[Federal Register Volume 62, Number 85 (Friday, May 2, 1997)]
[Proposed Rules]
[Pages 24065-24073]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11504]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300486; FRL-5617-5]
RIN AC18


Bromoxynil; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: This document proposes to establish the following time-limited 
tolerances, to expire on January 1, 1998, for the residues of the 
herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and its 
metabolite DBHA (3,5-dibromo-4-hydrobenzoic acid) resulting from the 
application of octanoic and heptanoic acid esters of bromoxynil to 
cotton: undelinted cottonseed at 7 ppm, cotton gin byproducts at 50 
ppm, cotton hulls at 21 ppm. (Active ingredient codes are 35302 for the 
octanoic acid ester, and 128920 for the heptanoic acid ester. CAS Reg. 
Nos. are 1689-99-2 for the octanoic acid ester, and 56634-95-8 for the 
heptanoic acid ester.) In addition, this document proposes to revise 
tolerances for the residues of bromoxynil, resulting from the 
application of octanoic and heptanoic acid esters of bromoxynil to 
cotton, in or on cattle, hogs, horses, goats, and sheep to 0.5 ppm in 
meat, 3.0 ppm in meat by-products, and 1.0 ppm in fat; and in milk to 
0.1 ppm. Further, this document proposes to establish tolerances for 
residues of bromoxynil, resulting from the application of octanoic and 
heptanoic acid esters of bromoxynil to cotton, at 0.05 ppm in eggs; and 
at 0.05 ppm in poultry meat, meat byproducts, and fat. EPA proposes 
that the tolerances for the cotton commodities expire on January 1, 
1998. Rhone-Poulenc AG Co. submitted a petition to EPA under the 
Federal Food, Drug, and Cosmetic Act as amended by the Food Quality 
Protection Act of 1996 requesting a tolerance on cottonseed.

DATES: Comments, identified by the docket control number ``OPP-
300486,'' must be received on or before May 19, 1997.

ADDRESSES: By mail, submit written comments to: Public Response and 
Program Resources Branch, Field Operations Division (7506C), Office of 
Pesticide Programs, Environmental Protection Agency, 401 M St., SW., 
Washington, DC 20460. In person, bring comments to Rm. 1132, CM #2, 
1921 Jefferson Davis Highway, Arlington, VA 22202.
    Comments and data may also be submitted electronically by following 
the instructions under Unit IX. of this document. No Confidential 
Business Information (CBI) should be submitted through e-mail.
FOR FURTHER INFORMATION CONTACT: By mail: Jim Tompkins, Product Manager 
(PM) 25, 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: Rm. 241, CM #2, 
1921 Jefferson Davis Hwy., Arlington, VA, (703) 305-5697, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: In the Federal Register of May 24, 1995 (60 
FR 27414), EPA established a time-limited tolerance under section 408 
of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a, 
for residues of the herbicide bromoxynil, (3,5-dibromo-

[[Page 24066]]

 4-hydroxybenzonitrile) on cottonseed. This tolerance expired on April 
1, 1997. The tolerance was established in response to a petition filed 
by the Rhone-Poulenc AG Co., P.O. Box 12014, 2 T.W. Alexander Drive, 
Research Triangle Park, NC 27709.
    In the Federal Register of December 24, 1996 (61 FR 67807) (FRL-
5576-8), EPA issued a notice of filing that stated that the Rhone-
Poulenc AG Co. had submitted a pesticide petition to EPA proposing to 
extend the time-limited tolerance on cottonseed. The Agency is issuing 
this proposed rule because, after review of the petition, the Agency 
has determined that as a result of bromoxynil use on cotton: (1) A 
higher tolerance will be needed for cottonseed; (2) existing tolerances 
for bromoxynil on animal commodities (meat, meat by-products, fat, and 
milk) need to be raised; and (3) additional tolerances will be needed 
for other cotton commodities (undelinted cottonseed and cotton gin 
byproducts) and other animal commodities (poultry meat, meat by-
products, fat, and eggs). Comments in response to the notice of filing 
were received from the Union of Concerned Scientists, the Pesticide 
Action Network, the Edmonds Institute, Friends of the Earth, and the 
Environmental Defense Fund. Many of the issues raised by these comments 
are addressed in this document. To the extent specific comments have 
not been addressed herein, they will be addressed in any final action 
on this proposal.

I. Statutory Background

    Section 408 of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 
U.S.C. 301 et seq., as amended by the Food Quality Protection Act of 
1996, Pub. L. 104-170) authorizes the establishment of tolerances 
(maximum residue levels), exemptions from the requirement of a 
tolerance, modifications in tolerances, and revocation of tolerances 
for residues of pesticide chemicals in or on raw agricultural 
commodities and processed foods. Without a tolerance or exemption, food 
containing pesticide residues is considered to be unsafe and therefore 
``adulterated'' under section 402(a) of the FFDCA, and hence may not 
legally be moved in interstate commerce. For a pesticide to be sold and 
distributed, the pesticide must not only have appropriate tolerances 
under the FFDCA, but also must be registered under section 3 of the 
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA, 7 U.S.C. 
136 et seq.).
    Section 408 was substantially amended by the Food Quality 
Protection Act of 1996 (FQPA). Among other things, the FQPA amends the 
FFDCA to bring all EPA pesticide tolerance-setting activities under a 
new section 408 with a new safety standard and new procedures. New 
section 408(b)(2)(A)(I) 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 food, drinking water, and from pesticide use in 
gardens, lawns, or buildings (residential and other indoor uses) 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. . . .''

