ALLYLMERCAPTURIC ACID AS URINARY BIOMARKER OF HUMAN EXPOSURE TO ALLYLCHLORIDE

Objective-To evaluate the use of urinary mercapturic acids as a biomar ker of human exposure to allyl chloride (3-chloropropene) (AC). During three regular shut down periods in a production factory for AC, both types of variables were measured in 136 workers involved in maintenanc e operations. Methods-Potential airborne exposure to AC was measured b y personal air monitoring in the breathing zone. In total 205 workshif ts were evaluated. During 99 workshifts no respiratory protection equi pment was used. Mercapturic acid metabolites were measured in urinary extracts by gas chromatography-mass spectrometry (GC-MS). Results-Duri ng 86 work shifts when no respiratory protection was used the air conc entrations of AC were below the Dutch eight hour time weighted average (8h-TWA) occupational exposure Limit (GEL) of AC (3 mg/m(3)), whereas in 13 workshifts the potential exposure, as measured by personal air monitoring, exceeded the OEL (3.3 to 17 mg/m(3)). With the aid of GC-M S, 3-hydroxypropylmercapturic acid (HPMA) was identified as a minor an d allylmercapturic acid (ALMA) as a major metabolite of AC in urine sa mples from the maintenance workers exposed to AC. The concentrations o f ALMA excreted were in a range from < 25 mu g/l (detection limit) to 3550 mu g/l. The increases in urinary ALMA concentrations during the w orkshifts correlated well. with the 8h-TWA air concentrations of AC (r = 0.816, P=0.0001, n = 39). Based on this correlation, for AC a biolo gical exposure index (BEI) of 352 mu g ALMA/g creatinine during an eig ht hour workshift is proposed. In some urine samples unexpectedly high concentrations of ALMA were found. Some of these could definitely be attributed to dermal exposure to AC. In other cases garlic consumption was identified as a confounding factor. Conclusion-The mercapturic ac id ALMA was identified in urine of workers occupationally exposed to a irborne AC and the increase in ALMA concentrations in urine during a w orkshift correlated well with the 8h-TWA exposure to AC. Garlic consum ption, but not smoking, is a potential confounding factor for this bio marker of human exposure to AC.