Hypertension and chronic exposure to noise.

The effects of noise on various cardiovascular parameters are conflicting and uncertain. In the current study, the authors studied 52 workers who were employed in a bedframe factory who were chronically exposed to noise and who had poor hearing. An additional group of 65 workers who had jobs in the light-metal sector and another group of 64 office workers served as two control groups; none of the controls were exposed to noise, and none had hearing defects. Blood pressure was measured for each person in the supine and standing positions, and an electrocardiogram was also performed. Sound-level measurements were taken in the workplaces. Mean systolic and diastolic blood pressures and diastolic blood pressure distributions were significantly higher in the noise-exposed group than in both control groups. Among the three groups, there were significantly different frequencies of hypertension, drops in blood pressure, and electrocardiogram anomalies. Within the group of bedframe workers, those exposed to a personal daily level of exposure (i.e., equivalent continuous noise level for exposure to noise for each individual workers in an 8-hr shift) that exceeded 90 dBA had a higher mean diastolic blood pressure and a higher frequency of diastolic hypertension than workers exposed to a personal daily level of exposure of < 90 dBA. The findings suggested that (a) work performed by the bedframe group had some effects on the cardiovascular system, (b) noise is a cardiovascular risk factor, and (c) cardiovascular effects are relative to intensity and type of exposure. Vascular damage often accompanies auditory damage, but--depending on individual susceptibility--the cardiovascular system can respond in various ways.