II. 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. For many 
of these 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 the studies have 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. 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 by EPA to pose a reasonable 
certainty of no harm. For threshold effects other than those assessed 
under the RfD, EPA generally calculates a margin of exposure (MOE). The 
MOE is a measure of how close the exposure comes to the NOEL. The NOEL 
is selected from a study of appropriate duration and route of exposure. 
The MOE is the NOEL from the selected study divided by exposure. MOEs 
greater than 100 are generally considered to show a reasonable 
certainty of no harm.
    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 margin of exposure 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.
    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, and other non-
occupational exposures, such as where residues leach into groundwater 
or surface water that is consumed as drinking water and exposures 
resulting from indoor and outdoor residential 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. The TMRC is a 
``worst-case'' estimate since it is based on the assumptions that food

[[Page 24067]]

contains pesticide residues at the tolerance level and that 100 percent 
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 which show, generally, that pesticide 
residues in most foods when they are eaten are well below established 
tolerances.

III. Toxicology 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. Bromoxynil is applied to crops in the form of bromoxynil 
octanoate and bromoxynil heptanoate. These starting materials are 
metabolized to bromoxynil phenol. The nature of the toxic effects 
caused by bromoxynil is discussed below.

A. Phenol Technical-grade Bromoxynil

    1. Several acute toxicity studies were performed, placing 
technical-grade bromoxynil in Toxicity Category II.
    2. An acute oral toxicity study in rats resulted in 
LD50=81 milligrams/kilograms (mg/kg) (males) and 93 mg/kg 
(females).
    3. A 2-year combined feeding/carcinogenicity study was conducted 
with rats administered (oral) dosages of 0, 60, 190, or 600 parts per 
million (ppm) (0, 2.6, 8.2, or 28 mg/kg/day in males; 0, 3.3, 11.0, or 
41 mg/kg/day in females) bromoxynil phenol in the diet. In males, the 
NOEL is 2.6 mg/kg/day, and the lowest-effect-level (LEL) is 8.2 mg/kg/
day. In females, the NOEL is 3.3 mg/kg/day, and the LEL is 11.0 mg/kg/
day. This study did not demonstrate any increase in tumor incidences in 
either male or female rats.
    4. A 120-week combined feeding/carcinogenicity study was conducted 
with rats administered bromoxynil phenol in the diet at dose levels of 
0, 10, 30, or 100 ppm (0, 0.5, 1.5, or 5 mg/kg/day). In both males and 
females, the NOEL and LEL was 5 mg/kg/day and >5 mg/kg/day, 
respectively. This study was negative for carcinogenicity. This study 
is considered supplementary.
    5. A 1-year chronic oral study was conducted with dogs administered 
bromoxynil phenol at dose levels of 0, 0.1, 0.3, 1.5, or 7.5 mg/kg/day 
in capsules. A threshold NOEL/LOEL of 1.5 mg/kg/day was determined in 
this study based on slightly decreased body weight gain in males. At 
7.5 mg/kg/day, additional toxic effects were observed in both males and 
females. The RfD is based on this study.
    6. An 18-month carcinogenicity study was conducted with mice 
administered bromoxynil phenol at dose levels of 0, 10, 30, or 100 ppm 
(0, 1.3, 3.9, or 13 mg/kg/day) in the diet. For males, dose-related 
increases in hyperplastic nodules and liver adenomas/carcinomas were 
observed which were statistically significant at the 13 mg/kg/day dose 
level. Increased relative liver weights were also observed at 13 mg/kg/
day. In females, increased absolute kidney weights and relative liver 
and kidney weights were observed at 13 mg/kg/day. The study was 
negative for carcinogenicity for females, but the doses were considered 
to be not high enough.
    7. An 18-month carcinogenicity study was conducted with mice 
administered bromoxynil phenol in the diet at dose levels of 0, 20, 75, 
or 300 ppm (0, 3.1, 12, or 46 mg/kg/day in males; 0, 3.7, 14, or 53 mg/
kg/day in females). In males, treatment-related increases in liver 
adenomas/carcinomas were observed at all dose levels. At 12 mg/kg/day 
and higher in males, gross pathologic and histopathologic effects were 
also noted in the liver. In females, treatment-related increases in 
liver carcinomas were observed at 53 mg/kg/day. At 14 mg/kg/day and 
higher in females, histopathologic effects were also noted in the 
liver. The results of this study are discussed more fully in Unit IV. 
of this preamble addressing carcinogenicity classification.
    8. A developmental toxicity study was conducted with rats 
administered (orally) bromoxynil phenol at dose levels of 0, 4, 12.5, 
or 40 mg/kg/day. The maternal NOEL and LEL are 12.5 mg/kg/day and 40 
mg/kg/day, respectively. The developmental NOEL and LEL are 4 mg/kg/day 
and 12.5 mg/kg/day, respectively, based on increased incidence of 
supernumerary ribs.
    9. A developmental toxicity study was conducted with rats 
administered (orally) bromoxynil phenol at dose levels of 0, 5, 15, or 
35 mg/kg/day. The maternal NOEL and LEL are 5 mg/kg/day and 15 mg/kg/
day, respectively. The developmental NOEL and LEL are less than 5 mg/
kg/day and 5 mg/kg/day, respectively, based on increased incidence of 
supernumerary ribs.
    10. A developmental toxicity study was conducted with rats 
administered (orally) bromoxynil phenol at dose levels of 0, 1.7, 5, or 
15 mg/kg/day. The maternal NOEL and LEL are 5 mg/kg/day and 15 mg/kg/
day, respectively. The developmental NOEL and LEL are 5 mg/kg/day and 
15 mg/kg/day, respectively, based on increased incidence of 
supernumerary ribs.
    11. A developmental toxicity study was conducted with rabbits 
administered (orally) bromoxynil phenol at dose levels of 0, 15, 30, or 
60 mg/kg/day. The maternal NOEL and LEL are 15 mg/kg/day and 30 mg/kg/
day, respectively. The developmental NOEL and LEL are <15 mg/kg/day and 
15 mg/kg/day, respectively, based on increased incidence of 
supernumerary ribs.
    12. A developmental toxicity study was conducted with rabbits 
administered (orally) bromoxynil phenol at dose levels of 0, 30, 45, or 
60 mg/kg/day. The maternal NOEL and LEL are 45 mg/kg/day and 60 mg/kg/
day, respectively. The developmental NOEL and LEL are <30 mg/kg/day and 
30 mg/kg/day, respectively, based on decreased fetal weights.
    13. A developmental toxicity study was conducted with mice 
administered (orally) bromoxynil phenol at dose levels of 0, 11, 32, or 
96 mg/kg/day. The maternal NOEL and LEL are 11 mg/kg/day and 32 mg/kg/
day, respectively. The developmental NOEL and LEL are 32 mg/kg/day and 
96 mg/kg/day, respectively, based on increased supernumerary ribs, 
decreased fetal weights, and unossified caudal vertebrae.
    14. A reproduction study was conducted with rats administered 
(orally) bromoxynil phenol at dose levels of 0, 10, 50, or 250 ppm (0, 
0.8, 4, or 21 mg/kg/day) in the diet for 2 generations. The systematic 
adult rat NOEL is 4 mg/kg/day, and the LEL is 21 mg/kg/day. The 
reproductive NOEL is 21 mg/kg/day, and the LEL is >21 mg/kg/day. The 
postnatal development NOEL is 4 mg/kg/day, and the LEL is 21 mg/kg/day.
    15. A reproduction study was conducted with rats administered 
(orally) bromoxynil phenol at dose levels of 0, 30, 100, or 300 ppm (0, 
1.5, 5, or 15 mg/kg/day) in the diet for 3 generations. The systemic 
adult rat NOEL is 1.5 mg/kg/day, and the LEL is 5 mg/kg/day. The 
reproductive NOEL is 15 mg/kg/day, and the LEL is >15 mg/kg/day. The 
offspring developmental NOEL is 5 mg/kg/day, and the LEL is 15 mg/kg/
day. All the NOELs and LELs in this study are considered to be 
tentative.
    16. Mutagenicity data included an unscheduled DNA synthesis study 
in rat primary hepatocytes (negative); an in vitro transformation assay 
in mouse cells (negative); a sister chromosomal

