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Fluroxypyr (Dow AgroSciences). May 14, 2003. Pesticide petition for several tolerances. Federal Register.
http://www.epa.gov/fedrgstr/EPA-PEST/2003/May/Day-14/p11759.htm
[Federal Register: May 14, 2003 (Volume 68, Number 93)]
[Notices]
[Page 25883-25888]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr14my03-55]
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ENVIRONMENTAL PROTECTION AGENCY
[OPP-2003-0118; FRL-7301-3]
Fluroxypyr; Notice of Filing a Pesticide Petition to Establish a
Tolerance for a Certain Pesticide Chemical in or on Food
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: This notice announces the initial filing of a pesticide
petition proposing the establishment of regulations for residues of a
certain pesticide chemical in or on various food commodities.
DATES: Comments, identified by docket ID number OPP- 2003-0118, must be
received on or before June 13, 2003.
ADDRESSES: Comments may be submitted electronically, by mail, or
through hand delivery/courier. Follow the detailed instructions as
provided in Unit I. of the SUPPLEMENTARY INFORMATION.
FOR FURTHER INFORMATION CONTACT: Joanne I. Miller, Registration
Division (7505C), Office of Pesticide Programs, Environmental
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-
0001; telephone number: (703) 305-6224; e-mail address:
miller.joanne@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Apply to Me?
You may be potentially affected by this action if you an
agricultural producer, food manufacturer or pesticide manufacturer.
Potentially affected entities may include, but are not limited to:
¥ 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 provides
a guide for readers regarding entities likely to be affected by this
action. Other types of entities not listed in this unit could also be
affected. 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 INFORMATION
CONTACT.
B. How Can I Get Copies of This Document and Other Related Information?
1. EPA Docket. EPA has established an official public docket for
this action under docket ID number OPP-2003-0118. The official public
docket consists of the documents specifically referenced in this
action, any public comments received, and other information related to
this action. Although, a part of the official docket, the public docket
does not include Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. The official
public docket is the collection of materials that is available for
public viewing at the Public Information and Records Integrity Branch
(PIRIB), Rm. 119, Crystal Mall #2, 1921 Jefferson Davis Hwy.,
Arlington, VA. This docket facility is open from 8:30 a.m. to 4 p.m.,
Monday through Friday, excluding legal holidays. The docket telephone
number is (703) 305-5805.
2. Electronic access. You may access this Federal Register document
electronically through the EPA Internet under the ``Federal Register''
listings at http://www.epa.gov/fedrgstr/.
An electronic version of the public docket is available through
EPA's electronic public docket and comment system, EPA dockets. You may
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public
comments, access the index listing of the contents of the official
public docket, and to access those documents in the public docket that
are available electronically. Although, not all docket materials may be
available electronically, you may still access any of the publicly
available docket materials through the docket facility identified in
Unit I.B.1. Once in the system, select ``search,'' then key in the
appropriate docket ID number.
Certain types of information will not be placed in the EPA
dockets. Information claimed as CBI and other information whose
disclosure is restricted by statute, which is not included in the
official public docket, will not be available for public viewing in
EPA's electronic public docket. EPA's policy is that copyrighted
material will not be placed in EPA's electronic public docket but will
be available only on printed, paper form in the official public docket.
To the extent feasible, publicly available docket materials will be
made available in EPA's electronic public docket. When a document is
selected from the index list in EPA dockets, the system will identify
whether the document is available for viewing in EPA's electronic
public docket. Although, not all docket materials may be available
electronically, you may still access any of the publicly available
docket materials through the docket facility identified in Unit I.B.
EPA intends to work towards providing electronic access to all of the
publicly available docket materials through EPA's electronic public
docket.
For public commenters, it is important to note that EPA's policy
is that public comments, whether submitted electronically or on paper,
will be made available for public viewing in EPA's electronic public
docket as EPA receives them and without change, unless the comment
contains copyrighted material, CBI, or other information whose
disclosure is restricted by statute. When EPA identifies a comment
containing copyrighted material, EPA will provide a reference to that
material in the version of the comment that is placed in EPA's
electronic public docket. The entire printed comment, including the
copyrighted material, will be available in the public docket.
