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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Diuron

Trade and Other Names: Trade names for products containing diuron include Crisuron, Diater, Di-on, Direx, Karmex, and Unidron. It is often used in combination with other pesticides such as bromacil and hexazinone.

Regulatory Status: Diuron is a General Use Pesticide (GUP). The U.S. EPA classifies it as toxicity class III - slightly toxic. However, products containing diuron bear the Signal Word WARNING because it can irritate the eyes and throat.

Chemical Class: substituted urea

Introduction: Diuron is a substituted urea herbicide used to control a wide variety of annual and perennial broadleaf and grassy weeds, as well as mosses. It is used on non-crop areas and many agricultural crops such as fruit, cotton, sugar cane, alfalfa, and wheat. Diuron works by inhibiting photosynthesis. It may be found in formulations as wettable powders and suspension concentrates.

Formulation: It may be found in formulations as wettable powders and suspension concentrates.

Toxicological Effects:

• Acute toxicity: Diuron is slightly toxic to mammals. The oral LD50 in rats is 3400 mg/kg. The dermal LD50 is greater than 2000 mg/kg [4,8]. Some signs of central nervous system depression have been noted at high levels of diuron exposure. For humans, the only reported case of acute, oral exposure to the herbicide produced no significant symptoms or toxicity [4,8,10].
• Chronic toxicity: Male rats given extremely high doses of diuron over a 2-week period showed changes in their spleen and bone marrow. Other chronic effects attributed to moderate to high doses of the pesticide over time included changes in blood chemistry, increased mortality, growth retardation, abnormal blood pigment, and anemia. When fed small amounts of diuron in food for 2 years, animal species showed no adverse effects [4,8].
• Reproductive effects: Daily low doses of diuron fed to female rats through three successive generations caused significantly decreased body weight of offspring in the second and third litters. The fertility rate remained unaffected [8]. It is unlikely that diuron will cause reproductive effects in humans at expected levels of exposure.
• Teratogenic effects: Diuron is teratogenic at high doses. Administered to pregnant rats on days 6 through 15 of gestation, it produced no birth defects in the offspring at doses of up to 125 mg/kg/day. However, doses of 250 mg/kg/day caused wavy ribs, extra ribs, and delayed bone formation. There were also weight decreases in offspring at 500 mg/kg/day. There was no increase in the severity of the rib deformation at this higher dose [4,8]. Pregnant mice given very high doses of diuron (nearly 2000 mg/kg/day) exhibited reproductive and embryotoxic effects. Developmental effects were found in their offspring [4,8].
• Mutagenic effects: Diuron does not appear to be mutagenic. The majority of tests have shown that diuron does not produce mutations in animal cells or in bacterial cells [4,8].
• Carcinogenic effects: Limited evidence indicates that low level exposures to diuron does not cause cancer [10].
• Organ toxicity: Low doses of diuron over extended periods of time can cause enlargement to the liver and the spleen [10].

• Fate in humans and animals: Diuron is excreted in the feces and urine of test animals. Breakdown of the compound is similar in animals, plants, and soil. Cows fed very low doses of diuron in their diets had small amounts of residues in whole milk. Cattle fed small amounts accumulated low levels of diuron in fat and muscle, liver, and kidney [4,8].

Ecological Effects:

• Effects on birds: Diuron is slightly toxic to birds. In bobwhite quail, the dietary LC50 is 1730 ppm. In Japanese quail and ring-necked pheasant, it is greater than 5000 ppm. The LC50 is approximately 5000 ppm in mallard ducks [4,8].
• Effects on aquatic organisms: The LC50 (48 hour) values for diuron range from 4.3 mg/L to 42 mg/L in fish, and range from 1 mg/L to 2.5 mg/L for aquatic invertebrates. The LC50 (96-hour) is 3.5 mg/L for rainbow trout [4,8]. Thus, diuron is moderately toxic to fish and highly toxic to aquatic invertebrates.
• Effects on other organisms: Diuron is non-toxic to bees [4].

Environmental Fate:

• Breakdown in soil and groundwater: Diuron is moderately to highly persistent in soils. Residue half -ives are from 1 month to 1 year [19]. Some pineapple fields contained residues 3 years after the last application. Mobility in the soil is related to organic matter and to the type of the residue. The metabolites are less mobile than the parent compound [20]. In California, diuron has been found in groundwater in the 2 to 3 ppb range. It has also been found in Ontario groundwater where it has been linked with land applications [20].
• Breakdown in water: Diuron is relatively stable in neutral water. Microbes are the primary agents in the degradation of diuron in aquatic environments [20].
• Breakdown in vegetation: Diuron is readily absorbed through the root system of plants and less readily through the leaves and stems [4].

Physical Properties:

• Appearance: Diuron is a colorles crystaline compound in its pure form [7].
• Chemical Name: N-(3,4-dichlorophenyl)-N,N-dimethyl urea [7]
• CAS Number: 330-54-1
• Molecular Weight: 233.10
• Water Solubility: 42 mg/L @ 25 C [7]
• Solubility in Other Solvents: s.s. in acetone, benzene, butyl stearate [7]
• Melting Point: 158-159 C [7]
• Vapor Pressure: 0.41 mPa @ 50 C [7]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 480 [19]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.002 mg/kg/day [31]
• PEL: Not Available
• HA: 0.01 mg/L (lifetime) [32]
• TLV: 10 mg/m3 (8-hour) [31]

Basic Manufacturer:

DuPont Agricultural Products
Walker's Mill, Barley Mill Plaza
P.O. Box 80038
Wilmington, DE 19880-0038

• Phone: 800-441-7515
• Emergency: 800-441-3637
  

References:

References for the information in this PIP can be found in Reference List Number 9

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.