Trifluralin. Pesticide Fact Sheet prepared for USDA.

FLUORIDE ACTION NETWORK PESTICIDE PROJECT

Trifluralin. Pesticide Fact Sheet. Prepared for USDA by Information Ventures, Inc.

FROM: http://infoventures.com/e-hlth/pestcide/triflura.html

Trifluralin

Pesticide Fact Sheet

Prepared for the U.S. Department of Agriculture, Forest Service by Information Ventures, Inc.

This fact sheet is one of a series issued by the Forest Service, the Bureau of Land Management, and the Bonneville Power Administration for their workers and the general public. It provides information on forest and land management uses, environmental and human health effects, and safety precautions for the herbicide trifluralin and its formulations. Unless otherwise stated, the toxicity data presented in this fact sheet refer to the active ingredient, trifluralin. When included, data on formulated products will be specifically identified. A list of definitions is included in Section VIII of the fact sheet.

I. Basic Information

Common name: Trifluralin

Chemical name: a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine

Common Product names: Treflan® 5G, Treflan® E.C., Trifluralin® 4EC

Pesticide classification: herbicide

Registered Use Status: "General Use"

Formulations: Commercial trifluralin products generally contain one or more inert ingredients. An inert ingredient is anything added to the product other than an active ingredient. Because of concern for human health and the environment, the U.S. Environmental Protection Agency (EPA) announced its policy on toxic inert ingredients in the Federal Register on April 22, 1987 (52 FR 13305). The intent of this policy is the regulation of inert ingredients. EPA's strategy for the implementation of this policy included the development of four lists of inerts based on toxicological concerns. Inerts of toxicological concern were placed on List 1. Potentially toxic inerts/high priority for testing were placed on List 2. Inerts of unknown toxicity were placed on List 3 and inerts of minimal concern were placed on List 4.

For pesticides containing List 1 inerts, the EPA has given the pesticide registrant the opportunity to reformulate the product to remove the List 1 inerts. If the registrant chooses not to reformulate the product, then the List 1 inerts must be identified on the product label. For List 2 inerts, the EPA is monitoring ongoing testing and gathering existing information on the potential adverse effects of these chemicals to determine if further regulatory action is required. The EPA has no particular regulatory plans for List 3 and List 4 inerts. The Forest Service will incorporate new data on inerts into updated fact sheets as it becomes available.

The contents of 3 trifluralin formulations are listed below.

Treflan® E.C.: trifluralin (5%) and inert ingredients (95%)

Treflan® E.C.: trifluralin (44.5%) and inert ingredients (55.5%) including xylene, ethylbenzene and naphthalene

Trifluralin 4EC: trifluralin (44.5%) and inert ingredients (55.5%)

Residue assay methods: Gas chromatography with electron capture detector is available for residue assay.

II. Herbicide Uses

Registered forestry, rangeland, right-of-way uses: for use on ornamental trees, rights of way, domestic outdoor and industrial sites.

Operational details:

Target Plants: Trifluralin is used to control annual grasses and certain broadleaf weeds.

Mode of action: Trifluralin applied to the soil kills weed seeds as they germinate. It does not control established weeds.

Method of application: Trifluralin is applied by low pressure ground spraying equipment, subsurface layering equipment, irrigation systems, aerial equipment, or granular applicators. Soil incorporation within 4 to 24 hours after application is recommended for most uses. For some products, surface application followed by irrigation is recommended. Do not apply to muck soils or to soils containing more than 10% organic matter.

Use rates: Use at * to 1 pound of active ingredient per acre

Special Precautions:

Always read all of the information on the product label before using any pesticide. Read the label for application restrictions.

Timing Of Application: Apply before weed germination or to cultivated weed-free areas. Do not apply when foliage is wet.

Drift Control: Do not allow careless application or spray drift. Do not spray aerially when wind speed is greater than 4 mph.

