Chemical Fact Sheet

Chemical Abstract Number (CAS #) 150685
CASRN 150-68-5
Urea, N'-(4-chlorophenyl)-N,N-dimethyl-
Analytical Methods EPA Method 553
EPA Method 632
Molecular FormulaC9H11ClN2O

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use The only known use of monuron is as a broad-spectrum herbicide for the control of many grasses and herbaceous weeds on non-cropland areas, such as right-of-way, industrial sites and drainage ditch banks. AS A SOIL STERILANT MONURON IS PREFERRED ON MEDIUM TO HEAVY SOILS AND UNDER INTERMEDIATE RAINFALL CONDITIONS. AT STERILANT DOSAGES IT CONTROLS A WIDE RANGE OF ANNUAL AND PERENNIAL GRASSES AND BROADLEAF WEEDS ON NONCROP AREAS. FORMER USE A plant growth regulator. Sugarcane flowering suppressant.
Consumption Patterns 100% AS HERBICIDE FOR USE ON CROPS (1971)
Odor SLIGHT ODOR ; Odorless solid
Melting Point 170.5-171.5 DEG C
Molecular Weight 198.65
Density 1.27 @ 20 DEG C/20 DEG C
Environmental Impact Monuron is a herbicide recommended for use in non-crop areas for total control of weeds, and it would be released to the environment as a result of this use. Monuron's registration with EPA for use as a herbicide was cancelled in 1977, and therefore if its is still manufactured, it would be manufactured for export. In soil, monuron is transformed to its metabolites primarily by biodegradation. The half-life of monuron in field soils ranges from less than 30 days to 166 days. Monuron has a moderate mobility in most soils. Although biodegradation is slow, it is probably the major degradative pathway in water. Loss of monuron due to hydrolysis and volatilization will not be important processes. However, some loss may result due to photolysis in surface layers of water. Monuron is not expected to bioconcentrate in aquatic organisms. The reaction with hydroxyl radicals with an estimated half-life of 5.5 hr may be the most important loss process for vapor phase monuron in the atmosphere. Removal of atmospheric monuron may also occur by dry and wet deposition. Monuron is not registered for use in the US and therefore exposure of applicators, other workers to monuron will be limited.
Environmental Fate TERRESTRIAL FATE: Biodegradation appears to be the major process by which monuron may be lost from most soils(1-2). The loss of monuron from soil surface by photolysis may account for a small fraction of loss of monuron as most of the monuron would move deeper into soil with rain . Volatilization loss of monuron from dry soil or wet soils should not be important . Monuron may moderately leach in most soils(3-4). Depending on the nature of soil and climatic conditions, the field half-life of monuron in soil range from less than 30 days to 166 days(5-7). AQUATIC FATE: At low concns (on the order of ug/l), the major process for the loss of monuron from water appears to be biodegradation(1-2). Neither hydrolysis nor any other chemical reaction is important for the loss of monuron in water(1,3). Monuron may photolyze in surface layers of water where sunlight penterates . The photolysis half-life of monuron in aqueous solution by natural sunlight is estimated to be 15 days . Photolysis is accelerated by the presence of surfactants . Based upon the low vapor pressure(6) and high water solubility(7), monuron should not volatilize from water. Monuron is not expected to bioconcentrate in aquatic organisms(7). ATMOSPHERIC FATE: Based upon on its vapor pressure, 5.03X10-7 mm Hg at 25 deg C , monuron is expected to be present partially in the vapor phase and partially in the particulate form in air(2,SRC). Vapor phase monuron will react with photochemically produced hydroxyl radicals with a half-life of 6.7 hr(3-4). Monuron may also be removed from the atmosphere by dry and wet deposition.
Drinking Water Impact GROUNDWATER: Monuron was detected in one groundwater sample from a rural area in Ontario, Canada that was contaminated with the herbicide as a result of a spill .

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