Unravelling the Relationship between Body Mass Index and Polychlorinated Biphenyl Concentrations Using a Mechanistic Model.

Human biomonitoring (HBM) often reveals statistical associations between persistent organic pollutant (POP) concentrations and body mass index (BMI). Both negative and positive associations have been observed, which has been hypothesized to reflect variable toxicokinetics in lean and obese individuals during times of increasing and decreasing exposure. We examined this hypothesis and assessed the influence of the obesity epidemic on time trends in human exposure to polychlorinated biphenyls (PCB) at the population level using a mechanistic modeling approach and data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004. Using model results for PCB-153, we simulated cross-sectional body burden versus BMI trends (CBBTs), as well as population level body burden versus time trends. Negative associations between PCB-153 concentrations and BMI are predicted for all birth cohorts in HBM studies conducted in the 1990s, while for future cross-sectional studies, we predict negative or positive relationships depending on the age group sampled. At the population level, demographic changes such as the obesity epidemic and population aging had only marginal influence on the simulated rate of decline in PCB-153 concentrations between 1980 and 2010. Mechanistic bioaccumulation models can help unravel relationships between age, BMI, and POP concentrations, informing efforts to understand potential obesogenic effects of POPs.