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amitrole (Amizol, Amino Triazole) Herbicide Profile 5/84

                            CHEMICAL FACT SHEET FOR:
                        3-AMINO-1,2,4-TRIAZOLE(AMITROLE)
FACT SHEET NUMBER: 20
DATE ISSUED:  MAY 14, 1984
                     1. DESCRIPTION OF CHEMICAL
- Generic Name:  Amitrole
- Common Name:  amitrole
- Trade Names:  Weedazole, Amino Triazole Weed Killer, Cytrol, Amitrol T,
  Domatol, Vorox, Amizole, X-All, Ustinex, AT, ATA, Aminotriazole 90 and
  Chempar Amitrole
- EPA Shaughnessy Code:  004401
- Chemical Abstracts Service (CAS) Number:  61-82-5
- Year of Initial Registration:  1948
- Pesticide Type:  Herbicide
- Chemical Family:
  U.S. and Foreign Producers:  Not produced in U.S.; major importers are
  Union Carbide, American Cyanamid, and Aceto Chemical
                     2. USE PATTERNS AND FORMULATIONS
Application sites:  Noncrop sites including rights-of-way, marshes, drainage 
ditches, ornamentals, and around commercial, industrial, agricultural, 
domestic, and recreational premises.
Types of formulations:  Technical (90%, 95%); wettable powder (15%, 25%); 
flowable concentrate (0.33 lb/gal, 0.44 lb/gal, 1%); soluble concentrate/ 
liquid (0.3 lb/gal, 2 lb/gal); soluble concentrate/solid (50%, 90%) and 
pressurized liquid (0.36%, 1%).
Types and methods of application:  Applied as a spray for broadcast, spot, or 
directed treatments, using aerial or ground equipment.
Application rates:  0.9 to 20 lbs a.i./A, depending upon weed species and 
method of application.
Usual carriers:  water
                             3. SCIENCE FINDINGS
Chemical Characteristics
- Physical state:  crystalline powder
- Color:  transparent, colorless
- Odor:  odorless
- Melting point:  159 degrees C
- Solubility:  28g/100g water, soluble in some polar solvents
- Stability:  Stable in heat to 100 degrees C. Amitrole sublimes under reduced
  pressure.
- pH:  aqueous solutions are neutral
- Unusual handling characteristics:  none
Toxicological Characteristics
Acute toxicology results
- Acute oral LD50 (rat):  > 4.08 gm/kg, Toxicity Category III
- Acute dermal LD50 (rabbit):  No mortalities reported, Toxicity 
  Category III
- Primary eye irritation (rabbit):  Amitrole is slightly irritating,
  additional testing is required.
Chronic toxicology results
- Feeding/Oncogenicity:  Amitrole has an anti-thyroid effect in laboratory
  rats.  Dogs fed Amitrole exhibited thyroid and pituitary changes.
- Reproduction:  Amitrole does not cause reproductive effects.
- Teratology:  Additional testing required.
- Mutagenicity:  Amitrole does not cause mutagenic effects.
- Metabolism:  Amitrole is rapidly eliminated from the body.
Major routes of exposure:  Mixers, loaders, and applicators would be expected 
to receive the most exposure via skin contact and inhalation.
Physiological and Biochemical Behavioral Characteristics
- Absorption and translocation:  It is readily absorbed and rapidly
  translocated in the roots and leaves of higher plants.
- Mechanism of pesticidal action:  Amitrole interferes with the metabolism of
  nucleic acid precursors, disrupts chloroplast development and regrowth from
  buds.
Environmental Characteristics
- Adsorption and leaching in basic soil types:  Amitrole exhibits intermediate
  soil mobility.
- Microbial breakdown:  Microbial metabolism is the expected major route of
  degradation.
- Resultant average persistence:  Amitrole residues degrade with a half-life
  of <1 to 56 days in non-sterile aerobic soils.  The soil dissipation rate is
  affected by moisture, temperature, cation exchange capacity, and clay
  content, but is unaffected by soil pH. Amitrole is persistent in pond water
  and hydrosoil.
