United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-738-F-04-007
July 31, 2004
R.E.D. FACTS
Pesticide
Reregistration
Benfluralin
All pesticides sold or distributed in the United States must be registered by
EPA, based on scientific studies showing that they can be used without posing
unreasonable risks to people or the environment. Because of advances in scientific
knowledge, the law requires that pesticides which were first registered before
November 1, 1984, be reregistered to ensure that they meet today's more stringent
standards.
In evaluating pesticides for reregistration, EPA obtains and reviews a complete
set of studies from pesticide producers, describing the human health and
environmental effects of each pesticide. To implement provisions of the Food
Quality Protection Act (FQPA) of 1996, EPA considers the special sensitivity of
infants and children to pesticides, as well as aggregate exposure of the public to
pesticide residues from all sources, and the cumulative effects of pesticides and other
compounds with common mechanisms of toxicity. The Agency develops any
mitigation measures or regulatory controls needed to effectively reduce each
pesticide's risks. EPA then reregisters pesticides that meet current human health and
safety standards and can be used without posing unreasonable risks to human health
and the environment.
When a pesticide is eligible for reregistration, EPA explains the basis for its
decision in a Reregistration Eligibility Document (RED) document. This fact sheet
summarizes the information in the RED document for benfluralin (Chemical Code
No. 084301; Case No. 2030).
Use Profile Benfluralin is a pre-emergent dinitroaniline herbicide used to control grasses
and other weed species. Annual usage is approximately 700,000 pounds active
ingredient. The majority of benfluralin use is on commercial and residential turf.
Benfluralin is also used on alfalfa, lettuce, birdsfoot trefoil, clover, non-bearing fruit
and nut trees, non-bearing berries, non-bearing vineyards, ornamentals, rights of way
(including industrial sites, utility substations, highway guardrails, sign posts, and
delineators), fence rows/hedgerows, and Christmas tree plantations. The use for
peanuts has been voluntarily canceled by the registrant and the tolerance for peanuts
will be proposed for revocation by the Agency. Benfluralin is formulated as
emulsifiable concentrate, granules, soluble concentrate/liquid, water dispersible
granules (dry flowable). Benfluralin is used alone and is also commonly formulated
with trifluralin and oryzalin.
Regulatory Benfluralin was registered in the United States in 1970. During the second
History Pnase of reregistration, the Agency conducted a review of the scientific data base
underlying pesticide registrations and identified missing or inadequate studies.
Subsequent Data Call-Ins (DCIs) were issued in 1991 and 1995 for benfluralin.
There are approximately 120 products containing benfluralin, registered under
Section 3 of the Federal Insecticide, Fungicide and Rodenticide Act (FTFRA).
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Human Health
Assessment
Currently, there are no Section 18 (Emergency Exemption) uses, or Section 24(c)
(Special Local Needs) uses registered for benfluralin.
Toxicity
In acute studies, benfluralin is practically non-toxic (Toxicity Category IV) by
the oral and dermal routes. For primary skin and eye irritation, benfluralin has low
acute toxicity (Toxicity Category HI). In guinea pig studies, technical benfluralin
was found to be a dermal sensitizer.
In longer-term studies, benfluralin is toxic to the kidneys and liver, and is toxic
to the thyroid at high dose levels. Rats show a lowest observed adverse effect level
(LOAEL) based on kidney toxicity. Dogs show a LOAEL based on liver toxicity
and mice show a LOAEL based on liver and kidney toxicity. Other dinitroaniline
pesticides show a mixture of kidney, liver, hematological, and thyroid toxicity at their
respective LOAELs.
In accord with the Agency's Draft Guidelines for Cancer Risk Assessment
(July, 1999), the Agency classified benfluralin into the category "suggestive evidence
of carcinogenicity, but not sufficient to assess human carcinogenic potential," based
on studies in two species (mice and rats).
Suggestive evidence of neuropathy occurring only in rats and only at study
termination was evaluated by the Agency. This neuropathy was considered to be due
to normal age related neuropathy in aging rats at excessive dose levels.
Benfluralin shows no developmental toxicity in two studies (in the rat and
rabbit) at maternally toxic doses. Also, no obvious endocrine related effects were
noted on the organs of reproduction. Thyroid toxicity in rats was seen at the highest
dose, but whether or not these thyroid effects were directly related to endocrine
modulation by benfluralin can not be determined based on the data submitted.
Dietary Exposure and Risk
Benfluralin's dietary risk assessment considered both acute and chronic risks
from residues in food based on field trials. The acute and chronic dietary (food) risks
are less than 100% of the Acute Population Adjusted Dose (aPAD) and Chronic
Population Adjusted Dose (cPAD) for all population subgroups and are not of
concern.
The Agency estimates potential surface water and ground water pesticide
contamination using models. All modeled surface water EECs (< 3.5) and ground
water EECs (< 0.07) are less than the drinking water levels of concern (DWLOCs)
(50 or greater) and therefore are not of concern. The available monitoring data
indicates that benfluralin is found at a lower level in surface water than the modeling
estimates indicate. All detections are well below the DWLOCs and are not of
concern.
