Some fish in New York’s Hudson River have become resistant to several of the waterway’s more toxic pollutants. Instead of getting sick from dioxins and related compounds including some polychlorinated biphenyls, Atlantic tomcod harmlessly store these poisons in fat, a new study finds.
But what’s good for this bottom-dwelling species could be bad for those feeding on it, says Isaac Wirgin of the New York University School of Medicine’s Institute of Environmental Medicine in Tuxedo. Each bite of tomcod that a predator takes, he explains, will move a potent dose of toxic chemicals up the food chain — eventually into species that could end up on home dinner tables.
From 1947 to 1976, two General Electric manufacturing plants along the Hudson River produced PCBs for a range of uses, including as insulating fluids in electrical transformers. Over the years, PCB and dioxin levels in the livers of the Hudson’s tomcod rose to become “among the highest known in nature,” Wirgin and his colleagues note online Feb. 17 in Science. Because these fish don’t detoxify PCBs, Wirgin explains, it was a surprise that they could accumulate such hefty contamination without becoming poisoned. His team now reports that the tomcod’s protection traces to a single mutation in one gene. The gene is responsible for producing a protein needed to unleash the pollutants’ toxicity.