Objectives Although styrene has been reported to cause colour vision impairment, the results were still inconclusive. Whether the impairment was related to short-term or long-term exposure was not known. The study aims to evaluate colour vision in high styrene exposed fibreglass-reinforced plastics (FRP) laminators.

Method Fifty workers from two yacht factories participated, including 23 FRP laminators and 27 non-FRP workers. Pre-shift colour confusion index (CCI) was measured on the first workday of a week by using Lanthony Desaturated Panel D-15d. Concentrations of volatile organic compounds related to FRP laminating were collected by a stainless canister, and then analysed using a GC/MS. Cumulative working hours for FRP laminating was obtained from daily administrative records of the companies. Logistic regression was used to assess correlation between cumulative working hours (past 0.5, 2, and 8 years) of FRP laminating and pre-shift CCI, where work time and CCI were stratified by median and the model was adjusted for age and regular alcohol consumption.

Results The mean styrene exposure during FRP laminating was 4.2 ppm. The median of cumulative working hours for FRP laminating in the past 0.5, 2 and 8 years was 2, 49, 248 h respectively. Higher cumulative working hours for FRP laminating was associated with poor CCI (past 0.5 yrs, odd ratio (OR)=3.1, p = 0.1; past 2 yrs, OR=4.8, p = 0.03; past 8 yrs, OR=6.5, p = 0.01). The effect of long-term exposure to styrene appeared to be stronger than short-term exposure.

Conclusions Long-term exposure to styrene from FRP laminating was associated with colour vision impairment.