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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

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

EXTOXNET primary files maintained and archived at Oregon State University

Revised 9/95.

AMETRYN

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 (51).

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 (48). It is also used as a vine desiccant on dry beans and potatoes (50). 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 (49).

TOXICOLOGICAL EFFECTS

• Acute Toxicity: Ametryn is slightly toxic to humans. Symptoms of acute exposure to high doses include nausea, vomiting, diarrhea, muscle weakness, and salivation (52). 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 (42). The LC50 for rats that inhale ametryn for four hours is greater than 2.2 mg/l of air (51). The dermal LD50 is greater than 3,100 mg/kg for rats and 8,160 mg/kg for rabbits (42). Acute eye exposure in rabbits causes a temporary irritation (56).
• Chronic Toxicity: No information is currently available
• Reproductive Effects: No information is currently available.
• Teratogenic Effects: No information is currently available.
• Mutagenic Effects: Studies have shown that ametryn is not mutagenic (54).
• Carcinogenic Effects: There is not adequate data to determine if ametryn can increase the risk of cancer in humans (48,55).
• Organ Toxicity: Animal studies indicate that consuming large amounts of ametryn over a long period of time results in liver damage (48).
• 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 (58).

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 (50).
• 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 (49, 50). Ametryn is highly toxic to crustaceans and moderately to highly toxic to mollusks (8).
• Effects on Other Animals (Nontarget species): Ametryn is only slightly toxic to bees (49).

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 (48, 50). Ametryn moves both vertically and laterally in soil due to its high water solubility (57). Because it is persistent, it may leach as a result of high rainfall, floods, and furrow irrigation (48). 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(54).
• Breakdown in Vegetation: Ametryn is broken down into non-toxic substances by tolerant plants and, to a lesser extent, by sensitive plants (50).

PHYSICAL PROPERTIES AND GUIDELINES:

Physical Properties:

• Appearance: White Powder
• Chemical Name: 2-(ethylamino)-4-isopropylamino-6-methyl-thio-s-triazine
• CAS Number: 834-12-8
• Molecular Weight: 227.3
• Water Solubility: 185 mg/l at 20 degrees C. It dissolves readily in organic solvents including hexane, toluene, methanol, and acetone (50, 54).
• Solubility in Other Solvents: Soluble in acetone (610), methanol (510), toluene (470), n-octanol (220), hexane (58)
• Melting Point: 84-85 degrees C (50)
• Vapor Pressure: 0.365 mPa
• Partition Coefficient: 676 (50).
• Adsorption Coefficient: Not Available

Exposure Guidelines:

• HA: 0.06 mg/l (lifetime); 8.6 mg/l (child) (57).
• DWEL: 0.3 mg/l (57).
• LOEL: 100mg/kg/day (53)
• NOAEL: 10 mg/kg/day (57)
• RfD: 0.0086 mg/kg/day (53, 57)
• ADI: Not Available
• PEL: Not Available
• TLV: Not Available
• MCL: Not Available

BASIC MANUFACTURER:

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

REFERENCES

References for the information in this PIP can be found in Reference List Number 8