United States Office of Pwtidd« and Toxic Substances
Environmental Protection Office of Pestiade Programs (TS-766C)
Agency Washington. DC 20460
v>EPA Pesticide
Fact Sheet
Name of Chemical: DIUKM
Reason for Issuance:
Date Issued: Oa983
Fact Sheet Number: 9
1. Description of the chemical:
Generic name: 3-(3,4-Dichlorophenyl) 1,1-dimethylurea
Common name: Diuron
Trade name: 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, Matchteshim-Agan, Pennvalt Holland B.V., Rhone-
Poulenc, Staveley Chemicals Ltd., Universal Crop Protection Ltd.
1. Lse 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 perer.-
nial 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 in wettable powder, granular,
flovable, pelleted/ tableted, liquid suspension, and soluble concen-
trate formulations.
Types and methods of applications: Diuron is applied as follows:
broadcast or banded on soil surface using ground or aerial equipment.
Aoplication rates: 0.6 Ibs. a.i./A to 6.C Ibs. a.i./A on crop sites;
and 15.C IDS. a.i./A to 48.C Ibs. a.i./A on non-crop sites.
Usual carriers: Water, oil and clay.
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3. Science Findings :
Summary science statement:
Diuron has low acute toxicity and It’s uses are not expected to affect
avian wildlife. But diuron is structurally related to li aron, whose
studies hav exhibited testicular adenomas in rats and liver cell adenotnas
In female mice. Therefore, the protocols for related chronic studies
of diuron should reflect the oncogenic concerns raised by the linuron
data.
Checical characteriS :s
Technical diuror. is a white, crystalline, oaorless solid. It is
stable towaros oxication anc moisture unoer conventional conditions
and decomposes at 180—190°C. The chemical does not exhibit any
unuaual handling hazards.
Toxicological characteristics:
Acute toxicology studies on diuron are as follows:
Oral LD 50 in rats: 3,400 mg/kg body weight, Toxicity Category III
Dermal LD 50 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 ar acute inhalation study has been completed.
In a two—year chronic feeding study, the no—observed—effect—level
(NOEL) was 25 p in male and female rats. No evidence of tu cr1-
genicity was found.
In a two—year feeding study, the no—observed—effect—level in dogs
was 25 ppm. No ‘viden: of tumorigenicity was found.
Major routes of human e p(’bure:
Current data does no: tndi ate that the U.S. population is exposed
to diuron througn the dietary or non—dietary routes.
Physiological and Bioc tcal Behavioral Characteristics:
Foliar absorption characteristics: Diuron is most readily absorbec
through the root system.
Translocatiofl: Diuron ib translocated upward primarily in the xv1e
Mechanism of pesticidal action: It is a strong inhibitor of phorosv-
thesis (Hill reaction).
Environmental characteristics:
Adsorption and leaching characteristics in basic soil types: Diuror.’
adsorption increases as clay content and/or organic matter conteri: o:
soil increases.
Microbial breakdown: Microbes are the primary factor in the breakoowr.
of diuron in soils and the aquatic environment.
Loss from photodecomposition and/or volatilization: Diuron’s lass
from photodecomposition Is minimal.
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Ecological characteriSticS
Avian oral LD 5 ç : >2,000 pp
Avian dietary LC 50 : >1,730 ppn
Fish LC 50 : 3 to 60 ppm.
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 residues 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 ppn in Papayas;
1.0 p in Apples; Artichokes; Barley grain; Blackberries; Blue-
berries; 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; Fielc corn, ear, and grain; Popcorn, ear; Sweetcorn,
ear: Cotton, seed; Currants; Dewberries; Gooseberries; Grapes;
Ruckleberries; Loganberries; Oats grain; Olives; Pears; Peas;
Pineapple; Potatoes; Raspberries; Rye grain; Sorghum grain;
Sugarcane; Vetcn, seed; and Wheat grain;
2.0 ppm in Alfalfa; Barley forage, hay, and strew; Clover forage
and hay, Corn fodder and forage; Popcorn fodder and forage;
Sweetccrn fodder and forage; Grass crops and grass hay (except
Bermuda grass and Bermudajrass 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 pnm (food additive) in Dried citrus pulp;
7.0 pnm ir. 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
he next year.
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Froblems known to have occurred with use:
The Pesticide Incident Monitoring System (PLMS) indicated several
inciaencs involving diuron alone from 1971 to 198C. 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 appli-
cation, the rotation of a sensitive crop onto previously treated land,
and injury to wheat resulting from wet weather. Two applicator5
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 followup or validation of reported incidents.
4. Summary of regulatory position and rationale :
Use classification:
General use classification:
Use, formulation, or geographical restrictions:
No use, formulation, or geographical restrictions are requirec..
Unique label warning scatem n::
Reserved pending f1l ing data gaps.
SummAry of risk/benaf .t rc-v ew;
No risk/benefit asscssment was conducted.
5. Suary of major data 3apb :
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 anothe:
species,
Two teratogenicity studies are reauired, one in rat and one in anothe:
species (rabbit),
The following mutagenicity data are recuired:
A test for gene mutations in bacterial ( Salmonella typhimuriun .
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.
An acute inhalation studyis required within 6 months after receipt
of this guidance package.
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The following environmental face 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 J. Taylor
Product Manager (25)
Environmental Protection Agency (TS—767C)
401 ii Street, S.W.
Washington, D.C. 20460
(703) 557—1800
DISCLAIMER: The information presented in this Chemical Information
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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