Differential uranium exposure and its association with hypertension and elevated blood pressure in American Indian communities in the Strong Heart Family Study

Abstract

Background: Urinary uranium (U) is present at higher concentrations in American Indian (AI) participants in the Strong Heart Study compared to the general US population. Cardiovascular disease is the leading cause of death among American Indians, of which hypertension is an important risk factor. We evaluated the association between U exposure and incident hypertension and increased blood pressure (BP) among Strong Heart Family Study (SHFS) participants. Methods: We included 1453 SHFS participants with baseline visits in 1998-1999 or 2001–2003, and follow-up visits in 2001-2003 and/or 2006–2009. We estimated the association of urinary U exposure with changes in systolic BP and diastolic BP levels using linear regressions, and hypertension incidence using Poisson regression with robust variance, accounting for family clustering. Results: Median (IQR) urinary uranium levels were 0.029 (0.013, 0.059) μg/g creatinine. At follow-up, 17.4% of participants developed hypertension. After adjustment for sociodemographic variables, eGFR, pre-diabetes status, and BMI, comparing the highest to lowest urinary uranium quartiles, the RR (95% CI) of incident hypertension was 1.38 (1.00, 1.91) and the mean difference (95% CI) in systolic BP levels between baseline and follow-up was -2.00 (-3.83, -0.16) mmHg. After adjustment for urinary cadmium and arsenic, the corresponding RR (95% CI) was 1.44 (1.04, 1.99) and the mean difference (95% CI) for systolic BP between baseline and follow-up was -1.48 (-3.32, 0.37) mmHg. The association between uranium and blood pressure levels at follow-up was non-linear, with an increased risk at higher urinary uranium levels. Conclusions: These findings suggest moderate increased risk for hypertension at urinary uranium levels greater than 0.06 μg/g, typical of the Southwest and Great Plains, furthermore a potential association with higher systolic BP levels and higher uranium exposure levels. Further work is needed to assess the cardiovascular effects of chronic uranium exposure in US populations. Keywords: Uranium, hypertension, blood pressure