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diuron (Karmex) Herbicide Profile 9/83

                      CHEMICAL FACT SHEET FOR:
                                DIURON
FACT SHEET NUMBER:  09
DATE ISSUED:  SEPTEMBER 30, 1983
                      1. DESCRIPTION OF CHEMICAL:
- Generic Name:  3-(3,4-dichlorophenyl) 1,1-dimethylurea (C9H10C12N20)
- Common Name:  diuron
- Trade Names:  Cekiuron, Dailon, Diater, Di-on, Diurox, Diurol, Drexel
  Diuron 4L, Dynex, Karmex, Unidron, Urox, and Vonduron
- EPA Shaughnessy Code:  035505
- Chemical Abstracts Service (CAS) Registry Number:  150-68-5
- Year of Initial Registration:  1966
- Pesticide Type:  Herbicide
- Chemical Family:  Substituted urea
- U.S. and Foreign Producers:  E.I. duPont de Nemours and Company,
  Vertac Chemical Corp., Bayer AG, Makhteshim-Agan, Pennwalt Holland
  B.V., Rhone-Poulenc, Staveley Chemicals Ltd., Universal Crop
  Protection Ltd.
                    2. USE PATTERNS AND FORMULATIONS
- Application sites:  Diuron is a substituted urea compound registered
  for use as a herbicide to control a wide variety of annual and
  perennial broadleaf and grassy weeds on both crop and noncrop sites.
  Diuron is registered for use on numerous crop sites such as forage
  crops, field crops, fruits, vegetables, nuts, and ornamental crops.
  In noncrop applications, diuron is used on industrial sites, on
  rights-of-way, around farm buildings, and on irrigation and drainage
  ditches.
- Types of formulations:  Diuron is available is wettable powder,
  granular, flowable, pelleted/tableted, liquid suspension, and soluble
  concentrate formulations.
- Types and methods of applications:  Diuron is applied as follows:
  broadcast or banded on soil surface using ground or aerial equipment.
- Application rates:  0.6 lbs. a.i./A to 8.0 lbs. a.i./A on crop sites;
  and 15.0 lbs. a.i./A to 48.0 a.i./A on non-crop sites.
- Usual carriers:  Water, oil, and clay.
                      3. SCIENCE FINDINGS
Chemical Characteristics
Technical diuron is a white, crystalline, odorless solid. It is
stable towards oxidation and moisture under conventional conditions
and decomposes at 180-190 degrees C. The chemical does not exhibit any
unusual handling hazards.
Toxicological Characteristics
- Acute toxicology studies on diuron are as follows:
  - Oral LD50 in rats: 3,400 mg/kg body weight, Toxicity Category III
  - Dermal LD50 in rabbits: > 20,000 mg/kg body weight, Toxicity
    Category IV
  - Skin irritation in rabbits: mild irritant, Toxicity Category IV
  - Eye irritation in rabbits: mild conjunctival irritant, Toxicity
    Category IV
- Chronic toxicology studies on diuron are as follows:
  - The requirement for a subchronic inhalation study is being
    deferred until an acute inhalation study has been completed.
  - In a 2-year chronic feeding study, the no-observed-effect-level
    (NOEL) was 25 ppm in male and female rats. No evidence of
    tumorigenicity was found.
  - In a 2-year feeding study, the no-observed-effect-level in dogs
    was 25 ppm. No evidence of tumorigenicity was found.
- Major routes of human exposure:
  - Current data does not indicate that the U.S. population is exposed
    to diuron through the dietary or non-dietary routes.
Physiological and Biochemical Behavioral Characteristics
- Foliar absorption characteristics:  Diuron is most readily absorbed
  through the root system.
- Translocation:  Diuron is translocated upward primarily in the
  xylem.
- Mechanism of pesticidal action:  It is a strong inhibitor of
  photosynthesis (Hill reaction).
Environmental Characteristics
- Adsorption and leaching characteristics in basic soil types:
  Diuron's adsorption increases as clay content and/or organic matter
  content of soil increases.
- Microbial breakdown:  Microbes are the primary factor in the
  breakdown of diuron in soils and the aquatic environment.
- Loss from photodecomposition and/or volatilization:  Diuron's loss
  from photodecomposition is minimal.
Ecological Characteristics
- Avian oral LD50: >2.000 ppm
- Avian dietary LC50: >1,730 ppm
- Fish LC50: 3 to 60 ppm
NOTE: Potential problems for endangered species: Additional ecological 
effects data must be submitted before a complete hazard assessment can 
be made.
