Plastics Decompose Faster in the Sea, But Not in a Good Way

Something else to think about when you think of throwing your Styrofoam coffee cup or other plastic debris out the car window. It may well find its way into storm drains, down waterways, and out to the sea.

While common lore tells us that plastic is fairly indestructible in nature, a new study shows that bodies of salt water are an exception. In oceans, plastics seem to decompose fairly rapidly and release toxic by-products into the water, or the sea creatures that ingest them. This is the first study to look at what happens over the years to billions of pounds of plastic waste floating in our oceans, like the two-Texas-sized “Great Pacific Garbage Patch” floating between California and Hawaii.

Study lead researcher Katsuhiko Saido, Ph.D., reported at the 238th National Meeting of the American Chemical Society (ACS) this month, and was met with surprise from scientists who always believed that plastics in the oceans were mostly a hazard to marine animals that eat or become ensnared in them. Saido reported that in Japan alone, as much as 150,000 tons of plastic debris, mostly Styrofoam, wash up on their shores each year.

Saido, a chemist with the College of Pharmacy, Nihon University, Chiba, Japan, and his team found that when plastic decomposes, it releases bisphenol A (BPA) and PS oligomer into the water. BPA and PS oligomer are of concern because they can disrupt the functioning of hormones in animals and can seriously affect reproductive systems.

Saido described a new method to simulate the breakdown of plastic products at low temperatures, such as those found in the oceans. The process involves modeling plastic decomposition at room temperature, removing heat from the plastic and then using a liquid to extract the BPA and PS oligomer. The study team was able to degrade the Styrofoam in the lab, mimicking conditions in the sea, and discovered that three new compounds not found in nature formed: styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST). SM is a known carcinogen and SD and ST are suspected in causing cancer.

SOURCE: American Chemical Society (ACS)