[Federal Register Volume 76, Number 105 (Wednesday, June 1, 2011)]
[Rules and Regulations]
[Pages 31485-31491]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-13565]



40 CFR Part 180

 [EPA-HQ-OPP-2010-0268; FRL-8873-9]

Bromoxynil; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.


SUMMARY: This regulation revises established tolerances for residues of 
bromoxynil in or on multiple commodities which are identified and 
discussed later in this document. Bayer CropScience LLC requested these 
tolerances under the Federal Food, Drug, and Cosmetic Act (FFDCA).

DATES: This regulation is effective June 1, 2011. Objections and 
requests for hearings must be received on or before August 1, 2011, and 
must be filed in accordance with the instructions provided in 40 CFR 
part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).

ADDRESSES: EPA has established a docket for this action under docket 
identification (ID) number EPA-HQ-OPP-2010-0268. All documents in the 
docket are listed in the docket index available at http://www.regulations.gov. Although listed in the index, some information is 
not publicly available, e.g., Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. Certain 
other material, such as copyrighted material, is not placed on the 
Internet and will be publicly available only in hard copy form. 
Publicly available docket materials are available in the electronic 
docket at http://www.regulations.gov, or, if only available in hard 
copy, at the OPP Regulatory Public Docket in Rm. S-4400, One Potomac 
Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. The Docket 
Facility is open from 8:30 a.m. to 4 p.m., Monday through Friday, 
excluding legal holidays. The Docket Facility telephone number is (703) 

FOR FURTHER INFORMATION CONTACT: Susan Stanton, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 305-5218; e-mail address: [email protected].


I. General Information

A. Does this action apply to me?

    You may be potentially affected by this action if you are an 
agricultural producer, food manufacturer, or pesticide manufacturer. 
Potentially affected entities may include, but are not limited to those 
engaged in the following activities:
     Crop production (NAICS code 111).
     Animal production (NAICS code 112).
     Food manufacturing (NAICS code 311).
     Pesticide manufacturing (NAICS code 32532).
    This listing is not intended to be exhaustive, but rather to 
provide a guide for readers regarding entities likely to be affected by 
this action. Other types of entities not listed in this unit could also 
be affected. The North American Industrial Classification System 
(NAICS) codes have been provided to assist you and others in 
determining whether this action might apply to certain entities. If you 
have any questions regarding the applicability of this action to a 
particular entity, consult the person listed under FOR FURTHER 

B. How can I get electronic access to other related information?

    You may access a frequently updated electronic version of EPA's 
tolerance regulations at 40 CFR part 180 through the Government 
Printing Office's e-CFR site at http://www.gpoaccess.gov/ecfr. To 
access the harmonized test guidelines referenced in this document 
electronically, please go to http://www.epa.gov/ocspp and select ``Test 
Methods and Guidelines.''

C. How can I file an objection or hearing request?

    Under FFDCA section 408(g), 21 U.S.C. 346a, any person may file an 
objection to any aspect of this regulation and may also request a 
hearing on those objections. You must file your objection or request a 
hearing on this regulation in accordance with the instructions provided 
in 40 CFR part 178. To ensure proper receipt by EPA, you must identify 
docket ID number EPA-HQ-OPP-2010-0268 in the subject line on the first 
page of your submission. All objections and requests for a hearing must 
be in writing, and must be received by the Hearing Clerk on or before 
August 1, 2011. Addresses for mail and hand delivery of objections and 
hearing requests are provided in 40 CFR 178.25(b).
    In addition to filing an objection or hearing request with the 
Hearing Clerk as described in 40 CFR part 178, please submit a copy of 
the filing that does not contain any CBI for inclusion in the public 
docket. Information not marked confidential pursuant to 40 CFR part 2 
may be disclosed publicly by EPA without prior notice. Submit a copy of 
your non-CBI objection or hearing request, identified by docket ID 
number EPA-HQ-OPP-2010-0268, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
     Mail: Office of Pesticide Programs (OPP) Regulatory Public 
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460-0001.
     Delivery: OPP Regulatory Public Docket (7502P), 
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South 
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only 
accepted during the Docket Facility's normal hours of operation (8:30 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays). 
Special arrangements should be made for deliveries of boxed 
information. The Docket Facility telephone number is (703) 305-5805.

II. Summary of Petitioned-For Tolerance

    In the Federal Register of June 23, 2010 (75 FR 35801) (FRL-8831-
3), EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21 
U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 
9F7678) by Bayer CropScience LLC, 2 T. W. Alexander Drive, Research 
Triangle Park, NC 27709. The petition requested that 40 CFR 180.324 be 
amended by increasing existing tolerances for residues of the herbicide 
bromoxynil, 3,5-dibromo-4-hydroxybenzonitrile, in or on sorghum, grain, 
grain from 0.05 parts per million (ppm) to 0.2 ppm; grass, hay from 3.0 
ppm to 5.0 ppm; and grass, forage from 3.0 ppm to 18 ppm. That notice 
referenced a summary of the petition prepared by Bayer CropScience LLC, 
the registrant, which is available in the docket, http://www.regulations.gov. There were no comments received in response to the 
notice of filing.
    Based upon review of the data supporting the petition, EPA has 
determined that the existing tolerances for aspirated grain fractions, 
milk, and grain sorghum forage must also be increased as a result of 
the proposed changes to the use patterns for sorghum and grasses. The 
reasons for these changes are explained in Unit IV.C.

