Urinary Excretion of Thioethers Related to Styrene Exposure

Abstract

Urinary Excretion of Thioethers Related to Styrene Exposure: Ginette Truchon et al. Institut de recherche en santé et en sécurité du travail, Montréal, Québec, Canada—The objective of this study was to test the suitability of styrene‐specific mercapturic acids as urinary bioindicators of occupational styrene exposure. The excretion of mandelic acid (MA), global thioethers and styrene‐specific mercapturic acids was measured in urine samples from 64 workers employed in three companies fabricating glass fiber‐reinforced polyester products. Global thioethers were measured by a spectrophotometric method while MA and specific mercapturic acids, N‐acetyl‐S‐(1‐phenyl‐2‐hydroxyethyl)‐L‐cysteine (M1) and N‐acetyl‐S‐(2‐phenyl‐2‐hydroxyethyl)‐L‐cysteine (M2), were measured by high pressure liquid chromatography with UV detection. Excretion of M1 and M2 was qualitatively verified by gas chromatography‐mass spectrometry. The environmental measurements were carried out with passive dosimeters. Workers had 8‐h TWA exposure levels ranging from 0 to 667 mg/m3. End‐of‐shift MA excretion ranged from 0 to 2.08 mmol/mmol creatinine and was well correlated with environmental styrene exposure (r=0.91, p<0.001). M1 and M2 were detected (i.e. above ca. 1 μmol/mmol creatinine) in urine samples of only three workers who were exposed to various concentrations of styrene. End‐of‐shift excretion of global thioethers was found to be significantly correlated to cigarette consumption as well as to styrene exposure, as measured by end‐of‐shift MA excretion. In opposition to data from rats, our results indicate that humans exposed to styrene excrete little styrene‐specific thioethers. The apparent inter‐individual variability in excretion of M1 and M2 suggests that they may not constitute suitable indicators of occupational styrene exposure.