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A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Michigan State University, Oregon State University, and University of California at Davis. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

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Ametryn

Publication Date: 9/95

TRADE OR OTHER NAMES

Product names include Evik, Ametryne, Ametrex, Gesapax (1), G34162, Trinatox-D (a combination with 2,4-D), Crisazina-Crisatrina Kombi (a combination with atrazine)(2), Doruplant, Mebatryne, and Amephyt (3).

REGULATORY STATUS

Ametryn is an unrestricted or General Use Pesticide (GUP). In Florida and Texas, ametryn may be applied alone on grapefruit and orange trees. In Florida, it may be applied with simazine for common bermuda grass and annual grasses and broadleaf weeds. In Hawaii, a mixture with diuron may be used on sugarcane (4).

INTRODUCTION

Ametryn, a member of the Triazine chemical family, is a herbicide which inhibits photosynthesis and other enzymatic processes. It is used to control broadleaf weeds and annual grasses in pineapple, sugarcane and bananas. It is used on corn and potato crops for general weed control (1). It is also used as a vine desiccant on dry beans and potatoes (3). Ametryn is available as an emulsifiable concentrate, flowable wettable powder and a wettable powder. Products containing ametryn should bear the SIGNAL WORD: CAUTION. The EPA classifies it as Toxicity Class III, slightly toxic (2).

TOXICOLOGICAL EFFECTS

ACUTE TOXICOLOGY

Ametryn is slightly toxic to humans. Symptoms of acute exposure to high doses include nausea, vomiting, diarrhea, muscle weakness, and salivation (5). Ametryn is moderately irritating to the eyes, skin, and respiratory tract.

The LD50 is the dose of ametryn which is lethal to half of the test animals that ingest it. The oral LD50 of ametryn is 508 mg/kg for rats and 945 mg/kg for mice (13). The LC50 for rats that inhale ametryn for four hours is greater than 2.2 mg/l of air (4). The dermal LD50 is greater than 3,100 mg/kg for rats and 8,160 mg/kg for rabbits (13). Acute eye exposure in rabbits causes a temporary irritation (9).

CHRONIC TOXICITY

Reproductive Effects

No information is currently available.

Teratogenic Effects

No information is currently available.

Mutagenic Effects

Studies have shown that ametryn is not mutagenic (7).

Carcinogenic Effects

There is not adequate data to determine if ametryn can increase the risk of cancer in humans (1, 8).

Organ Toxicity

Animal studies indicate that consuming large amounts of ametryn over a long period of time results in liver damage (1).

Fate in Humans and Animals

Excretion of ametryn is rapid. In rats, all but 2 to 7% is eliminated in the urine and feces within 72 hours (12).

ECOLOGICAL EFFECTS

Effects on Birds

Ametryn is only slightly toxic to birds. The dietary LC50 (8 day) is 30,000 mg/kg for bobwhite quail and 23,000 mg/kg for mallard ducks (3).

Effects on Aquatic Organisms

Ametryn is moderately toxic to fish. The LC50 for rainbow trout exposed for 96 hours is 8.8 mg/l. The LC50 for bluegill is 4.1 mg/l and for goldfish it is 14.1 mg/l (2, 3). Ametryn is highly toxic to crustaceans and moderately to highly toxic to mollusks (10).

Effects on Other Animals (Nontarget species)

Ametryn is only slightly toxic to bees (2).

ENVIRONMENTAL FATE

Breakdown in Soil & Groundwater

Ametryn's half-life in soils, the amount of time it takes to degrade to half of the original concentration, is 70 to 250 days, depending on the soil type and weather conditions. Loss from the soil is principally by microbial degradation (1, 3). Ametryn moves both vertically and laterally in soil due to its high water solubility (11). Because it is persistent, it may leach as a result of high rainfall, floods, and furrow irrigation (1).

In a study of surface and groundwater contaminants in the U.S, ametryn was found in six states, in very few surface water samples and in 4% of the groundwater samples. The maximum concentration found was 0.1 micrograms/l in surface water and 450 micrograms/l in groundwater (7).

Breakdown in Vegetation

Ametryn is broken down into non-toxic substances by tolerant plants and, to a lesser extent, by sensitive plants (3).

PHYSICAL PROPERTIES AND GUIDELINES

Ametryn is a colorless crystal. It is non-corrosive and is stable in neutral and weak acid or basic solutions. However, it is hydrolyzed by strongly acidic or basic solutions into an inactive derivative. It is decomposed slowly by UV light (2).

Physical Properties:

CAS #: 834-12-8
Chemical Name: 2-(ethylamino)-4-isopropylamino-6-methyl-thio-s-triazine
Melting point: 84-85 degrees C (3)
Solubility in water: 185 mg/l at 20 degrees C. It dissolves readily in organic solvents including hexane, toluene, methanol, and acetone (3, 7).
Partition Coefficient (octanol/water): Kow = 676 (3).

Exposure Guidelines:

HA: 0.06 mg/l (lifetime); 8.6 mg/l (child) (11).
DWEL: 0.3 mg/l (11).
LOEL: 100mg/kg/day (6)
NOAEL: 10 mg/kg/day (11)
RfD: 0.0086 mg/kg/day (6, 11)

BASIC MANUFACTURER:

CIBA
Agricultural Division
P.O. Box 18300
Greensboro, NC 27419-8300
Telephone: 919-632-6000

Review by Basic Manufacturer:

Comments solicited: October, 1994
Comments received:

REFERENCES

  1. U.S. Environmental Protection Agency. 1989. Health Advisory Summary: Ametryn. U.S. EPA. Washington, DC.
  2. Meister, R. T. 1992. Farm Chemicals Handbook '92. Meister Publishing Company. Willoughby, OH.
  3. The Agrochemicals Handbook, Third Edition. 1994. Royal Society of Chemistry Information Systems, Unwin Brothers Ltd., Surrey, England.
  4. Farm Chemicals Handbook '94. 1994. Meister Publishing Company. Willoughby, OH.
  5. U.S. Environmental Protection Agency. 1994. Pesticide Poisoning Action Guide for Agricultural Pesticides in the Midwest. EPA. Chicago, IL.
  6. Hayes Jr., Wayland and Edward Laws, Jr., (eds.) 1991. Handbook of Pesticide Toxicology. Academic Press, Inc. New York, NY.
  7. U.S. EPA Office of Drinking Water. 1987. Ametryn Health Advisory. EPA. Washington, D.C.
  8. U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry. 1990. Draft Health Assessment Guidance Manual. U.S. Department of Health and Human Services. Atlanta, GA.
  9. U.S. Environmental Protection Agency. 1989. Toxchem No. 431 Document #002372 and 002373. EPA. Washington, DC.
  10. Briggs, Shirley. 1992. Basic Guide to Pesticides. Hemisphere Publishing. Washington, DC.
  11. Thomson, W. T. 1982. Agricultural Chemicals Book II Herbicides. Thomson Publications. Fresno, CA.
  12. U.S. Department of Health and Human Services. 1993. Hazardous Substance Data Base. HHS. Washington, DC.
  13. National Institute for Occupational Safety and Health (NIOSH). 1993. Registry of Toxic Effects of Chemical Substances (RTECS). NIOSH. Cincinnati, OH.