III. Environmental Effects/Fate

Soil:

Residual Soil Activity: Trifluralin is active in the soil. Germination of crops may be impacted for up to 1* years after soil treatment, especially in arid conditions. It is not usually absorbed from the soil by plants.

Adsorption: Trifluralin is strongly adsorbed by the soil.

Persistence and Agents of Degradation: Trifluralin remains unchanged in the soil for varying lengths of time but is generally persistent. In the field, trifluralin degrades to half of its original concentration in 2 to 4 months. Trifluralin is photodegraded but not hydrolyzed in soil. Under laboratory conditions, degradation is faster in soil where no air is present.

Metabolites/Degradation Products and Potential Environmental Effects: Break-down products of trifluralin in the soil include a,a,a-trifluoro-2,6-dinitro-p-toluidine (the major breakdown product); a,a,a-trifluoro-2,6-dinitro-n-propyl-p-toluidine; a,a,a-trifluoro-N,N-dipropyl-5-nitrotoluene-3,4-diamine; a,a,a-trifluoro-N,N-dipropyltoluene-3,4,5-triamine. No information is available on the environmental effects of these breakdown products.

Water:

Solubility: Trifluralin does not dissolve easily in water.

Potential For Leaching Into Ground-Water: The potential for leaching into the ground-water is very low. Trifluralin is strongly adsorbed to soil particles and is not readily leached. The mobility of trifluralin is greatest in fine sand and least in muck soils; it is relatively immobile in sand, sandy loam, silt, loam and clay loam soils. No information is available on the half-life of trifluralin in water.

Surface Waters: Trifluralin could enter surface waters through the runoff of sediment; one study showed very little runoff, however. When trifluralin is applied to ditch banks, irrigation water should not be used on food or feed crops for 18 months after application or until the water is free of trifluralin residues.

Air:

Volatilization: Trifluralin does not evaporate easily.

Potential For By-Products From Burning of Treated Vegetation: No information is available. However, trifluralin is applied directly to soil and is therefore not present in great concentration in foliage.

IV. Ecological Effects

Non-Target Toxicity:

Soil Microorganisms: No information available.

Plants: Trifluralin did not accumulate in crops grown in silt loam soil treated with 1 pound active ingredient per acre. Contact with susceptible non-target plants may injure these plants.

Aquatic Animals: Trifluralin is highly toxic to cold- and warm-water fish and to aquatic invertebrate animals. It is very highly toxic to amphibians (tadpoles). It has not been tested for effects on estuarine and marine animals. It may build up (bioaccumulate) in fish exposed to trifluralin in water at low levels; but in one test it was eliminated from edible fish tissues 7 days after exposure ended. Trifluralin affected the survival of minnows at chronic exposures as low as 5.1 ppb; and affected the survival of water fleas at chronic exposures as low as 7.2 ppb.
Acute toxic level:

species	LC50	Source Table
rainbow trout	41 ppb	(Table II, Aquatic)
fathead minnow	105 ppb	(Table II, Aquatic)
channel catfish	2.2 ppm	(Table II, Aquatic)
bluegill sunfish	58 ppb	(Table II, Aquatic)
largemouth bass	75 ppb	(Table II, Aquatic)
goldfish	145 ppb	(Table II, Aquatic)
species	TL50 (96 hour)	Source Table
tadpole	0.1 ppm	---
species	LC50	Source Table
water flea	0.56-0.9 ppm	---
stone fly	2.8 ppm	---
side swimmer	2.2 ppm	---

Terrestrial Animals: Trifluralin is practically nontoxic to birds when fed the chemical on both an acute and a subacute basis. It did not impair reproduction in birds at dietary exposures below 50 ppm. Trifluralin is practically nontoxic to mammals. It is of low acute toxicity to honeybees. Acute toxic level:

species	LD50	Source Table
birds	<2,000 mg/kg	(Table II, Avian)
rats	<5,000 mg/kg	(Table II, Mammalian)

Threatened and Endangered Species: Use of trifluralin for certain agricultural applications may be a hazard to endangered species if it is applied to areas where they live. The endangered species of concern are the slackwater darter, woundfin, solano grass, and several freshwater mussel species. Rangeland and right-of-way uses are under evaluation, but are probably of minimal risk to endangered species.

