Colour vision impairment in workers exposed to low concentrations of toluene

Colour vision was examined by the Lanthony-D-15 desaturated test in 41 women exposed to toluene and in 29 non-exposed referents. Toluene exposure was evaluated by methods of environmental and biological monitoring. In the exposed group the median value of toluene in air was 35 ppm (range 11.2-49.9 ppm). Quantitative colour vision impairment was expressed as colour confusion index and colour confusion index corrected for alcohol intake. Qualitative impairment was expressed as normal, yellow-blue, red-green range or complex impairment. Statistical analysis showed the index values to be significantly correlated with age in both groups. In the exposed group they were significantly higher than in the non-exposed group. There was no significant difference in the prevalence of impairment in the blue-yellow range between the examined groups, although the prevalence of impairment in the exposed group was higher than in the non-exposed one. Results suggest that exposure to low toluene concentrations may induce colour vision impairment in women.