Background Hypertension is a common chronic noncommunicable disease. The combined effects of productive noise and lead exposure on hypertension have been rarely explored in previous studies.

Objective To investigate the combined effects of industrial noise and lead exposure on hypertension risk, and to provide a scientific basis for hypertension prevention and treatment in occupational population.

Methods Participants were recruited from a cigarette factory in Hubei Province in 2010. Data on demographic characteristics, and physical examination results were collected. Noise exposure level and blood lead concentration were measured. Based on a noise exposure level of 80 dB(A), the participants were classified into a control group and a noise-exposed group. Mixed-effects model and generalized estimating equation (GEE) were applied to analyze the association between blood lead level and blood pressure using a set of 7-year longitudinal data. Restricted cubic spline model was used to evaluate a potential dose-response relationship between blood lead levels and hypertension risk. GEE analysis was conducted to explore the potential interaction between noise and lead exposure on hypertension.

Results A total of 419 workers were included in this study, with an average age of (39.06 ± 7.34) years in 2010. After adjusting for covariates, the GEE model indicated a positive association between blood lead level and hypertension risk in both the control and the noise-exposed groups (P<0.05). The restricted cubic spline models revealed a nonlinear dose-response relationship between blood lead level and hypertension risk. In the control group, hypertension risk increased when blood lead level exceeded 18.12 μg∙L⁻¹ (P<0.05). In the noise-exposed group, hypertension risk increased when blood lead level exceeded 15.54 μg∙L⁻¹ (P<0.05). The interaction analysis demonstrated a positive interaction between noise and blood lead on hypertension risk, with a multiplicative interaction index of 1.75 95% confidence interval (CI): 1.05, 2.91, a relative excess risk due to interaction of 1.04 (95%CI: 0.04, 2.04), an attributable proportion due to interaction of 0.43 (95%CI: 0.15, 0.71).

Conclusion Combined exposure to industrial noise and lead is positively associated with hypertension risk. Exposure to noise levels ≥80 dB(A) and blood lead levels exceeding 15.45 μg∙L⁻¹ may increase hypertension risk.