V. Toxicology Data

Acute toxicity:

Acute oral toxicity: In tests in male and female rats exposed to trifluralin, the acute oral LD50 was >5,000 mg/kg. (Toxicity Category IV, Table I, Oral).
Acute dermal toxicity: The acute dermal (skin) LD50 was >2,000 mg/kg in rabbits exposed to trifluralin. (Toxicity Category III, Table I, Dermal). The Environmental Protection Agency is requiring information on the dermal penetration potential of trifluralin.

Primary irritation score: In laboratory tests in rabbits, trifluralin was not an irritant. (Toxicity Category IV, Table I, Skin irritation). Trifluralin is a skin sensitizer in guinea pigs.

Primary eye irritation: In laboratory tests in rabbits, trifluralin was a mild eye irritant. (Toxicity Category III, Table I, Eye irritation).

Acute Inhalation: In tests in rats exposed to trifluralin, the acute inhalation LC50 was >2.8 mg/L. (Toxicity Category III, Table I, Inhalation).

Chronic toxicity:

Carcinogenicity: A laboratory test in male and female mice fed up to 4,500 ppm trifluralin in their diet for up to 2 years showed no evidence of carcinogenicity. However, laboratory testing in rats fed up to 325 mg/kg per day trifluralin in their diet for up to 2 years did show some evidence of carcinogenicity. In this study there were increased malignant kidney tumors in male rats exposed to trifluralin dietary levels greater than 41 mg/kg per day; there were increased benign bladder tumors in female rats. A carcinogenic nitrosamine contaminant of trifluralin was not detectable in either of these studies; therefore the carcinogenic activity was due to the trifluralin itself.

Developmental: Laboratory studies with trifluralin in pregnant rats (at dose levels up to 1,000 mg/kg per day) and rabbits (at dose levels up to 500 mg/kg per day) indicated no evidence of teratogenesis (birth defects).

Reproduction: A two-generation reproduction study in rats did not show any adverse effects on fertility or reproduction at doses up to 2,000 ppm trifluralin in the diet.

Mutagenicity: Trifluralin was negative in 4 tests for mutagenicity (the ability to cause genetic damage). Additional tests for mutagenicity are required by the EPA.

The data reported above are results of animal studies which the Environmental Protection Agency has evaluated in support of the registration of trifluralin. These data are used to make inferences relative to human health.

HAZARD: Based on the results of animal studies, trifluralin does not cause genetic damage or birth defects, and has no effect on fertility, reproduction or development of offspring. There is no evidence in humans that trifluralin causes cancer; however there are some animal studies in which trifluralin was carcinogenic. Trifluralin is considered by the EPA to be a "possible human carcinogen."

VI. Human Health Effects

Acute toxicity (poisoning):

Reported effects: Most incidents of trifluralin exposure reported in humans have involved dermal and eye irritation and nausea. Dizziness and headache, fever or chills, and muscle aches or weakness have also been reported.

Chronic toxicity:

Reported effects: There are no reported cases of long term health effects in humans due to trifluralin or its formulations.

Potential for adverse health effects from contacting or consuming treated vegetation, water or animals: The exposure levels a person could receive from these sources, as a result of routine operations, are probably below levels shown to cause harmful effects in laboratory studies.

Potential for adverse health effects from inert ingredients contained in the formulated product: Inert ingredients found in the emulsifiable concentrate (E.C.) of trifluralin include xylene, ethylbenzene and naphthalene. The effects of these compounds include: corneal (eye) damage, liver changes, fetotoxicity, and teratogenicity (xylene); blistering of skin, and liver, kidney and testicular changes (ethylbenzene); and cataracts and liver changes (naphthalene).

Health effects of exposure to formulated products: The Trifluralin E.C. formulation may cause skin and eye irritation. No specific effects of exposure to the granular formulation have been noted.

