Association between toenail scandium concentrations and incidence of hypertension among American young adults: 28 years of follow-up.

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.