Biochemical effects of chronic exposure to noise in man.

Biochemical parameters in 75 normal healthy male subjects exposed to intense noise of 88-107 dB(A)(6-8 h/day) for 10 to 15 years during their work situation have been monitored and compared with 35 normal unexposed subjects. Levels of free cholesterol (P less than 0.001), gamma-globulin (P less than 0.01) and cortisol (P less than 0.01) were found to be significantly higher in the exposed subjects. Significant changes in free cholesterol also altered the ratio of free to esterified cholesterol significantly (P less than 0.001). The value of the A/G ratio was also lower in the exposed group. Uric acid did not show any change. The study shows that in the exposed group the esterification process of cholesterol was modified. There was an effect on pituitary-adrenal axis as well as host-defence mechanism.