Abstract
BACKGROUND: Data on the health impacts of scandium (Sc) exposure are sparse. We aimed to investigate the association between Sc exposure and the incidence of hypertension among American young adults. METHODS: This secondary analysis utilized data from the Coronary Artery Risk Development in Young Adults (CARDIA) study - a longitudinal cohort established in 1985-86. Participants with toenail Sc measurements from exam year 2 (1987-88) and follow-up data through exam year 30 (2015-16) were enrolled. Toenail Sc concentrations were quantified using instrumental neutron-activation analysis. Incident hypertension was defined according to the 2017 American College of Cardiology/American Heart Association guidelines. Cox proportional hazards regression models were applied to assess the association between Sc exposure and hypertension risk over time. RESULTS: Among 3302 participants without prevalent hypertension at baseline (exam year 2), 1617 (49.0%) developed hypertension during follow-up. After adjusting for potential confounders, higher toenail Sc concentrations were associated with a modestly increased incidence of hypertension. Compared with participants in the lowest quintile of toenail Sc concentration, those in the highest quintile had a 24% higher incidence of hypertension [HR (95% CI) for quintile 5 vs. quintile 1: 1.24 (1.04 - 1.47), P for trend = 0.03] in the fully adjusted model. CONCLUSION: In this cohort of American young adults, higher Sc exposure was associated with modestly elevated incidence of hypertension over nearly three decades of follow-up. These findings warrant for further investigations to confirm the association and to elucidate the underlying biological mechanisms.