Association between blood lead level and hypertension: the United States National Health Nutrition and Examination Survey 1999-2006

Abstract

Introduction: Lead is a heavy metal without a biological role in human. High level exposure is known to be associated with hypertension. However, their association at low levels of exposure is uncertain. Methods: Adult participants with blood lead measurements and blood pressure measurements, or selfreported hypertension diagnosis, whose data were included in the United States National Health Nutrition and Examination Survey were included in this analysis. If not already diagnosed, hypertension was defined according to the American Heart Association/American College of Cardiology 2017 hypertension guidelines. Results were analysed using R statistics version 3.5.1 with package ‘survey’ and sample weight adjustment. Logistic regression was used to study the association between blood lead level and hypertension. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated. Results: A total of 39 477 participants were included in this analysis. Every doubling in blood lead level was associated with hypertension (OR=1.45, 95% CI=1.40-1.50). This association remained significant after adjusting for age, sex, ethnicity, waist circumference, and smoking status. Using quartile 1, blood lead level <0.89 μg/dL, as reference, higher blood lead levels were associated with increased adjusted odds of hypertension (quartile 4 vs quartile 1: 1.22 [1.09-1.36]; quartile 3 vs quartile 1: 1.15 [1.04-1.28]; quartile 2 vs quartile 1: 1.14 [1.05-1.25]). Conclusion: Blood lead level is associated with hypertension in the general population. Most of the population do not have elevated blood lead levels. Our findings suggest that reducing present levels of environmental lead exposure may benefit adults by reducing blood pressure and its attendant cardiovascular risk.