Jump to main content.



Acetochlor Degradates

Overview
 
Quick Links
Ionic Degradate Acetochlor Ethanesulfonic Acid (ESA) Structural Formula
Ionic Degradate Acetochlor Ethanesulfonic Acid (ESA) Structural Formula
Ionic Degradate Acetochlor Oxanilic Acid (OXA) Structural Formula
Ionic Degradate Acetochlor Oxanilic Acid (OXA) Structural Formula
CAS Number:
Synonyms: acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid (OXA), acetochlor sulfinylacetic acid
Contaminant Type: Chemical

Acetochlor is a synthetic organic compound of the chloroacetanilide class of herbicides, primarily used for selective pre- and early post-emergent control of broadleaf weeds and annual grasses for corn. Its IUPAC name is 2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide [1444]. Acetochlor is not currently regulated by USEPA in drinking water, but was listed on the Contaminant Candidate Lists 1, 2 and 3 [529, 859]. USEPA has classified acetochlor as “likely to be carcinogenic to humans” based on tumor incidence in animals [1444].

In the environment, acetochlor generates several degradation products that can be divided into two categories: ionic degradates, which include acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid (OXA) and acetochlor sulfinylacetic acid, and neutral degradates, which mainly include hydroxyacetochlor, deschloroacetochlor, 2-chloro-2’-ethyl-6’-methylacetanilide, 2-hydroxy-2’-ethyl-6’-methylacetanilide, 2’-ethyl-6’-methylacetanilide, 2-ethyl-6-methylaniline [1820]. The principal means of degradation is microbial. 

Some research states that metabolites of herbicides may be more important environmental contaminants than the parent compounds, and that they are typically encountered at concentrations much higher than the parent herbicides [1446, 1820]. Other research states that some neutral degradates appear to be more toxic than their ionic counterparts [1450].

Although environmental degradates of the chloroacetamide herbicides are not currently regulated in the United States, the CCL3 includes acetochlor ESA and acetochlor OXA for which drinking water standards may be established in the future [859].

Acetochlor ESA is 2-[(2-ethyl-6-methylphenyl)(ethoxymethyl)amino]-2-oxoethanesulfonic acid.  Acetochlor OXA is 2-[(2-ethyl-6-methylphenyl)(ethoxymethyl)amino]-2-oxoacetic acid. 

Reregistration documents for acetochlor state that ESA and OXA are found frequently in source and drinking waters.  In surface waters, their concentrations are in the same order of magnitude as the parent acetochlor.  In ground waters, their concetrations may exceed those of the parent.  ESA and OXA are not likely to be carcinogenic and are significantly less toxic than the parent.

Date of Literature Search: August 2010



529 USEPA; 2006; Regulatory Determinations Support Document for Selected Contaminants from the Second Drinking Water Contaminant Candidate List (CCL2); Regulatory Determinations Support Document for Selected Contaminants from the Second Drinking Water Contaminant Candidate List (CCL2); EPA Report 815-D-06-007. Chapter 13 pp. 1-29. Office of Ground Water and Drinking Water, U.S. Environmental Protection Agency, Washington, DC.
859 USEPA; 2009; USEPA Contaminant Candidate List 3 (CCL 3); http://www.epa.gov/safewater/ccl/ccl3.html#ccl3; As posted December 16, 2009.
1444 Hackett, A., Gustafson, D., Moran, S., Hendley, P., van Wesenbeeck, I., Simmons, N., Klein, A., Kronenberg, J., Fuhrman, J., Honegger, J., Hanzas, J., Healy, D. and Stone, C.; 2005; The acetochlor registration partnership surface water monitoring program for four corn herbicides; Journal of Environmental Quality; 34:877
1446 Verstraeten, I., Thurman, E., Lindsey, M., Lee, E. and Smith, R.; 2002; Changes in concentrations of triazine and acetamide herbicides by bank filtration, ozonation and chlorination in a public water supply; J. Hydrol.; 266:3-4:190
1449 Hladik, M., Roberts, A. and Bouwer, E.; 2005; Removal of neutral chloroacetamide herbicide degradates during simulated unit processes for drinking water treatment; Wat. Res.; 39::20:5033
1450 Hladik, M., Bouwer, E. and Roberts, A.; 2008; Neutral degradates of chloroacetamide herbicides: occurence in drinking water and removal during conventional water treatment; Wat. Res.; 42:20:4905
1820 Hladik, M., Hsiao, J., Roberts, A.; 2005; Are neutral chloroacetamide herbicide degradates of potential environmental concern? Analysis and occurrence in the upper Chesapeake Bay; Environ. Sci. Technol.; 39::17:6561



Local Navigation


Jump to main content.