Low-level hydrocarbon solvent exposure and neurobehavioural effects.

Studies of workers exposed to hydrocarbon solvents are reviewed in order to address the question, 'Does long-term human exposure to hydrocarbon solvents at concentrations around occupational exposure limits result in clinically important neurobehavioural effects?' Studies selected evaluated exposure-response (E-R) trends with some control of potential confounders. Tests of neurobehavioural performance were classified into specific functional categories, within those of cognitive, psychomotor and sensory functions to increase specificity and power to detect patterns of effect. The weight-of-evidence was evaluated with respect to criteria for determining causality. The temporality criterion was met as latency was adequate for the occurrence of chronic effects. There were few significant associations, and when present, were consistently weak even in the most-exposed workers. Exposure response showed no consistent or significant pattern for any tests of functional mortality. The weight of evidence suggests that exposure to hydrocarbon solvents at current limits does not appear to cause adverse neurobehavioural effects.