H. Ukai et al., OCCUPATIONAL EXPOSURE TO SOLVENT MIXTURES - EFFECTS ON HEALTH AND METABOLISM, Occupational and environmental medicine, 51(8), 1994, pp. 523-529
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.