United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-95-035
April 1996
R.E.D. FACTS
Pesticide
Reregistration
Trifluralin
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 reregi strati on, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human
health and environmental effects of each pesticide. The Agency develops
any mitigation measures or regulatory controls needed to effectively reduce
each pesticide's risks. EPA then reregisters pesticides that can be used
without posing unreasonable risks to human health or the environment.
When a pesticide is eligible for reregi strati on, EPA explains the basis
for its decision in a Reregistration Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 0179, trifluralin.
Use Profile
Regulatory
History
Trifluralin is a preemergent herbicide used to control annual grasses
and broadleaf weeds on a variety of food crops and is also currently
registered for non-food uses, including residential use sites. The herbicide
is formulated as a liquid, emulsifiable concentrate, granular, flowable
concentrate, impregnated material, soluble concentrate/liquid, soluble
concentrate/solid, and water dispersible granules (dry flowable). Trifluralin
is typically applied at the dormant, semi-dormant, preplant, pre-transplant,
postplant, preemergence, postemergence, layby, or postharvest stage as a
soil-incorporated treatment. It can be applied by aerial equipment, tractor-
drawn groundbooms, tractor-drawn granular spreaders, push-type
spreaders, "whirly-bird" spreaders, and commercial granular turf spreaders.
Trifluralin was first registered in the United States in 1963 as a
selective preemergent herbicide. A Registration Standard for trifluralin was
issued in April 1987 (NTIS# PB87-201935) and a Data Call-In (DCI) for
reentry protection data and mixer/loader/applicator exposure monitoring
data for trifluralin products used on turf was issued in March 1995.
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Human Health
Assessment
EPA initiated a Special Review of trifluralin in August, 1979 because
it was found to contain N-nitroso-di-n-propylamine (NDPA or nitrosamine)
at levels that met or exceeded the Agency's oncogenic risk criterion. In
concluding the Special Review in 1982, EPA required registrants to achieve
a 0.5 ppm upper limit for nitrosamines in their technical products. As part
of the reregi strati on eligibility decision on trifluralin, the Agency is
requiring that all technical and manufacturing-use registrants submit
nitrosamine analysis data to confirm that levels remain at or below the 0.5
ppm limit.
Toxicity
Trifluralin technical is classified under Toxicity Category IV
(practically non-toxic) for acute oral toxicity and dermal irritation, and
Toxicity Category III (slightly toxic) for acute dermal toxicity, acute
inhalation toxicity and eye irritation potential. Trifluralin is also classified
as a dermal sensitizer.
Trifluralin has been classified as a Group C, possible human
carcinogen by the OPP Carcinogenicity Peer Review Committee on April 4,
1986. Limited evidence of carcinogenicity exists in male and female rats
based on an increase in combined malignant and benign urinary bladder
tumors in females, renal pelvis carcinomas in male rats, and thyroid gland
follicular cell tumors in males.
Dietary Exposure
People may be exposed to residues of trifluralin through the diet.
Tolerances or maximum residue limits have been established for residues of
trifluralin in many food and feed crops (40 CFR 180.207). EPA has
reassessed the trifluralin tolerances and found that some are acceptable,
while others must be revoked because of refinements in established crop
group tolerances and where no registered uses exist. Tolerances that are
revoked because of refinements in crop groups must be replaced with new
tolerances for the new crop groupings. The tolerance for residues of
trifluralin in/on wheat straw, barley straw, and barley hay should be
increased to 0.1 ppm.
Processing studies show that residues of trifluralin concentrate in
peppermint oil and spearmint oil. New processing data are required on a
confirmatory basis for both peppermint and spearmint oils to determine the
actual amount of trifluralin that concentrates in both commodities.
Available processing data are sufficient, however, to determine that
trifluralin residues in ready-to-eat foods prepared from the mint oils will not
exceed existing raw agricultural commodity tolerances. Therefore, the
existing tolerance is sufficient to cover the residue levels of trifluralin in
food containing mint oil, and a food additive regulation under Section 409
of the Federal Food, Drug, and Cosmetic Act is not necessary.
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Environmental
Assessment
EPA has assessed the dietary risk posed by trifluralin. The
Anticipated Residue Concentration (ARC) for the overall U.S. population
represents 1% of the Reference Dose (RfD), or amount believed not to
cause adverse effects if consumed daily over a 70-year lifetime. The most
highly exposed subgroup, non-nursing infants less than one year old, has an
ARC which represents 2% of the RfD. This low fraction of the allowable
RfD is considered to be an acceptable dietary exposure risk.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and
applicators) may be exposed to trifluralin during and after applications in
agricultural and other use sites. The occupational/residential cancer
exposure risk assessment for all uses indicates a level of risk that does not
exceed 10"5 for occupational handlers or 10"7 for residential handlers, levels
considered reasonable by the Agency.
Human Risk Assessment
Trifluralin generally is of low acute toxicity, but has been classified as
a Group C, possible human carcinogen. Many food crop uses are
registered, however, dietary exposure to trifluralin residues in food is at a
low level, as is the cancer risk posed to the general population.