[[Page 24068]]

exchange study in CHO cells (negative); a forward mutation study in 
mouse lymphoma cells (negative without activation and positive with 
activation); a DNA repair test in E. coli (positive without and with 
activation); an in vitro chromosomal aberration assay in CHO cells 
(negative without activation and positive with activation); two 
separate micronucleus assays in mice (both negative); a forward 
mutation assay in CHO cells (negative); and an Ames study in Salmonella 
typhimurium (negative with and without activation).

B. Heptanoate Technical-grade Bromoxynil

    1. Several acute toxicity studies were performed, placing 
technical-grade bromoxynil heptanoate in Toxicity Category II.
    2. An acute oral toxicity study in rats resulted in 
LD50=362 mg/kg (males) and LD50=292 mg/kg 
(females).
    3. A general metabolism study was conducted with rats. Bromoxynil 
heptanoate is rapidly absorbed and widely distributed in most tissues. 
Most of the radioactivity was excreted in the urine, mostly in the form 
of bromoxynil phenol. There was no significant retention in tissues 
after 7 days. Essentially, bromoxynil heptanoate was metabolized to 
bromoxynil phenol via ester hydrolysis.

C. Octanoate Technical-grade Bromoxynil

    1. Several acute toxicity studies were performed, placing 
technical-grade bromoxynil octanoate in Toxicity Category II.
    2. An acute oral toxicity study in rats resulted in 
LD50=400 mg/kg (males) and LD50=238 mg/kg 
(females).
    3. A 13-week oral study was conducted with rats administered 
bromoxynil octanoate at dose levels of 0, 150, 600, or 1,100 ppm (0, 
11, 45, or 91 mg/kg/day in males; 0, 13, 55, or 111 mg/kg/day in 
females) in the diet. In males, the NOEL and LEL are 45 mg/kg/day and 
91 mg/kg/day, respectively. In females, the NOEL and LEL are 13 mg/kg/
day and 55 mg/kg/day, respectively.
    4. A 13-week oral study was conducted with dogs administered 
bromoxynil octanoate in capsules at dose levels of 0, 0.43, 1.43, or 
7.14 mg/kg/day. In males and females, the NOEL and LEL are 0.43 mg/kg/
day and 1.43 mg/kg/day, respectively.
    5. A developmental toxicity study was conducted with rats 
administered (orally) bromoxynil octanoate at dose levels of 0, 2.4, 
7.3, or 21.8 mg/kg/day. The maternal NOEL and LEL are 7.3 mg/kg/day and 
21.8 mg/kg/day, respectively. The developmental NOEL and LEL are 7.3 
mg/kg/day and 21.8 mg/kg/day, respectively, based on increased 
supernumerary ribs and decreased fetal weights.
    6. Mutagenicity data included the following: an Ames study in 
Salmonella typhimurium (negative with and without activation); a 
micronucleus assay in mice (negative); and an unscheduled DNA synthesis 
study in rat primary hepatocytes (negative).
    7. A general metabolism study was conducted with rats. Bromoxynil 
octanoate is rapidly absorbed and widely distributed in most tissues. 
Most of the radioactivity was excreted in the urine, mostly in the form 
of bromoxynil phenol. There was no significant retention in tissues 
after 7 days. Essentially, bromoxynil octanoate was metabolized to 
bromoxynil phenol via ester hydrolysis.

