When plastic bags blow away, they often end up in the ocean. Exposed to wave action and sunlight, plastic bags break down into small particles called “microplastics.” Microplastics absorb toxins from the water, including persistent organic pollutants such as flame retardants, dioxins, PCBs and pesticides. Plankton eat microplastic particles, introducing toxins into the marine food web. When fish eat these plankton, they bioaccumulate the toxins in their bodies. People who eat fish that have bioaccumulated toxins can be exposed to dangerous levels of pollution. When contaminated fish are used as animal feed, they can transfer pollutants to chickens, farm-raised fish and pigs, which could also contain high levels of toxins. Despite these risks, the U.S. Food and Drug Administration does not yet monitor for many of the toxins that could be found in fish and shellfish. Fish consumption advisories for commercial seafood are sometimes based on samples taken many years ago, well before microplastics became recognized by the scientific community as a problem.