Low-level lead exposure, risk of hypertension, and the mediating effect of oxidative stress: Evidence from Southern China

Lead exposure has been linked to hypertension; nonetheless, the impact of low-level lead exposure on hypertension risk and underlying mechanisms remain inconclusive. To study how low-level lead exposure contributes to hypertension and potential mediators, data from Southern China were used. This dataset included 54,013 and 5255 lead-exposed workers in the cross-sectional and follow-up studies, respectively. Data collected demographics, physical exams, and assessment of lead exposure levels. Additionally, a subgroup of 1082 workers from a coking facility was included, which included comprehensive assessment of oxidative damage indicators and behavioral factors. We used logistic regression and mixed-effect models, assessed nonlinearity with restricted cubic splines regression, conducted stratified analyses, and performed mediation analysis to explore mechanisms. In the fully adjusted models, workers in the highest quartile exhibited a 38-65 % higher risk of hypertension compared with that of workers in the lowest quartile (OR:1.50, 95%CI:1.38, 1.65), with consistent findings in the follow-up study (OR:1.90, 95 %CI:1.37, 2.63). We found a nonlinear association in the cross-sectional analysis but a linear trend in the follow-up study (P_non-linear<0.001 and P_non-linear=0.407, respectively). Prolonged exposure duration and older age were associated with heightened longitudinal blood pressure effects (OR:1.16, 95 %CI:1.03,1.31; β:0.53, 95 %CI:0.18,0.87, P_interaction<0.05). 8-iso-PGF_2α mediated 56.6 % of the effects of lead exposure on blood pressure. These findings indicated a significant association between low-level lead exposure and hypertension. The association appeared to be partially mediated through oxidative stress pathways.