IV. Dose Response Assessment

    1. Carcinogenicity classification. Using EPA's ``Guidelines for 
Carcinogen Risk Assessment'' published September 24, 1986 (51 FR 
33992), EPA has classified bromoxynil as a Group ``C'', possible human 
carcinogen, with a Q1* for bromoxynil phenol of 1.03 x 10-1 
(mg/kg/day)-1. This classification was based primarily on 
results in two mouse carcinogenicity studies. In one study, a 
statistically significant increase in and combined liver adenomas/
carcinomas was observed in male mice at the highest dose tested. For 
carcinomas, there was not a statistically significant increase at any 
dose. A statistically significant increased incidence of neoplasms was 
not observed in female mice, but the doses for females were determined 
to be inadequate. In another study, a statistically significant 
increased incidence of combined liver adenomas/carcinomas was observed 
in male mice at all dose levels and in female mice at the highest dose. 
For carcinomas, the male mice had a statistically significant increase 
at the high and low dose (but not the mid-dose) and the females had a 
statistically significant increase at the high dose. Following a second 
pathology examination of the male mice, the results were a 
statistically significant increase at the low and high doses for 
combined adenomas/carcinomas and for carcinomas a statistically 
significant increase at the high dose. Bromoxynil was not carcinogenic 
in the rat. Information from the mutagenicity studies, which included 
three positive studies, provided additional support for the ``C'' 
classification.
    2. Reference Dose (Rfd). For systemic effects other than cancer, 
the RfD represents the level at or below which daily aggregate dietary 
exposure over a lifetime will not pose appreciable risks to human 
health. The RfD is determined using the toxicological end-point or NOEL 
from the most sensitive mammalian toxicological study. To assure the 
adequacy of the RfD, the Agency uses an uncertainty factor in deriving 
it. The RfD for bromoxynil is 0.015 mg/kg/day based on the threshold 
NOEL/LOEL of 1.5 mg/kg/day determined in the 1-year chronic oral study 
in dogs using bromoxynil phenol as the test material. An uncertainty 
factor of 100 was used for interspecies extrapolation and intraspecies 
variability.
    3. Developmental toxicant determination. Bromoxynil phenol and 
bromoxynil octanoate both induce developmental toxicity at levels below 
those which cause maternal toxicity. The induction of supernumerary 
ribs is the most sensitive indicator of developmental toxicity in rats, 
mice and in certain studies in rabbits. Other forms of developmental 
toxicity are observed at higher dose levels.
    4. Acute risk/developmental effects. For acute dietary risk 
assessment, EPA has chosen to use the NOEL of 4 mg/kg/day, based on 
developmental effects in an oral rat developmental toxicity study (MRID 
# 40466802) at the LOEL of 5 mg/kg/day from a second oral rat 
developmental toxicity study (MRID # 00116558). Since the effect of 
concern, increased incidence of supernumerary ribs in fetuses, occurs 
in utero during gestation, this risk assessment is only directly 
applicable to females of child-bearing age (population sub-group of 
females 13+ yrs old).
    5. Acute risk/systemic effects other than developmental. EPA has 
concluded that an additional endpoint of concern should be established 
for assessing the acute dietary risk for bromoxynil exposure to 
population groups (including infants and children) other than females 
13+ years. Acute (one-day) dietary exposure estimates will be compared 
to an endpoint (NOEL) of 8 mg/kg/day derived from the data of a 13-week 
oral toxicity study in dogs using bromoxynil phenol as the test 
material (MRID 43166701). The LOEL was established at 12 mg/kg/day, 
based on increased incidence of panting on day 1 following a single 
oral dose of the test material. This suggests a compensatory reaction 
to the effects of the test material, which at higher doses is expressed 
as elevated body temperature.

V. Aggregate Exposure Assessment

    In examining aggregate exposure, FFDCA section 408(b)(2) directs 
EPA to

[[Page 24069]]

consider available information concerning exposures from pesticide 
residue in food, water, and all other nonoccupational exposures. The 
aggregate sources of exposure the Agency looks at includes food, 
drinking water (which includes both surface water and groundwater), and 
exposure from pesticide use in gardens, lawns, or buildings 
(residential and other indoor uses).

A. Non-dietary (Residential ) Exposure Assessment

    Currently, there are no registered homeowner uses for bromoxynil 
and current labeling restricts all turfgrass use to non-residential 
areas. The possibility of post-application exposure to persons 
following bromoxynil application to nonresidential turfgrass exists, 
but is not likely to be significant in either amount or duration (and 
cannot be quantified at this point).

