Heavy Metal Exposure, Vulnerability and Cardio- Metabolic Health: Results from the Survey of the Health of Wisconsin (SHOW)

Abstract

Background: Heavy metals including cadmium (Cd) and mercury (Hg) have both been associated with increased risk for cardiovascular disease and implicated as endocrine disruptors. Despite calls for improved cumulative risk assessments, few studies have linked empirical data of chemical mixtures concurrently with non-chemical stressors. Aims: Examine the distribution of low-level mixtures of urinary cadmium and mercury in a population-based sample as predictors of cardio-metabolic risk and non-chemical stressors (poverty). Methods: Baseline variation in urinary markers of geometric mean Cd and Hg exposure (ug/g-creatinine) were explored in a sub-sample of 300 adults aged 21-74 from the Survey of the Health of Wisconsin and compared to National Health and Nutrition Examination Survey estimates. Associations between log-transformed urinary markers and cardio-metabolic outcomes (body mass index, systolic and diastolic blood pressure, HbA1c) were examined. Comparisons between top and bottom quartiles of exposures and interactions by combined exposures and socio-demographics were explored while adjusting for confounders (age, gender, body mass, diet, and smoking status). Results: Geometric mean (GM) estimates of Cd (GM = .28, 95% CI .26-.31) and Hg (GM = .35; 95% CI .31, .39) were lower than national estimates. Significant predictors of Cd and Hg were age and gender (p<.001). The individual and combined effects of Cd and Hg on cardio-metabolic markers were not significant with the exception of Cd and body mass index (B =-1.5, P<.01). Assocations were seen among individuals with mean family incomes above 200% of poverty (B =-1.7, P<.05) but not among those below ( B=-.01, p=75). Conclusions: Findings suggest exposures to low-level mixtures of heavy metals and risk of adverse cardiovascular outcomes are low. Significant inverse associations with body mass index and cadmium and interactions with income may be related to variation in diet and differences in kidney function.