Public comments submitted on computer disks that are mailed or
delivered to the docket will be transferred to EPA's electronic public
docket. Public comments that are mailed or delivered to the docket will
be scanned and placed in EPA's electronic public docket. Where
practical, physical objects will be photographed, and the photograph
will be placed in EPA's electronic public docket along with a brief
description written by the docket staff.
C. How and to Whom Do I Submit Comments?
You may submit comments electronically, by mail, or through hand
delivery/courier. To ensure proper receipt by EPA, identify the
appropriate docket ID number in the subject line on
[[Page 25884]]
the first page of your comment. Please ensure that your comments are
submitted within the specified comment period. Comments received after
the close of the comment period will be marked ``late.'' EPA is not
required to consider these late comments. If you wish to submit CBI or
information that is otherwise protected by statute, please follow the
instructions in Unit I.D. Do not use EPA dockets or e-mail to submit
CBI or information protected by statute.
1. Electronically. If you submit an electronic comment as
prescribed in this unit, EPA recommends that you include your name,
mailing address, and an e-mail address or other contact information in
the body of your comment. Also, include this contact information on the
outside of any disk or CD ROM you submit, and in any cover letter
accompanying the disk or CD ROM. This ensures that you can be
identified as the submitter of the comment, and allows EPA to contact
you in case EPA cannot read your comment due to technical difficulties
or needs further information on the substance of your comment. EPA's
policy is that EPA will not edit your comment, and any identifying or
contact information provided in the body of a comment will be included
as part of the comment that is placed in the official public docket,
and made available in EPA's electronic public docket. If EPA cannot
read your comment due to technical difficulties and cannot contact you
for clarification, EPA may not be able to consider your comment.
i. EPA Dockets. Your use of EPA's electronic public docket to
submit comments to EPA electronically is EPA's preferred method for
receiving comments. Go directly to EPA dockets at http://www.epa.gov/
edocket, and follow the online instructions for submitting comments.
Once in the system, select ``search,'' and then key in docket ID number
OPP-2003-0118. The system is an ``anonymous access'' system, which
means EPA will not know your identity, e-mail address, or other contact
information unless you provide it in the body of your comment.
ii. E-mail. Comments may be sent by e-mail to opp-docket@epa.gov,
Attention: Docket ID number OPP-2003-0118. In contrast to EPA's
electronic public docket, EPA's e-mail system is not an ``anonymous
access'' system. If you send an e-mail comment directly to the docket
without going through EPA's electronic public docket, EPA's e-mail
system automatically captures your e-mail address. E-mail addresses
that are automatically captured by EPA's e-mail system are included as
part of the comment that is placed in the official public docket, and
made available in EPA's electronic public docket.
iii. Disk or CD ROM. You may submit comments on a disk or CD ROM
that you mail to the mailing address identified in Unit I.C.2. These
electronic submissions will be accepted in WordPerfect or ASCII file
format. Avoid the use of special characters and any form of encryption.
2. By mail. Send your comments to: Public Information and Records
Integrity Branch (PIRIB) (7502C), Office of Pesticide Programs (OPP),
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460-0001, Attention: Docket ID Number OPP-2003-0118.
3. By hand delivery or courier. Deliver your comments to: Public
Information and Records Integrity Branch (PIRIB), Office of Pesticide
Programs (OPP), Environmental Protection Agency, Rm. 119, Crystal Mall
#2, 1921 Jefferson Davis Hwy., Arlington, VA, Attention: Docket
ID Number OPP-2003-0118. Such deliveries are only accepted during the
docket's normal hours of operation as identified in Unit I.B.1.
D. How Should I Submit CBI to the Agency?
Do not submit information that you consider to be CBI
electronically through EPA's electronic public docket or by e-mail. You
may claim information that you submit to EPA as CBI by marking any part
or all of that information as CBI (if you submit CBI on disk or CD ROM,
mark the outside of the disk or CD ROM as CBI and then identify
electronically within the disk or CD ROM the specific information that
is CBI). Information so marked will not be disclosed except in
accordance with procedures set forth in 40 CFR part 2.
In addition to one complete version of the comment that includes
any information claimed as CBI, a copy of the comment that does not
contain the information claimed as CBI must be submitted for inclusion
in the public docket and EPA's electronic public docket. If you submit
the copy that does not contain CBI on disk or CD ROM, mark the outside
of the disk or CD ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and EPA's
electronic public docket without prior notice. If you have any
questions about CBI or the procedures for claiming CBI, please consult
the person listed under FOR FURTHER INFORMATION CONTACT.
