BIOLOGICAL MONITORING OF EXPOSURE TO LOW CONCENTRATIONS OF STYRENE

A field study was conducted on 39 male workers exposed to styrene at c oncentrations below 40 ppm (time weighted average, TWA). Analyses were carried out on environmental air, exhaled air, blood, urine, and two major urinary metabolites of styrene: mandelic acid (MA) and phenylgly coxylic acid (PGA). Head space gas chromatography (GC) with a flame io nization detector (FID) was used for determination of styrene in blood and urine. Postexposure exhaled air was analyzed using capillary GC. Environmental styrene exposure was measured by personal sampling using carbon cloth personal samplers. Urinary metabolites of styrene were d etermined by high pressure liquid chromatograph (HPLC). When the end-o f-shift breath, blood, and urine styrene levels were compared with env ironmental TWA values, blood styrene correlated best with styrene in a ir (r = 0.87), followed by breath styrene (r = 0.76). Poor correlation (r = 0.24) was observed between environmental styrene exposure and ur ine styrene. When styrene metabolites were compared with environmental styrene, the sum of urinary MA and PGA correlated better with styrene in air than MA or PGA alone. The correlations between urinary metabol ites and environmental styrene improved when corrected for the specifi c gravity of urine. Even better correlations were observed when the ur inary metabolites were corrected for creatinine. The correlation coeff icients for environmental styrene and end-of-shift MA, PGA, and MA + P GA were 0.83, 0.84, and 0.86, respectively. The correlation coefficien ts between environmental styrene and next morning urinary metabolites fell to 0.47, 0.61, and 0.65 for MA, PGA, and MA + PGA, respectively. These results suggest that determination of the total MA and PGA in ur ine samples is preferred than separate measurements of MA or PGA. The good correlation between environmental exposure and styrene in the exh aled air also suggests that breath styrene level can be a useful indic ator for low level styrene exposure, as the method is specific, noninv asive, and rapid. Urinary styrene seems to be a less reliable indicato r for low level styrene exposure. (C) 1994 Wiley-Liss, Inc.