[[Page 31486]]

III. Aggregate Risk Assessment and Determination of Safety

    Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a 
tolerance (the legal limit for a pesticide chemical residue in or on a 
food) only if EPA determines that the tolerance is ``safe.'' Section 
408(b)(2)(A)(ii) of FFDCA defines ``safe'' to mean that ``there is a 
reasonable certainty that no harm will result from aggregate exposure 
to the pesticide chemical residue, including all anticipated dietary 
exposures and all other exposures for which there is reliable 
information.'' This includes exposure through drinking water and in 
residential settings, but does not include occupational exposure. 
Section 408(b)(2)(C) of FFDCA 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 * * 
    Consistent with section 408(b)(2)(D) of FFDCA, and the factors 
specified in section 408(b)(2)(D) of FFDCA, EPA has reviewed the 
available scientific data and other relevant information in support of 
this action. EPA has sufficient data to assess the hazards of and to 
make a determination on aggregate exposure for bromoxynil including 
exposure resulting from the tolerances established by this action. 
EPA's assessment of exposures and risks associated with bromoxynil 

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
    Bromoxynil phenol has moderate acute toxicity via the oral and 
inhalation routes of exposure and low acute toxicity via the dermal 
route. Bromoxynil octanoate has moderate acute toxicity via the oral 
and dermal routes and low acute toxicity via the inhalation route. Due 
to rapid conversion of the ester forms of the chemical (heptanoate and 
octanoate) to the phenol, toxicity testing was conducted with both 
phenol and octanoate material, but the risk assessment is based on 
exposure to the phenol.
    In the repeated dose studies of the mammalian toxicology database, 
the liver was the primary target organ of bromoxynil toxicity. Across 
species, duration and gender, changes in weight, clinical chemistry and 
pathology indicated treatment-related perturbations in and adverse 
effects on liver function. Treatment-related effects were also observed 
on body weight and body weight gain in rats, mice, dogs, and rabbits. 
Subchronic and chronic studies in dogs showed that bromoxynil elevated 
body temperature, manifested by increased panting at lower dose levels, 
and hyperthermia and death as dose levels increased.
    Developmental toxicity was manifested in rats, mice and rabbits via 
the oral and dermal routes by increased incidence of supernumerary 
(13th and/or 14th) ribs at dose levels as low as 5 milligrams/kilogram/
day (mg/kg/day) in rats. At higher dose levels, malformations such as 
hydrocephalus, enophthalmia, micropththalmia, fused ribs, scoliosis, 
misshapen thoracic centrum and incomplete ossification of sternebrae 
were observed in rabbits. In reproduction studies, delayed development 
manifested as decreased body weight and body weight gain, and delayed 
eye opening.
    Bromoxynil is classified as a ``possible human carcinogen'' based 
on the presence of hepatocellular tumors in male and female mice. There 
is no concern for mutagenicity. The method of quantification of cancer 
risk is linear, using the cancer slope factor (Q*) of 0.103 (mg/kg/
day)-1 in human equivalents.
    Specific information on the studies received and the nature of the 
adverse effects caused by bromoxynil as well as the no-observed-
adverse-effect-level (NOAEL) and the lowest-observed-adverse-effect-
level (LOAEL) from the toxicity studies can be found at http://www.regulations.gov in document ``Bromoxynil: Human Health Risk 
Assessment for Amended Uses on Grass Grown for Seed, Conservation 
Reserve Program Areas, and Grain Sorghum,'' p. 50 in docket ID number 

B. Toxicological Points of Departure/Levels of Concern

    Once a pesticide's toxicological profile is determined, EPA 
identifies toxicological points of departure (POD) and levels of 
concern (LOC) to use in evaluating the risk posed by human exposure to 
the pesticide. For hazards that have a threshold below which there is 
no appreciable risk, the toxicological POD is used as the basis for 
derivation of reference values for risk assessment. PODs are developed 
based on a careful analysis of the doses in each toxicological study to 
determine the dose at which the NOAEL and the lowest dose at which 
adverse effects of concern are identified (the LOAEL). Uncertainty/
safety factors are used in conjunction with the POD to calculate a safe 
exposure level--generally referred to as a population-adjusted dose 
(PAD) (a = acute and c = chronic) or a reference dose (RfD)--and a safe 
margin of exposure (MOE). For non-threshold risks, the Agency assumes 
that any amount of exposure will lead to some degree of risk. Thus, the 
Agency estimates risk in terms of the probability of an occurrence of 
the adverse effect expected in a lifetime. For more information on the 
general principles EPA uses in risk characterization and a complete 
description of the risk assessment process, see http://www.epa.gov/pesticides/factsheets/riskassess.htm.
    A summary of the toxicological endpoints for bromoxynil used for 
human risk assessment is shown in the following table.

