Purpose: To evaluate the effects of a chronic occupational exposure to toluene on color vision.
Methods: Color vision was tested in 51 workers exposed to pure toluene and in 51 matched control subjects. Current exposure was determined by biological monitoring. Blood samples were taken at the end of a Friday shift. Color vision ability was assessed using the Ishihara plates (to screen for congenital dyschromatopsia), the Farnsworth panel D-15 test, the Lanthony panel D-15 desaturated test, the Velhagen plates, and the Standard Pseudoisochromatic Plates Part 2.
Results: Median toluene concentration was 1.59 mg/l (quartiles 0.78 and 2.65). The whole group of workers did not perform worse than the controls. The same applies to 20 printers, who regularly assessed hues. Assessed with the most sensitive Lanthony panel D-15 desaturated test, color vision of 24 permanently exposed assistants was impaired (median color confusion index of the 1st eyes 1.08 vs. 1.02, p < 0.02; 2nd eyes 1.08 vs. 1.0, p < 0.05; sign test). The assistants made almost exclusively blue-yellow errors. The other color vision tests did not reveal any differences between the groups.
Conclusion: Changes in the retina are a possible explanation for the observed blue-yellow dyschromatopsia.
Keywords: Biological monitoring; Color vision; Dyschromatopsia; Occupational; Retina; Toluene.