IMPAIRED COLOR DISCRIMINATION AMONG WORKERS EXPOSED TO STYRENE - RELEVANCE OF A URINARY METABOLITE

Objectives-To survey the loss of colour vision among Japanese workers who have been exposed to styrene concentrations currently considered l ow (about 20 ppm). Also to assess the effects of styrene by examinatio n of the nature of the relation between disorder of colour vision and age, alcohol consumption, and other variables. Methods-Colour discrimi nation was examined in 64 male workers exposed to styrene (mean age; 3 8.0, mean exposed years; 7.0) and in 69 controls (mean age; 38.0). A s tandardised questionnaire was adopted to collect work history, occupat ional or non-occupational solvent exposure, alcohol consumption, and d rug use. Colour vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the colour confu sion index (CCI). Results-The mean atmospheric styrene concentration w as about 20 ppm. The mean urinary concentration of mandelic acid was 0 .22 g/l. There was a significant difference in CCI between exposed wor kers and age matched controls. Colour vision of workers whose concentr ation of urinary mandelic acid was greater than or equal to 0.42 gn wa s significantly impaired when compared with workers whose concentratio n was Multiple linear regression that controlled confounding such as a ge, alcohol consumption smoking, and educational attainment showed tha t the CCI was significantly related to the concentration of urinary ma ndelic acid. In both exposed workers and controls, the types of defect s were mostly blue-yellow loss, although a few subjects showed complex loss. No one showed only red-green loss. Conclusions-These findings s uggest that exposure to moderate styrene concentrations can lead to im pairment of colour vision, and that there is a significant cot relatio n with the urinary metabolite of styrene.