Can habitual exercise help reduce serum concentrations of lipophilic chemical mixtures? Association between physical activity and persistent organic pollutants

Background: Low-dose persistent organic pollutants (POPs), especially organochlorine pesticides (OCPs), have emerged as a new risk factor of many chronic diseases. As serum concentrations of POPs in humans are mainly determined by both their release from adipose tissue to circulation and their elimination from circulation, management of these internal pathways may be important in controlling the serum concentrations of POPs. As habitual physical activity can increase the elimination of POPs from circulation, we evaluated whether chronic physical activity is related to low serum POP concentrations. Methods: A cross-sectional study of 1,850 healthy adults (age ≥20 years) without cardio-metabolic diseases who participated in the U.S. NHANES 1999-2004 was conducted. Information on moderate or vigorous leisure-time physical activity was based on questionnaires. Serum concentrations of OCPs and polychlorinated biphenyls were investigated as typical POPs. Results: Serum concentrations of OCPs among physically active subjects were significantly lower than those among physically inactive subjects (312.8 ng/g lipid vs. 538.0 ng/g lipid, P<0.001). This difference was maintained after adjustment for potential confounders. When analyses were restricted to physically active subjects, there were small decreases in the serum concentrations of OCPs with increasing duration of physical activity, showing a curvilinear relationship over the whole POP range (Pquadratic<0.001). In analyses stratified by age, sex, body mass index, and smoking status, a strong inverse association was similarly observed among all subgroups. Conclusion: Physical activity may assist in decreasing serum concentrations of lipophilic chemical mixtures such as OCPs.