Residential Exposure and Risk
Residential handlers may be exposed to benfluralin during and after application
on home lawns and ornamental plants; or after applications at golf courses, parks, and
schools. Benfluralin products are marketed for homeowner use on residential lawns
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and landscape ornamental plants. Benfluralin containing products are also marketed
for use by professional applicators (Lawn Control Operators, or LCOs) on residential
turf, golf courses, other turf such as recreational or commercial areas, and on
ornamental plantings.
For the residential use of benfluralin, EPA is concerned about any Margin of
Exposure (MOE) less than 100, which incorporates a Food Quality Protection Act
(FQPA) safety factor of 1. Benfluralin is not assessed for systemic dermal toxicity
(because no systemic toxicity was observed from a dermal toxicity study in rats), but
is assessed for systemic inhalation toxicity. All residential handler MOEs are greater
than 100 and therefore risks to residential handlers are not of concern.
For the residential postapplication assessment, children are the population
group most likely to be significantly exposed. Since systemic toxicity was not
observed in a dermal toxicity study, up to a dose level of 1,000 mg/kg/day, the only
risk addressed in the assessment is the possible oral exposure of small children from
treated turf, or from treated soil (i.e., soil ingestion, granule ingestion, and
hand-/object-to-mouth transfer). A Margin of Exposure of 100 (or more) is
considered protective for this assessment. The oral MOE from all ingestion
exposures to children is above 100, and therefore these risks are not of concern.
Postapplication inhalation exposure is expected to be minimal.
Occupational Exposure and Risk
Based on current use patterns, occupational handlers (mixers, loaders, and
applicators) may be exposed to benfluralin during and after normal use. The Agency
identified 13 handler scenarios resulting from mixing/loading and applying
benfluralin for crop and non-crop uses. Of the 13 scenarios, all short- and
intermediate-term exposures resulted in an MOE above 100 and are therefore not of
concern.
FQPA Considerations
The Agency has concluded that the FQPA Safety Factor for benfluralin should
be removed (equivalent to IX) based on a complete database for FQPA
consideration and a conclusion that there is no increased susceptibility following pre-
and/or postnatal exposure. The FQPA Safety Factor recommendation assumes that
the exposure databases (food, drinking water, and residential) are complete, the risk
assessment for each potential exposure scenario includes all metabolites and/or
degradates of concern, and does not underestimate the potential risk for infants and
children. These criteria have been met in the benfluralin risk assessment.
Tolerance Reassessment
The tolerances for benfluralin meet the FQPA safety standards for the U.S.
population and sensitive populations, including infants and children. The technical
registrant has requested voluntary cancellation of the peanut use. A Federal Register
Notice was published on June 25, 2003, announcing the receipt of this voluntary use
cancellation request. The cancellation was effective on December 22, 2003 (68 FR
37811). The tolerance will be proposed for revocation.
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Environmental Environmental Fate
Assessment Available data indicates that benfluralin is of variable soil persistence with
different mechanisms of degradation. Benfluralin has low mobility in soils.
Acceptable field dissipation studies observed in three different locations indicate
moderate half-lives of 22 to 79 days. Benfluralin volatilizes rapidly, as indicated
in laboratory volatility studies.
Parent benfluralin is not expected to leach into ground water, based on its
low mobility in soil. However, degradate 2,6 dinitro-4-trifluoromethyl-phenol
was formed at 6% of parent in the soil metabolism study. Based on limited
environmental fate information, it has the potential to contaminate groundwater,
and was included in the drinking water assessment. Trifluoroacetic acid (TFA)
was not found in environmental fate studies, but was noted as a plant metabolite.
Based on its measured bioaccumulation factor in whole fish (1580), parent
benfluralin is considered to be bioaccumulative. The depuration rate was 0.54 per
day for whole fish.
Ecological Toxicity
Benfluralin is considered to be practically non-toxic to birds on an acute
and subacute basis. However, benfluralin caused reproductive effects in chronic
avian studies. The endpoint from the bobwhite quail study cannot be assumed
conservative, as effects were observed at the lowest dose tested of 96 ppm.
Another quail study is needed to establish a No Observed Adverse Effect
Concentration (NOAEC) for reproductive effects.
Benfluralin is classified as practically nontoxic to small mammals on an
acute oral basis. Although no data are available on the toxicity of benfluralin to
wild mammals, adverse effects were observed in a reproduction study on rats.
Benfluralin has been found to be very highly toxic to freshwater fish on an
acute basis. No acceptable data is available to assess risk to freshwater
invertebrates. Also, no acceptable data is available to determine toxicity to
estuarine fish. Available acute toxicity data on technical benfluralin indicate that
it is very highly toxic to estuarine/marine invertebrates.
