The neurotoxicity of paint solvents
Objectives- To investigate the relationship between neuropsychological symptoms, as measured by questionnaire, and formal measurements of neurological and psychological function. To investigate the relationship between neuropsychological symptoms and solvent exposure estimates. To test the hypothesis that neuropsychological disorder in solvent exposed workers is more likely to those with genetic predisposition. Methods - A nested case-control study was carried out in a cohort of former dockyard painters and community controls. The 78 painters and 42 community controls had previously participated in a postal study that had shown an excess of neuropsychological symptoms amongst painters. The 120 participants in the nested - case control study underwent detailed neuropsychological testing, colour vision testing, estimation of solvent exposure indices and genetic testing for GSTM1, GSTT1, NAT1 and NAT2 enzyme polymorphisms. Results - A case-control analysis of 68 patients failed to demonstrate significant differences in neuropsychological function between symptomatic and asymptomatic painters as measured by the Q16. Subsequent regression analyses of all 120 subjects showed a range of neuropsychological deficits with an exposure response relationship. There was no convincing evidence of risk modification by any of the enzyme polymorphisms studied. During the study a pattern of deficits was recognised, sufficient to constitute a syndrome of impaired colour vision, cognitive impairment impaired vibration perception and resting tremor. Conclusions - Exposure to mixed solvents is associated with neuropsychological impairment, the risk increasing with increasing intensity of exposure. The risk of impairment was not altered in this study by the presence of different enzyme polymorphisms.