A study of noise-induced hearing loss and blood pressure in steel mill workers

A cross-sectional study on noise-induced hearing loss and blood pressure was conducted in a steel mill company. Three hundred testees were selected by cluster sampling. They were physically examined and an audiometry was done. Only 151 workers, who had the highest hearing threshold at 4000 Hz and without any family history of hypertension or treatment of drugs on cardiovascular troubles, were selected as subjects in this study. Multiple regression analyses revealed that body mass index, employment duration, age and hearing loss explained a significant amount of variation in systolic and diastolic blood pressure (R2 = 0.16 and 0.12, respectively). There was no significant relationship between hearing loss and blood pressure. In order to adjust confounding factors, analyses of covariances were used and the results suggest that hearing loss is unrelated to blood pressure. It seems that hearing loss is not appropriate as a noise exposure index to measure the relationship between noise exposure and blood pressure.