Ecological Characteristics
- Hazards to fish and wildlife:
- Avian dietary LC50:  Mallard duck > 5,000 ppm; ring-neck pheasant 
  > 5,000 ppm
- Freshwater fish LC50:  Rainbow trout > 180 mg/l; bluegill sunfish
  > 180 mg/l
- Aquatic invertebrate LC50 > 10 ppm
Tolerance Assessments
Temporary maximum residue limits for amitrole of 0.02 ppm have been 
established by FAO/WHO for those crops where residues are likely to occur. 
There are no established tolerances for amitrole in the U.S., Canada, and 
Mexico.  There are no food or feed uses in the U.S., and residues are not 
permitted on any food or water intended for irrigation, drinking, or other 
domestic purposes.
Problems Known to Have Occurred From Use
The Pesticide Incident Monitoring System (PIMS) l.listed eight incidents 
resulting from the use of amitrole alone from 1972 to 1977.  One incident 
involved illegal residue on apples, and two others involved plant injury 
resulting from soil residues.  The remaining five incidents involved pesticide 
applicators receiving medical attention after exposure.  Symptoms included 
skin rash, vomiting, diarrhea, and nosebleed.  There were no reported 
fatalities.  PIMS incidents are voluntarily reported, do not include detailed 
followups, and are not validated in any way.
Summary Science Statement
Extensive data gaps exist for amitrole in product chemistry, toxicology, 
ecological effects, and environmental fate. Amitrole has demonstrated 
oncogenic potential and is a candidate for Special Review. Because of this 
oncogenic risk, all use patterns and application techniques (except for 
homeowner uses) are classified as restricted.
          4. SUMMARY OF REGULATORY POSITION AND RATIONALE
Use classification:  Restricted (for all uses except for homeowner uses)
Use, formulation, or geographical restrictions:  Noncropland areas only
Unique label warning statements:
- Manufacturing-Use Products:  Products intended for formulation into end-use
  products must bear the following statements:
- For formulation only into end-use herbicide products intended for
  noncropland, outdoor use.
- The use of this product may be hazardous to your health. This product
  contains amitrole, which has been determined to cause cancer in laboratory
  animals. Products intended for formulation into restricted-use pesticides
  must require on their labeling that a respirator be worn during mixing and
  loading. Lightweight waterproof clothing (jumpsuit [or coverall, boots [or
  shoes], gloves, and a wide-brimmed plastic hardhat) must be worn when mixing
  and loading all products and when applying all products to control dense,
  tall vegetation. Workers applying this product in all other situations must
  wear lightweight waterproof gloves and boots (or shoes). Products intended
  for formulation into general-use pesticides must require on their labeling
  that waterproof gloves be worn while handling the product.
All products must bear the following statements:
- Each formulator is responsible for obtaining EPA registrations for its
  formulated product(s).
- Do not discharge into lakes, streams, ponds, or public waters unless in
  accordance with NPDS permit. For guidance, contact your Regional Office
  of the EPA.
End-Use Products:  All restricted-use products must bear the following 
statements:
Restricted Use Pesticide
- For retail sale to and application only by certified applicators or
  personnel under their direct supervision.
- The use of this product may be hazardous to your health. This product
  contains amitrole, which has been determined to cause cancer in laboratory
  animals. Wear a respirator during mixing and loading of all products. Wear
  lightweight, waterproof clothing (jumpsuit [or coverall], boots [or shoes],
  gloves, and a wide- brimmed plastic hardhat) when applying all products to
  control dense, tall vegetation. Workers applying this product in all other
  situations must wear lightweight waterproof gloves and boots (or shoes).
- All homeowner products must bear the following statement:
The use of this product may be hazardous to your health. This product contains 
amitrole, which has been determined to cause cancer in laboratory animals. 
Wear waterproof gloves when using this product.
- All products intended for nonaquatic uses must bear the following statement 
on the label:
Do not apply directly to water or wetlands. Do not contaminate water by 
cleaning of equipment or disposal of wastes.