   Table--Summary of Toxicological Doses and Endpoints for Bromoxynil for Use in Human Health Risk Assessment
                                      Point of departure
         Exposure/scenario            and  uncertainty/      RfD, PAD, LOC for risk     Study and toxicological
                                        safety factors             assessment                   effects
Acute dietary.....................  NOAEL = 4 mg/kg/day..  Acute RfD = 0.04 mg/kg/day  Developmental Studies in
(Females 13-50 years of age)......  UFA = 10x............  aPAD = 0.04 mg/kg/day.....   Rats.
                                    UFH = 10x............                              LOAEL = 5 mg/kg/day based
                                    FQPA SF = 1x.........                               on an increase of
                                                                                        supernumerary ribs. The
                                                                                        NOAEL is derived from a
                                                                                        co-critical rat
                                                                                        developmental study.

[[Page 31487]]

Acute dietary.....................  NOAEL = 8 mg/kg/day..  Acute RfD = 0.08 mg/kg/day  Subchronic Study in Dogs.
(General population including       UFA = 10x............  aPAD = 0.08 mg/kg/day.....  LOAEL = 12 mg/kg/day
 infants and children).             UFH = 10x............                               based on panting. In
                                    FQPA SF = 1x.........                               addition to panting,
                                                                                        elevated rectal
                                                                                        temperatures occurred at
                                                                                        16 mg/kg and above, and
                                                                                        death occurred at 30 mg/
                                                                                        kg and above after a
                                                                                        single dose on day 1.
Chronic dietary...................  NOAEL= 1.5 mg/kg/day.  Chronic RfD = 0.015 mg/kg/  Chronic (1 year) Study in
(All populations).................  UFA = 10x............   day.                        dogs.
                                    UFH = 10x............  cPAD = 0.015 mg/kg/day....  LOAEL = 7.5 mg/kg/day
                                    FQPA SF = 1x.........                               based on increased
                                                                                        incidences of
                                                                                        salivation, panting,
                                                                                        liquid feces and pale
                                                                                        gums; statistically
                                                                                        significant decreased
                                                                                        body weight gain over
                                                                                        entire duration of
                                                                                        study, but particularly
                                                                                        during first 8 weeks of
                                                                                        study; statistically
                                                                                        significant decreased
                                                                                        erythrocytes (RBC),
                                                                                        hemoglobin (Hb) and
                                                                                        packed cell volume
                                                                                        (PCV); statistically
                                                                                        significant increased
                                                                                        urea nitrogen; increased
                                                                                        absolute liver weights
                                                                                        and liver/body weight
Cancer (Oral, dermal, inhalation).    Bromoxynil phenol has been classified by EPA as a Group C, possible human
                                        carcinogen, based on male mouse hepatocellular tumors. The Agency has
                                        determined that a linear low dose extrapolation model (Q1*) should be
                                      applied to the experimental animal tumor data for quantification of human
                                                          risk. Q1* = 0.103 (mg/kg/day)-\1\
UFA = extrapolation from animal to human (interspecies). UFH = potential variation in sensitivity among members
  of the human population (intraspecies). FQPA SF = Food Quality Protection Act Safety Factor. Pad = population
  adjusted dose (a = acute, c = chronic), LOC = level of concern, RfD = Reference dose.

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. In evaluating dietary 
exposure to bromoxynil, EPA considered exposure under the petitioned-
for tolerances as well as all existing bromoxynil tolerances in 40 CFR 
180.324. EPA assessed dietary exposures from bromoxynil in food as 
    i. Acute exposure. Quantitative acute dietary exposure and risk 
assessments are performed for a food-use pesticide, if a toxicological 
study has indicated the possibility of an effect of concern occurring 
as a result of a 1-day or single exposure. Such effects were identified 
for bromoxynil. As shown in the table in this unit, EPA identified 
different PODs for assessing acute dietary exposure for the general 
population (including infants and children) and women of childbearing 
age (13 to 50 years).
    In estimating acute dietary exposure, EPA used food consumption 
information from the U. S. Department of Agriculture (USDA) 1994-1996 
and 1998 Nationwide Continuing Surveys of Food Intake by Individuals 
(CSFII). As to residues in food, EPA assumed either tolerance level or 
anticipated residues. Tolerance levels were assumed for cotton, garlic, 
onion, peppermint, and spearmint. For all grains, average field trial 
values were used, since grains are considered to be blended 
commodities. Livestock anticipated residues were estimated using 
results from the crop field trials in conjunction with animal feeding 
studies. Additionally, maximum percent crop treated (PCT) estimates 
were used for all crop commodities. Default processing factors were 
used to estimate residues in processed commodities.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the food consumption data from the USDA 1994-1996 
and 1998 CSFII. As to residue levels in food, EPA used average field 
trial residues for all commodities except spearmint and peppermint, for 
which tolerance values were assumed. Livestock anticipated residues 
were estimated using average percent crop treated data, average field 
trial residue values, and results from the animal feeding studies. 
Additionally, average PCT estimates were used for all crop commodities. 
Default processing factors were used to estimate residues in processed 
    iii. Cancer. EPA determines whether quantitative cancer exposure 
and risk assessments are appropriate for a food-use pesticide based on 
the weight-of-the-evidence from cancer studies and other relevant data. 
If quantitative cancer risk assessment is appropriate, cancer risk may 
be quantified using a linear or nonlinear approach. If sufficient 
information on the carcinogenic mode of action is available, a 
threshold or non-linear approach is used and a cancer RfD is calculated 
based on an earlier noncancer key event. If carcinogenic mode of action 
data are not available, or if the mode of action data determines a 
mutagenic mode of action, a default linear cancer slope factor approach 
is utilized. Based on the data summarized in Unit III.A., EPA has 
concluded that bromoxynil should be classified as a ``Possible Human 
Carcinogen,'' and a linear approach has been used to quantify cancer 
risk. Cancer risk was quantified using the same exposure estimates as 
discussed in Unit III.C.1.ii.--chronic exposure.
    iv. Anticipated residue and percent crop treated (PCT) information. 
Section 408(b)(2)(E) of FFDCA authorizes EPA to use available data and 
information on the anticipated residue levels of pesticide residues in 
food and the actual levels of pesticide residues that have been 
measured in food. If EPA relies on such information, EPA must require 
pursuant to FFDCA section 408(f)(1) that data be provided 5 years after 
the tolerance is established, modified, or left in effect, 
demonstrating that the levels in food are not above the levels 
anticipated. For the present action, EPA will issue such data call-ins 
as are required by FFDCA section 408(b)(2)(E) and authorized under 
FFDCA section 408(f)(1). Data will be required to be submitted no later 
than 5 years from the date of issuance of these tolerances.

