Intervention Study on Acquired Color Vision Deficiencies in Styrene-Exposed Workers

Abstract

The main aim of the study was to examine the possible effects of occupational exposure to styrene on color vision function and the course after reduction of exposure. Color vision function was examined in 22 styrene-exposed laminators and 11 control subjects at a boat manufacturing plant. The Lanthony D-15 desaturated panel was used to test acquired dyschromatopsia. In all, six examinations were performed: Monday morning and Thursday afternoon of the same week, before and immediately after a vacation of 4 weeks (altogether, phase 1), and approximately 10 months later (phase 2), after the exposure level of styrene had been reduced. Styrene uptake was objectified by biological monitoring measuring the metabolites mandelic acid and phenylglyoxcylic acid in urine samples taken on Thursday afternoon. In both Thursday examinations, styrene-exposed workers had higher color confusion index (CCI) values compared with controls, which indicated quantitative color vision loss. After an exposure-free period of 4 weeks, a significant decrease of CCI values to normal range was found in laminators. Reexamination 10 months later showed also lower CCI values in exposed workers, indicating a dose-effect relationship. Abnormal CCI values occurred primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine or more. We concluded that styrene-induced color vision dysfunction is reversible after an exposure-free interval of 4 weeks. The current Biological Tolerance Value of 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine, as used in Germany, protects styrene-exposed workers from this subclinical effect.

Pilot Study on Prevalence of Color Vision Dysfunction in Long-Term Solvent-Exposed Painters.

“…Muttray et al 4) showed that CCI values of this magnitude do not restrict the suitability of workers, even in occupations such as printing, in which good color vision is usually necessary. Solvent induced color vision dysfunction is to a great extent or even completely reversible after exposure stops as was shown in the case of tetrachlorethylene and styrene 3,15) . Triebig et al 3) recently described, that the effect of styrene exposure on color vision is completely reversible after the exposure was stopped for 4 weeks, and partly reversible after a weekend without exposure.…”

“…In recent years, several studies concerning slight dyschromatopsia and color vision deficiencies in workers exposed to organic solvents have been published [1][2][3] . Only a few studies, however, focused on mixtures of organic solvents 4,5) .…”

Effect of pesticides on color vision and anterior ocular structure of farmers

“…Many studies have shown that color vision was very sensitive to occupational chemicals (toluene, styrene, mixture of organic solvents) and the effects were dose-dependent [14][15][16][17][18][19][20]. In a number of studies, the observed color vision impairment was dose-related.…”

Walk-through survey report: styrene and noise exposures during fiber reinforced plastic boat manufacturing at U.S. Marine Incorporated, Arlington, Washington.

“…Exposure may also damage peripheral nerves and cause changes to the kidney and blood. Numerous studies have shown that styrene exposures were linked to central and peripheral neurologic, 2,3,4 optic, 5,6 and irritant 7 effects when occupational exposures to styrene emissions were greater than 50 parts per million (ppm). There is also evidence concerning the influence of occupational styrene exposure on sensory nerve conduction indicating that 1) 5-10% reductions can occur after exposure at 100 ppm or more, 2) reduced peripheral nerve conduction velocity and sensory amplitude can occur after styrene exposure at 50 to 100 ppm, 3) slowed reaction time appears to begin after exposures as low as 50 ppm and 4) statistically significant reductions in color discrimination (dyschromatopsia) may occur.…”