Occupational noise exposure and blood pressure: longitudinal and cross-sectional observations in a group of underground miners.

The question of an association between occupational noise exposure and blood pressure has important public health implications. The harmful effects of hypertension are well known, and noise is considered the most pervasive of all occupational exposures. Most previous studies have looked cross-sectionally at blood pressure and noise exposures in workers. The present study examined historic medical and personnel records of 2,197 white male South African miners. At approximately 3-y intervals, the job title, diastolic and systolic blood pressures, height, weight, and use of medication for hypertension were recorded. Noise levels were estimated, based on noise measurements of individual jobs and work areas. In the cross-sectional analyses, multiple linear regression was used with blood pressure as the dependent variable; age, body mass index (BMI), and noise exposure were the independent variables. Longitudinal analyses were performed for those miners who had observations at four or more time periods, by calculating regression coefficients for individuals for blood pressure and noise, controlling for age and BMI. Additional longitudinal analyses compared blood pressure changes between two points in time for individual miners with changes in noise exposure, controlling for changes in age and BMI. The results of the cross-sectional and longitudinal analyses indicated no association between blood pressure and noise exposure. On the basis of these results, it does not appear that occupational noise exposure has an effect on blood pressure. Inconsistencies in the literature and shortcomings in the present study indicate that additional study is needed.