Associations of organochlorine pesticides and polychlorinated biphenyls with total, cardiovascular, and cancer mortality in elders with differing fat mass

Background: We investigated if certain persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, predicted total, cardiovascular disease (CVD), and cancer mortality among the elderly, with the hypothesis that associations differ by the amount of fat mass. Methods: We studied serum concentrations of 11 PCBs in 633 elders (age≥70 years) and of 5 OC pesticides in 675 elders within the National Health and Nutrition Examination Survey (NHANES) 1999-2004. Mean follow-up was 4.1-years. Results: Neither PCBs nor OC pesticides were associated with total mortality when fat mass was not considered in analyses. However, associations of PCBs and OC pesticides with total mortality depended on fat mass (P_interaction<0.01 and 0.06, respectively). PCBs associated inversely with total mortality for high fat mass, but not for lower fat mass. On the contrary, OC pesticides associated positively with total mortality for low fat mass and this association weakened at higher fat mass. The interaction was also observed with CVD mortality. In elders with low fat mass, higher PCBs associated with 2-3 fold higher risk of CVD mortality, while this association was absent in elders with more fat mass (P_interaction=0.03). The positive association between OC pesticides and CVD mortality was also observed only among elderly with low fat mass (P_interaction=0.03). Conclusions: The possibility of interaction between POPs and the amount of fat mass on risk of mortality from chronic diseases is clinically important in modern societies with an obesity epidemic and requires confirmation in other studies with larger sample size.