Tolerance Assessments
- Tolerances are currently established for residents of the herbicide
  3-(3,4-dichlorophenyl) 1,1-dimethylurea in or on the following raw
  agricultural commodities:
  - 0.1 ppm (Negligible residues) in bananas, nuts, and peaches
  - 0.5 ppm in papayas
  - 1.0 ppm in apples; artichokes; barley grain; blackberries;
    blueberries; boysenberries; fat of cattle, goats, hogs, horses,
    and sheep; meat of cattle, goats, hogs, horses, and sheep; meat
    byproducts of cattle, goats, hogs, horses, and sheep; citrus
    fruits- field corn, ear, and grain; popcorn, ear; sweetcorn, ear;
    cotton seed; currants; dewberries; gooseberries; grapes;
    huckleberries; loganberries; oats grain; olives; pears; peas;
    pineapple; potatoes; raspberries; rye grain; sorghum grain;
    sugarcane; vetch, seed; and wheat grain
  - 2.0 ppm in alfalfa; barley forage, hay, and straw; clover forage
    and hay; corn fodder and forage; popcorn fodder and forage; sweet
    corn fodder and forage; grass crops and grass hay (except Bermuda
    grass and Bermudagrass hay); rye forage, hay, and straw; pea
    forage and hay; peppermint hay; sorghum forage and fodder; oats
    forage, hay, and straw; trefoil, birdsfoot forage and hay; vetch
    forage and hay; wheat forage, hay, and straw
  - 4.0 ppm (food additive) in dried citrus pulp
  - 7.0 ppm in asparagus; and Bermudagrass and Bermudagrass hay
- A reassessment of the diuron tolerances indicates that those
  originally set for certain commodities in 40 CFR, 180.106 were too
  high. The Agency will propose the reduction of certain tolerances
  during the next year.
Problems Known to Have Occurred With Use of the Chemical
The Pesticide Incident Monitoring System (PIMS) indicated several 
incidents involving diuron alone from 1971 to 1980. Two fish kills were 
reported after aquatic areas were sprayed for weed control and the dying 
weeds depleted the water of oxygen. Three instances of crop injury were 
reported involving an accidental aerial application, the rotation of a 
sensitive crop onto previously treated land, and injury to wheat 
resulting from wet weather. Two applicators received medical attention 
after exposure from spraying. Symptoms included vomiting, dizziness, and 
diarrhea. No fatalities were reported. PIMS is a voluntary reporting 
system and does not include detailed follow up or validation of reported 
incidents.
Summary Science Statement
Diuron has low acute toxicity, and its uses are not expected to affect 
avian wildlife. But diuron is structurally related to linuron, whose 
studies have exhibited testicular adenomas in rats and liver cell 
adenomas in female mice. Therefore, the protocols for related chronic 
studies of diuron should reflect the oncogenic concerns raised by the 
linuron data.
            4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Use classification: general use
- Use, formulation, or geographical restrictions: No use, formulation,
  or geographical restrictions are required.
- Unique label warning statement: Reserved pending filling data gaps.
- Summary of risk/benefit review: No risk/benefit assessment was
  conducted.
                   5. SUMMARY OF MAJOR DATA GAPS
- The following toxicology data are required within 48 months after
  receipt of this guidance package unless otherwise noted:
  - Two oncogenicity tests are required, one in rat and one in another
    species
  - Two teratogenicity studies are required, one in rat and one in
    another species (rabbit)
- The following mutagenicity data are required:
  - A test for gene mutations in bacterial (Salmonella typhimurium)
    plate test
  - A test for gene mutation in mammalian cells in culture
  - A test for DNA repair induction: in vivo mammalian sister chromatid
    exchange test
  - A test for chromosome effects either in vivo or in vitro mammalian
    chromosome aberration analysis.
NOTE: An acute inhalation study is required within 6 months after 
receipt of this guidance package.
- The following environmental fate data are required within 48 months
  after receipt of this guidance package:
  - Hydrolysis test
  - Photodegradation test in water
  - Photodegradation test in soil
  - Metabolism test in anaerobic soil
  - Metabolism test in aerobic aquatic site
  - Mobility (volatility) test in the lab
  - Mobility (volatility) test in the field
  - Dissipation study in soil
  - Dissipation study in an aquatic site
- The following ecological effects data are required within 48 months
  after receipt of this guidance package.
  - Acute and chronic tests of diuron on estuarine fish, shrimp, and
    oysters.
  - An aquatic field study may be needed for the aquatic uses pending
    the outcome of the environmental fate studies.
                      6. CONTACT PERSON AT EPA
Robert U. Taylor
Product Manager (25)
Environmental Protection Agency (TS-767C)
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.