[[Page 31488]]

    Section 408(b)(2)(F) of FFDCA states that the Agency may use data 
on the actual percent of food treated for assessing chronic dietary 
risk only if:
     Condition a: The data used are reliable and provide a 
valid basis to show what percentage of the food derived from such crop 
is likely to contain the pesticide residue.
     Condition b: The exposure estimate does not underestimate 
exposure for any significant subpopulation group.
     Condition c: Data are available on pesticide use and food 
consumption in a particular area, the exposure estimate does not 
understate exposure for the population in such area.
    In addition, the Agency must provide for periodic evaluation of any 
estimates used. To provide for the periodic evaluation of the estimate 
of PCT as required by FFDCA section 408(b)(2)(F), EPA may require 
registrants to submit data on PCT.
    The Agency estimated the maximum PCT for existing uses in the acute 
dietary exposure assessment as follows: Alfalfa 2.5%; barley 35%; corn 
5%; cotton 5%; flax 35%; garlic 70%; mint 25%; oats 5%; onion 70%; rye 
1%; sorghum 2.5%; and wheat 35%.
    The Agency estimated the average PCT for existing uses in the 
chronic and cancer dietary exposure assessments as follows: Alfalfa 1%; 
barley 20%; corn 2.5%; cotton 2.5%; flax 35%; garlic 50%; mint 25%; 
oats 5%; onion 55%; rye 1%; sorghum 2.5%; and wheat 15%.
    The sorghum PCT values used in the acute and chronic assessments 
were based on existing uses. Because there is a proposed change in the 
sorghum use pattern (i.e., shorter pre-harvest interval), there is a 
potential for a change in the PCT value. However, grain sorghum is a 
small contributor to the overall livestock dietary burden estimate. If 
the PCT value for sorghum was assumed to be 100%, the overall impact to 
dietary exposure and risk assessment would be negligible.
    In most cases, EPA uses available data from U. S. Department of 
Agriculture/National Agricultural Statistics Service (USDA/NASS), 
proprietary market surveys, and the National Pesticide Use Database for 
the chemical/crop combination for the most recent 6-7 years. EPA uses 
an average PCT for chronic dietary risk analysis. The average PCT 
figure for each existing use is derived by combining available public 
and private market survey data for that use, averaging across all 
observations, and rounding to the nearest 5%, except for those 
situations in which the average PCT is less than one. In those cases, 
1% is used as the average PCT and 2.5% is used as the maximum PCT. EPA 
uses a maximum PCT for acute dietary risk analysis. The maximum PCT 
figure is the highest observed maximum value reported within the recent 
6 years of available public and private market survey data for the 
existing use and rounded up to the nearest multiple of 5%.
    The Agency believes that the three conditions discussed in Unit 
III.C.1.iv. have been met. With respect to Condition a, PCT estimates 
are derived from Federal and private market survey data, which are 
reliable and have a valid basis. The Agency is reasonably certain that 
the percentage of the food treated is not likely to be an 
underestimation. As to Conditions b and c, regional consumption 
information and consumption information for significant subpopulations 
are taken into account through EPA's computer-based model for 
evaluating the exposure of significant subpopulations including several 
regional groups. Use of this consumption information in EPA's risk 
assessment process ensures that EPA's exposure estimate does not 
understate exposure for any significant subpopulation group and allows 
the Agency to be reasonably certain that no regional population is 
exposed to residue levels higher than those estimated by the Agency. 
Other than the data available through national food consumption 
surveys, EPA does not have available reliable information on the 
regional consumption of food to which bromoxynil may be applied in a 
particular area.
    2. Dietary exposure from drinking water. The Agency used screening 
level water exposure models in the dietary exposure analysis and risk 
assessment for bromoxynil in drinking water. These simulation models 
take into account data on the physical, chemical, and fate/transport 
characteristics of bromoxynil. Further information regarding EPA 
drinking water models used in pesticide exposure assessment can be 
found at http://www.epa.gov/oppefed1/models/water/index.htm.
    Based on the FQPA Index Reservoir Screening Tool (FIRST) and 
Screening Concentration in Ground Water (SCI-GROW) models, the 
estimated drinking water concentrations (EDWCs) of bromoxynil for acute 
exposures are estimated to be 11.5 parts per billion (ppb) for surface 
water and 3.26 parts per trillion (ppt) for ground water. EDWCs for 
chronic exposures for non-cancer assessments and cancer assessments are 
estimated to be 0.19 ppb for surface water and 3.26 ppt for ground 
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model. For acute dietary risk 
assessment, the water concentration value of 11.5 ppb was used to 
assess the contribution to drinking water. For chronic and cancer 
dietary risk assessment, the water concentration value of 0.19 ppb was 
used to assess the contribution to drinking water.
    3. From non-dietary exposure. The term ``residential exposure'' is 
used in this document to refer to non-occupational, non-dietary 
exposure (e.g., for lawn and garden pest control, indoor pest control, 
termiticides, and flea and tick control on pets). Bromoxynil is not 
registered for any specific use patterns that would result in 
residential exposure.
    4. Cumulative effects from substances with a common mechanism of 
toxicity. Section 408(b)(2)(D)(v) of FFDCA 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.''
    EPA has not found bromoxynil to share a common mechanism of 
toxicity with any other substances, and bromoxynil does not appear to 
produce a toxic metabolite produced by other substances. For the 
purposes of this tolerance action, therefore, EPA has assumed that 
bromoxynil does not have a common mechanism of toxicity with other 
substances. For information regarding EPA's efforts to determine which 
chemicals have a common mechanism of toxicity and to evaluate the 
cumulative effects of such chemicals, see EPA's Web site at http://www.epa.gov/pesticides/cumulative.

