Combined effects of exposure to occupational noise and mixed organic solvents on blood pressure in car manufacturing company workers.

BACKGROUND

Recent studies suggest that occupational exposures such as noise and organic solvents may affect blood pressure. The aim of this study was to investigate interaction of noise and mixed organic solvents on blood pressure.

METHODS

Four hundred seventy-one workers of a car manufacturing plant were divided into four groups: group one or G1 workers exposed to noise and mixed organic solvents in the permitted limit or control group, G3 exposed to noise only, G2 exposed to solvents only, and G4 workers exposed to noise and mixed organic solvents at higher than the permitted limit or co-exposure group. Biological interaction of two variables on hypertension was calculated using the synergistic index.

RESULTS

The workers of co-exposure group (G4), noise only group (G3), and solvents only group (G2) had significantly higher mean values of SBP and DBP than workers of control group (G1) or office workers (P < 0.05). Also logistic regression analysis showed a significant association between hypertension and exposure to noise and mixture of organic solvents. Odds ratio for hypertension in the co-exposure group and the noise only and solvents only exposed groups was 14.22, 9.43, and 4.38, respectively, compared to control group. In this study, the estimated synergism index was 1.11.

CONCLUSIONS

Our results indicate that exposure to noise or a mixture of organic solvents may be associated with the prevalence of hypertension in car manufacturing company workers and co-exposure to noise and a mixture of solvents has an additive effect in this regard. Therefore appropriate preventive programs in these workers recommended.