E. What Should I Consider as I Prepare My Comments for EPA?
You may find the following suggestions helpful for preparing your
comments:
1. Explain your views as clearly as possible.
2. Describe any assumptions that you used.
3. Provide copies of any technical information and/or data you used
that support your views.
4. If you estimate potential burden or costs, explain how you
arrived at the estimate that you provide.
5. Provide specific examples to illustrate your concerns.
6. Make sure to submit your comments by the deadline in this
notice.
7. To ensure proper receipt by EPA, be sure to identify the docket
ID number assigned to this action in the subject line on the first page
of your response. You may also provide the name, date, and Federal
Register citation.
II. What Action Is the Agency Taking?
EPA has received a pesticide petition as follows proposing the
establishment and/or amendment of regulations for residues of a certain
pesticide chemical in or on various food commodities under section 408
of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a.
EPA has determined that this petition contains data or information
regarding the elements set forth in FFDCA section 408(d)(2); however,
EPA has not fully evaluated the sufficiency of the submitted data at
this time or whether the data support granting of the petition.
Additional data may be needed before EPA rules on the petition.
List of Subjects
Environmental protection, Agricultural commodities, Feed additives,
Food additives, Pesticides and pests, Reporting and recordkeeping
requirements.
Dated: April 30, 2003.
Debra Edwards,
Director, Registration Division, Office of Pesticide Programs.
Summary of Petition
The petitioner's summary of the pesticide petition is printed below
as required by FFDCA section 408(d)(3). The summary of the petition was
prepared by Dow AgroSciences and represents the view of the petitioner.
The petition summary announces the availability of a description of the
analytical methods available to EPA for the detection and measurement
of the
[[Page 25885]]
pesticide chemical residues or an explanation of why no such method is
needed.
Dow AgroSciences
PP 9F6050
EPA has received a pesticide petition (9F6050) from Dow
AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268 proposing,
pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act
(FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180 by establishing
tolerances for residues of fluroxypyr in or on the raw agricultural
commodities as follows: tolerances for residues of fluroxypyr 1-
methylheptyl ester (MHE) in or on sweet corn are being proposed in
support of this registration as follows: 0.02 parts per million (ppm)
for kernels plus cob with husk removed, and 1.0 ppm for forage.
Tolerances for residues of fluroxypyr MHE in or on field corn are being
proposed in support of this registration as follows: 0.02 ppm for
grain; 1.0 ppm for forage; and 0.5 ppm for stover. Tolerances for
residues of fluroxypyr MHE in or on sorghum are being proposed as
follows: Sorghum grain, 0.02 ppm; sorghum forage, 2.0 ppm; sorghum
stover, 4.0 ppm. Tolerances for residues of fluroxypyr MHE in or on
grasses are proposed as follows: grass forage, 120 ppm; grass hay, 160
ppm; and grass silage, 100 ppm. Based on the above tolerances and an
animal feeding study, increased tolerances are also proposed for
fluroxypyr MHE and fluroxypyr, expressed as combined residues of total
fluroxypyr, in or on the following animal commodities: milk of cattle,
goats, hogs, horses and sheep, 0.3 ppm; and kidney of cattle, goats,
hogs, horses and sheep, 1.5 ppm. EPA previously received a pesticide
petition (9F6050) for fluroxypyr and the Notice of Filing was published
in the Federal Register on January 15, 2003. The notice of filing
erroneously omitted tolerances proposed for residues of fluroxypyr on
corn. Thus, this notice will supercede the previously published notice
of filing.
A. Residue Chemistry
1. Plant metabolism. Fluroxypyr is a systemic herbicide that is
readily translocated and rapidly converts to the acid form following
absorption. Fluroxypyr moves readily throughout the plant via the
phloem (nutrient transporting) system and to a lesser extent through
the xylem (water transporting). Fluroxypyr is distributed throughout
the entire plant, including the meristems and other developing plant
parts.
2. Analytical method. There is a practical method gas
chromatography (GC) with mass spectrometry detection (MSD) for
measuring levels of fluroxypyr MHE in or on food with a limit of
detection that allows monitoring of food with residues at or above the
levels set for the proposed tolerances. Fluroxypyr has been tested
through the Food and Drug Administration's (FDA's) Multi residue
Methodology, Protocols C, D, and E. The results have been published in
the FDA Pesticide Analytical Manual, Volume I.
