OCCUPATIONAL NOISE EXPOSURE AND BLOOD-PRESSURE

Objective: To investigate the relationship between occupational noise exposure and blood pressure. Methods: We studied 8811 workers at a met allurgical factory who were exposed to different levels of noise at th e worksite: less than or equal to 80 dB for 8078 workers and >80 dB fo r 733 workers. A clinical examination, including measurements of blood pressure (by mercury sphygmomanometer, Korotkoff phases I and V), hea rt rate (by pulse palpation), body weight and height, was performed. T he subjects were stratified into four age groups (18-30, 31-40, 41-50 and >50 years) and into two body mass index groups: normal weight (les s than or equal to 25 kg/m(2)) and overweight (>25 kg/m(2)). in order to eliminate possible confounding factors and statistical bias, a retr ospective case versus control analysis was also carried out. Results: The epidemiologic approach showed that the systolic blood pressure (SB P) but neither the diastolic blood pressure (DBP) nor the heart rate v alues were statistically higher in the group who were exposed to noise levels of >80 dB, although the difference could be considered clinica lly relevant only in the older age group. The prevalence of hypertensi on (according to World Health Organization criteria) was higher among the workers who were exposed to the higher levels of noise. Stratifica tion for body mass index confirmed the existence of a higher prevalenc e of hypertension in the exposed group. The results from the case vers us control analysis indicated that both the SBP and the DBP levels in the exposed group were significantly higher than those in the referenc e group, and confirmed the existence of a higher prevalence of hyperte nsion in the exposed group. Conclusions: The present data suggest that occupational exposure to noise levels exceeding 80 dB may lead to a h igher prevalence of hypertension and to increased blood pressure value s, although the results appear quantitatively different according to t he approach that is taken to the problem (i.e. the epidemiologic or th e case versus control approach).