propazine (Milocep, Milogard) Herbicide Profile 12/88
EPA Pesticide Fact Sheet
Name of Chemical: Propazine
Reason for Issuance: Registration Standard
Date Issued: December 20, 1988
Fact Sheet Number: 189
1. DESCRIPTION OF CHEMICAL
- Generic Name: 2-chloro-4,6-bis(isopropylamino)-s-triazine
- Common Name : Propazine
- Trade Name : Milogard, Gesamil, Milo-Pro, Pramitol, Prozinex
- 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., I.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 following planting by ground or aerial
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
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.
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.
- Physical State: Solid
- Color: Colorless, white
- Odor: Odorless
- Melting Point: 212-214 degrees C
- Density: 1.16 + 0.002 g/cm3 at 20 degrees C
- Solubility: 8.6 ppm; water 20-22 degrees C
- Vapor Pressure: 2.9 x 10-3 mmHg at 20 degrees C
- Stability: Minimum of 3 years at room temperature
- Acute Toxicity:
- Acute Oral--Rat: > 5 g/kg (Toxicity Category IV)
- Acute Dermal--Rabbit: > 2 g/kg (Toxicity Category III)
- Acute Inhalation--Rat: > 2.1 mg/L/4 hr (Toxicity Category III)
- Primary Eye Irritation--Rabbit: No corneal opacity at 24 hours
(Toxicity Category III)
- Primary Skin Irritation--Rabbit: Score of 3.9/8.0 with erythema,
eschar, and edema with improvement within 72 hours (Toxicity
- 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.
- 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 mammary 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)
- Absorption Characteristics: Propazine is absorbed through plant
- Translocation: Propazine is absorbed by plant roots and is trans-
located 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 photosynthesis
Propazine is persistent, moderately mobile and stable to hydrolysis,
photolysis and microbial degradation, demonstrating a potential to
contaminate 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.
Propazine is slightly toxic to coldwater fish with a toxicity value
(LC50) of 16.5 ppm for rainbow trout. It is practically nontoxic to
waterfowl with a toxicity value (LC50) 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.
Tolerances are established for negligible 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 feeding study in
which the systemic NOEL was set at 100 ppm (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
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 propazine. 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
5. SUMMARY OF MAJOR DATA GAPS
Chronic Toxicity (Nonrodent)
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.