The neuropsychological and neurophysiological effects of occupational exposure to styrene in the boat building industry

Abstract

New Zealand's boat building industry has a high reputation internationally. The industry commonly uses plastic composites, and building with these exposes workers to chemicals such as organic solvents. Styrene is an organic solvent commonly employed in the industry, and it has been linked to neurotoxic effects such as OSN (organic solvent neurotoxicity). OSN is a syndrome of symptoms that include fatigue; difficulties with concentration, learning and memory; and mood changes. Previous studies on this chronic disorder have reported measurable changes in solvent-exposed workers on neuropsychological tests, and electroencephalographic (EEG) studies reported prolonged latencies and/or smaller amplitudes in the P300 event-related potential. This pilot study is one of few to examine the possible transient effects of acute exposure, with a view to potentially identifying workers who may be more susceptible to developing OSN. Initially, information on solvent-related symptoms was gathered from 29 boat builders at two sites, and a high prevalence of symptoms were reported. Six boat builders and seven control participants, matched on age, education and type of work, were then tested using a battery of neuropsychological tests and an auditory "oddball" paradigm designed to elicit the P300 during EEG monitoring. Each subject was tested four times, at monthly intervals, using an ABAB design. Condition A testing occurred on Monday mornings, when boat builders had been free of solvent exposure for 2 days, and condition B on Thursday or Friday afternoons, when boat builders had worked with styrene that morning and on the preceding weekdays. Urinary analyses indicated that styrene exposure levels were generally low. Boat builders performed generally more poorly on the neuropsychological tests across both conditions. P300 latency was found to differentiate both groups and conditions, however. Both groups showed longer P300 latencies and smaller amplitudes in condition B, however latency was significantly more prolonged in condition B in styrene-exposed boat builders, suggesting a slowing in cognitive processing following acute styrene exposure. Recommendations are made for future research, and the implications of these findings for the health and safety of workers in the boat building industry are discussed.