A honey bee acute toxicity study indicated that technical benfluralin is
practically non-toxic to the honey bee. The Agency is unable to assess risk to
non-target plants due to a lack of toxicity data on non-target plants.
Additional data is being required to assess risk to birds, freshwater
invertebrates, freshwater and estuarine fish, and non-target plants.
Risks to Terrestrial and Aquatic Organisms
The Agency conducted a screening level ecological risk assessment to
determine the potential impact of benfluralin use on non-target terrestrial and
aquatic organisms. The Agency used modeling to evaluate ecological risks for
benfluralin.
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Most ecological risk quotient (RQ) values are 9 and below, including RQ
values for acute risk to freshwater fish, freshwater invertebrates, and estuarine
invertebrates, and for chronic risk to birds, mammals, and freshwater fish. The
highest RQ value for non-cropland areas at the maximum application rate of 12 Ib
ai/A per year is 24 for chronic risk to mammals. The RQs for non-target
terrestrial and aquatic plants have not been calculated due to lack of toxicity data.
The Agency's screening level risk assessment for benfluralin concluded
that there is a potential for risk to endangered species. Reductions in application
rates and/or number of applications will reduce overall risk. The rates for
non-cropland sites, ornamentals, and Christmas tree farms are being reduced. The
use of benfluralin on alfalfa and lettuce is limited in terms of application rate,
frequency of application and the states that use it for these crops. The endangered
species assessment on all use sites will be refined using data that will be
submitted as a result of this RED. After the new data are reviewed, the risk
assessment will be refined, and exceedences of the levels of concern for risks for
endangered species will be addressed.
Risk Mitigation
To lessen the risks posed by benfluralin, EPA is requiring the following
ecological risk mitigation measures:
The yearly maximum use rate for benfluralin has been reduced at several use
sites. For field-grown ornamentals, container-grown ornamentals, non-bearing
berries, non-bearing fruit trees, non-bearing nut trees, and non-bearing
vineyards, the maximum yearly rate has been reduced from 9 Ibs ai/acre to 6
Ibs ai/acre; for landscape ornamentals and Christmas trees, the maximum
yearly rate has been reduced from 8 Ibs ai/acre to 4 Ibs ai/acre; and for
non-cropland areas (Industrial Sites, Utility Substations, Highway Guardrails,
Sign Posts, and Delineators) the maximum yearly use rate has been reduced
from 12 Ibs ai/acre to 4 Ibs ai/acre.
Additional Data
Required
EPA is requiring multiple confirmatory data requirements for benfluralin,
including acute fish toxicity, acute aquatic invertebrate toxicity, acute
estuarine/marine toxicity in fish and mollusk, fish life cycle, avian reproduction,
aquatic plant growth, vegetative vigor, aerobic aquatic metabolism, 90-day inhalation
in rat, and carcinogenicity in mouse, among others. For a complete listing of
required studies with corresponding guideline number, see Section V of the
Benfluralin RED document.
Product Labeling
Changes Required
All benfluralin end-use products must comply with EPA's current pesticide
product labeling requirements and with the following:
• For Manufacturing Use Products with greater than 60% active ingredient
benfluralin, the labeling statement "Prolonged or frequently repeated skin
contact may cause allergic reactions in some individuals."
• Directions for watering-in granular formulations used on turfgrass.
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• A 12-month plant back interval for crops other than the crops listed on the
label.
• Label amendments to minimize the potential for spray drift are required.
For a comprehensive list of labeling requirements, please see Section V of the
Benfluralin RED document.
Regulatory EPA has determined that all products containing benfluralin as the active
Conclusion ingredient are eligible for reregistration, provided changes specified in the
Benfluralin RED are incorporated into the label and additional data identified in
Section V of the RED confirm this conclusion.
Electronic copies of the RED and this fact sheet are available on the Internet.
See http://www.epa.gov/pesticides/reregistration/status.htm or
http ://www epa. gov/edockets.
Printed copies of the RED and fact sheet can be obtained from EPA's National
Service Center for Environmental Publications (EPA/NSCEP), PO Box 42419,
Cincinnati, OH 45242-2419, telephone 1-800-553-6847; fax 513-489-8695.
The Benfluralin RED document also will be available from the National
Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA
22161, telephone 1-800-553-6847, or 703-605-6000.
For more information about EPA's pesticide reregistration program, the
Benfluralin RED, or reregistration of individual products containing benfluralin,
contact the Special Review and Reregistration Division (7508C), OPP, US EPA,
Washington, DC 20460, telephone 703-308-8000.
For information about the health effects of pesticides, or for assistance in
recognizing and managing pesticide poisoning symptoms, please contact the National
Pesticide Information Center (NPIC). Call toll-free 1-800-858-7378, from 6:30 am to
4:30 am Pacific Time, or 9:30 am to 7:30 pm Eastern Standard Time, seven days a
week. The NPIC internet address is http://npic.orst.edu.
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