In an article published on January 30, 2016 by the San Diego Union-Tribune, journalist Joshua Emerson Smith reports on a new study finding that levels of toxic pollutants in fish have dropped over the past 50 years. Researchers from Scripps Institution of Oceanography, La Jolla, U.S., reviewed about 2,700 studies on pollutants in fish conducted between 1962 and 2012. They focused their review on chlordane (CAS 57-74-9), dichlorodiphenyltrichloroethane (DDT, CAS 50-29-3), mercury (7439-97-6), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Their analysis showed that concentrations of these contaminants known to accumulate in fish have significantly decreased, indicating that clean-water regulations, lawsuits and public pressure have led to less chemicals leaking into fresh waters and the oceans. However, the researchers emphasize that current levels of toxics in fish remain of concern and can be unsafe for frequent human consumption. Also, the researchers found no predictable pattern of contamination – neither regarding fish species, nor geographic region.
Another article published on February 3, 2016 by the magazine National Geographic highlights the occurrence of intersex fish in national wildlife refuges in the U.S., considered to be pristine environments. Journalist Lindsey Konkel reports on a study conducted by the U.S. Fish and Wildlife Service and the U.S. Geological Survey (USGS) finding that 60 to 100% of the examined male smallmouth bass had female egg cells growing in their testes. The exact causes of intersex in fish are unknown; however, the condition has been linked to exposure to environmental chemicals, in particular endocrine disrupting chemicals (EDCs). It also remains unclear what the feminization of fish implies for the health of the species, the environment, and possibly human health. According to Luke Iwanowicz from the USGS “the take away here is that everything we do, everything we use or put on the land, ends up in the water at some point.”
Joshua Emerson Smith (January 30, 2016). “Fish toxins at lowest levels in decades.” The San Diego Union-Tribune
Lindsey Konkel (February 3, 2016). “Why are these male fish growing eggs?” National Geographic
Bonito, L.T. et al. (2016). “Evaluation of the global impacts of mitigation on persistent, bioaccumulative and toxic pollutants in marine fish.” PeerJ (published online January 28, 2016).
Iwanowicz, L.R. et al. (2016). “Evidence of estrogenic endocrine disruption in smallmouth and largemouth bass inhabiting Northeast U.S. national wildlife refuge waters: A reconnaissance study.” Ecotoxicology and Environmental Safety 124:50-59.