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CAS Number: 15972-60-8
Synonyms: Alanex, Alochlor, Lasso, Lazo, Metachlor, Pillarzo
Contaminant Type: Chemical

Alachlor or 2-chloro-2'-6'-diethyl-N-methoxymethyl acetanilide is an herbicide widely used in the United States, Europe and Japan.

The major source of environmental release af alachlor is through its manufacture and use as as herbicide [760].  Alachlor has been detected in raw, tap, treated, and rain waters at concentrations of ranging from <1.0 to 270 μg/L[705].   It has also been found in groundwater and surface water in many places in North America at concentrations ranging from 0.1 to 10 μg/l [709][721].

Alachlor is a herbicide used for preemergent control of annual grasses and braodleaf weeds in crops, primarily on corn and sorghum (57%) and soybean (43%) [760].  Application to peanuts, cotton, vegetables and forage crops contributes to less than 1% of its use.  Alachlor is the second most widely used herbicide in the USA (about 37 million kg) [728], with particularly heavy use on corn and soybeans in Illinois, Indiana, Iowa, Minnesota, Nebraska, Ohio, and Wisconson [760].

In water, both photolysis and biodegradation are important for the loss of alachlor, although the role of photolysis becomes important in shallow clean water, particularly in the presence of sensitizers [760].

The U.S. Environmental Protection Agency has established a maximum contaminant level (MCL) of 2 μg/L. 

Alachlor, a herbicide and endocrine distruptor, has been classified as a carcinogen of B2 group by USEPA. USEPA has found alachlor to potentially cause slight  skin and eye irritation from acute exposures at levels above the MCL.  Alachlor has the potential  to cause damage to the liver, kidney, spleen, nasal mucosa and eye from long-term exposure above the MCL. [760]

Treatment using granular activated carbon is designated as Best Available Technology for alachlor removal [760].

Date of  Literature Search: June 2009.

705 Badri, B., Varadarajan, R., Walter, D. and Massoud, P.; 2003; Bioadsorber efficiency, design, and performance forecasting for alachlor removal; Wat. Res.; 37:17:4051
709 Li, H., Qu, J. and Liu, J.; 2007; Decomposition of alachlor by ozonation and its mechanism; J. Environ. Sci.; 19:7:769
717 Chu, W. and Wong, C.; 2004; Study of herbicide alachlor removal in a photocatalytic process through the examination of the reaction mechanism; Ind. Eng. Chem. Res.; 43:17:5027
721 Beltrán, F., Acedo, B. and Rivas, J.; 1999; Use of Ozone to Remove Alachlor from Surface Water; Bull. Environ. Contam. Toxicol.; 62:3:324
728 Miltner, R., Fronk, C. and Speth, T.; 1987; Removal of alachlor from drinking water; ACSE National Conference on Environmental Engineering; Proceedings. Orlando, FL July 7-9, 1987
760 USEPA; 2010; Technical Factsheet on: Alachlor; http://www.epa.gov/safewater/pdfs/factsheets/soc/tech/alachlor.pdf; As posted on May 11, 2009. USEPA Office of Ground Water and Drinking Water, Washington, DC.