Effects of low-level occupational exposure to styrene on color vision: dose relation with a urinary metabolite

Environ Res. 2001 Jan;85(1):25-30. doi: 10.1006/enrs.2000.4227.


To investigate the threshold effects of chronic low-level occupational exposure to styrene on color vision, we examined color discrimination in 105 male workers exposed to styrene (mean age 37.7 years; mean length of exposure 6.2 years; mean urinary concentration of mandelic acid 0.21 g/L) and in 117 referents (mean age 37.7 years). We also assessed the effects of styrene by examination of the nature of the relation between disorders of nervous function and age, alcohol consumption, and other variables. A standardized questionnaire was adopted to collect information about work history, occupational or nonoccupational solvent exposure, alcohol consumption, and drug use. Color vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the color confusion index (CCI). There was a dose-dependent relationship between the urinary concentration of mandelic acid and color vision loss. The CCIs of the subgroups whose urinary mandelic acid levels were 0.1-0.2 and >0.2 g/L were significantly higher than those of each referent group (P<0.05 and P<0.01, respectively), but not in the subgroup whose urinary mandelic acid level was lower than 0.1 g/L. Our study suggests that a low level of styrene, presumably 0.1-0.2 g/L, involves the risk of inducing adverse effects on color vision. After confounding factors were adjusted for, the urinary mandelic acid level had a significant positive relationship with color vision.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Alcohol Drinking
  • Color Perception / drug effects*
  • Color Perception / physiology
  • Color Perception Tests
  • Dose-Response Relationship, Drug
  • Educational Status
  • Humans
  • Male
  • Mandelic Acids / urine*
  • Occupational Exposure / adverse effects*
  • Regression Analysis
  • Smoking
  • Statistics, Nonparametric
  • Styrene / adverse effects*
  • Styrene / pharmacokinetics
  • Substance-Related Disorders
  • Surveys and Questionnaires


  • Mandelic Acids
  • Styrene
  • mandelic acid