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dipropetryn (Sancap) Herbicide Profile 6/85

CHEMICAL FACT SHEET FOR:
DIPROPETRYN
FACT SHEET NUMBER:  55
DATE ISSUED:  JUNE 30, 1985
                  1. DESCRIPTION OF THE CHEMICAL
- Generic Name:  2(ethylthio)-4,6-bis(isopropylamino)-s-triazine
- Common Name:  dipropetryn
- Trade Names:  Sancap, Cototar, and GS-16068
- EPA Shaughnessy Code:  104401
- Chemical Abstracts Service (CAS) Number:  4147-51-7
- Year of Initial Registration:  1973
- Pesticide Type:  Herbicide
- Chemical Family:  S-triazine
- U.S. Producer:  Ciba-Geigy Corporation
                   2. USE PATTERNS AND FORMULATIONS
- Application sites:  Dipropetryn is registered for preemergence control
  of pigweed and Russian thistle on cotton. In addition, dipropetryn is
  registered for use only on cotton grown on the sandy soils in
  Oklahoma, Texas, Arizona, and New Mexico.
- Type of formulation: Dipropetryn is available in a wettable powder
  formulation.
- Types and methods of applications:  Dipropetryn can be banded or
  broadcast applied to the soil surface with ground equipment, or
  broadcast applied with aerial equipment as a preemergence spray.
- Application rates:  1.2 to 2.0 lbs. a.i./A on crop sites.
- Usual carriers:  Water
                        3. SCIENCE FINDINGS
Chemical Characteristics
- Dipropetryn is a solid at room temperature. Its molecular weight is
  255.40. The melting point is 104-106 degrees C. Dipropetryn is soluble
  in water (at 20 degrees C) to 16.0 ppm, and soluble in aromatic and
  chlorinated hydrocarbon solvents.
Toxicological Characteristics
- Acute toxicity effects of dipropetryn are as follows:
  - Acute oral toxicity in rats:  >2,197 mg/kg body weight, Toxicity
    Category III
  - Acute dermal toxicity in rabbits:  >10,000 mg/kg body weight,
    Toxicity Category IV
  - Acute inhalation toxicity in rats:  >320 mg/l (4-hour exposure),
    Toxicity Category IV
  - Skin irritation in rabbits:  Not an irritant, Toxicity Category IV
  - Eye irritation in rabbits:  Not an irritant, Toxicity Category IV
- Subacute toxicity effects on dipropetryn are as follows:
  - A 19-week rat feeding study and a 14-week dog feeding study
    indicated effects on various organs at 1200 ppm dosage (the Lowest
    Effect Level). The No Observable Effect Level is 400 ppm.
- Chronic toxicological effects of dipropetryn have not been evaluated
  because there are no valid chronic toxicity studies in both the rat
  and dog, oncogenicity studies in both the rat and mouse, terato-
  genicity studies in both the rat and rabbit, a 2-generation repro-
  duction study in the rat, a general rat metabolism study, and no
  mutagenicity tests (gene mutation in bacteria, gene mutation in
  mammalian cells in culture, chromosomal aberration analysis in
  mammalian cells in culture, or DNA damage in mammalian cells in
  culture).
- Major routes of human exposure:  Non-dietary exposure to dipropetryn
  by a farmer as an applicator during mixing, loading, spraying, and
  flagging is possible.
Physiological and Biochemical Behavioral Characteristics
- Absorption characteristics:  Dipropetryn appears to penetrate
  foliage rapidly, minimizing removal from foliage by rain.
- Translocation:  Readily translocated through the xylem from roots
  and foliage, accumulating in the apical meristems and leaf tips.
- Mechanism of pesticidal action:  Dipropetryn inhibits photolysis of
  water in the photosynthetic process.
- Metabolism in plants:  In cotton, dipropetryn's total residues are
  evenly distributed in the seed with crude oil extracts containing
  less than the intact seed.
Environmental Characteristics
- Adsorption and leaching in basic soil types:  Dipropetryn is more
  readily adsorbed on soils with high clay and organic matter
  content. Dipropetryn and other alkylthio-s-triazines are adsorbed
  to a greater extent than most other commercial triazines.
- Microbial breakdown: Soil microorganisms do appear to play a
  significant role in degradation of dipropetryn.
- Loss from photodecomposition and/or volatilization:  Slight losses.
- Average persistence at recommended rates:  When used at recommended
  rates under normal environmental conditions, dipropetryn's residual
  activity is from one to three months.
Ecological Characteristics
- Avian acute oral toxicity:  >1,000 mg/kg
- 96-hour fish toxicity:  3.130 ppm for bluegill sunfish (moderately
  toxic), and 2.430 ppm for rainbow trout (moderately toxic).
- Potential problem for endangered species:
  - The Agency has evaluated dipropetryn under the cotton cluster/
    use patterns. Available data show a low order of dipropetryn
    toxicity, suggesting that the potential hazard to endangered
    species is low.
  - Currently, there are no identifiable endangered plants that would
    be affected by dipropetryn.
  - The Agency believes that the conventional labeling for dipropetryn
    is adequate to properly inform the users on how to protect any
    endangered species.
