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Identification of a major human metabolite of acetochlor in exposed herbicide applicators by high performance liquid chromatography-tandem mass spectrometry.

Hines C; Striely C; Barr D; Olsson A; Bravo R; Norrgan J; Needham L; Deddens J
American Industrial Hygiene Conference and Exposition, May 13-16, 2006, Chicago, Illinois. Fairfax, VA: American Industrial Hygiene Association, 2006 May; :44
Acetochlor is pre-emergent chloroacetanilide herbicide used to control annual grasses and small-seeded broadleafweeds. It is the second most abundantly applied herbicide on corn crops in the United States. Acetochlor was widely substituted for alachlor in 1990s. The US EPA has classified acetochlor as "likely to be carcinogenic to humans"; however, data on human metabolites associated with known exposure to acetochlor have been lacking. We positively identified acetochlor mercapturate (ACM) as a primary metabolite of acetochlor in all urine samples collected during a 24-hour period from custom applicators who had applied acetochlor on either the day of or the day before urine collection. Concentrations in applicator urine samples ranged from 0.5-449 ug/L (0.3-121 ug/g creatinine). Total nanomoles of ACM excreted in 24-hrs ranged from 7.71-350 nmo1/24h. We observed the highest ACM level (449 ug/L) in the person who had applied the most acetochlor over the two-day period (total of 1,385 lb). Mean ACM concentrations unadjusted for creatinine for the custom applicators were up to 40-fold higher than those reported for farmer applicators. We found thatACM accounted for as much as 42% of the total acetochlor-derived metabolites in urine; however, as the exposure level decreased, ACM became a less abundant metabolite of acetochlor (17%). Unmetabolized acetochlor was also measured in the urine samples analyzed. At high exposures, acetochlor accounted for less than 1 % of the total excreted acetochlor metabolites (approximately 2% of the ACM concentrations). At lower exposures, ACM and acetochlor concentrations were similar. Additionally, we tentatively identified two other acetochlor metabolites that appeared to be important at low levels of exposure.
Herbicides; Agriculture; Agricultural-products; Chemical-composition; Chemical-properties; Carcinogens; Cancer; Metabolites; Exposure-levels; Urinalysis; Sampling; Risk-factors
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American Industrial Hygiene Conference and Exposition, May 13-16, 2006, Chicago, Illinois
Page last reviewed: August 26, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division