In search of dose-response relationships of solvent mixtures to neurobehavioural effects in paint manufacturing and painters.

Four exposure indices for the evaluation of mixtures of solvents are outlined. The hygienic effect is a relative measure depending on the limit values of the single compounds of the mixture. The cumulative lifetime exposure (CE) and the lifetime-weighted average exposure (LWAE) are approaches based on measurements of total hydrocarbons at workplaces in different time periods. Estimations of litres of solvents used per day years (l/d years) are necessary if air monitoring is not available. Five studies on neurobehavioural effects due to solvent mixtures in paint manufacturing are compared as example for dose-response relations. The best prediction of neurobehavioural dose-response relations seems to be possible using CE and LWAE for total hydrocarbon as the exposure index. Moreover, four studies on neurobehavioural effects due to solvent mixtures in paints and glues are compared. These studies indicate that the index l/d years is helpful in predicting neurobehavioural deficits. Of numerous neurobehavioural tests, the test symbol digit substitution shows the most significant dose-response relations in the studies. For symptom questionnaires these relations appear only occasionally. In principle, associations between doses of solvent mixtures in paints and neurobehavioural effects are reproducible to a limited extent.