Most of us are aware of the problem that is microplastics. Especially prevalent in the marine environment, these minuscule particles are plastic physically broken down by weathering. However, this may not be the only result of the interaction of marine plastic with environmental factors.

A new study suggests that sunlight may be breaking down marine plastics into thousands of chemical compounds. The resultant derivatives are polymer-, dissolved-, and gas-phased products. The chemical breakdown of marine plastic due to sunlight could be taking mere weeks.

Thus far, studies have been considering the impact of environmental factors on plastic breakdown by using pure polymer. The new research used three plastic bags from major USA-based retailers (Target, Walmart, and CVS) which are easily accessible to consumers. Pure polyethylene film was used for comparison.

It was found that these bags include more than pure resin bases in their composition. Up to one-third of their composition was inorganic additives. The Target bag produced about 5000 formulas, while the one from Walmart gave up to 15,000. Pure polyethylene created about 9000 chemical compositions.

The study shows that plastics of various kinds could face varying fates in the ocean. Much of it may be ending up as new chemicals not originally present in plastic, dissolved in water. How they affect the marine ecosystem, or the extent of the damage they could cause was not recorded by this study.

“It’s astonishing to think that sunlight can break down plastic, which is essentially one compound that typically has some additives mixed in, into tens of thousands of compounds that dissolve in water. We need to be thinking not only about the fate and impacts of the initial plastics that get leaked into the environment but also about the transformation of those materials. We don’t really know yet what impacts these products might pose to aquatic ecosystems or to biogeochemical processes such as carbon cycling. While plastics breaking down more quickly than expected may seem like a good thing, it’s unclear how these chemicals may affect the environment,” said Collin Ward, assistant scientist at Woods Hole Oceanographic Institute and one of the authors of the study.

The authors further point out that this is a collaboration opportunity for academia and industry. Based on the findings of this study and how the chemical breakdown of plastic under sunlight affects the environment, plastic could be reformulated to reduce the chemicals created in the marine environment.

The results of this study have been published in the Environmental Science & Technology journal.

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