Sleep apnoeas and neurobehavioral effects in solvent exposed workers

Exposure to organic solvents may cause an increase of sleep apnoeas, which may explain the excess of fatigue, concentration and memory problems reported in exposed workers.

Polysomnography was performed in 21 long-term exposed printers and 27 controls. In addition, a questionnaire regarding sleep related complaints, Q16 questionnaire and computerized neurobehavioral tests were administered. The groups matched well regarding age, weight, neck circumference and schooling level. A semi-quantitative cumulative exposure index was calculated.

Excessive sleepiness while watching TV (p<0.01) and diminished sexual interest (p=0.03) was found in the organic solvent-workers. The sleep complaints score correlated positively with the exposure index and duration (both p=0.01). The polysomnography results showed an increase of central apnoeas in the exposed workers (67%) compared to the referents (30%). The presence of central apnoeas was positively correlated with the exposure index (p<0.05) in regression models. Of the neurobehavioral test only hand-eye coordination was dose-related impaired in the exposed workers. The co-existence of abnormal values on at least one neurobehavioral test and the presence of central apnoeas was observed in the exposed workers, but did not reach significance.

Workers chronically exposed to low organic solvent levels may experience mild sleeping problems, however, our data do not support the hypothesis that the clinical picture of chronic toxic encephalopathy can be primarily caused by the induction of sleep apnoea syndrome. It seems thus that the risk to experience central apnoeas rather accompanies the risk of impaired neurobehavioral performance with increasing exposure in a working population.