Interaction Between Occupational Vanadium Exposure and hsp70-homon Neurobehavioral Function

Objective In determine the effect of heat shock protein 70-hom gene (hsp70-hom) polymorphism on the neurobehavioral function of workers exposed to vanadium. Methods Workers from the vanadium products and chemical industry were recruited by cluster sampling. Demographic data and exposure information were collected using a questionnaire. Neurobehavioral function was assessed by Neurobehavioral Core Test Battery. The hsp70-hom genotype was detected by restricted fragment length polymorphism-polymerase chain reaction (RFLP-PCR). A neurobehavioral index (NBI) was formulated through principal component analysis. Results Workers with a T/C genotype had worse performance in average reaction time, visual retention, digital span (backward), Santa Ana aiming (non-habitual hand), pursuit aiming (right points, total points), digit symbol and NBI score than others (P<0.05). The relative risk of abnormal NBI score of the workers with a T/C genotype was 1.748 fold of those with a T/T genotype. The relative risk of abnormal NBI score of the workers exposed to vanadium was 3.048 fold of controls (P<0.05). But after adjustment with age and education, only vanadium exposure appeared with a significant effect on NBI score. When gene polymorphism and vanadium exposure coexisted, the effect of vanadium on neurobehavioral function was attenuated, but the influence of T/C genotype increased 〔odds ratio (OR=4.577,p<0.05〕. After adjustment with age and education, the OR of T/C genotype further increased to 7.777 (P<0.05). Vanadium exposure and T/C genotype had a bio-interaction effect on NBI score 〔relative excess risk due to interaction （RERI）=4.12, attributable proportion （AP）=0.7, synergy index （S）=6.45〕. After adjustment with age and education, the RERI became 2.49 and the AP became 0.75, but no coefficient of interaction was produced. Conclusion Priorities of occupational protection should be given to vanadium-exposed workers with a hsp70-hom T/C genotype and low education level.