Dioxins-including polychlorinated biphenyls (PCBs), polychlorinated dibenzo furans (PCDFs), and polychlorinated dibenzo dioxins (PCDDs)-are aromatic compounds that can build up in the fat of humans and animals and may increase the risk of cancer, disrupt the endocrine system and have other undesirable health effects.

The Environmental Protection Agency has categorized dioxins and research shows these compounds cause a wide range of detrimental health effects on hormone systems, fetal development, reproductive capacity and immune function.

According to the Food and Drug Administration, most dioxin exposure occurs through the diet, with over 95% coming through the dietary intake of animal fats, specifically beef, pork, poultry, fish and dairy products. The best way to avoid dioxins is to choose organic meats and poultry and "wild" fish as opposes to "farmed".

References

Harvard Reports on Cancer Prevention: Environmental Pollution; Andersson AM, Skakkebaek NE. Exposure to exogenous estrogens in food: possible impact on human development and health. Eur J Endocrinol. 1999 Jun;140(6):477-85.; Demers A, Ayotte P, Brisson J, Dodin S, Robert J, Dewailly E. Plasma concentrations of polychlorinated biphenyls and the risk of breast cancer: a congener-specific analysis.Am J Epidemiol. 2002 Apr 1;155(7):629-35.; Charlier CJ, Albert AI, Zhang L, Dubois NG, Plomteux GJ. Polychlorinated biphenyls contamination in women with breast cancer. Clin Chim Acta. 2004 Sep;347(1-2):177-81; Ritchie JM, Vial SL, Fuortes LJ, Robertson LW, Guo H, Reedy VE, Smith EM. Comparison of proposed frameworks for grouping polychlorinated biphenyl congener data applied to a case-control pilot study of prostate cancer. Environ Res. 2005 May;98(1):104-13. ;Ritchie JM, Vial SL, Fuortes LJ, Guo H, Reedy VE, Smith EM. Organochlorines and risk of prostate cancer. J Occup Environ Med. 2003 Jul;45(7):692-702.