Sleep apnoeas and neurobehavioral effects in solvent exposed workers.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Nocturnal oxygen desaturation, as assessed by home oximetry, in long-term solvent-exposed workers.

Recent studies have suggested that occupational exposure to solvents may be a cause of sleep apnea. Digital oximetry during one night was performed in solvent-exposed offset printers (n = 21) and in a control group (n = 21), using a Palco 400 Pulse Oximeter. The threshold for recording was set at an arterial oxygen saturation (SaO2) of 90%. Furthermore, computerized neurobehavioral tests (NES) and a solvent-related complaints questionnaire (NSC-60) were administered. The mean exposure time was 15 years (SD = 10). Hygiene measurements revealed a large number of different solvents and a cumulative exposure between 15% and 97% of the "cumulative TLV." The exposed workers had more solvent-related complaints, especially regarding mood (analysis of covariance, P = 0.02), than the nonexposed workers. The neurobehavioral tests indicated that hand-eye coordination was significantly worse in the exposed group (analysis of covariance, P = 0.03). The frequency of nocturnal desaturation was significantly higher in the printers (1.7 events/hr +/- SD = 1.5) than in the controls (0.6 events/hr +/- SD = 1.3) (Mann-Whitney test, P < 0.01). Also, the duration of desaturation was longer in the exposed workers: 3.2 min/hr (SD = 3.2) vs 1.2 min/hr (SD = 2.3) (Mann-Whitney test, P < 0.01). In the analysis of covariance, exposure (P = 0.04) and the interaction between smoking and exposure (P = 0.02) were shown to contribute significantly to the excess of nocturnal desaturation in the exposed. The same was true for the mean duration of desaturation (exposure: P = 0.02 and interaction exposure smoking: P = 0.02). The significant interaction was due to a more pronounced effect of solvent exposure among the nonsmoker group. No relation was found between the excess of complaints or the neuroperformance effects and the oximetry data. These data reinforce the presumption that occupational solvent exposure might contribute to sleep-disordered breathing.