Effects of noise on functional cardiovascular parameters: a follow-up study.

The aim of this follow-up design study is to give a contribution to the knowledge of the controversial relations between noise and functional cardiovascular parameters. The study population consisted of 757 male employees working for 5 different firms in the oil chemical area (refining and distribution of fuel) with different qualifications--345 workers, 212 drivers, 200 clerks--and thus exposed to 3 different levels of noise (85-90 dBA, 80-85 dBA and < 80 dBA respectively). Heart rate, systolic and diastolic blood pressure were monitored 3 days a week at the beginning of the working shift, for a period of 12 years. The analysis of the data obtained indicates that all the 3 parameters under observation tend to increase progressively with the age and working age of the subjects. In the comparison between the 3 levels of exposure, heart rate results not affected by the exposure to noise; systolic blood pressure results sensitive only for the discrimination of the effects due to exposure, showing a statistically significant difference only between clerks on one side and workers and drivers on the other; diastolic blood pressure is highly influenced by the level of exposure to noise, showing significantly different slopes for the 3 groups. In conclusion, blood pressure is a parameter definitely more reliable for the correlation to the level of exposure, while heart rate cannot be considered a marker of exposure to noise.