3. Magnitude of residues. The metabolism of fluroxypyr MHE in
plants and animals (goats and poultry) is adequately understood for the
purposes of these tolerances. Magnitudes of residue studies were
conducted for field corn, sweet corn, sorghum and grasses. A process
products study was not conducted in field corn since residues of
fluroxypyr MHE were not detected in corn grain at 5X the application
rate. In addition, processing of sorghum was not conducted since
residue data for flour are not required at this time, because sorghum
flour is used exclusively in the United States as a component for
drywall, and not as either a human food or a feedstuff. No residues of
fluroxypyr are expected in root or leafy vegetable crops grown in
rotation to fluroxypyr-treated field corn, sweet corn, sorghum, and
grasses, after a 30-day plant-back interval at the maximum allowable
label rate of 8 oz. active ingredient/Acre (a.i./A). Field corn, sweet
corn, sorghum and grasses grown in rotation may contain low levels of
fluroxypyr residues; however, the tolerance values proposed for these
crops will adequately assure compliance with the labeled use patterns.
B. Toxicological Profile
1. Acute toxicity. Fluroxypyr MHE has low acute toxicity. The rat
oral LD50 is >5,000 milligrams/kilogram (mg/kg), the rabbit
dermal LD50 is >2,000 mg/kg, and the rat inhalation
LC50 is > 1.0 milligrams/per liter (mg/l) 1,000 mg/cubic
meter. In addition, fluroxypyr MHE is not a skin sensitizer in guinea
pigs, has no dermal irritation in rabbits, and shows mild ocular
irritation in rabbits. The end use formulation of fluroxypyr MHE has a
similar low acute toxicity profile.
2. Genotoxicty. Short term assays for genotoxicity consisting of a
bacterial reverse mutation assay (Ames test), an in vitro assay for
cytogenetic damage using the Chinese hamster ovary cells, an in vitro
chromosomal aberration assay using rat lymphocytes, and an in vivo
cytogenetic assay in the mouse bone marrow (micronucleus test) have
been conducted with fluroxypyr MHE. These studies show a lack of
genotoxicity. In addition, short term assays for genotoxicity
consisting of an Ames metabolic activation test, possible induction of
point mutations at the hypoxanthine guanine phophoribosyl transferase
(HGPRT)-Locus of Chinese hamster ovary cells, in vivo and in vitro
chromosomal aberrations in the Chinese hamster ovary cells, unscheduled
DNA synthesis in human embryonic cells, and an assay in mouse lymphoma
cells have been conducted with fluroxypyr. These studies also show a
lack of genotoxicity.
3. Reproductive and developmental toxicity. Developmental studies
in rats and rabbits were conducted with both fluroxypyr MHE and
fluroxypyr. Studies with fluroxypyr MHE showed maternal and fetal no
observed adverse effect levels (NOAELs) of 300 mg/kg/day (rat) and 500
mg/kg/day (rabbit). Studies with fluroxypyr showed NOAELs in the rat of
250 mg/kg/day for maternal effects and 500 mg/kg/day for fetal effects
and a NOAEL in the rabbit of 250 mg/kg/day for both maternal and fetal
effects. These studies show that fluroxypyr and fluroxypyr MHE are not
teratogenic nor will they interfere with in utero development. Two
multi-generation reproduction studies were conducted with fluroxypyr in
rats. The first in Wistar rats showed no effect on fertility or
reproductive performance and had a NOAEL of 500 mg/kg/day (highest dose
tested). The second study in Sprague-Dawley rats showed a parental
NOAEL for systemic effects of 100 mg/kg/day in male rats and 500 mg/kg/
day in female rats. The NOAEL for reproductive effects was 750 mg/kg/
day for males and 1,000 mg/kg/day for females (highest dose tested).
The NOAEL for neonatal effects was 500 mg/kg/day.
4. Subchronic toxicity. Fluroxypyr MHE showed a NOAEL of 1,000 mg/
kg/day in a 90-day rat dietary study and a 21-day rabbit dermal study.
