Airborne metals exposure and risk of hypertension in the Sister Study

Hypertension-related disease burden is a major challenge globally, with an estimated 1.56 billion adults expected to be affected by hypertension by 2025. Environmental factors, such as metals, could be risk factors for hypertension, but the relationship between airborne metals and hypertension is rarely studied.

Census-tract airborne metal concentrations (arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, selenium, and antimony) from the U.S. Environmental Protection Agency 2005 National Air Toxics Assessment database were linked to enrollment residential addresses of 47,595 women in the Sister Study cohort. Hypertension was defined as high systolic (≥140 mm Hg) or diastolic (≥90 mm Hg) blood pressure measured by trained examiners at enrollment or taking anti-hypertensive medications. Multivariable log binomial regression was used to estimate adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) for the association between individual metals and hypertension, with and without co-adjustment for other metals. Quantile-based g-computation was used to estimate the joint effect of the overall metal mixture.

Comparing the highest to lowest quartiles, risk of hypertension was higher among women with higher residential exposure to arsenic (PR = 1.05, 95%CI = 1.02,1.09), lead (PR = 1.04, 95%CI = 1.01,1.08), chromium (PR = 1.03, 95%CI = 1.00,1.06), cobalt (PR = 1.03, 95%CI = 1.00,1.07), and manganese (PR = 1.03, 95%CI = 1.00,1.06). Selenium was associated with lower risk of hypertension (PR = 0.96, 95%CI = 0.93,0.99). Results were similar with mutual adjustment for all other metals. The associations varied by race/ethnicity, with greater PRs in other races/ethnicities (Hispanic, black, and other participants) compared to non-Hispanic white participants. The joint effect of a quartile increase in exposure to all the metals was 1.02 (95%CI = 0.99,1.04).

We found that living in areas of higher exposure to arsenic, lead, chromium, cobalt, and manganese was related to higher risk of hypertension, whereas living in areas with higher selenium was inversely related to the risk of hypertension.