OCCUPATIONAL EXPOSURE TO SOLVENT MIXTURES - EFFECTS ON HEALTH AND METABOLISM

Exposure monitoring by personal diffusive samplers, biological monitor ing of toluene exposure by urinary hippuric acid determination, haemat ology, serum biochemistry for liver function, and a subjective symptom survey by questionnaire were conducted on 303 male solvent workers. T hey were exposed to a mixture of solvents including toluene (geometric mean 18 ppm), methyl ethyl ketone (MEK; 16 ppm), isopropyl alcohol (I PA; 7 ppm), and ethyl acetate (9 ppm). The intensity was mostly below unity using the additiveness formula based on current Japanese occupat ional exposure limits, but more than eight times unity at the maximum. The results were compared with the findings in 135 non-exposed male w orkers of similar ages. Haematology and liver function tests did not s how any exposure related abnormality, and subjective symptoms were mos tly related to central nervous system depression and local irritation. Further analysis suggested that the irritation effects were not relat ed to exposure to MEK. Analysis of the relation between toluene exposu re and hippuric acid excretion in urine showed that there was no metab olic interaction between MEK and toluene, or between IPA and toluene. Overall, therefore, it is concluded that there was no sign or symptom detected to suggest anything other than toluene toxicity, that there w as no evidence to indicate any modification of toluene toxicity or met abolism due to coexposure, and that the additiveness assumption is rea sonable for risk assessment for the combination of solvents under thes e exposure conditions.