Effects of Legacy Persistent Organic Pollutants (POPs) in Fish—Current and Future Challenges

Persistent organic pollutants (POPs) are ubiquitous environmental contaminants that are not readily degraded in the environment. They are typically lipophilic, bioaccumulating in tissues of aquatic organisms and biomagnifying in freshwater and marine food webs. POPs include a wide range of halogenated legacy contaminants [e.g., polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), chlordanes, hexachlorobenzene (HCB)] that have been banned because of their toxicity to humans and wildlife; compounds such as polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs) that can be produced naturally (e.g., through forest fires and volcanic eruptions) or through industrial processes; and chemicals of emerging concern [e.g., polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds]. Although many POPs are no longer being released into the environment, they continue to be reported at toxic concentrations in fish, and there is much that is not yet understood about their modes of action and their ecological effects on aquatic habitats. This chapter reviews current information on (1) uptake and metabolism of these compounds by fish; (2) their biological effects, including their actions as endocrine disruptors, reproductive, developmental, neurological, immunological, and metabolic toxicants and carcinogens; and (3) recent efforts to evaluate the ecological risks of exposure to such compounds on fish populations and aquatic communities.