Ninety day feeding studies with fluroxypyr showed NOAELs of 80 mg/kg/
day (Wistar rats), 700 mg/kg/day (Fischer 344 rats), 1,342 mg/kg/day
(male mice), and 1,748 mg/kg/day (female mice). In a 4-week dietary,
range finding study with fluroxypyr in dogs the NOAEL found was > 50
mg/kg/day.
5. Chronic toxicity. Based on chronic testing with fluroxypyr in
the mouse, dog, and rat (two studies), a reference dose (RfD) of 0.8
mg/kg/day is proposed for fluroxypyr and fluroxypyr MHE. The RfD has
incorporated a 100-fold safety factor to the NOAEL found in the rat
chronic test. NOAELs found in the chronic dietary studies are as
follows: 150 mg/kg/day (dog), 300 mg/kg/day
[[Page 25886]]
(mouse), 80 mg/kg/day (Wistar rats), 100 mg/kg/day (male Fischer 344
rats), and 500 mg/kg/day (female Fischer 344 rats).
6. Animal metabolism. Both fluroxypyr and fluroxypyr MHE have been
evaluated in rat metabolism studies. In summary, these studies show
that fluroxypyr MHE is rapidly hydrolyzed and the fate of the
hydrolysis products, fluroxypyr and 1-methylheptanol, are independent
of whether they were given as the ester or the acid. Fluroxypyr, per
se, was extensively absorbed and rapidly excreted principally unchanged
in the urine; 1-methylheptanol also was rapidly absorbed and rapidly
eliminated. Repeated administration of fluroxypyr MHE was not
associated with accumulation in tissues. Also, the metabolism and
pharmacokinetics of 1-methylheptanol are comparable to that of the
methylheptyl portion of fluroxypyr MHE.
7. Metabolite toxicology. Administration of fluroxypyr, as the acid
or methylheptyl ester in a variety of toxicological studies, has
produced similar effects. The principal response to sufficiently high
dosages, whether administered over the short-term or, in some cases,
over a lifetime, was nephrosis. Fluroxypyr is an organic acid that is
actively excreted into the urine by the kidney. Thus, the target organ
and dose response relationship for fluroxypyr toxicity is entirely
consistent with the data on the toxicokinetics of fluroxypyr.
Metabolism studies have shown that fluroxypyr MHE is rapidly and
completely hydrolyzed to fluroxypyr acid and methylheptanol.
8. Endocrine disruption. There is no evidence to suggest that
fluroxypyr and fluroxypyr MHE have an effect on any endocrine system.
C. Aggregate Exposure
1. Dietary exposure--i. Food. Tier I dietary risk assessments were
conducted for acute, short-term, and chronic exposures. Very
conservative assumptions were made in these risk assessments. The
dietary exposure assessments were based on all commodities with
tolerances for fluroxypyr established at 40 CFR 180.535 together with
proposed tolerances for field corn, sweet corn, grain sorghum, and
forage grass and hay, including revised tolerances for milk and meat.
It was assumed that fluroxypyr residues were present at tolerance or
proposed tolerance levels and that 100% of the crops were treated.
Potential dietary exposure and risk was estimated using
DEEMTM software (Dietary Exposure Evaluation Model, Version
7.075, Novigen Sciences, Inc., Washington, DC).
Developmental toxicity was not observed in the absence of maternal
toxicity and there was no indication of increased susceptibility in
young animals to prenatal or postnatal exposure to fluroxypyr in the
toxicology studies. Therefore, an additional Food Quality Protection
Act (FQPA) safety factor for infants and children was not included in
this assessment. Acute dietary risk was assessed using an acute RfD of
1.25 mg/kg/day, based on a maternal NOAEL of 125 mg/kg/day from a rat
developmental toxicity study and an uncertainty factor of 100 (10X for
interspecies extrapolation and 10X for intraspecies variation). EPA
previously established the maternal NOAEL for this study at 125 mg/kg/
day and it was used here for a very conservative assessment of
potential developmental toxicity. Pregnant females are estimated to
have acute dietary exposure of 0.006582 mg/kg/day, which occupies only
0.53% of the acute RfD. Adverse effects are not expected for exposures
occupying 100% or less of the RfD. Therefore, acute dietary exposure
and risk are well within acceptable levels.
