
    iv. Pre- and post-natal sensitivity. The pre- and post-natal 
toxicology data base for hexythiazox is complete with respect to 
current toxicological data requirements. There are no pre- or post-
natal toxicity concerns for infants and children, based on the results 
of the rat and rabbit developmental toxicity studies and the 2-
generation rat reproductive toxicity study. In the developmental study 
in rats, the developmental NOEL and LOEL is the same as the maternal 
NOEL and LOEL demonstrating that no extra-sensitivity for infants and 
children is present. In rabbits, there are no maternal or developmental 
effects up to the limit dose of 1,080 mg/kg/day HDT. In the 2-
generation reproductive toxicity study in rats, there are no pup 
effects at doses below maternal effects and the common effects in both 
pups and parental animals decreased body weight also demonstrates that 
there is no extra-sensitivity for infants and children.
    v. Conclusion. Based on the above, EPA concludes that reliable data 
support use of the standard 100-fold uncertainty factor and that an the 
additional safety factor is not needed to protect the safety of infants 
and children.
    2. Chronic risk. Using the conservative exposure assumptions 
described above, EPA has concluded that aggregate exposure to 
hexythiazox from food will utilize is less than 1% of the RfD for 
infants and children. 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 hexythiazox in drinking water and from non-dietary, non-occupational 
exposure, EPA does not

[[Page 62991]]

expect the aggregate exposure to exceed 100% of the RfD. Therefore, 
taking into account the completeness and reliability of the toxicity 
data, the conservative exposure assessment and the fact that 
residential uses do not fall under a chronic exposure scenario, EPA 
concludes that there is a reasonable certainty that no harm will result 
to infants and children from aggregate exposure to hexythiazox 
residues.

V. Other Considerations

A. Metabolism In Plants and Animals

    1. For the purpose of this section 18 request, the nature of the 
residue in plants is adequately understood. The residue of concern is 
hexythiazox and its metabolites containing the (4-chlorophenyl)-4-
methyl-2-oxo-3-thiazolidine moiety (as specified in 40 CFR 180.448).
    2. Although no livestock commodity tolerances are established, the 
nature of the residue in animals is considered to be understood. The 
residue of concern is hexythiazox and its metabolites containing the 
(4-chlorophenyl)-4-methyl-2-oxo-3-thiazolidine moiety.

B. Analytical Enforcement Methodology

    Adequate methods to enforce the tolerance expression have been 
submitted for publication in PAM II. The approved method is designated 
as AMR 985-87 which has been used in a variety of commodities. This 
method is available in PP 5F3254, and by request from U.S. EPA, IRSD/
PIRIB (7502C), 401 M St., SW., Washington DC 20460.

C. Magnitude of Residues

    1. Residues of hexythiazox and its metabolites containing the (4-
chlorophenyl)-4-methyl-2-oxo-3-thiazolidine moiety (expressed as parent 
compound) are not expected to exceed 0.10 ppm in/on cotton, undelinted 
seed. A time-limited tolerance is being established at this level.
    2. It is unknown if residues will concentrate in processed products 
of cotton seed. Therefore, the tolerance level for the RAC has been 
adjusted to account for any possible concentration of the residue. 
Additional tolerances on processed products of cotton are not required 
for this section 18 request.
    3. Residue data are not available for cotton gin byproducts. For 
the purpose of this section 18 request, EPA has estimated residue 
levels in cotton gin byproducts. A search by EPA of the data currently 
available indicates two chemicals for which tolerances are established 
on both cotton gin byproducts and cotton seed. One use is for an at-
planting use of an insecticide. The other cotton seed/cotton gin 
byproducts tolerance pair, 6 ppm and 100 ppm respectively, was 
established for a preharvest desiccant use of a herbicide. Since this 
preharvest desiccant use would be considered a worst case scenario, the 
hexythiazox residues on cotton gin byproducts will be estimated based 
on the concentration factor from that use, 16.6  x  (100/6). Thus, EPA 
estimates that the residue level of hexythiazox on cotton gin 
byproducts will be 2 ppm. A time-limited tolerance is being established 
at 2 ppm for hexythiazox residues in/on cotton gin byproducts. EPA 
notes that residue data for hexythiazox in/on cotton gin byproducts 
will be required for a section 3 registration decision to be made.
    4. Tolerances for secondary residues of hexythiazox in livestock 
commodities are not established. Livestock feedstuffs for cattle (dairy 
and beef), poultry (discussed below)and swine are derived from cotton 
(meal,seed, and hulls). The maximum dietary burden from established 
tolerances on apples and this time-limited tolerance are 0.53 ppm for 
beef cattle, and 0.51 ppm for dairy cattle. EPA has previously reviewed 
a hexythiazox feeding study in dairy cows, in which the only measurable 
residues were in kidney and liver. For the purpose of this time-limited 
tolerance, EPA has translated these data to swine commodities. Based 
upon available data, EPA would not expect detectable residues of 
hexythiazox and its metabolites in commodities derived from cattle 
(beef and dairy), and swine.
    5. Poultry feedstuffs are derived from cotton (cotton seed meal). 
Data concerning the potential for secondary residues in poultry are 
available. The maximum dietary burden from poultry, resulting from use 
associated with this time-limited tolerance is 0.02 ppm. Hexythiazox 
tolerances are not established on other poultry feed items. Based upon 
the total radioactive residue levels from the poultry metabolism study, 
tolerances for secondary residues of hexythiazox in poultry commodities 
are not required for this section 18 request.

