A new study from Duke University has found that chronic exposure to microplastic fibers can cause aneurysms, erosion of surface layers, and other serious damage to fish gills. The study also found that chronic exposure to microplastic fibers increase egg production in female fish, which the scientists say is a sign that chemicals in the fibers are acting as endocrine disruptors.
Microplastic is tiny fibers made of polyester, polypropylene, and other types of plastics that are shed or washed from synthetic textiles used in clothing and other consumer or industrial products. When those fibers are shed, they enter wastewater and eventually accumulate in oceans, rivers, and lakes around the globe. Past studies have shown that many fish eat large quantities of the fibers every day but have protective mechanisms in the gut that seem to prevent damage.
However, the team says when the study is extended down to tissue and cellular levels, they did observe harmful changes. Scientists say that in addition to fibers eaten by fish, hundreds of thousands of microfibers pass through their gills each day, which is where much of the damage occurs. Scientists exposed fish to high levels of microplastic fibers in tanks for 21 days.
During that timeframe, the fish exhibited aneurysms, fused membranes, and increased mucus production in their gills along with significant changes to the epithelial cells lining gills, among other effects. One scientist says that each of those changes can affect respiration in fish. The team says the gut appears to be protected from similar damage. The study did find that when microplastic fibers are in the gut, they may release chemical coatings that are taken up in the fish’s bloodstream.
Scientists say that globally nearly 6 million tons of synthetic fibers such as polyester or polypropylene were produced in 2016. The textile shed microfibers during washing or regular use, and the researchers say one garment can shed nearly 2000 microfibers per wash. Since wastewater treatment plants aren’t equipped to remove the fibers, they escape in the downstream surface waters and accumulate in the environment.