Chronic dietary exposure estimates along with a short-term oral
NOAEL were used to assess short-term dietary exposure and risk. The
assessment of chronic dietary exposure and risk is discussed below. The
chronic exposure values reported for the total U.S. population and for
children 1-6 years old was used to estimate dietary exposure for adults
and toddlers, respectively. A 90-day dietary study in rats with a NOAEL
of 80 mg/kg/day was selected for establishing a short-term oral
toxicity endpoint. A 90-day subchronic study was selected for
evaluating risk from short-term oral exposure since the 90-day exposure
interval is more appropriate than chronic exposure for assessing short-
term risk. Of the 90-day subchronic studies conducted with fluroxypyr,
the one selected provided the lowest NOAEL. The short-term oral NOAEL
(80 mg/kg/day) was divided by the estimated dietary exposure for adults
and toddlers to calculate the respective short-term margins of exposure
(MOEs). A conservative Tier I estimate of chronic dietary exposure to
fluroxypyr estimated exposure at 0.003160 mg/kg/day and 0.010321 mg/kg/
day for the total U.S. population and for children 1-6 years old,
respectively. A short-term dietary (food) MOE was calculated by
dividing the short-term oral NOAEL (80 mg/kg/day) by the estimated
exposure (0.003160 mg/kg/day). The resulting food MOE for adults and
toddlers was calculated to be 25,316 and 7,751, respectively. Since the
MOE is substantially greater than 100, risk is estimated to be well
within acceptable levels.
Tolerances for fluroxypyr exist for several raw agricultural
commodities and as discussed previously, tolerances for additional
commodities have been proposed. Chronic dietary exposure to fluroxypyr
is possible due to the potential presence of fluroxypyr residue in
certain foods. Therefore, a chronic dietary risk assessment was
conducted. The assessment used a chronic RfD of 0.8 mg/kg/day based on
a NOAEL of 80 mg/kg/day from a combined chronic toxicity and
carcinogenicity study in rats and an uncertainty factor of 100 (10X for
interspecies extrapolation and 10X for intraspecies variation). A Tier
I chronic dietary exposure and risk assessment was conducted. It was
assumed that fluroxypyr residues were present at tolerance or proposed
tolerance levels and that 100% of the crops were treated.
DEEMTM estimates dietary exposure and the percent of the
chronic RfD that is occupied by the input residue values for several
population subgroups in the United States. Chronic dietary exposure for
the general U.S. population was estimated to be 0.003160 mg/kg/day,
which occupies 0.4% of the RfD. Children 1-6 years old comprise the
population subgroup predicted to have the highest potential level of
dietary exposure. Children 1-6 years old are estimated to have a
chronic dietary exposure of 0.010321 mg/kg/day, which occupies 1.3% of
the RfD. Adverse effects are not expected for exposures occupying 100%
or less of the RfD. Therefore, chronic dietary exposure and risk for
both the general U.S. population and children 1-6 years old are well
within acceptable levels.
ii. Drinking water. There are no established maximum contaminant
levels for residues of fluroxypyr in drinking water and health advisory
levels for fluroxypyr in drinking water have not been established.
Guidance from EPA has indicated that Tier I screening level models,
such as GENEEC and SCI-GROW, may be used to estimate upper-bound
pesticide residues in surface water and ground water when assessing
potential exposure through drinking water. Estimated concentrations of
a pesticide in surface water or ground water are then compared to a
drinking water level of comparison (DWLOC) as a surrogate estimate of
exposure and risk. The DWLOC is the concentration of a pesticide in
drinking water that would be acceptable as an upper limit in light
[[Page 25887]]
of total aggregate exposure to that pesticide. Potential drinking water
concentrations of fluroxypyr were estimated in ground water and surface
water using the screening concentration in ground water (SCI-GROW) and
the generic expected environmental concentration (GENEEC) models,
respectively. Both SCI-GROW are Tier I screening level models that use
conservative assumptions.
The estimated concentration of fluroxypyr in ground water
according to SCI-GROW is 0.16 mg/L. EPA has indicated that peak
concentrations of a pesticide in surface water should be used in an
acute assessment for comparison with DWLOC values. The estimated peak
concentration of fluroxypyr in surface water using GENEEC is 20.88 mg/
L. The upperbound estimated fluroxypyr concentrations in ground water
(0.16 mg/L) and surface water (20.88 mg/L) are substantially below the
acute DWLOC of 37,303 mg/L for pregnant females. Therefore, even with
the numerous conservative assumptions included in this assessment,
aggregated acute fluroxypyr exposure for pregnant females resulting
from dietary exposure and upper-bound drinking water exposure is well
within acceptable limits of exposure and risk.
