Plastics are forever, but a forever changing threat

Plastic lasts a long time, but new research indicates that in the ocean, it changes form and can become even more of a threat to marine life with time.

A team of researchers reported that plastics break down comparatively quickly at sea—but even as they change appearance, they remain or become even more dangerous to marine life.

(Image: Hawai'i residents know that tons of plastic debris washes up on our beaches, but the rest of the North Pacific is also a target for this marine debris. Here, a Japanese boy stands by a huge chunk of Styrofoam. Katsuhiko Saido photo.)

Larger plastic objects can be a choking hazard to sea creatures. An example is a plastic shopping bag mistaken by a sea turtle for a jellyfish.

Smaller pieces—toothbrushes, bottle caps, cigarette lighters—can kill young seabirds like Laysan albatrosses, whose bellies are so full of plastic trash that they can't eat real food. At the Northwestern Hawaiian Islands rookeries, you find their dried up bodies decomposing, with fist-sized clutches of plastic debris where there bellies were.

But as these pieces pf [plastic crack and break up into smaller and smaller pieces over time, they release man-made chemicals into the ocean. These chemicals can be even more hazardous to marine life than the larger pieces, said Katsuhiko Saido, a chemist at Nihon University in Japan.

“Plastics in daily use are generally assumed to be quite stable,” said study lead researcher Katsuhiko Saido, speaking at an American Chemical Society meeting in Washington. “We found that plastic in the ocean actually decomposes as it is exposed to the rain and sun and other environmental conditions, giving rise to yet another source of global contamination that will continue into the future.”

His team studied decomposing polystyrene plastics in a lab, and were able to measure the production of a range of chemical compounds. The decomposition occurs even in cool ocean waters and does not require high heat.

“When the study team was able to degrade the plastic, it discovered that three new compounds not found in nature formed. They are styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST). SM is a known carcinogen and SD and ST are suspected in causing cancer,” said the American Chemical Society release on the report.

Other stories on this research here and here.

Here is the American Chemical Society release on the work.

© Jan TenBruggencate 2009