B. Dietary Exposure Assessment

    Use of a agricultural pesticide may result, directly or indirectly, 
in pesticide residues in food. Primary residues or indirect/inadvertent 
residues in agricultural commodities are determined by chemical 
analysis. To account for the diversity of growing conditions, cultural 
practices, soil types, climates, crop varieties and methods of 
application of the pesticide, data from studies that represent the 
commodities are collected and evaluated to determine an appropriate 
level of residue that would not be exceeded if the pesticide is used as 
represented in the studies. In evaluating food exposures, EPA takes 
into account varying consumption patterns of major identifiable 
subgroups of consumers, including infants and children.
    1. Plant/animal metabolism and magnitude of the residue tolerance 
assessment. The nature (metabolism) of bromoxynil in plants and animals 
is adequately understood for the purposes of these tolerances. There 
are no Codex, Canadian, or Mexican maximum residue levels established 
for residues of bromoxynil on cotton. In all the plant and animal 
(poultry and ruminants) metabolism studies submitted, the residue of 
concern were parent bromoxynil and the metabolite DBHA. The tolerances 
for cotton commodities are expressed in terms of bromoxynil and DBHA. 
Tolerances for meat and milk commodities, however, are expressed only 
in terms of bromoxynil because no satisfactory enforcement method has 
been validated for DBHA in such commodities. Transfer of DBHA residues 
to tissues in animals is likely to be equal to or less than that for 
parent bromoxynil. Based on this determination, coupled with worst-case 
assumptions concerning the amount of bromoxynil and DBHA present in 
animal feed, the Agency can make reasonable estimates of maximum DBHA 
concentrations in animal commodities based on measured parent 
bromoxynil residues. Therefore, the Agency has determined that 
expressing tolerances for bromoxynil in terms of the parent only can 
serve as an adequate indicator of the total amount of residue 
(bromoxynil parent and DBHA combined) that is present.
    Although the maximum application rate for this use is 1.5 lb active 
ingredient/acre (ai/acre), field trial residue data are currently 
available only for a 4.5 lb ai/acre application rate. After conducting 
these studies, the petitioner proposed lowering the maximum application 
rate from 4.5 lb ai/acre to 1.5 lb ai/acre. These tolerances were 
determined based on extrapolation of data from studies conducted using 
the 4.5 lb ai/acre application rate. The Agency does not believe that 
there will necessarily be a linear relationship between maximum 
residues and the application rate due to the variability in residue 
levels in individual commodities. However, at the 1.5 lb ai/acre rate, 
lower maximum residues would be expected compared to those observed in 
the studies conducted at 4.5 lb ai/acre. The Agency has determined the 
required tolerances for this use based on the variability observed in 
the available residue data for cotton and the reduction in the 
application rate. EPA is proposing to include a tolerance for cotton 
gin byproducts, although this was not done previously, because EPA 
procedures have been revised since the previous tolerance was set to 
include cotton gin byproducts in the dietary assessment for livestock. 
In addition, a separate tolerance is being set for cottonseed hulls 
because data show that bromoxynil and DBHA residues concentrate in 
cottonseed hulls. Further, because of the inclusion of cotton gin trash 
in the livestock dietary assessment, revised tolerances are needed for 
milk and meat of cattle, hogs, horses, goats and sheep. Inclusion of 
the metabolite DBHA in the livestock dietary assessment also resulted 
in the need to establish tolerances for bromoxynil residues in poultry. 
Required tolerances for residues of bromoxynil and DBHA in cotton 
commodities are 7 ppm in cottonseed, 50 ppm in cotton gin by-products, 
and 21 ppm in cottonseed hulls. Required tolerances for residues of 
bromoxynil in cattle, hogs, horses, goats, and sheep are 0.5 ppm in 
meat, 3.0 ppm in meat byproducts, and 1.0 ppm in fat. Required 
tolerances for residues of bromoxynil in milk are 0.1 ppm. Required 
tolerances for residues of bromoxynil in poultry are 0.05 ppm in meat, 
meat-byproducts, fat, and eggs.
    2. Plant/animal metabolism and magnitude of the residue 
determination of anticipated residues. Anticipated residues used for 
risk assessment determination were calculated based on a maximum 
application rate of 1.5 lb ai/acre and treatment of 3 percent of cotton 
in the U.S. with bromoxynil, and estimated bromoxynil-treated 
percentages of other crops. 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 the upper end estimate of percent 
of crop treated, the Agency is reasonably certain that exposure is not 
understated for any significant subpopulation group. For cotton, the 
percent of the crop that can be treated will be capped at 3 percent by 
the bromoxynils registration. 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. As a result of this use, the maximum 
combined residues of parent bromoxynil and DBHA are not expected to 
exceed 0.38 ppm in cottonseed meal and 1.26 ppm in cottonseed oil. 
Based on the bromoxynil ruminant feeding study, the maximum residues 
possible in animal commodities are 0.53 ppm in meat, 2.96 ppm in meat 
byproducts, 1.08 ppm in fat, and 0.059 ppm in milk. Based on the 
bromoxynil poultry feeding study, the maximum residues possible in 
poultry commodities are 0.064 ppm in meat, 0.47 ppm in meat by-
products, 0.10 ppm in fat, and 0.0313 ppm in eggs. Based on the 
bromoxynil ruminant feeding study, the anticipated residues in animal 
commodities are 0.0025 ppm in meat, 0.014 ppm in meat by-products, 
0.005 ppm in fat, and 0.00044 ppm in milk. Based on the bromoxynil 
poultry feeding study, the anticipated residues in poultry commodities 
are 0.00015 ppm in meat, 0.00116 ppm in meat by-products, 0.00025 ppm 
in fat, and 0.00008 ppm in eggs.
    3. Drinking water. Available data indicate that bromoxynil is not a 
groundwater contaminant because it does not exhibit the mobility or 
persistence characteristics of pesticides that are normally found in 
ground water. Although bromoxynil octanoate

[[Page 24070]]

