Pesticide Fact Sheet

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Mefluidide

Pesticide Fact Sheet

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

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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 mefluidide and its formulations. Unless otherwise stated, the toxicity data presented in this fact sheet refer to the active ingredient, mefluidide. When included, data on formulated products will be specifically identified. A list of definitions is included in Section VIII of the fact sheet.

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I. Basic Information

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Common name: Mefluidide

Chemical name: N-[2,4-dimethyl-5-[[(trifluoromethyl)-sulfonyl]amino]phenyl]acetamide

Common Product names: Embark 2-S®, Embark Lite®

Pesticide classification: herbicide

Registered Use Status: "General Use"

Formulations: Commercial mefluidide 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 two mefluidide formulations are listed below.

Embark 2-S®: mefluidide (28%) and inert ingredients (72%)

Embark Lite®: mefluidide (3.2%) and inert ingredients (96.8%)

Residue assay methods: Gas-liquid chromatography methods are available for residue assay.

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II. Herbicide Uses

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Registered forestry, rangeland, right-of-way uses: Control plants on rights-of-way, road and curbside grass areas, fenceline areas, steep banks, rough or rocky terrain grass areas, and fringe turf areas.

Operational details:

Target Plants: Mefluidide is used to control ornamental and non-ornamental woody plants, ground cover, hedges, trees, turf grasses, grass and broadleaf weeds.

Mode of action: Mefluidide applied to foliage inhibits plant cell division, stem elongation, and seedhead development.

Method of application: ground equipment or boom sprayer

Timing Of Application: Apply to turf grass before or after mowing. Spray ornamental or non-ornamental woody plants just before or after trimming and shaping. Mefluidide may be applied at any time of the year when the plant is healthy and actively growing.

Use rates: Use 0.125 to 2 pounds active ingredients per acre.

Special Precautions:

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

Drift Control: Do not allow careless application or spray drift. Do not permit spray or spray drift to contact desirable plants or food crops.

Surface-Water: Do not apply directly to lakes, ponds, or streams. Do not contaminate water when disposing of equipment wash waters. Do not apply directly to water or wetlands.

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III. Environmental Effects/Fate

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Soil:

* Residual Soil Activity: Mefluidide is not generally active in the soil. It is not usually absorbed from the soil by plants.

* Adsorption: Mefluidide is not strongly adsorbed by the soil.

* Persistence and Agents of Degradation: Mefluidide remains unchanged in the soil for varying lengths of time, depending on soil texture and organic matter content. The half-life of mefluidide can range from less than 1 week to 2 weeks. Soil microorganisms break down mefluidide.

* Metabolites/Degradation Products and Potential Environmental Effects: 5-Amino-2,4-dimethyltrifluoromethane sulfone anilide has been found as a metabolite of mefluidide.

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Water:

* Solubility: Mefluidide is slightly soluble in water.

* Potential For Leaching Into Ground-Water: Data on the potential of mefluidide to leach into ground-water is incomplete. The EPA is requiring additional studies.

* Surface Waters: In water, mefluidide is broken down by ultraviolet light.

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Air:

* Volatilization: Mefluidide does not evaporate easily.

* Potential For By-Products From Burning of Treated Vegetation: No information available.

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IV. Ecological Effects

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Non-Target Toxicity:

* Soil Microorganisms: Mefluidide does not cause adverse effects in soil microorganisms.

* Plants: Contact with non-target plants may injure or kill susceptible plants.

* Aquatic Animals: Mefluidide is practically nontoxic to fish. It does not build up (bioaccumulate) in fish. Acute toxic level:

species LC50 Source Table

fish <100 ppm (Table II, Aquatic)

* Terrestrial Animals: Mefluidide is slightly toxic to birds and mammals. Mefluidide is non-toxic to bees. Acute toxic level:

species LD50 Source Table

birds <4,620 mg/kg (Table II, Avian)

* Threatened and Endangered Species: Mefluidide may be a hazard to endangered plants if it is applied to areas where they live.

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V. Toxicology Data

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Acute toxicity:

* Acute oral toxicity: The acute oral LD50 of mefluidide was greater than 4,000 mg/kg in rats. In mice the LD50 was 1,920 mg/kg. (Toxicity Category III, Table I, Oral).

