Occupational noise exposure and cardiovascular disease risk factors in China: mediating role of hearing loss.

BACKGROUND: The health risks of noise pollution have attracted global attention, especially the potential cardiovascular effects of occupational noise exposure. Our study aimed to investigate the associations of occupational noise with cardiovascular disease risk factors [fasting blood glucose (FBG), systolic blood pressure (SBP), diastolic blood pressure (DBP), and electrocardiogram (ECG) abnormality], and further evaluate the possible mediating role of hearing loss in the associations. METHODS: This cross-sectional study included 64,382 participants exposed to occupational noise in China. Individual level of noise exposure with an 8-h equivalent A-sound level (LAeq, 8h) was measured by personal noise dosimeter. And the noise exposure level of workers was approximated using the average of measured individual noise values within each enterprise. Generalized linear models and logistic regression models were used to analyze the associations of noise exposure with cardiovascular disease risk factors. Mediation analyses were performed to assess the mediating roles of hearing loss on above associations. RESULTS: LAeq, 8h was positively associated with FBG (β = 0.006, 95% CI: 0.001-0.011), SBP (β = 0.036, 95% CI: 0.003-0.068), and risk of ECG abnormality (OR = 1.014, 95% CI: 1.009-1.019). We observed positive linear dose-response associations of noise exposure with blood pressure, as well as non-linear relationships with FBG and ECG abnormality risk [LAeq, 8h exceeded around 82 dB(A) as a turning point]. Age, dust exposure, high temperature, and length of service significantly modified above associations (P modification < 0.05), and the effects were more obvious in participants >43 years, workers with dust or high temperature exposure, and workers with length of service >5 years. Hearing loss mediated 3.7%-10.9% of the associations of noise exposure with elevated blood pressure and risk of ECG abnormality. CONCLUSIONS: Occupational noise exposure was associated with adverse changes in FBG, blood pressure, and risk of ECG abnormality. Older people, workers exposed to dust or high temperature, and those with longer working duration were more susceptible. Hearing loss might play potential role in cardiovascular damage induced by noise exposure. Efficient strategies for reducing occupational noise exposure should be enhanced to control the cardiovascular threat from occupational noise pollution.