EXPOSURE OF WORKERS TO A MIXTURE OF TOLUENE AND XYLENES .1. METABOLISM

The urinary excretion of hippuric acid and methylhippuric acid was stu died in workers (233 subjects; 122 men and 111 women) exposed to tolue ne and xylenes in combination and in non-exposed controls (281 subject s; 141 men and 140 women) recruited from the same factories or factori es of the same regions. Smoking and drinking habits of the subjects we re obtained by medical interviews. From each worker, one urine sample was collected at the end of a shift and analysed for hippuric and meth ylhippuric acids by high performance liquid chromatography. Air sample s for the estimation of toluene and xylenes were collected with diffus ive personal samplers. There was a linear correlation between the time weighted average exposure either to toluene or xylene isomers and the concentrations of hippuric acid or methylhippuric acid isomers in uri ne. Essentially no difference was found in the correlation between qua ntitative exposure and excretion in the three xylene isomers. Comparis on of the slopes of regression lines indicated the absence of metaboli c interaction between toluene and xylenes at the measured concentratio ns. The metabolism of toluene and xylenes was significantly reduced am ong smokers or drinkers compared with non-smokers and non-drinkers.