United States Office of Pesticides and Toxic Substances
Environmental Protection Office of Pesticide Programs (TS-766C)
Agency Washington, DC 20460
540/FS-89-021
&EPA Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuance: Registration Standard
Date Issued: December 20, 1988
Fact Sheet Number: 189
1. DESCRIPTION OF CHEMICAL
2-chloro-4f6-bis(isopropylamino)-s-triazine
Propazine
Milogard,ｮ Gesamil,ｮ Milo-Pro, Pramitol, Prozinex
Generic Name
Common Name
Trade Name
OPP Chemical Code: 080808
Chemical Abstracts Service (CAS) Number: 139-40-2
Year of Initial Registration: 1974
Pesticide Type: Herbicide
Chemical Family: S-Triazine
U.S. and Foreign Producers: Ciba-Geigy, Drexel, Makhteshim-Agan,
Griffin Corp., l.pi.ci.
2. USE PATTERNS AND FORMULATIONS
Application Sites: Propazine is registered for use on the
terrestrial food crop sorghum and for noncrop areas.
Percent of Pesticide Applied: 99+% of propazine is used on
sorghum.
Types and Methods of Application: Propazine is used as a
selective preemergent herbicide to control broadleaf and
grass weeds. Propazine is applied as a spray, at the
time of planting, prior to planting or immediately follow-
ing planting by ground or aerial equipment.
Application Rates: Propazine is applied generally from 1 to
2 pounds active ingredient per acre; however, as much as
3.2 pounds active ingredient per acre may be used on
certain fine textured or highly organic soils for sorghum
and from 1.6 to 13.3 pounds per acre for non-crop areas.
Types of Formulations: Wettable powders (90 to 26.67% active
ingredient); flowable concentrates (44.5 to 18.7% active
ingredient); soluble concentrates (43% active ingredient)
Usual Carrier: Water. Agitation in the spray tank is necessary
to keep the chemical in suspension.
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3. SCIENCE FINDINGS
Summary Science Statement: Propazine has low acute oral
toxicity and is classified in Toxicity Category III*.
Propazine is not considered to be teratogenic in rats.
Propazine did not induce tumors in mice but an increased
incidence of mammary gland tumors was observed in female
rats. Based on the rat study, the Agency has classified
propazine at a Group C oncogen (potential human carcinogen)
but has concluded that quantitative risk assessment is
not warranted because tumors in the rat study occurred in
only one sex, were mostly benign and were significantly
increased only at the highest dose tested.
Propazine can be characterized as slightly toxic to cold-
water fish and practically nontoxic to waterfowl. It will
not pose a hazard to endangered plant or wildlife species.
Propazine does have the potential to contaminate groundwater
Chemical Characteristics:
Physical State: Solid
Color: Colorless, white
Odor: Odorless
Melting Point: 212-214 ｰC
Density: 1.16 +_ 0.002 g/cm3 at 20 ｰC
Solubility: 8.6 ppm; water 20-22 ｰC
Vapor Pressure: 2.9 x 10~8 mmHg at 20 ｰC
Stability: Minimum of 3 years at room temperature
Toxicology Characteristics:
Acute Toxicity:
Acute Oral-由at: > 5 g/kg (Toxicity Category IV)
Acute Dermal由abbit: > 2 g/kg (Toxicity Category III)
Acute Inhalation由at: > 2.1 mg/L/4 hr (Toxicity
Category III)
Primary Eye Irritation由abbit: No corneal opacity at
24 hours (Toxicity Category III)
Primary Skin Irritation由abbit: Score of 3.9/8.0
with erythema, eschar, and edema with improvement
within 72 hours (Toxicity Category III)
Subchronic Toxicological Results: No acceptable studies
are available. However, because an acceptable chronic
rat study is available and a nonrodent chronic study
is required, subchronic studies are not required.
Refer to 40 CFR 156.10 for a discussion
of the toxicity categories.
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Chronic Feeding Results: In a chronic feeding study in
rats, the NOEL was 100 ppm. A chronic feeding study
in nonrodents is required.
Oncogenic Testing Results: Propazine was not oncogenic in
a mouse study. In a rat study, however, it did produce
an increased incidence of mammory gland tumors in female
rats at the highest dosage level tested (1,000 ppm).
Developmental and Reproductive Study Results: Propazine did
not induce terata in a rat developmental toxicity study.
The reproductive NOEL was 100 ppm. An additional
developmental study in a second species is required.
Major Route of Exposure: Dermal (mixers, loaders and
applicators)
Physiological Characteristics:
Absorption Characteristics: Propazine is absorbed through
plant roots.
Translocation: Propazine is absorbed by plant roots and is
translocated upwardly in the plant to the leaves. It
.accumulates in the growing parts and leaves of plants.
Mechanism of Action: Inhibition of cell division and photo-
synthesis
Environmental Characteristics: Propazine is persistent,
moderately mobile and stable to hydrolysis, photolysis and
microbial degradation, demonstrating a potential to con-
taminate groundwater. It has been detected in groundwater
samples in 8 states with maximum concentrations of 20 ppb
in surface water and 300 ppb in groundwater. Available
data are insufficient to fully assess the environmental
fate and transport of propazine.
Ecological Characteristics: Propazine is slightly toxic to
coldwater fish with a toxicity value (LC5Q) of 16.5 ppm
for rainbow trout. It is practically nontoxic to waterfowl
with a toxicity value (LCsg) of 32000 ppm for Mallards.
Based on use, estimated concentrations and the available
toxicity data, there is no threat to endangered wildlife or
plant species.
Tolerance Assessment: Tolerances are established for negli-
gible residues of propazine in or on sweet sorghum, its
grain, fodder and forage at 0.25 ppm (40 CFR 180.243).
The provisional acceptable daily intake (PADI) for
propazine is 0.02 mg/kg/day, based on a 2-year rat feed-
ing study in which the systemic NOEL was set at 100 ppm
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(5 mg/kg). The safety factor used was 300 based on an
uncertainty factor of 100 to account for inter- and intra-
species differences with an additional factor of 3 to
account for the incompleteness of the chronic data base.
The theoretical maximum residue contribution (TMRC) for
the U.S. population average is 0.0003 mg/kg/day, equivalent
to 1.7 percent of the PADI.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE. As the result
of a Data Call-in Notice, issued in April 1988, for a
groundwater monitoring study, all propazine registrations
have been either cancelled or suspended. Therefore, the
Agency has determined, at this time, that it is not
necessary to formulate specific regulatory positions
regarding prdpazine. If a registrant commits to generate
the required data and complies with the requirements of
FIFRA, the Agency will then address specific regulatory
positions for this chemical.
5. SUMMARY OF MAJOR DATA GAPS
Product Chemistry
Toxicology
Dermal Sensitization
21-Day Dermal
Chronic Toxicity (Nonrodent)
Teratogenicity (Rabbit)
General Metabolism
Residue Chemistry
Environmental Fate
Ecological Effects
6. EPA CONTACT
Robert J. Taylor, Product Manager (25)
Office of Pesticide Programs
Registration Division (TS-767C)
Environmental Protection Agency
401 M Street, SW.
Washington, DC 20460
Telephone: (703) 557-1800
DISCLAIMER; The information presented in this Pesticide Fact Sheet
is for informational purposes only and may not be used to fulfill
data requirements for pesticide registration and reregistration.
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