Page 41 - Plastics News June - 2020

Plastics mydegrade in decades, breakdown completely in carbon dioxide

The long-standing mystery around the life expectancy of degradation will be key to solving one of the enduring
plastic goods has prompted a new study from Woods Hole mysteries of plastic pollution: more than 99 percent of
Oceanographic Institution looking at how the lifetime the plastic that should be detected in the ocean is
estimates of straws, cups, bags, and other products are missing. "Researchers are beginning to talk about the
being communicated to the public via infographics. global plastic cycle," says Rochman. "A key part of this
Ward, the lead author of a new paper published in the will be understanding the persistence of plastics in
journal Proceedings of the National
Academy of Sciences, along with WHOI
marine chemist Chris Reddy, analyzed nearly
60 individual infographics and documents
from a variety of sources, including
governmental agencies, non-profits,
textbooks, and social media sites. To their
surprise, there was little consistency in the
lifetime estimates numbers reported for
many everyday products, like plastic bags,
among the materials. one of the biggest
misconceptions surrounding the fate of
plastics in the environment is that they
simply break down in to smaller bits that
hang around forever. "This is the narrative
we see all the time in the press and social
media, and it's not a complete picture," says
WHOI marine chemist Chris Reddy. "But
through our own research and collaborating
with others, we've determined that in nature. We know they break down into smaller and
addition to plastics breaking down into smaller smaller pieces, but truly understanding mechanisms and
fragments, they also degrade partially into different transformation products are key parts of the puzzle."
chemicals, and they break down completely into CO2." "The question of environmental persistence of plastics is
These newly identified breakdown products no longer not going to be easy to answer," says Collin Ward, a
resemble plastic and would be otherwise missed when marine chemist at Woods Hole Oceanographic Institution
scientists survey the oceans for missing plastics. In one and member of the its Microplastics Catalyst Program, a
of their own peer-reviewed studies on the life long-term research program on plastics in the ocean..
expectancy of plastics published last year, Ward and his "But by bringing transparency to this environmental
team found that polystyrene, one of the world's most issue, we will help improve the quality of information
ubiquitous plastics, may degrade in decades when available to all stakeholders consumers, scientists, and
exposed to sunlight, rather than thousands of years as legislators to make informed, sustainable decisions."
previously thought. Chelsea Rochman, a biologist at the This research was funded by The Seaver Institute and
University of Toronto who wasn't involved in the study, internal funding from the WHOI Microplastics Catalyst
says that understanding the various forms of plastic Program.

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June 2020 41 Plastics News