Building a Path to Health Equity: Investigating Lead Exposure, Chronic Stress, and Cardiovascular Dysfunction - The exposome is the totality of exposure individuals experience over their lives and how those exposures affect their overall health. Limited studies have explored the combined effect of chronic stress and lead (Pb) exposure on cardiovascular disease risk among urban Black residents. Urban populations face elevated chronic stress levels, leading to short-term issues like increased heart rate and blood pressure, and long-term effects such as sustained hypertension and vascular damage. The presence of Pb in urban residential areas is largely due to Pb-based paints widely used until 1978, leaded gasoline used until 1996, and mining and smelting associated with some industrialized urban centers. Exposure is intensified by urban factors like traffic, which resuspends Pb-contaminated soil particulates. Because of these factors, residents in low-income communities are at greater risk for exposure to Pb through dust, soil, and water.
In this study, we will enroll a cohort of predominantly urban Black adults living in low-income neighborhoods, previously demonstrated to contain measurable levels of Pb in buildings and soils, in Greensboro, NC. In the household of each enrolled adult, we will evaluate Pb levels in soil samples, samples of dust from floors and windowsills, and water samples. Pb exposure in the enrolled adults will be assessed by blood lead levels (BLL) representing acute Pb exposure, and zinc protoporphyrin (ZPP) representing chronic exposure. Blood samples will be used to measure fasting total cholesterol, LDL, HDL, triglycerides, isoprostane and inflammatory biomarkers. In this study, we will investigate the synergistic impact of combined exposure to lead (Pb) and stress on the risk of cardiovascular disease (CVD). To assess stress levels, we will measure cortisol, a known stress marker, in both hair samples and saliva. Questionnaires will be administered to gather data on various factors, including perceived stress and cumulative stress. Additionally, blood pressure measurements will be taken. Our hypothesis is that the concurrent exposure to Pb and stress will significantly elevate the risk of cardiovascular disease compared to individual exposures. Moreover, we expect that different sources of Pb exposure (soil, dust, or water) will contribute to this risk by varying degrees. This hypothesis will be explored in two specific aims.
Aim 1: Characterize the relationships among the environmental Pb levels and the chronic and acute levels of Pb exposure. Approach: In the population of interest, we hypothesize that soil and dust, as compared to water, are the residential sources most closely associated with Pb exposure. We will estimate the associations of soil, dust, and water with chronic and acute Pb exposures via model-based methods for the cross-sectional data. The main analysis will account for sex, age (18-30,30-60, ≥ 60yrs), occupation (in-home, out-of-home), length of time in residence (brief, moderate, long-term).
Aim 2: Characterize associations of cardiovascular dysfunction with Pb exposure, measures of stress, and the interactions of Pb exposure with stress. Approach: We hypothesize that Pb exposure, chronic stress, and the interaction of Pb exposure with chronic stress all contribute to adverse cardiovascular health outcomes. The main statistical analysis will rely on model-based methods for cross-sectional clustered data. For the primary outcome (a composite index of cardiovascular dysfunction), and for secondary outcomes (8 cardiovascular measures, isoprostane and inflammatory biomarkers), the models will account for chronic and acute Pb exposure, chronic stress, stress-by-exposure interactions, and participant characteristics.
Impact: This investigation of the Pb exposome's impact on cardiovascular dysfunction can guide healthcare planning, resource allocation, and policy development to mitigate harmful exposures, aligning perfectly with the objectives of the CMS Minority Research Grant Program.
