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Cumulative exposure to styrene and visual functions.
L Castillo1, M Baldwin, M P Sassine
1Centre d'étude des interactions biologiques entre la santé et l'environnement (CINBIOSE), Université du Québec à Montreal, Montréal, Québec, Canada.
American Journal of Industrial Medicine
|April 27, 2001
Summary
Long-term styrene exposure may cause lasting vision problems. While color vision remained stable, contrast sensitivity declined with cumulative exposure, suggesting neuro-optic pathway damage.
Area of Science:
- Occupational Health
- Neuroscience
- Ophthalmology
Background:
- A previous study indicated styrene exposure reduction improved color vision but worsened contrast sensitivity.
- Reinforced plastics plant workers were the initial study cohort.
Purpose of the Study:
- To re-evaluate visual functions in workers previously studied for styrene exposure.
- To investigate the relationship between cumulative styrene exposure and visual function changes over time.
Main Methods:
- 18 workers with good visual acuity were retested in 1999.
- Cumulative Exposure Index (CEI) was calculated, accounting for respirator use.
- Mandelic acid (MA) levels and visual functions (color vision, contrast sensitivity) were assessed.
Main Results:
- Mandelic acid levels significantly decreased over time but did not correlate with CEI.
- Color vision showed no significant change between 1992 and 1999.
- Contrast sensitivity showed a significant decline over time, particularly at intermediate frequencies, and correlated with higher CEI.
Conclusions:
- Long-term cumulative styrene exposure is associated with progressive loss of contrast sensitivity.
- The findings suggest chronic damage to the neuro-optic pathways from styrene exposure.
- Contrast sensitivity may serve as a biomarker for chronic neuro-optic effects of styrene.