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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.
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
   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.
                   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  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
Toxicology Characteristics:
- 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
    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.
- 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)
Physiological Characteristics:
- 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
Environmental Characteristics:
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.
Ecological Characteristics:
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.
Tolerance Assessment:
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
   the PADI.
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
   this chemical.
                 5.  SUMMARY OF MAJOR DATA GAPS
Product Chemistry
    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.