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

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


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







IV. Ecological Effects


Non-Target Toxicity:


V. Toxicology Data


Acute toxicity:

Chronic toxicity:

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:


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


  1. Final Environmental Impact Statement for Managing Competing and Unwanted Vegetation. Pacific Northwest Region. Forest Service, U.S. Department of Agriculture, Portland, Oregon. 1988.
  2. 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.
  3. 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
Eye Irritation Skin Irritation
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
(Acute Oral)*
(Acute Oral)*
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

Copyright (c) 1994-2002, Information Ventures, Inc.
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