Of greater concern is the carcinogenicity risk posed to trifluralin
handlers, particularly mixers/loaders/applicators, and field workers who
come into contact with treated areas. Exposure and risk to workers will be
mitigated by the use of Personal Protective Equipment required by the
Worker Protection Standard, including coveralls, chemical-resistant gloves,
shoes, and socks. Post-application reentry workers will be required to
observe a 12-hour Restricted Entry Interval.
Environmental Fate
Trifluralin is moderately persistent and non-mobile in a microbially
active soil environment. In general, high persistence and high mobility
promote movement into ground water. Because annual average surface
water concentrations are not likely to exceed the lifetime health advisory
level (2 ug/L) and peak/short term averages are not likely to exceed 1 day
and 10 day health advisory levels, exposure/risk from trifluralin in drinking
water is expected to be minimal. Although trifluralin has no direct aquatic
applications, contamination of surface water may occur by spray drift and
under some circumstances, runoff.
Ecological Effects
Trifluralin is practically non-toxic to birds and mammals on an acute
basis. It does not pose acute risks of concern to terrestrial vertebrates,
except to those which are endangered species. Also, two of four laboratory
bird studies indicate chronic risk, as evidenced by egg shell cracking.
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Additional Data
Required
Product Labeling
Changes
Required
For aquatic animals (fish and invertebrates), trifluralin is considered
moderately to highly toxic, and poses acute toxicity risks of concern to
endangered species. In addition, laboratory and field studies suggest
exposure-related abnormalities in vertebral development, at concentrations
below those where acute effects are anticipated. Also, this assessment is
based on trifluralin dissolved in the water column and does not take into
account trifluralin adsorbed to sediment. Trifluralin adsorbed to sediment
may pose a risk for fish species that forage by feeding from sediment,
particularly since it has a moderate tendency to bioaccumulate. EPA will
explore the need for further monitoring efforts or additional analyses with
the registrants of technical trifluralin in order to obtain more refined
characterization of the risk to fish.
While semi-aquatic plants exceed the "high risk" level of concern,
EPA does not note concerns for effects on aquatic plants resulting from use
of trifluralin. To control adverse effects resulting from aerial application of
trifluralin, the Agency will require a spray drift advisory as precautionary
labeling.
EPA is requiring the following additional generic studies for
trifluralin to confirm its regulatory assessments and conclusions:
nitrosamine analysis data and peppermint oil and spearmint oil processing
data. Residue chemistry data are also required for nongrass
forage/fodder/straw/hay and dill uses because the Agency does not have
enough information at this time to make an eligibility decision for trifluralin
products labeled for those uses.
The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs), and revised labeling for reregi strati on.
All trifluralin end-use products must comply with EPA's pesticide
product labeling requirements. A 12-hour restricted-entry interval (RET) is
required for uses within the scope of the WPS on all trifluralin end-use
products. Early-entry personal protective equipment (PPE) required for
occupational uses within the scope of the WPS include coveralls, chemical-
resistant gloves and socks plus shoes. Aquatic impact labeling is required
for all trifluralin end-use products. For all trifluralin products that can be
applied aerially, special spray drift prevention language is required.
Regulatory
Conclusion
The use of currently registered products containing trifluralin in
accordance with approved labeling will not pose unreasonable risks or
adverse effects to humans or the environment. EPA has determined that
products containing trifluralin are eligible for reregi strati on except products
labeled for use on nongrass forage/fodder/straw/hay and dill. EPA does
not have enough information at this time to make an eligibility decision for
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For More
Information
trifluralin products labeled for those uses. The Agency is requiring
additional data in order to develop a more complete data base regarding
these uses of trifluralin.
Before reregistering any trifluralin product, the Agency will review
product specific data, Confidential Statements of Formula and revised
labeling imposed by the RED. Once this information is accepted, the
Agency will reregister trifluralin products bearing only eligible uses. After
the Agency receives the data necessary to make a reregi strati on eligibility
decision on nongrass forage/fodder/straw/hay and dill and the data show
that these uses will not cause unreasonable adverse effects, the Agency will
reregister products bearing these uses. Products which contain active
ingredients in addition to trifluralin will be reregistered when all of their
other active ingredients also are eligible for reregi strati on.
EPA is requesting public comments on the Reregi strati on Eligibility
Decision (RED) document for trifluralin during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
Electronic copies of the RED and this fact sheet can be downloaded
from the Pesticide Special Review and Reregi strati on Information System
at 703-308-7224. They also are available on the Internet on EPA's gopher
server, GOPHER.EPA.GOV, or using ftp on FTP.EPA.GOV, or using
WWW (World Wide Web) on WWW.EPA.GOV.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone
513-489-8190, fax 513-489-8695.
Following the comment period, the trifluralin RED document also
will be available from the National Technical Information Service (NTIS),
5285 Port Royal Road, Springfield, VA 22161, telephone 703-487-4650.
For more information about EPA's pesticide reregi strati on program,
the trifluralin RED, or reregi strati on of individual products containing
trifluralin, please contact the Special Review and Reregi strati on Division
(7508W), 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 Pesticides Telecommunications Network (NPTN). Call toll-
free 1-800-858-7378, between 9:30 am and 7:30 pm Eastern Standard
Time, Monday through Friday.
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