[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:
tompkins.jim@epamail.epa.gov.
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:
opp-docket@epamail.epa.gov
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