Acute dermal toxicity: The acute dermal (skin) LD50 was greater than 4,000 mg/kg in rabbits. (Toxicity Category III, Table I, Dermal).

* Primary irritation score: Mefluidide was not a skin irritant when tested in laboratory animals. (Toxicity Category IV, Table I, Skin irritation).

* Primary eye irritation: Mefluidide was a mild eye irritant when tested in rabbits. (Toxicity Category III, Table I, Eye irritation).

* Acute Inhalation: The 4 hour LC50 for inhalation of mefluidide was greater than 8.5 mg/L of air in rats. (Toxicity Category III, Table I, Inhalation).

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Chronic toxicity:

* Carcinogenicity: In an 18-month feeding study in mice, mefluidide did not show any evidence of carcinogenicity at dose levels up to 6,000 ppm (highest dose tested).

* Developmental: Teratogenicity studies carried out in rabbits and rats established a no observed effect level (NOEL) of 60 mg/kg per day.

* Reproduction: A three-generation reproduction study in rats showed that mefluidide had a no effect level of 1,800 ppm. At dosages of 6,000 ppm and above pups had reduced body and organ weights.

* Mutagenicity: Mefluidide showed no evidence of mutagenic activity in laboratory tests.

HAZARD: Based on the results of laboratory tests, mefluidide is not classified as a carcinogen, mutagen, teratogen, or reproductive inhibitor.

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VI. Human Health Effects

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Acute toxicity (poisoning):

Reported effects: There have been no reports of acute poisoning with mefluidide in humans.

Chronic toxicity:

Reported effects: There have been no reports of long term, adverse health effects in humans due to mefluidide.

Potential for adverse health effects from contacting or consuming treated vegetation, water or animals: No information available.

Potential for adverse health effects from inert ingredients contained in the formulated product: Because of concern for human health and the environment, the U.S. Environmental Protection Agency (EPA) announced its policy on inerts of toxicological concern (Lists 1 and 2) in the Federal Register on April 22, 1987 (52 FR 13305). The intent of this policy is to encourage the use in pesticide products of the least toxic inert ingredients available. EPA's strategy for the implementation of this policy included the development of four lists of inert ingredients according to toxicity. The toxicity categories for the lists of inert ingredients are:

* List 1 - Inerts of toxicological concern

* List 2 - Potentially toxic inerts/high priority for testing

* List 3 - Inerts of unknown toxicity for which there is little concern that they will be shown to be toxic

* List 4 - Inerts of minimal concern

No inerts cited on EPA List 1 are included in the Embark 2-S or Embark Lite formulations. None of the inerts in these formulations have been publicly identified by the manufacturer.

Health effects of exposure to formulated products: Mefluidide formulations may cause skin and eye irritation.

Health effects associated with contaminants: No hazardous contaminants have been identified in mefluidide or the Embark 2-S or Embark Lite formulations.

Health effects associated with other formulations: Mefluidide is not commercially formulated with other pesticides.

Health risk management procedures: The Forest Service evaluates 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 take into consideration the potential for both worker and public exposure from Forest Service operations. This information is 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 mefluidide.

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VII. Safety precautions:

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Signal word and definition:

CAUTION - HARMFUL IF SWALLOWED OR ABSORBED THROUGH THE SKIN. MAY CAUSE SKIN OR EYE IRRITATION.

Protective Precautions for Workers: Avoid contact with eyes, skin or clothing. Avoid breathing vapors or spray mist. Wear protective clothing, including rubber gloves, when handling mefluidide. Remove clothing immediately if pesticide gets inside. Wash body thoroughly with soap and water and put on clean clothes. Wash contaminated clothing before reuse.

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VIII. Definitions

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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.

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 kill 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

mg/L - milligrams per liter

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

ppm - parts per million

residual activity - the remaining amount of activity as a pesticide

teratogenicity - the ability to cause birth defects

volatility - the tendency to become a vapor at relatively low temperature

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X. Toxicity Categories

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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

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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 Mefluidide 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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