It's unfortunate but true, and something we've known for years now—there's lots of plastic waste floating around our oceans.
But new research published in the journal Nature, Scientific Reports, answers one of the "so what" questions, discovering that plastic in fish is a serious problem, and one that threatens the purity of seafood, thanks to plastics' ability to attract other toxic chemicals like a magnet.
Before this study, scientists didn't really know much about plastic's chemical hitchhikers. "We were able to answer this question using an experimental design that was ecologically relevant," says study author Chelsea Rochman, PhD, a postdoctoral researcher at the University of California–Davis. "The concentrations of plastics we exposed the fish to and the chemicals on the plastics were consistent with what we find in nature."
Several chemical pollutants are hydrophobic, meaning they want to get out of the water column because they don't dissolve in water, Rochman explains. Instead, they are attracted to and accumulate in other things that are persistent and organic, such as plastic. Pesticides like DDT, flame retardants like PBDEs, and industrial chemicals like PCBs and PAHs, along with metals like lead and copper, love to bind with plastic waste in the ocean.
In Rochman's team's laboratory experiment, they split fish up into three groups, feeding one group regular fish food, one a diet consisting of 10 percent virgin plastic with no pollutants, and the third, 10 percent plastic soaked in the San Diego Bay for several months.
The fish eating the bay-soaked plastic contained much higher levels of persistent organic pollutants than the ones eating regular plastic. Those eating the
marine plastic also experienced liver toxicity, glycogen depletion (which causes energy loss and fatigue), abnormal lipid metabolism, and tumor development.
For the everyday consumer, this study serves as a message to be mindful of our waste. "Everything on Earth is connected, and our findings are an example of how our waste may come back to us in another, and potentially hazardous, form," Rochman explains.
Rochman's study didn't look at which fish tend to ingest more of this tainted plastic, so we can't recommend one type of fish over another, but as a general rule it's best to stick with smaller fish—the larger, predatory fish often bioaccumulate toxic chemicals as they eat smaller fish. For tips on picking better fish, read The Seafood You Should (and Shouldn't) Eat.