has been found to be mobile under certain conditions (sand, sandy loam, 
and loam soils), it dissipates in the environment by abiotic 
hydrolysis, photodegradation and microbially-mediated metabolism. Also, 
although bromoxynil has the potential to leach to ground water under 
certain conditions, its rapid aerobic and anaerobic degradation reduces 
the likelihood of ground water contamination. As a worst-case screen, 
modeled chronic and acute estimates for bromoxynil in runoff water have 
been used to assess possible exposure via drinking water. The EPA 
drinking water risk estimates are based on an exposure modeling 
procedure called GENEEC (GENeric Expected Environmental Concentration), 
routinely used to estimate residue surface water runoff (for ecological 
risk assessment) but a new tool for human exposure and risk assessment. 
GENEEC estimates concentrations based on a few basic chemical 
parameters and pesticide label application information. GENEEC is a 
model which uses a chemical's soil/water partition coefficient and 
degradation half-life values to estimate runoff from a 10 hectare 
agricultural field into a 1 hectare by 2 meter deep pond. GENEEC 
considers reduction in dissolved pesticide concentration due to 
adsorption of pesticide to soil or sediment, incorporation, degradation 
in soil before wash off to a water body, direct deposition of spray 
drift into the water body, and degradation of the pesticide within the 
water body. It does not consider the potential reduction or removal of 
the pesticide and/or its degradates by a drinking water treatment 
system. Again, GENEEC should be considered a screen since it can 
substantially over-estimate the actual drinking water concentrations. 
Based on the model, EPA estimated the high-end level of exposure in 
surface water to be 7.2 ppb, and the average level to 0.3 ppb. For 
analysis of acute risk, EPA used high end consumption estimates from 
the publication Total Water and Tapwater Intake in the United States 
Population-Based Estimates of Quantities and Sources of 40.5 g/kg/day 
for the entire U.S. population, 126.5 g/kg/day for nonnursing infants, 
39.6 g/kg/day for pregnant women (>13 years old), and 53.3 g/kg/day for 
the southern U.S. For analysis of chronic risk, EPA used an average 
consumption estimate from this publication of 20.9 g/kg/day for the 
southern U.S. The estimate for water consumption in the southern U.S. 
was used for the chronic risk assessment because this value is slightly 
higher than that for the entire U.S. population, and, therefore, 
calculation based on consumption in the southern U.S. adequately 
accounts for risk in the south as well as the overall U.S. population.
    3. 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 be helpful in 
determining whether a pesticide shares a common mechanism of toxicity 
with any other substances, EPA does not at this time have the 
methodology to resolve the scientific issues concerning common 
mechanism of toxicity in a meaningful way. EPA has begun a pilot 
process to study this issue further through 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 
mechanisms issues can be resolved. These pesticides include pesticides 
that are toxicologically dissimilar to existing chemical substances (in 
which 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 bromoxynil 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, bromoxynil 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 bromoxynil has a 
common mechanism of toxicity with other substances. After EPA develops 
methodologies for more fully applying common mechanism of toxicity 
issues to risk assessments, the Agency will develop a process (either 
as part of the periodic review of pesticides or otherwise) to reexamine 
those tolerance decisions made earlier.
    The registrant must submit, upon EPA's request and according to a 
schedule determined by the Agency, such information as the Agency 
directs to be submitted in order to evaluate issues related to whether 
bromoxynil shares a common mechanism of toxicity with any other 
substance and, if so, whether any tolerance for bromoxynil needs to be 
modified or revoked.

VI. Determination of Safety

A. General

    1. Acute dietary. As part of the hazard assessment process, the 
Agency reviews the available toxicology data base to determine the 
endpoints of concern. For acute dietary risk, the Agency has determined 
Margin of Exposure (MOE) by dividing the NOEL from the relevant 
toxicological study by the expected consumption during one day (MOE = 
NOEL/exposure). An estimated MOE of 100 will be considered to be 
adequately protective for bromoxynil. To estimate acute dietary risk 
for developmental effects from food sources, an MOE of 400 was 
calculated using 1-day dietary exposure estimates for U.S women (age 
13+ years) and the NOEL of 4 mg/kg/day derived from an oral 
developmental toxicity study in rats. To estimate acute dietary risk 
for developmental effects from water sources, an MOE of >10,000 was 
calculated using an estimate of 7.2 parts per billion (ppb) water 
contamination and the endpoint (NOEL) of 4 mg/kg/day. An increased 
incidence of supernumerary ribs was observed at the LEL in the oral 
developmental toxicity study in rats and in several other developmental 
toxicity studies. To estimate acute dietary risk for systemic effects, 
other than developmental from food sources, an MOE of 270 was 
calculated using 1-day dietary exposure for infants (the most highly 
exposed population group) and a NOEL of 8 mg/kg/day derived from a 13-
week oral

[[Page 24071]]

toxicity study in dogs. To estimate acute dietary risk for systemic 
effects, other than developmental from water sources, an MOE of >8,000 
was calculated using an estimate of 7.2 ppb water contamination and a 
NOEL of 8 mg/kg/day. In the oral toxicity study in dogs, an increased 
incidence of panting, suggestive of a compensatory reaction to elevated 
body temperatures, was observed on day 1.
    An assessment of aggregate (food/water) acute exposure has been 
made on the assumption of a constant background contamination level in 
water and an acute (one day) exposure from food sources. The relatively 
low level of contamination assumed for water does not significantly 
increase the upper-bound exposure estimate from foods of 0.01 mg/kg/day 
(MOE = 400 for U.S. women).
    2. Chronic dietary. Based on the exposure assessment above, the 
general U.S. population and all population sub-groups are estimated to 
be exposed at a level less than 1 percent of the bromoxynil RfD of 
0.015 mg/kg/day. For food sources, the lifetime upperbound carcinogenic 
risk estimate including cotton is 1.5 x 10-6 for the U.S. 
population including infants and children. For water sources, 
carcinogenic risk, based on the estimated chronic level of 0.3 ppb and 
estimated drinking water consumption (20.9 g/kg/day for the southern 
U.S.) is at most 6.3 x 10-7 for the southern U.S., and is 
probably much lower.
    EPA believes that a risk estimate of this level generally 
represents a negligible risk, as EPA has traditionally applied that 
concept. EPA has commonly referred to a negligible risk as one that is 
at or below 1 in 1 million (1 x 10-6). Quantitative cancer 
risk assessment is not a precise science. There are a significant 
number of uncertainties in both the toxicology used to derive the 
cancer potency of a substance and in the data used to measure and 
calculate exposure. Thus, EPA generally does not attach great 
significance to numerical estimates that differ by approximately a 
factor of 2. Additionally, there are several other factors here which 
support a negligible risk finding. The component of this risk from 
bromoxynil residues in water (6.3 x 10-7) is significantly 
overstated. The level of bromoxynil residues in water was estimated by 
a model that does not take into account either the reduction that could 
be expected from treatment of the water or that residues would be 
reduced because bromoxynil use is permitted only on certain crops and 
only some fraction of those crops would be treated. This latter factor 
alone can be quite significant. For example, for cotton, treatment is 
limited to 3 percent of the crop. Further, EPA is in the process of 
reevaluating all of the bromoxynil uses this year as a part of FIFRA 
reregistration. This will permit EPA to better evaluate the total 
bromoxynil cancer risk and take steps to reduce any cancer risks of 
concern. For all of these reasons, EPA considers the carcinogenic risk 
from bromoxynil to be negligible within the meaning of that standard as 
it has been traditionally applied by EPA.
    Accordingly, EPA concludes that there is a reasonable certainty 
that no harm will result to the general population and major 
identifiable population subgroups from aggregate exposure to 
bromoxynil. Specific risks to infants and children other than cancer 
are discussed below.

