Chronic Occupational Exposure to Low Levels of Organic Vapors Can Affect Color Vision and Contrast Sensitivity

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This study evaluated the level of exposure to organic vapors in chromatic and achromatic vision of 38 male gas-station workers (average of 6.82 ± 5.62 years worked). The level of exposure was found by passive method with gas chromatography. Color vision was assessed by Lanthony desaturated D15 tests (D15d; Lanthony, 1978) the Cambridge Color Test (CCT; Mollon, & Reffin, 1989), and contrast sensitivity by sinusoidal gratings at frequencies 0.2, 0.5, 1, 2.0, 5, 10 and 16 cycles per degree (cpd). The highest average daily concentrations found in gasoline (168 ppm) were below the threshold limit values (300 ppm), yet gas-station workers had a higher color-confusion index (CCI) for D15d (p < .01), predominantly for blue/yellow (75%), larger ellipse areas in the CCT (p < .05), and lower sensitivity contrast for 5, 10, and 16 cpd (p < .01). Prolonged service time correlated with the areas A1 (ρ = 0.46; p < .01), A2 (ρ = 0.63; p < .01), and 5 cpd (ρ = – 0.36; p < .05). Gas-station attendants with 8–20 years of service had lower performances for the areas A1 and A2 (p < .0083) than those with less exposure (1–3 years of service). The results show that chronic exposure to organic vapors can reduce the chromatic and achromatic visual perception of luminance in gas-station workers with age, even at low levels, suggesting the inadequacy of tolerance levels used for gasoline. The also highlight the need for chronic systematic long-term monitoring, and not just daily.

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