Polychlorinated diphenyl ethers (PBDEs), common in flame retardants, have shown steady increases in the environment. These compounds accumulate through the food chain, reaching high levels in top predators. A new study published in the latest issue of Environmental Toxicology and Chemistry provides the first evidence of the harmful effects of these contaminants to a mammalian top predator, the mink.
Because PBDEs are similar to substances such as polychlorinated biphenyls (PCBs) that have been shown to be harmful to top predators, concern has been increasing regarding possible harmful effects from their accumulation. However, to date, evidence of potential harmful effects came only from laboratory studies with mice.
This study focused on mink in the Great Lakes Basin. Mink that were fed diets dosed with PBDEs experienced systemic toxicity, decreased weight, increased organ weights relative to body weight, and reduced hematocrit, which is an increased ratio of red blood cells to the total volume of blood. Their immune systems were stimulated, which may adversely affect autoimmunity and cause hypersensitivity.
Wild mink may be particularly at risk because approximately half of their diet comes from fish, which have demonstrated that the lower-brominated PBDE congeners bioaccumulate readily and are saved in the fatty tissue. Mink are widely distributed in temperate North America and are found in environments close to urbanization, further increasing their risk of exposure to PBDEs originating from, for example, sewage effluents.
If environmental levels of PBDEs continue their exponential increase in the Great Lakes Basin ecosystem, mink and other top predators inhabiting PBDE-contaminated bodies of water may experience immune dysfunction, lowering resistance to environmental pathogens and disease.