Pollutants in Fish Could Disrupt Your Defenses to Toxins

Human defense mechanisms could be disrupted by the presence of a class of organic pollutants in fish and other food, according to new research.

The study, published in the journal Science Advances, appears to be the first to identify the mechanism by which chemicals like flame retardants—present in many household furniture items, like sofas and mattresses—and the pesticide DDT block a key protein from removing toxins from the body. P-glycoprotein, the protein in question, defends against toxins that entered the body by transporting them for removal. The new research shows that persistent organic pollutants, known as POPs, latch onto proteins and prevent them from functioning.

“These environmental chemicals form intimate interactions,” says study author Amro Hamdoun of the Scripps Institution of Oceanography at the University of California, San Diego. “But instead of being expelled, these proteins interfere with the ability of p-glycoprotein from doing its job.”

Awareness about the risks of POPs is nothing new. Public health campaigners have sought to remove POPs from the environment for decades, and a 2001 treaty even committed countries to take measures to reduce human exposure to the pollutants.

But until now scientists did not understand exactly how the pollutant harmed humans. Researchers had previously thought that POPs simply slipped by the protein, like a sneaky patron might get past a bouncer in club, says Hamdoun. But the new study shows that the pollutants actually interact with the protein and make it less effective.

The study also shows that POP can exist at risky levels in the environment. Some fish caught in the Gulf of Mexico off the coast of Louisiana were found to have levels of the pollutant to could lead to high levels of p-glycoprotein inhibitors. That finding could prevent humans who consume polluted fish from defending themselves against a variety of toxins, according to the study. And, while the study looked only at fish, Hamdoun says elevated levels of POPs could be present in meat and dairy.

“This is something that scientists and policymakers will want to think about very carefully,” says Hamdoun. “It’s very important to make sure that those fish don’t end up in our food supply.”