D. Safety Factor for Infants and Children

    1. In general. Section 408(b)(2)(C) of FFDCA provides that EPA 
shall apply an additional tenfold (10X) margin of safety for infants 
and children in the case of threshold effects to account for prenatal 
and postnatal toxicity and the completeness of the database on toxicity 
and exposure unless EPA determines based on reliable data that a 
different margin of safety will be safe for infants and children. This 
additional margin of safety is commonly referred to as the FQPA SF. In 
applying this provision, EPA either retains the default value of 10X, 
or uses a different additional safety factor when reliable data 
available to EPA support the choice of a different factor.

[[Page 31489]]

    2. Prenatal and postnatal sensitivity. The prenatal and postnatal 
toxicity database for bromoxynil includes five developmental toxicity 
studies in rats, two developmental toxicity studies in rabbits, a 
developmental study in mice, and 2- and 3-generation reproduction 
toxicity studies in rats. The available data indicate that bromoxynil 
produces developmental effects (supernumerary ribs) in rats and rabbits 
at or below the maternal NOAELs in both oral and dermal studies, and 
that bromoxynil octanoate produces supernumerary ribs at the maternal 
NOAEL in a dermal study. Supernumerary ribs were observed in rats, mice 
and rabbits after oral and/or dermal administration. Therefore, there 
is evidence of quantitative susceptibility in the database. However, 
clear NOAELs exist for the developmental effects, and basing the point 
of departure on these effects addresses Agency concerns for 
quantitative susceptibility.
    In EPA's previous risk assessment for bromoxynil (1998), the FQPA 
SF was retained at 10X for the acute dietary endpoint for females, 13 
to 50 years old, despite the POD being an adverse effect (supernumerary 
ribs) in the fetus. The primary reason for the retention was an 
apparent steepness of the dose-response curve (NOAEL = 4 mg/kg/day, 
LOAEL = 5 mg/kg/day) derived by combining the results of two co-
critical studies. However, since the previous risk assessment for 
bromoxynil was conducted, a more refined data evaluation tool, 
benchmark dose (BMD) analysis, has become available and EPA has used it 
in this risk assessment to better characterize the dose-response 
relationship for supernumerary ribs. The analysis was conducted using 
the fetal and/or litter data available from the two rat developmental 
studies, plus a third developmental study which demonstrated similar 
results at similar dose levels. EPA also re-examined the underlying 
data for each study. EPA concluded that it was no longer appropriate to 
combine the rat developmental study with a NOAEL of 4 mg/kg/day with 
other studies in characterizing the dose-response relationship and that 
none of the studies indicate a steep dose-response curve. EPA further 
found that the results of the BMD analysis as to the study used to 
derive the POD (the rat developmental study with a NOAEL of 4 mg/kg/
day) suggest a POD substantially higher than the NOAEL of 4 mg/kg/day, 
which supports the position that the NOAEL of 4 mg/kg/day is adequately 
protective of the adverse effect of supernumerary ribs in rat fetuses 
without an additional safety factor. Accordingly, EPA has determined, 
after re-examining all three studies, that the data on developmental 
effects do not raise any residual concerns.
    3. Conclusion. EPA has determined that reliable data show the 
safety of infants and children would be adequately protected if the 
FQPA SF were reduced to 1X. That decision is based on the following 
    i. The toxicity database for bromoxynil is complete, except for an 
immunotoxicity study (OPPTS Guideline 870.7800), and acute and 
subchronic neurotoxicity studies (OPPTS Guideline 870.6200a and 
870.6200b), now required under 40 CFR 158.500 for pesticide 
registration. In the absence of specific immunotoxicity and acute and 
