NEPHROTOXIC AND GENOTOXIC N-ACETYL-S-DICHLOROVINYL-L-CYSTEINE IS A URINARY METABOLITE AFTER OCCUPATIONAL 1,1,2-TRICHLOROETHENE EXPOSURE IN HUMANS - IMPLICATIONS FOR THE RISK OF TRICHLOROETHENE EXPOSURE

Excretion of mercapturic acids in the urine is indicative of the formation of electrophiles in the metabolism of xenobiotics. The determination of these mercapturic acids thus may be a useful method to estimate the exposure. We identified the nephrotoxic and mutagenic mercapturic adds N-acetYl-S-(1,2-dichlorovinyl)-L-cysteine and N-acetyl-S- (2,2-dichloro-vinyl)-L-cysteine in the urine of workers exposed to 1,1,2-trichloroethene. A method to quantify these mercapturic acids by gas chromatography-mass spectrometry-selected ion monitoring was developed and appreciable amounts (2.8-3.8 mumole/L were found in human urine samples. Because deacetylation determines notably the amount of the excreted mercapturic acids, the formation of the resulting cysteine S-conjugates was comparably measured in subcellular fractions of rodent and human kidneys; significant species differences in acylase activity were found. The formation of mutagenic and nephrotoxic metabolites during 1,1,2-trichloroethene metabolism mandates a revision of the risk assessment of trichloroethene exposure.