As indicated above, the estimated concentration of fluroxypyr in
ground water according to SCI-GROW is 0.16 mg/L. EPA has indicated that
the 56-day value from GENEEC should be divided by 3 for comparison to
short-term, intermediate-term and chronic DWLOC values. The estimated
56-day concentration of fluroxypyr in surface water using GENEEC is
7.08 mg/L. Therefore, the surface water concentration used in this
assessment is 2.36 mg/L (7.08 mg/L / 3). Potential residential exposure
resulting from fluroxypyr use on turf was included along with potential
dietary exposure when calculating the short-term DWLOC for adults and
toddlers. The short-term DWLOC for toddlers and the general population
of adults was calculated to be 7,843 mg/L and 27,450 mg/L,
respectively. The DWLOCs are substantially greater than high-end
estimated exposure from surface water or ground water, indicating risk
from potential drinking water exposure is well within acceptable
levels.
As indicated above with short-term exposure, Tier I screening
level estimates of potential fluroxypyr concentrations in ground water
and surface water are 0.16 mg/L and 2.36 mg/L, respectively. Chronic
DWLOCs for children 1-6 years old and for the general population of
adults are 7,896 mg/L and 27,889 mg/L, respectively. Since the chronic
DWLOCs are substantially greater than potential exposure through ground
water or surface water, risk from potential chronic exposure through
drinking water is well within acceptable levels.
2. Non-dietary exposure. The proposed use of fluroxypyr on
residential turf presents the potential for short-term residential
exposure. Homeowners may have dermal and inhalation exposure to
fluroxypyr during application to turf and also may have dermal exposure
due to post-application activity on the treated turf. Toddlers may have
dermal and oral exposure to fluroxypyr due to post-application activity
on treated turf. Transferable residue of fluroxypyr from turf was found
to range from 0.03 to 0.74% (used as a high end stimate) of the
fluroxypyr applied and to dissipate with a half-life ranging from 1.4
to 2.5 days. Exposure was estimated based on equations and default
values given in the Standard Operating Procedures (SOPs) for
Residential Exposure Assessment. Risk from short-term dermal exposure
was assessed using a NOAEL of 1,000 mg/kg/day from a 21-day rabbit
dermal study. Short-term oral and inhalation exposure was assessed
using a NOAEL of 80 mg/kg/day from a 90-day rat feeding study.
A high-end estimate of exposure for adults was developed by
combining dermal exposure from application of fluroxypyr to turf with
post-application dermal exposure also on the day of treatment (day 0).
Homeowner exposure during the application of fluroxypyr to turf
includes both dermal and inhalation exposure. Surrogate dermal and
inhalation exposure data from Pesticide Handlers Exposure Data base
(PHED V1.1) was used in estimating applicator exposure. The PHED
surrogate data used to estimate exposure assumes residential applicator
attire to include short pants, shortsleeve shirt, and no gloves. The
applicator exposure estimate was based on a broadcast application using
a garden hose end sprayer. Margin of exposure (MOE) values for dermal
and inhalation exposures were calculated using the toxicity endpoints
previously described. Based on these Tier I screening-level estimates,
the general population of adults was estimated to have potential dermal
and inhalation exposures resulting in MOE values of 8,635 and
2,666,667, respectively. These MOEs are substantially greater than 100,
indicating that risk from these potential exposures is well within
acceptable levels.
Toddlers may have exposure to fluroxypyr due to post-application
activity on treated turf. When a pesticide in liquid formulation is
applied to turfgrass toddlers may experience post-application exposure
through dermal exposure and also, through oral exposure due to hand-to-
mouth transfer of pesticide residue and ingestion of treated turfgrass
from treated areas. Based on Tier I screening-level estimates, the MOE
values for dermal exposure and oral exposures are 34,722 and 26,667,
respectively. Even with conservative Tier I estimates the MOEs are well
above 100, indicating that risk from these potential exposures is well
within acceptable levels.
D. Cumulative Effects
The potential for cumulative effects of fluroxypyr MHE and
fluroxypyr and other substances that have a common mechanism of
toxicity is also considered. There is no reliable information to
indicate that toxic effects produced by fluroxypyr MHE and fluroxypyr
would be cumulative with those of any other pesticide chemical. Thus,
it is appropriate to consider only the potential risks of fluroxypyr
MHE and fluroxypyr in an aggregate exposure assessment.