D. International Residue Limits

    There are no Codex, Canadian or Mexican maximum residue limits 
established for hexythiazox and its metabolites on cotton seed. Thus, 
harmonization is not an issue for this time-limited tolerance.

E. Rotational Crop Restrictions

    As hexythiazox is not registered for use on crops that are 
typically rotated, rotational crop data are not available and rotation 
crop restrictions are not present on the hexythiazox label. Therefore, 
EPA cannot determine the potential for uptake of residues into crops 
that may be rotated into hexythiazox treated fields. In the absence of 
data, the following rotational crop restriction has been added to the 
section 18 product label: ``In order to avoid illegal residues, do not 
rotate treated fields to crops, other than cotton, for one year 
following application of hexythiazox. After one year following 
application of Hexythiazox, any crops may be rotated into treated 
fields.''

VI. Conclusion

    Therefore, the tolerance is established for combined residues of 
hexythiazox (trans-5-(4-chlorophenyl) -N-cyclohexyl-4-methyl-2- 
oxothiazolidine-3-carboxamide) and its metabolites containing the (4-
chlorophenyl)-4-methyl in cotton, undelinted seed at 0.1 ppm, and on 
cotton gin byproducts at 2.0 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 January 26, 1998 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 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

[[Page 62992]]

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 Record and Electronic Submissions

    The official record for this rulemaking, as well as the public 
version, has been established for this rulemaking under docket control 
number [OPP-300568] (including comments and data submitted 
electronically as described below). 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 official rulemaking record is located at the Virginia 
address in ``ADDRESSES'' at the beginning of this document.
    Electronic comments can be sent directly to EPA at:
    <a href="/cdn-cgi/l/email-protection#620d12124f060d01090716220712030f030b0e4c0712034c050d14"><span class="__cf_email__" data-cfemail="ff908f8fd29b909c949a8bbf9a8f9e929e9693d19a8f9ed1989089">[email protected]</span></a>


    Electronic comments must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption. Comment and data 
will also be accepted on disks in Wordperfect 5.1/6.1 or ASCII file 
format. All comments and data in electronic form must be identified by 
the docket control number [OPP-300568]. Electronic comments on this 
rule may be filed online at many Federal Depository Libraries.

IX. Regulatory Assessment Requirements

    This final rule establishes a tolerance under FFDCA section 408(d). 
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 this tolerance does 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: October 29, 1997.

Peter Caulkins,
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. Section 180.448 is amended as follows:
    i. By designating the existing text as paragraph (a) and adding a 
heading.
    ii. Adding paragraph (b) with a heading.
    iii. Paragraphs (c) and (d) are added and reserved with headings.


Sec. 180.448 Hexythiazox; tolerances for residues.

    (a) General.       *      *      *      

    (b) Section 18 emergency exemptions. Time-limited tolerances are 
established for the combined residues of the insecticide hexythiazox 
and its metabolites containing the (4-chlorophenyl)-4-methyl 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 
------------------------------------------------------------------------
cotton seed, undelinted.........  0.1                 10/1/98           
cotton gin byproducts...........  2.0                 10/1/98           
------------------------------------------------------------------------



[[Page 62993]]

    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]

[FR Doc. 97-31104 Filed 11-25-97; 8:45 am]
BILLING CODE 6560-50-F


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