Relationship between low-level lead, cadmium and mercury exposures and blood pressure in children and adolescents aged 8–17 years: An exposure-response analysis of NHANES 2007–2016

This study investigated whether low-level blood and urinary lead, cadmium and mercury exposures were associated with blood pressure (BP) in children and adolescents. Data from National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016 for children and adolescents aged 8-17 years (n = 7076) were analyzed. Outcome variables were systolic BP, diastolic BP and high BP status. High BP was defined as: self-reported antihypertensive medication usage or a diagnosis of hypertension; classified as having elevated BP/hypertension according to 2017 AAP guidelines. Multivariable linear and logistic regressions models were performed and stratified by race/ethnicity and gender. Blood lead was negatively associated with diastolic BP among blacks, and positively associated with diastolic BP among whites. For a two-fold increase of blood lead concentration, the change in diastolic BP was -1.59 mm Hg (95% CI: -3.04 to -0.16 mm Hg) among blacks and 1.38 mm Hg (95% CI: 0.40 to 2.36 mm Hg) among whites. No significant associations between either systolic BP or diastolic BP with urinary lead were observed. The inverse associations between blood lead and high BP were found in females, Mexican Americans and other Hispanics. No associations between blood cadmium and BP were observed, except in other Hispanics. Urinary cadmium levels were inversely correlated with systolic BP, diastolic BP and high BP in all participants and in men. When compared to the lowest quartile of urinary cadmium levels, participants with a urinary cadmium level ≥ 0.12 μg/L had 0.48 (95% CI: 0.29-0.78) times and 0.53 (95% CI: 0.30-0.94) times reduced odds of having high BP in all participants and in men, respectively. No associations between either blood mercury or urinary mercury with systolic BP were observed. Significant inverse associations were found between blood total mercury and methyl mercury with diastolic BP in all participants and in men. Future prospective studies are warranted to confirm these findings.