E. Safety Determination
1. U.S. population. Acute dietary exposure for pregnant females to
residues of fluroxypyr from current and proposed uses was estimated to
occupy only 0.53% of the acute RfD, which is well below levels expected
to pose any appreciable risk to human health. Additionally, the acute
DWLOC was calculated to be over 1,700-fold greater than potential
fluroxypyr residue in drinking water predicted by conservative
screening level models. Thus, aggregated acute exposure to fluroxypyr
resulting from current and proposed uses is well within acceptable
levels of risk.
Use of fluroxypyr on turf results in potential short-term
residential exposure for adults. Potential short-term dietary and
residential exposures were combined into an aggregate MOE. Potential
exposure through drinking water was not included in the aggregate MOE,
but was evaluated in aggregate through use of a DWLOC calculated for
short-term exposure. The short-term aggregate MOE for the general
population of adults was calculated to be 6,423. Additionally, the
short-term DWLOC for the general population of adults was over 10,000-
fold greater than potential fluroxypyr residues in drinking water
predicted by conservative screening level models.
[[Page 25888]]
Therefore, aggregate short-term exposure and risk for adults is
expected to be well within acceptable levels.
Using conservative exposure assumptions previously described,
chronic dietary exposure to residues of fluroxypyr from current and
proposed uses was estimated to occupy only 0.4% of the RfD for the
general U.S. population. The chronic DWLOC for adults was calculated to
be over 10,000 fold greater than potential fluroxypyr residue in
drinking water predicted by conservative screening-level models.
Thus, based on the completeness and reliability of the toxicity
data and the conservative exposure assessment it is concluded that
there is a reasonable certainty that no harm will result to the general
U.S. population, pregnant females, or developing young from acute,
short-term, or chronic aggregate exposures to fluroxypyr residues from
current and proposed uses.
2. Infants and children. FFDCA Section 408 provides that EPA may
apply an additional safety factor for infants and children in the case
of threshold effects to account for prenatal and postnatal toxicity and
the completeness of the data base. Based on the current toxicological
data requirements, the data base for fluroxypyr MHE relative to
prenatal and postnatal effects for children is complete. There were no
indications of neurotoxicity and developmental toxicity was not
observed in the absence of maternal toxicity. It is concluded that
there is no indication of increased sensitivity of infants and children
relative to adults and that an additional FQPA safety factor is not
required.
The acute and short-term exposures were assessed for pregnant
females to evaluate the risk for developmental toxicity and it was
concluded that, there was reasonable certainty of no harm from
aggregate exposures resulting from current and proposed uses of
fluroxypyr.
Toddlers may experience short-term dermal and oral exposure to
fluroxypyr as a result of postapplication activities on treated
residential turf. Additionally, there is the potential for exposure to
fluroxypyr through residue in food and drinking water. Tier I
assessments were conducted to develop very conservative estimates of
potential short-term exposure through residential, dietary and drinking
water pathways. Potential dietary and residential exposures were
combined into an aggregate MOE value. The aggregate MOE was 5,120, well
above 100, indicating risk is well within acceptable levels.
Additionally, the short-term DWLOC for toddlers was greater than
potential fluroxypyr residue in drinking water predicted by
conservative screening level models.
Based on a conservative Tier I assessment, chronic dietary
exposure to residues of fluroxypyr from current and proposed uses was
estimated to occupy only 1.3% of the RfD for children 1-6 years old,
the population subgroup predicted to be most highly exposed.
Additionally, the DWLOC was calculated to be over 3,000-fold greater
than potential fluroxypyr residue in drinking water predicted by
conservative screening level models.
Thus, based on the completeness and reliability of the toxicity
data and the conservative exposure assessment it is concluded, that
there is a reasonable certainty that no harm will result to infants and
children from acute, short term, and chronic aggregate exposures to
fluroxypyr residues from current and proposed uses.
F. International Tolerances
There are no Codex maximum residue levels established for residues
of fluroxypyr MHE and fluroxypyr on any food or feed crop.
[FR Doc. 03-11759 Filed 5-13-03; 8:45 am]
BILLING CODE 6560-50-S