- All products intended for aquatic uses must bear the following
  statement on the label:
Consult your state Fish and Game Agency before applying this product to public 
waters. Permits may be required before treating such waters.
- All products must bear the following statements, regardless of 
classification:
- Do not allow spray or spray drift to contaminate edible crops or water
  intended for irrigation, drinking, or other domestic purposes.
- Do not allow livestock to graze or feed in treated noncrop areas.
Summary of preliminary risk/benefit review:
Risks:
- Amitrole is not used on food crops. and there is no dietary exposure to
  amitrole. Dermal exposure is the major source of exposure with inhalation
  furnishing only a minor contribution to the total body burden. Human
  exposure, in some circumstances, occurs at doses which resulted in
  antithyroid effects in laboratory animals.
- Conservatively assuming 100% dermal penetration, the oncogenic risk
  associated with some use patterns and application techniques is high.
  Lightweight, waterproof clothing and a respirator are expected to reduce
  exposure and risk for all uses except the power wagon application.
Benefits:
The largest use site by production volume, the highway rights-of-way site was 
selected for this limited analysis. Amitrole is not produced in the United 
States, with under 800 thousand pounds being imported by Union Carbide, 
American Cyanamid, and Aceto Chemical. Amitrole, in combination with other 
chemicals, offers low cost, broad spectrum control of both newly emerged or 
established broadleaf weeds, as well as seasonal control by residual chemicals 
with which it is mixed. Alternatives include contact herbicides and mechanical 
cutting.
                  5. SUMMARY OF MAJOR DATA GAPS
Generic Data Requirements:
Product chemistry:  data due 6 months after receipt of Standard
- Statement of composition
- Discussion of formation of unintentional ingredients
- Preliminary analysis
- Density, bulk density, or specific gravity
- Solubility
- Vapor pressure
- Dissociation constant
- Octanol/Water partition coefficient
- Submittal of samples
Toxicology:
Acute testing:  data due 6 months after receipt of Standard
- Primary eye irritation
- Primary skin irritation
- Dermal sensitization
Subchronic testing:  data due 6 months after receipt of Standard
- 90-day dermal
- 90-day inhalation
Chronic testing:  data due 24 months after receipt of Standard
- Teratogenicity - 2 species
Special testing:  data due 6 months after receipt of Standard
- Dermal absorption study
Wildlife and aquatic organisms:  data due 24 months after receipt of Standard
- Avian oral LD50
- Freshwater fish LC50
- Acute LC50 freshwater invertebrates
- Acute LC50 estuarine and marine organisms
Environmental fate:
Data due 6 months after receipt of Standard
- Hydrolysis studies
- Photodegradation studies in water
- Photodegradation studies on soil
- Leaching and adsorption/desorption
- Special exposure study - protective clothing effectiveness
Data due 24 months after receipt of Standard
- Aerobic soil metabolism study
- Anaerobic aquatic metabolism study
- Aerobic aquatic metabolism study
- Soil dissipation study - field
- Aquatic (sediment) dissipation study - field
- Forestry dissipation study - field
- Soil, long-term dissipation study (field) - reserved, depending upon results
  of field dissipation study
- Accumulation studies - irrigated crops
Product specific data requirements for manufacturing-use products containing 
amitrole:
Product chemistry:  data due 6 months after receipt of Standard
- Statement of composition
- Discussion of formation of unintentional ingredients
- Preliminary analysis
- Certification of limits
- Analytical methods for enforcement of limits
- Density, bulk density, or specific gravity
- pH
- Oxidizing or reducing action
- Flammability
- Explodability
- Storage stability
Toxicology:
- Acute testing:  data due 6 months after receipt of Standard
- Primary eye irritation - rabbit
- Primary dermal irritation
- Dermal sensitization
                     6.  CONTACT PERSON AT EPA
Robert J. Taylor
Product Manager (25), TS-767C
Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(703)557-1800
DISCLAIMER:  THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT SHEET 
IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL DATA 
REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.