Environmental Contaminant Body Burdens and the Relationship with Blood Pressure Measures Among Indigenous Adults
Blood pressure (BP) increase cardiovascular disease (CVD) risk. Indigenous Canadians experience slightly higher CVD compared with nonIndigenous Canadians. This study examined the role of polychlorinated biphenyls (PCBs), other organic compound concentrations (OCs), and toxic metals on blood pressure measures among Indigenous Canadians.
Methods: Using data from the Environment-and-Health Study, the sample was restricted to adults with valid BP measures and detectable body burden mixtures. In total, n = 759 participants were eligible, of which, n = 447(59%) were females. Principal Component Analysis (PCA) was used to reduce the complexity of the contaminant data. Orthogonal principal component (PC) variables, and sum (∑) of contaminant compounds were used as independent predictors in modified Poisson regression models with robust variance estimation, deriving prevalence ratios (PR) for hypertension, that is, systolic BP (SBP) ≥140 ml of mercury (mmHg), or diastolic BP ≥90 mm Hg. Additionally, using multivariable generalized linear regression, sex-stratified continuous SBP measure was regressed on ∑ contaminant compounds.
Results: Two PCs were extracted from the PCA analysis. PCBs and OCs positively highly loaded on the first axis (PC-1). Lead loaded positively on the second (PC-2) axis. Hypertension was consistently associated with PC-1 across models, PR = 1.08 (95% confidence intervals = 1.003 to 1.172) fully adjusted model. Examining ∑ of contaminants, the strength of association with hypertension was strongest for ∑OCs compared with ∑PCBs. The measure of effect for continuous SBP measures with ∑ dichlorodiphenyltrichloroethane(p,p'-DDT) and dichlorodiphenyldichloroethylene(p,p'-DDE) concentrations although small was similar for both females and males, β = 0.04 (95% confidence intervals = 0.005 to 0.075) among females; however, for males the estimate is imprecise after adjusting for body mass index.
Conclusion: This cross-sectional analysis found that PCBs and OCs were associated with associated prevalent hypertension; and exposure to OC pesticides, particularity DDT/DDE were found to be associated with prevalent SBP measures among females and not males.