subchronic neurotoxicity studies, EPA has evaluated the available 
bromoxynil toxicity database to determine whether an additional 
database UF is needed to account for potential immunotoxicity or 
    With the exception of a marginal increase in the severity, but not 
the incidence, of thymic lymphocyte necrosis at otherwise toxic dose 
levels in a subchronic rat study, there is no evidence of 
immunotoxicity in the toxicology database for bromoxynil. Similarly, 
there is no evidence of neurotoxicity in the database. Consequently, 
EPA believes the existing data are sufficient for endpoint selection 
for exposure/risk assessment scenarios and for evaluation of the 
requirements under FQPA, and an additional database UF is not needed to 
account for the lack of these studies.
    ii. Although there is evidence that bromoxynil results in increased 
quantitative susceptibility in in utero rats and rabbits in the 
prenatal developmental studies, EPA did not identify any residual 
uncertainties after establishing toxicity endpoints and traditional UFs 
to be used in the risk assessment of bromoxynil.
    iii. There are no residual uncertainties identified in the exposure 
databases. Although the dietary assessments were refined, they were 
based on reliable and acceptable field trial and feeding studies and 
valid estimates of PCT. EPA made conservative (protective) assumptions 
in the ground water and surface water modeling used to assess exposure 
to bromoxynil in drinking water. These assessments will not under 
estimate the exposure and risks posed by bromoxynil.

E. Aggregate Risks and Determination of Safety

    EPA determines whether acute and chronic dietary pesticide 
exposures are safe by comparing aggregate exposure estimates to the 
aPAD and cPAD. For linear cancer risks, EPA calculates the lifetime 
probability of acquiring cancer given the estimated aggregate exposure. 
Short-, intermediate-, and chronic-term risks are evaluated by 
comparing the estimated aggregate food, water, and residential exposure 
to the appropriate PODs to ensure that an adequate MOE exists.
    1. Acute risk. Using the exposure assumptions discussed in this 
unit for acute exposure, the acute dietary exposure to bromoxynil from 
food and water will occupy 7.4% of the aPAD for infants less than 1 
year old, the population group receiving the greatest exposure. The 
acute dietary exposure to bromoxynil from food and water will occupy 
4.4% of the aPAD for females 13 to 50 years old.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that chronic exposure to 
bromoxynil from food and water will utilize <1% of the cPAD for all 
population groups, including infants and children. There are no 
residential uses for bromoxynil.
    3. Short- and intermediate-term risk. Short- and intermediate-term 
aggregate exposure take into account short- or intermediate-term 
residential exposure plus chronic exposure from food and water 
(considered to be a background exposure level). Short- and 
intermediate-term adverse effects were identified; however, bromoxynil 
is not registered for any use patterns that would result in short- or 
intermediate-term residential exposure. Short- and intermediate-term 
risks are assessed based on short- or intermediate-term residential 
exposure plus chronic dietary exposure. Because there is no short- or 
intermediate-term residential exposure and chronic dietary exposure has 
already been assessed under the appropriately protective cPAD (which is 
at least as protective as the POD used to assess short- and 
intermediate-term risk), no further assessment of short- or 
intermediate-term risk is necessary, and EPA relies on the chronic 
dietary risk assessment for evaluating short- and intermediate-term 
risk for bromoxynil.
    4. Aggregate cancer risk for U.S. population. Using the exposure 
assumptions described in this unit for the cancer risk assessment, EPA 
has concluded that exposure to bromoxynil from food and water will 
result in a lifetime cancer risk of 1.5 x 10-6 for the

