Cognitive functions in workers exposed to toluene: evaluation at least 48 hours after removal from exposure

Objectives: Long-term exposure to toluene may result in subtle impairment of cognitive functions. However, it is not clear whether this impairment is due to the presence of the solvent in the body or if it persists after its elimination from blood. The aim of this study is to compare cognitive functions between toluene-exposed workers (at least 48 h after removal from exposure) and non-exposed workers. Methods: Seventy-two workers exposed for at least 5 years to toluene (9 to 467 ppm) completed a questionnaire and psychometric tests. The results were compared with those of 61 non-exposed workers. An alveolar air sample was taken just before the tests to ensure the absence of toluene. Results: Results of the vocabulary test were slightly better in exposed (correct words: 21 ± 0.6) than in non-exposed workers (19 ± 0.8) (P < 0.05). No differences were found for simple reaction time, digit symbol, digit span, continuous tracking test, color word and switching attention test. Conclusions: The results of this study do not support the notion of the persistence of cognitive effects of toluene after elimination of the solvent from blood. Received: 5 June 2000 / Accepted: 9 December 2000