Tolerance Assessment
- Data are not available for calculating the Acceptable Daily Intake
  (ADI) for dipropetryn.
- The Agency is unable to complete a full tolerance reassessment,
  because the available dipropetryn toxicology and residue data do not
  fully support the established tolerance listed below. The metabolism
  of dipropetryn in animals and plants is not fully understood.
  Therefore, the Agency is requiring data on the metabolism of
  dipropetryn and related metabolite(s) in crops and animals. Additional
  long-term rodent and non-rodent toxicological studies are also
  required. The additional data will be used to assess dietary exposure
  to dipropetryn and may lead to revisions in the existing tolerance.
  The Agency will not grant any significant pending or new tolerances
  for dipropetryn until the data are submitted.
- Tolerance for cottonseeds, 0.1 ppm
- International tolerances: Presently, there are no tolerances for res-
  idues of dipropetryn in Canada, Mexico, or in the Codex Alimentarius.
Problems Known to have Occurred with Use
The Pesticide Incident Monitoring System (PIMS) does not indicate any
incident involving agricultural uses of dipropetryn.
Summary Science Statement
- Dipropetryn is not acutely toxic by the oral, dermal, and eye
  irritation routes of exposure. The available data are insufficient to
  show that any of the risk criteria listed in 162.11(a) of Title 40 of
  the U.S. Code of Federal Regulations have been met or exceeded for the
  uses of dipropetryn at the present time. There are no valid chronic
  toxicity and mutagenicity studies for dipropetryn. There are also
  extensive residue chemistry and environmental fate data gaps.
- Available data indicate that dipropetryn is slightly toxic to birds
  and moderately toxic to fish and freshwater invertebrates. A detailed
  ecological hazard assessment cannot be made until certain environ-
  mental chemistry data requirements are fulfilled.
           4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Based on the review and evaluation of all available data and other
  relevant information on dipropetryn, the Agency has made the following
  determinations:
  - The available data are insufficient to show that any of the risk
    criteria listed in 162.11(a) of Title 40 of the U.S. Code of Federal
    Regulations have been met or exceeded for the uses of dipropetryn at
    the present time.
  - The Agency has concerns about dipropetryn's lack of chronic toxicity
    data and its use on a food and feed crop when it is structurally
    related to certain other s-triazine pesticides which are known to be
    potential groundwater contaminants, and to cyanazine, an s-triazine
    pesticide that may be regulated as a teratogen.
  - The Agency will not allow any significant new uses to be established
    for dipropetryn until the toxicological, residue chemistry, and
    groundwater data deficiencies identified in the registration
    standard have been satisfied.
  - The Agency is imposing restrictions on rotational crops. The
    extent of the restrictions will be reconsidered when additional data
    are received.
- Specific label precautionary statements:
  - Hazard information:  The human precautionary statements must appear
    on all manufacturing-use products (MPs) labels as prescribed in 40
    CFR 162.10.
  - Environmental hazard statements:
    - All MPs intended for formulation into end-use products (EPs) must
      bear the following statements:
      - This pesticide is toxic to fish. Do not discharge effluent
        containing this product directly into lakes, streams, ponds,
        estuaries, oceans, or public waters unless this product is
        specifically identified and addressed in a National Pollutant
        Discharge Elimination System (NPDES) permit. Do not discharge
        effluent containing this product into sewer systems without
        previously notifying the sewage treatment plant authority.
        For guidance, contact your State Water Board or Regional Office
        of the Environmental Protection Agency.
      - Do not apply directly to water. Do not contaminate water by
        cleaning of equipment or disposal of wastes. In case of spills,
        cover or incorporate spills.
    - Restrictions on rotational crops: Do not plant food and feed
      crops in dipropetryn-treated fields unless dipropetryn is
      authorized for use on those crops.
                     5. SUMMARY OF MAJOR DATA GAPS
The following toxicological studies are required:
- A 90-day inhalation study (October 30, 1986).
- Chronic toxicity studies and oncogenicity studies
  (September 30, 1989)
- Teratology studies (October 30, 1986).
- A 2-generation reproduction study (October 30, 1988).
- Mutagenicity data (April-July, 1986).
- A general metabolism study (July 30, 1987).
The following environmental fate data are required:
- A hydrolysis study (April 30, 1986).
- Photodegradation studies in water and on soil (April 30, 1986).
- Metabolism tests in aerobic soil and in anaerobic soil
  (October 30, 1986).
- Accumulation studies on rotational crops (confined - October 30,
  1988; field - September 30, 1989).
 - An accumulation study in fish (duly 30, 1986).
The following ecological effects data are required:
- Two subacute dietary studies (April 30, 1986).
- An acute freshwater invertebrate toxicity study (April 30, 1986).
Product chemistry data are required during 1986.
The following residue chemistry data are required:
- Additional plant metabolism data (duly 30, 1987).
- Metabolism studies utilizing ruminants and chickens
  (January 30, 1987).
                       6. CONTACT PERSON AT EPA
Robert J. Taylor
Office of Pesticide Programs, EPA
Registration Division (TS-767C)
Fungicide-Herbicide Branch
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.