[[Page 31490]]

general U.S. population. EPA generally considers cancer risks in the 
range of one in one million (1 x 10-6) or less to be 
negligible. The precision which can be assumed for cancer risk 
estimates is best described by rounding to the nearest integral order 
of magnitude on the log scale; for example, risks falling between 3 x 
10-7 and 3 x 10-6 are expressed as risks in the 
range of 10-6. Considering the precision with which cancer 
hazard can be estimated, the conservativeness of low-dose linear 
extrapolation, and the rounding procedure described above, cancer risk 
should generally not be assumed to exceed the benchmark level of 
concern of the range of 10-6 until the calculated risk 
exceeds approximately 3 x 10-6. This is particularly the 
case where some conservatism is maintained in the exposure assessment. 
Although the bromoxynil exposure risk assessment is refined, it retains 
some conservatism due, among other things, to the use of field trial 
data and screening level PCT information to estimate residues in food. 
Accordingly, EPA has concluded the cancer risk for all existing 
bromoxynil uses and the uses associated with the tolerances established 
in this action falls within the range of 1 x 10-6 and is 
thus negligible.
    5. Determination of safety. Based on these risk assessments, EPA 
concludes that there is a reasonable certainty that no harm will result 
to the general population, or to infants and children from aggregate 
exposure to bromoxynil residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology is available to enforce the 
tolerance expression for residues of bromoxynil in grass and grain 
sorghum commodities. Method I in the Pesticide Analytical Manual (PAM), 
Vol. II, is a gas liquid chromatography/microcoulometric detection 
(GLC/MCD) method that has undergone a successful EPA method validation 
on wheat grain. Method Ia is the same method except that it uses gas 
chromatography/electron capture detection (GC/ECD) for determination of 
methylated bromoxynil.
    Adequate residue analytical methodology is available for tolerance 
enforcement for bromoxynil in livestock commodities. Method A is a GC/
MCD or GC/ECD method for the analysis of bromoxynil residues in 
livestock tissues and is essentially the same as Method I. Method B is 
a GC/ECD method that is also similar to Method I, with modifications to 
the cleanup procedures. The methods may be requested from: Chief, 
Analytical Chemistry Branch, Environmental Science Center, 701 Mapes 
Rd., Ft. Meade, MD 20755-5350; telephone number: (410) 305-2905; e-mail 
address: [email protected].

B. International Residue Limits

    In making its tolerance decisions, EPA seeks to harmonize U.S. 
tolerances with international standards whenever possible, consistent 
with U.S. food safety standards and agricultural practices. EPA 
considers the international maximum residue limits (MRLs) established 
by the Codex Alimentarius Commission (Codex), as required by FFDCA 
section 408(b)(4). The Codex Alimentarius is a joint U.N. Food and 
Agriculture Organization/World Health Organization food standards 
program, and it is recognized as an international food safety 
standards-setting organization in trade agreements to which the United 
States is a party. EPA may establish a tolerance that is different from 
a Codex MRL; however, FFDCA section 408(b)(4) requires that EPA explain 
the reasons for departing from the Codex level.
    The Codex has not established a MRL for bromoxynil on the 
commodities in this rule.

C. Revisions to Petitioned-For Tolerances

    The proposed increases in the tolerance levels for ``grass, 
forage;'' ``grass, hay;'' and ``sorghum, grain'' were determined to be 
appropriate for these commodities. However, EPA determined that the 
existing tolerance for ``sorghum, grain, forage'' must also be 
increased from 0.5 ppm to 0.8 ppm, based on analysis of the field trial 
data using the Agency's tolerance/MRL calculator in accordance with the 
Agency's Guidance for Setting Pesticide Tolerances Based on Field Trial 
Data. In addition, because the tolerance on the grain of grain sorghum 
is being increased from 0.05 ppm to 0.2 ppm, higher residues may occur 
in aspirated grain fractions; and EPA has determined that the existing 
tolerance should be increased from 0.3 ppm to 1.2 ppm. Finally, based 
on calculated livestock dietary burdens in light of the new tolerances 
and data from a cattle feeding study, EPA has determined that the 
established tolerance for milk must be increased from 0.1 ppm to 0.4 
    EPA is also revising the tolerance expression for existing 
tolerances and the new tolerances to clarify the chemical moieties that 
are covered by the tolerances and specify how compliance with the 
tolerances is to be determined. Tolerances for most plant commodities 
are currently expressed in terms of ``bromoxynil (3,5-dibromo-4-
hydroxybenzonitrile) resulting from application of its octanoic and/or 
heptanoic acid ester.'' Livestock tolerances and tolerances for cotton 
commodities are currently expressed in terms of ``bromoxynil (3,5-
dibromo-4-hydroxybenzonitrile) and its metabolite 3,5-dibromo-4-
hydroxybenzoic acid (DBHA) resulting from application of its octanoic 
and/or heptanoic acid ester.'' The tolerance expression for plants, 
except cotton, is being revised to make clear that the tolerances cover 
residues of bromoxynil, including its metabolites and degradates, but 
that compliance with the tolerances is to be determined by measuring 
only bromoxynil. Similarly, the tolerance expression for livestock 
commodities and cotton is being revised to clarify that the tolerances 
cover residues of bromoxynil, including its metabolites and degradates, 
but that compliance with the tolerance levels will be determined by 
measuring only bromoxynil and its metabolite DBHA. EPA has determined 
that it is reasonable to make these changes final without prior 
proposal and opportunity for comment, because public comment is not 
necessary, in that the changes have no substantive effect on the 
tolerances, but rather are merely intended to clarify the existing 
tolerance expressions.