B. Determination of Safety for Infants and Children

    In assessing the potential for additional sensitivity of infants 
and children to residues of bromoxynil, EPA considered data from 
several developmental toxicity studies and reproduction studies. The 
developmental toxicity studies are designed to evaluate adverse effects 
on the developing organism resulting from pesticide exposure during 
prenatal development. 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 10-
fold 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 data base 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 
margin of exposure analysis or through using uncertainty (safety) 
factors in calculating a dose level that poses no appreciable risk to 
humans. In either case, EPA generally defines the level of appreciable 
risk as exposure that is greater than 1/100 of the NOEL in the animal 
study appropriate to the particular risk assessment. This 100-fold 
uncertainty (safety) factor/margin of exposure (safety) is designed to 
account for combined inter- and intra-species variability. EPA believes 
that reliable data support using the standard 100-fold margin/factor 
and not the additional 10-fold margin/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 
margin/factor.
    The data base for developmental and reproductive toxicity of 
bromoxynil is considered to be complete at this time. Based on this 
database, EPA has concluded that, although developmental toxicity was 
observed in the absence of maternal toxicity, the results of these data 
did not raise concerns regarding the adequacy of the standard margin of 
exposure. Central to this conclusion were the findings that: (1) 
Developmental toxicity was well-characterized in multiple species, 
providing a reliable NOEL, and further studies would not be expected to 
provide new information that would change the developmental endpoints 
on which bromoxynil is regulated; and (2) the observed developmental 
effect (supernumerary ribs) raised no unusual or special concern for 
developmental toxicity.
    Accordingly, EPA concludes that reliable data support reliance upon 
the standard 100-fold margin of exposure/safety factor in assessing the 
risk to children. As detailed above, both chronic and acute assessments 
show no appreciable threshold risks to children and the non-threshold 
cancer risk is no greater than negligible. Thus, EPA concludes that 
there is a reasonable certainty that no harm will result to infants and 
children from aggregate exposure to bromoxynil.

VII. Other Considerations

    1. Residue analytical methods. Analytical methodology suitable for 
the enforcement of bromoxynil tolerances in plant and animal 
commodities is available. The analytical method for bromoxynil per se 
is published as Method I in Pesticide Analytical Manual Vol. II. Method 
RES9603 has been proposed for determination of DBHA in cotton RACs. 
This analytical method for determination of DBHA in plants has been 
validated by an independent laboratory. The Agency is currently 
carrying out confirmatory validation of this method.
    2. Endocrine effects. Existing data do not support a conclusion 
that bromoxynil causes endocrine effects. Other than equivocal effects 
in the prostate gland of dogs at the highest dose tested in a chronic 
oral study and in the prostate gland of rats at the highest dose tested 
in a dermal reproduction study, no evidence of endocrine effects were 
reported in any other subchronic or chronic toxicology

[[Page 24072]]

studies on bromoxynil phenol or bromoxynil octanoate.
    3. Data gaps. The following data gaps remain for use of bromoxynil 
on BXN cotton: (1) DBHA storage stability data, (2) successful petition 
method validation (i.e., method validation by Agency analytical 
chemists) of the enforcement method for DBHA in plants, (3) multi-
residue method testing for DBHA, (4) limited field trials for 
rotational crops, (5) a poultry feeding study using DBHA, and (6) crop 
field trials, conducted at the 1.5 lb ai/acre application rate, in 
which the magnitude of residues is measured in cotton commodities.

VIII. Public Comment

    Under FFDCA 408(e)(2), EPA must provide for a public comment period 
before issuing a final tolerance or tolerance exemption under 
408(e)(1). The public comment period is to be for 60 days unless EPA 
for good cause finds that it is in the public interest to reduce that 
comment period. The Agency has determined that there is good cause to 
reduce the comment period for these tolerances. First, the public has 
already had an opportunity to comment on the question of approval under 
the FFDCA of the use of bromoxynil on cotton. The Rhone Poulenc 
petition to establish a tolerance to cover bromoxynil residues on 
cottonseed resulting from application of bromoxynil to cotton squarely 
presented this issue. Second, the additional comment period is being 
provided to address a fairly narrow issue: what should the tolerance 
levels be for bromoxynil on livestock commodities (meat, milk, and 
eggs) due to residues of bromoxynil in cotton livestock feed 
commodities and what should the tolerance level be on two additional 
cotton livestock feed commodities (cotton gin byproducts and cottonseed 
hulls). All of these tolerance levels are necessary because of the use 
of bromoxynil on cotton, the subject of the Rhone Poulenc petition. 
Third, an extended comment period in this case will essentially mean 
that bromoxynil will not be available to growers in the 1997 growing 
season. The time for application of this herbicide is between roughly 
the end of April and the end of June. Growers who have paid a premium 
for bromoxynil-resistant seed may suffer consider financial loss if 
bromoxynil is not available. EPA would like to be in a position to make 
a final decision prior to the end of that period. Therefore, the Agency 
is allowing a 15-day instead of a 60-day public comment period for 
these proposed tolerances.
    Interested persons are invited to submit written comments on this 
proposed regulation. Comments must bear a notation indicating the 
docket control number ``OPP-300486.''

