title: Cumulative exposure to styrene and visual functions.
abstract: BACKGROUND
  Results from a 1990-1992 longitudinal study of several reinforced plastics plants showed that for those workers whose styrene exposure had decreased, color vision (CV) improved; while near visual contrast sensitivity (CS) was poorer.
  
  
  METHODS
  In 1999, we retested these visual functions in 18 workers with good visual acuity. A cumulative exposure index (CEI), corrected for respirator use, was calculated for each worker.
  
  
  RESULTS
  Intra-individual comparison of mandelic acid (MA) showed a significant decrease over time (Friedman; P = 0.015), but current values were not related to CEI. For CV, no significant difference was observed between 1992 and 1999; present results were not related to MA or CEI. The CS profile decreased over time, with significant differences at 3 cpd (Friedman; P < 0.05). CS did not vary with MA levels, but was significantly depressed at the intermediate frequencies among those in the upper CEIH category (Kruskal-Wallis; P < 0.05).
  
  
  CONCLUSIONS
  These findings suggest that CS loss increases with long-term cumulative exposure, reflecting chronic damage to the neuro-optic pathways.
authors.affiliation: Centre d'étude des interactions biologiques entre la santé et l'environnement (CINBIOSE), Université du Québec à Montreal, Montréal, Québec, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Castillo
authors.forename: M
authors.initials: M
authors.lastname: Baldwin
authors.forename: M P
authors.initials: MP
authors.lastname: Sassine
authors.forename: D
authors.initials: D
authors.lastname: Mergler
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000652:urine; D003117:Color Vision Defects / Q000139:chemically induced / Q000652:urine; D015350:Contrast Sensitivity / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008333:Mandelic Acids / Q000652:urine; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000652:urine; D016273:Occupational Exposure / Q000009:adverse effects*; D010969:Plastics; D020058:Styrene / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D013997:Time Factors; D014786:Vision Disorders / Q000139:chemically induced* / Q000652:urine
chemical_list: D015415:Biomarkers; D008333:Mandelic Acids; D010969:Plastics; D020058:Styrene