V. Conclusion

    Therefore, previously established tolerances are amended for 
residues of bromoxynil, including its metabolites and degradates, as 
set forth in the regulatory text.

VI. Statutory and Executive Order Reviews

    This final rule establishes tolerances under section 408(d) of 
FFDCA in response to a petition submitted to the Agency. The Office of 
Management and Budget (OMB) has exempted these types of actions from 
review under Executive Order 12866, entitled Regulatory Planning and 
Review (58 FR 51735, October 4, 1993). Because this final rule has been 
exempted from review under Executive Order 12866, this final rule is 
not subject to Executive Order 13211, entitled Actions Concerning 
Regulations That Significantly Affect Energy Supply, Distribution, or 
Use (66 FR 28355, May 22, 2001) or Executive Order 13045, entitled 
Protection of Children from Environmental Health Risks and Safety Risks 
(62 FR 19885, April 23, 1997). This final rule does not contain any 
information collections subject to OMB approval under the Paperwork 
Reduction Act, 44 U.S.C. 3501 et seq.,

[[Page 31491]]

nor does it require any special considerations under Executive Order 
12898, entitled Federal Actions to Address Environmental Justice in 
Minority Populations and Low-Income Populations (59 FR 7629, February 
16, 1994).
    Since tolerances and exemptions that are established on the basis 
of a petition under section 408(d) of FFDCA, such as the tolerances in 
this final rule, do not require the issuance of a proposed rule, the 
requirements of the Regulatory Flexibility Act (5 U.S.C. 601 et seq.) 
do not apply.
    This final rule directly regulates growers, food processors, food 
handlers, and food retailers, not States or tribes, nor does this 
action alter the relationships or distribution of power and 
responsibilities established by Congress in the preemption provisions 
of section 408(n)(4) of FFDCA. As such, the Agency has determined that 
this action will not have a substantial direct effect on States or 
tribal governments, on the relationship between the national government 
and the States or tribal governments, or on the distribution of power 
and responsibilities among the various levels of government or between 
the Federal Government and Indian tribes. Thus, the Agency has 
determined that Executive Order 13132, entitled Federalism (64 FR 
43255, August 10, 1999) and Executive Order 13175, entitled 
Consultation and Coordination with Indian Tribal Governments (65 FR 
67249, November 9, 2000) do not apply to this final rule. In addition, 
this final rule does not impose any enforceable duty or contain any 
unfunded mandate as described under Title II of the Unfunded Mandates 
Reform Act of 1995 (Pub. L. 104-4).
    This action does not involve any technical standards that would 
require Agency consideration of voluntary consensus standards pursuant 
to section 12(d) of the National Technology Transfer and Advancement 
Act of 1995, Public Law 104-113, section 12(d) (15 U.S.C. 272 note).

VII. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report to each House of the Congress and to 
the Comptroller General of the United States. EPA will submit a report 
containing this rule and other required information to the U.S. Senate, 
the U.S. House of Representatives, and the Comptroller General of the 
United States prior to publication of this final rule in the Federal 
Register. This final rule is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

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

    Dated: May 18, 2011.
Lois Rossi,
Director, Registration Division, Office of Pesticide Programs.

    Therefore, 40 CFR chapter I is amended as follows:


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

    Authority:  21 U.S.C. 321(q), 346a and 371.

2. Section 180.324 is amended as follows:
i. Revise the introductory text in paragraph (a)(1), and the entries 
for grain, aspirated fractions; grass, forage; grass, hay; sorghum, 
grain, forage; and sorghum, grain, grain in the table to paragraph 
ii. Revise the introductory text in paragraph (a)(2), and the entry for 
``milk'' in the table to paragraph (a)(2).
    The revisions read as follows:

Sec.  180.324  Bromoxynil; tolerances for residues.

    (a) General. (1) Tolerances are established for residues of the 
herbicide bromoxynil, including its metabolites and degradates, in or 
on the commodities in the table below. Compliance with the tolerance 
levels is to be determined by measuring only bromoxynil, 3,5-dibromo-4-
hydroxybenzonitrile, resulting from application of its octanoic and/or 
heptanoic acid ester, in or on the commodities.

                                                              Parts per
                         Commodity                             million
                                * * * * *
Grain, aspirated fractions.................................          1.2
Grass, forage..............................................         18
Grass, hay.................................................          5.0
                                * * * * *
Sorghum, grain, forage.....................................          0.8
Sorghum, grain, grain......................................          0.2
                                * * * * *

    (2) Tolerances are established for residues of the herbicide 
bromoxynil, 3,5-dibromo-4-hydroxybenzonitrile, including its 
metabolites and degradates, in or on the commodities in the table 
below. Compliance with the tolerance levels is to be determined by 
measuring only bromoxynil and its metabolite, 3,5-dibromo-4-
hydroxybenzoic acid (DBHA), resulting from application of its octanoic 
and/or heptanoic acid ester, in or on the commodities.

                                                              Parts per
                         Commodity                             million
                                * * * * *
Milk.......................................................          0.4
                                * * * * *

* * * * *
[FR Doc. 2011-13565 Filed 5-31-11; 8:45 am]