IX. Public Docket

    The official record for this proposed rule, as well as the public 
version, has been established for this proposal under docket control 
number ``OPP-300486'' (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 record is located at the address in 
``ADDRESSES'' at the beginning of this document.
    Electronic comments can 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. Comment and data 
will also be accepted on disks in Wordperfect 5.1 file format or ASCII 
file format. All comments and data in electronic form must be 
identified by the docket control number OPP-300486. Electronic comments 
on this proposed rule may be filed online at many Federal Depository 
Libraries.

X. Regulatory Assessment Requirements

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this 
action is not a ``significant regulatory action `` and since this 
action does not impose any information collection requirements subject 
to approval under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq., 
it is not subject to review by the Office of Management and Budget. In 
addition, this action does not impose any enforceable duty, or contain 
any ``unfunded mandates'' as described in Title II of the Unfunded 
Mandates Reform Act of 1995 Pub. L. 104-4), or require prior 
consultation as specified by Executive Order 12875 (58 FR 58093, 
October 28, 1993), or special considerations as required by Executive 
Order 12898 (59 FR 7629, February 16, 1994).
    Pursuant to the requirements of the Regulatory Flexibility Act 
(Pub. L. 96-354, 94 Stat. 1164, 5 U.S.C. 601-612), the Administrator 
has determined that regulations establishing new tolerances or raising 
tolerance levels or establishing exemptions from tolerance requirements 
do not have a significant economic impact on a substantial number of 
small entities. A certification statement explaining the factual basis 
for this determination was published in the Federal Register of May 4, 
1981 (46 FR 24950).

List of Subjects in 40 CFR Part 180

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

    Dated: April 28, 1997.
Jim Jones,
Acting Director, Registration Division, Office of Pesticide Programs.
    Therefore, it is proposed that 40 CFR part 180 be amended as 
follows:
    1. The authority citation for part 180 continues to read as 
follows:
    Authority: 21 U.S.C. 346a. and 371.
    2. Section 180.324 is revised to read as follows:


Sec. 180.324   Bromoxynil; tolerances for residues.

    (a) General. (1) Tolerances are established for residues of the 
herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) resulting from 
application of its octanoic and/or heptanoic acid ester in or on the 
following commodities:

                                                                        
------------------------------------------------------------------------
                 Commodity                        Parts per million     
------------------------------------------------------------------------
Alfalfa, seeding                            0.1 ppm                     
Barley, forage, green                       0.1 ppm                     
Barley, grain                               0.1 ppm                     
Barley, straw                               0.1 ppm                     
Cattle, meat                                0.5 ppm                     
Cattle, meat by-products                    3 ppm                       
Cattle, fat                                 1 ppm                       
Corn, fodder (dry)                          0.1 ppm                     
Corn, fodder (green)                        0.1 ppm                     
Corn, grain                                 0.1 ppm                     
Corn, fodder, field (dry)                   0.1 ppm                     
Corn, fodder, field (green)                 0.1 ppm                     
Corn, grain, field                          0.1 ppm                     
Eggs                                        0.05 ppm                    
Flaxseed                                    0.1 ppm                     
Flax straw                                  0.1 ppm                     
Garlic                                      0.1 ppm                     
Goats, meat                                 0.5 ppm                     
Goats, meat by-products                     3 ppm                       
Goats, fat                                  1 ppm                       
Grass, canary, annual, seed                 0.1 ppm                     
Grass, canary, annual, straw                0.1 ppm                     
Hogs, meat                                  0.5 ppm                     
Hogs, meat by-products                      3 ppm                       
Hogs, fat                                   1 ppm                       
Horses, meat                                0.5 ppm                     
Horses, meat by-products                    3 ppm                       
Horses, fat                                 1 ppm                       
Milk                                        0.1 ppm                     
Mint hay                                    0.1 ppm                     
Oats, forage, green                         0.1 ppm                     
Oats, grain                                 0.1 ppm                     

[[Page 24073]]

                                                                        
Oats, straw                                 0.1 ppm                     
Onions (dry bulb)                           0.1 ppm                     
Poultry, meat                               0.05 ppm                    
Poultry, meat by-products                   0.05 ppm                    
Poultry, fat                                0.05 ppm                    
Rye, forage, green                          0.1 ppm                     
Rye, grain                                  0.1 ppm                     
Rye, straw                                  0.1 ppm                     
Sheep, meat                                 0.5 ppm                     
Sheep, meat by-products                     3 ppm                       
Sheep, fat                                  1 ppm                       
Sorghum, fodder                              0.1 ppm                    
Sorghum, forage                              0.1 ppm                    
Sorghum, grain                               0.1 ppm                    
Wheat, forage, green                         0.1 ppm                    
Wheat, grain                                0.1 ppm                     
Wheat, straw                                0.1 ppm                     
------------------------------------------------------------------------

    (2) Tolerances are established for residues of the herbicide 
bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and its metabolite 3,5-
dibromo-4-hydroxybenzoic acid resulting from application of its 
octanoic and/or heptanoic acid ester in or on the following 
commodities:

                                                                        
------------------------------------------------------------------------
                                                          Expiration/   
            Commodity              Parts per million    Revocation Date 
------------------------------------------------------------------------
Cotton, undelinted seed           7 ppm               1/1/1998          
Cotton, hulls                     21 ppm              1/1/1998          
Cotton gin byproducts             50 ppm              1/1/1998          
------------------------------------------------------------------------

    (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]
[FR Doc. 97-11504 Filed 5-01-97; 8:45 am]
BILLING CODE 6560-50-F