Occupational exposure to different levels of mixed organic solvents and colour vision impairment

Mixed organic solvents have a broad range of applications in industry. Occupational exposure to organic solvents has been shown to be associated with colour vision impairment. The study was designed to determine the impact of chronic occupational exposure to organic solvent mixtures on colour vision of car industry painters. 408 workers of assembly location and 2 different paint locations of a car manufacturing company were included in the study. The workers were studied in three groups. The first group consisted of those working in the assembly location with no exposure to organic solvents. The second and third groups included those working in the new and old paint locations, exposed to organic solvents at lower and higher levels than the permissible level, respectively. The Lanthony D-15 desaturated (LD-15) test was used for screening acquired colour vision impairment. The frequency of acquired colour vision impairment was 44.28% for workers of the old paint location, 29.31% for workers of the new paint location, and 3.90% for workers of the assembly location, indicating a significant difference (p < 0.001). The results of logistic regression indicated there was a significant relationship between colour confusion index (CCI) and exposure to organic solvents (p < 0.001) for the old and new paint locations. We suggest that chronic occupational exposure to organic solvents at higher and even lower levels than the permitted levels may lead to acquired colour vision impairment. It is recommended that LD-15 test would be implicated in the early diagnosis of nervous system disorders in workers exposed chronically to organic solvents.