Eating seafood tainted with a class of common, long-lasting environmental contaminants can weaken the human body’s ability to defend itself against toxic substances, reports Alter-Net on a new study. California scientists, led by Amro Hamdoun of the Scripps Institution of Oceanography, tested how exposure to 10 persistent organic pollutants, or POPs, affected an important cellular protein found in most animals and plants.
The pollutants, all detected in the past both in humans and in yellowfin tuna, included the upholstery flame retardant PBDE; pesticides such as dieldrin and DDT; and PCB, an industrial chemical.
A protein, called P-gp, usually ejects toxins from the body. But the team found that all 10 pollutants weakened P-gp’s protective function. One form of flame retardant, PBDE-100, bound itself to the protein and blocked it from transporting the toxin out of the body cell.
“When we eat contaminated fish, we could be reducing the effectiveness of this critical defense system in our bodies,” said Hamdoun in a statement.
POPs are known to cause reproductive, immune system, and neurological impairments in humans and other animals. POPs enter, spread, and concentrate in the food chain years and even decades after initial use.
“The chemicals that we found to inhibit P-gp are ubiquitous, legacy pollutants that have been widely reported in humans and wildlife,” the scientists report. “Humans are likely to be exposed to these compounds through consumption of contaminated food, raising questions on the environmental levels and impacts of these inhibitor mixtures. Previous studies have demonstrated that marine environments are major global repositories of POPs and that fish can have high levels of these compounds as compared to other foods. We focused on tuna because they are among the most widely consumed fish in the world.”
The idea that environmental pollutants could perturb P-gp was first postulated nearly 20 years ago, however, the precise mechanisms and environmental relevance have largely remained a mystery. “Our results argue for consideration of these interactions in risk assessment of environmental chemicals.”
The study was published in the journal Science Advances. http://advances.sciencemag.org/content/2/4/e1600001