Health effects associated with contaminants: Trifluralin contains the contaminant N-nitroso-di-n-propylamine (NDPA). This contaminant is an N-nitrosamine class chemical; these chemicals have a known potential for causing cancer. However, the Environmental Protection Agency (EPA) requires that manufacturers of trifluralin certify that technical trifluralin products contain a total N-nitrosamine concentration of no greater than 0.5 ppm. The EPA concluded that the benefits of trifluralin outweighed the identified risks. They also conclude that exposure to NDPA in trifluralin is not of toxicological significance in evaluating the risk of exposure to trifluralin.

Health effects associated with other formulations: Some formulations of trifluralin also contain other herbicides such as alachlor. The information in this fact sheet only applies to trifluralin. Consult other fact sheets for information on the other herbicides.

Health risk management procedures: The Forest Service has evaluated health effects data in the development of both pesticide background statement documents and environmental impact statements for pesticide use on forest lands. These health effects evaluations have taken into consideration the potential for both worker and public exposure from Forest Service operations. This information has been used in assessing health risks and consequently in formulating protective measures to reduce risk to forest workers and to the public. Section VII of this fact sheet, Safety Precautions, provides guidance for the safe handling and use of trifluralin.

VII. Safety precautions:

Signal word and definition:

Treflan® 5G: CAUTION - CAUSES EYE IRRITATION. HARMFUL IF SWALLOWED, INHALED, OR ABSORBED THROUGH THE SKIN.
Treflan® E.C.: WARNING - CAUSES SUBSTANTIAL BUT TEMPORARY EYE INJURY. CAUSES SKIN IRRITATION. HARMFUL IF SWALLOWED, INHALED, OR ABSORBED THROUGH THE SKIN. MAY CAUSE SKIN SENSITIZATION REACTIONS IN CERTAIN INDIVIDUALS.
Trifluralin® 4EC: WARNING - CAUSES EYE AND SKIN IRRITATION. HARMFUL IF SWALLOWED OR ABSORBED THROUGH THE SKIN.

Protective Precautions for Workers: Avoid contact with eyes, skin or clothing. Avoid breathing vapors or spray mist. Wear goggles, face shield or safety glasses, and protective clothing, such as coveralls, a long-sleeved shirt, and impermeable gloves when handling. Wash thoroughly with soap and water after handling. Remove contaminated clothing and wash before reuse. Do not allow children or pets on treated areas until * inch of water has been applied and the water has dried or until 24 hours have passed.

Medical Treatment Procedures (Antidotes): For exposure to the eyes, hold eyelids open and flush with a steady, gentle stream of water for 15 minutes. Get medical attention. For exposure to the skin, immediately wash with plenty of soap and water. If granular formulation is swallowed, drink one or two glasses of water (if conscious) and induce vomiting. If E.C. formulation is swallowed, administer activated charcoal (6-8 heaping teaspoons) with water. If inhaled, move individual to fresh air and get medical attention if breathing difficulty occurs. If not breathing, provide cardiopulmonary resuscitation assistance. In case of emergency, call your local poison control center for advice.

Handling, Storage, And Disposal: Do not apply directly to water or wetlands (swamps, bogs, or marshes). Drift or runoff from treatment areas may be hazardous to aquatic organisms in neighboring aquatic sites. Do not discharge water containing trifluralin into lakes, streams, ponds estuaries, oceans, or public water unless disposal is specifically permitted. Do not discharge into sewer systems without first notifying the sewage treatment plant authority. Wastes resulting from use of trifluralin may be disposed of on site or at an approved waste disposal facility.

Emergency (Spill) Hazards And Procedures: Use absorbent materials to contain and clean up small spills and dispose of as waste. Prohibit use of hot or sparking equipment in area of spill of E.C. formulations. Prevent runoff. Do not contaminate water, food, animal feeds or seed by storage or disposal. In case of a large spill, call CHEMTREC at 1-800-424-9300 for advice.

