dipropetryn (Sancap) Herbicide Profile 6/85
CHEMICAL FACT SHEET FOR:
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
- 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
- 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.
- Acute toxicity effects of dipropetryn are as follows:
- Acute oral toxicity in rats: >2,197 mg/kg body weight, Toxicity
- 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
- 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.
- 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.
- 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
- 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
- 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
- Specific label precautionary statements:
- Hazard information: The human precautionary statements must appear
on all manufacturing-use products (MPs) labels as prescribed in 40
- 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)
401 M Street S.W.
Washington, DC 20460
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.