VIII. Definitions

adsorption - the process of attaching to a surface
avian - of, or related to, birds
carcinogenicity - ability to cause cancer
dermal - of, or related to, the skin
ecotoxicology - the study of the effects of environmental toxicants on populations of organisms originating, being produced, growing, or living naturally in a particular region or environment.
ecotoxicological - related to the study of the effects of environmental toxicants on populations of organisms originating, being produced, growing, or living naturally in a particular region or environment.
formulation - the form in which the pesticide is supplied by the manufacturer for use
half-life - the time required for half the amount of substance to be reduced by natural processes
herbicide - a substance used to destroy plants or to slow down their growth
LC50 - the concentration in air, water, or food which will kill approximately 50% of the subjects
LD50 - the dose which will kill approximately 50% of the subjects
leach - to dissolve out by the action of water
mg/kg - milligrams of the substance per kilogram of body weight
microorganisms - living things too small to be seen without a micro-scope
mutagenicity - ability to cause genetic changes
non-target - animals or plants other than the ones which the pesticide is intended to kill
persistence - tendency of a pesticide to remain active after it is applied
ppb - parts per billion
ppm - parts per million
TL50 - the concentration in water which will kill approximately 50% of the subjects during a specific exposure period
residual activity - the remaining amount of activity as a pesticide
volatility - the tendency to become a vapor at relatively low temperature

IX. Additional Reading

Final Environmental Impact Statement for Managing Competing and Unwanted Vegetation. Pacific Northwest Region. Forest Service, U.S. Department of Agriculture, Portland, Oregon. 1988.

Final Environmental Impact Statement. Vegetation Management in the Coastal Plain/Piedmont. Forest Service, U.S. Department of Agriculture, Atlanta, Georgia. Management Bulletin R8-MB-23, 1989.

Registration Standard for Pesticide Products Containing Trifluralin as the Active Ingredient. Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington, DC. EPA Publication No. 540/RS-87-195, 1987.

X. Toxicity Categories

Tables of Categories of Toxicity

Table I: Human Hazards
		Route of Administration			Hazard
Category	Signal word	Oral (mg/kg)	Dermal (mg/kg)	Inhalation (mg/L)	Eye Irritation	Skin Irritation
I	DANGER Poison	0-50	0-200	0-0.2	corrosive: corneal opacity not reversible within 7 days	corrosive
II	WARNING	>50-500	>200-2000	>0.2-20	corneal opacity reversible within 7 days; irritation persisting for 7 days	severe irritation at 72 hours
III	CAUTION	>500-5000	>2000-20,000	>2.0-20	no corneal opacity; irritation reversible within 7 days	moderate irritation at 72 hours
IV	none	>5000	>20,000	>20	no irritation	mild or slight irritation at 72 hours

40 CFR 162.10 (h) (1), July 3, 1975

Table II: Ecotoxicological Categories
Toxicity Category	Mammalian (Acute Oral)* mg/kg	Avian (Acute Oral)* mg/kg	Avian (Dietary)^_ ppm	Aquatic Organisms^‡ ppm
very highly toxic	<10	<10	<50	<0.1
highly toxic	10-50	10-50	50-500	0.1-1
moderately toxic	51-500	51-500	501-1000	>1-10
slightly toxic	501-2000	501-2000	1000-5000	>10-100
practically non-toxic	>2000	>2000	>5000	>100

* Reflects dose given to test animals and is based on body weight of the test animal.
_Concentration in the diet. Unrelated to body weight of the test animal. Measure of environmental exposure.
‡Concentration in water. Unrelated to body weight of test animal. Measure of environmental exposure.

Adapted from Insecticides, Brooks, H.L. et al. (1973) Cooperative Extension, Kansas State University, Manhattan, Kansas
For more information on Trifluralin contact your local Forest Service, Bureau of Land Management, or Bonneville Power Administration office.
Prepared by Information Ventures, Inc. under U.S. Forest Service Contract. November 1995

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