Study challenges ocean plastic assumptions; US a major source of pollution

Researchers in marine plastics pollution say the U.S. ranks high among nations responsible for plastics debris, revising their previous study that some had interpreted to place the blame more on five countries in Asia.

A 2015 study that said the five countries in Asia account for more than half of the plastics in oceans is frequently mentioned in plastics pollution debates along with official documents like U.S. Environmental Protection Agency documents and congressional testimony.

The authors now say that study is no longer true, if it ever was.

A new study published Oct. 30 in the journal Science Advances backs away from the earlier research and estimates the U.S. could rank as high as third among ocean plastics emitters, up from 20th in the older study.

What changed, they say, is what they were able to measure. The new estimates for the first time include the substantial impact of U.S. plastic scrap recycling shipped overseas that ultimately can't be properly recycled and materials that are illegally dumped within the U.S.

The authors, including prominent researchers Kara Lavender Law and Jenna Jambeck, challenge "the once-held assumption" that the United States adequately manages its plastic waste, according to a news release.

In 2016, the U.S. had 4 percent of the world's population but accounted for 17 percent of all plastic waste, according to the study. And U.S. residents generate almost twice as much plastic waste per capita than residents of the European Union.

"As the largest producer of plastic waste in the world, the United States must simultaneously act to reduce the amount of plastic waste we generate and take full responsibility for its reprocessing and its ultimate disposal," said Law, a research professor of oceanography at the Sea Education Association in Woods Hole, Mass.

Blaming Asia

The previous study blaming five Asian countries — China, Indonesia, the Philippines, Thailand and Vietnam — has taken a prominent spot in public dialogue.

As one example, an Oct. 19 news release from EPA specifically says those five countries contribute more than half the ocean plastic waste. It was made as part of an announcement for a new U.S. strategy on reducing marine litter. The statement is in the full report as well, with a citation to the 2015 study.

Members of Congress and industry sometimes cite that 2015 research in their public comments, as has President Donald Trump. In the new EPA strategy report, Trump is quoted saying he wants to "stop other nations from making our oceans into their landfills."

Authors of the new research say their findings have implications for government policy.

"I would not use that language about the top five countries anymore, because there is new information available that is changing our picture," Law said.

She said the 2015 study was the first to try to quantify the amount of plastic leaking from land into the oceans, an important exercise but also inherently "squishy" given different data collection by different countries and difficulties measuring.

"[The 2015 study] was not intended to be a finger pointing, sort of rank-the-bad-people exercise," Law said. "You could completely redo that study again, and you would get different results."

Impact of US exports

In a news conference to announce their results, Law and other researchers said the original 2015 work only looked at estimates of littering in the U.S. and contributions that would make to ocean plastic. At the time, they ranked the U.S. as the 20th-largest emitter of plastic to the marine environment and the only developed nation in the top 20.

But adding in the impact of plastic scrap exported from the United States, mostly to developing countries, and illegal dumping in the country, they estimated the U.S. contributions is significantly larger.

It potentially ranks the country as high as the world's third-largest emitter, when you take a fuller account of plastic consumption by Americans, the study said.

"We are contributing a substantial mass of plastic to the environment, both in this country and abroad," Law said.

Including exports and new domestic sources, they estimate that in 2016, the U.S. contributed up to 2.25 million metric tons of plastics to the environment, and 1.5 million tonnes of that ended up on coasts around the world, where it has a higher chance of leaking into oceans.

But they also acknowledge a fair amount of data uncertainty. For scrap exports, they said the U.S. contribution could range from 0.15 million to 1 million tonnes. It estimated litter contributes 0.84 million tonnes and illegal dumping up to 0.41 million tonnes.

The original 2015 study also gave the widely quoted figure of a global total of 8 million tonnes of plastic leaking into the ocean year. But that estimate, which came from 2010 data, was itself derived from a range of other numbers. It estimated between 4.8 million and 12.7 million tonnes of plastic enter the oceans each year, and it's been widely shorthanded to 8 million tonnes.

The American Chemistry Council's plastics division said in a statement that it agreed with the authors that any litter or mismanaged waste is too much. But it also said U.S. plastic waste exports have fallen sharply since 2016, as China and other countries have implemented widespread import limits.

"Unfortunately, the study does not mention that U.S. exports of plastic waste have declined dramatically — nearly 70 percent — since their peak in 2016," said Joshua Baca, ACC's vice president of plastics. "The fact is, U.S. exports of mixed plastic waste will be forbidden to many countries under the Basel Convention as of Jan. 1, 2021."

ACC said there has been $5.3 billion in announced private sector investments in the U.S. to modernize recycling since 2017, and it pointed to new policy changes for the group, like supporting mandatory recycled-content standards, as ways to help reduce plastic waste.

The study said it used 2016 data because that's the last year full statistics are available.

Numbers aside, the environmental group Ocean Conservancy, which also helped write the study, argued it shows the problem is more complex than targeting developing countries in Asia.

"This global issue of plastic waste and plastic pollution and ocean plastic pollution is not something as simple as an issue pertaining to five or six countries and rapidly developing economies," said Nick Mallos, senior director of conservancy's Trash Free Seas program.

"Rather, it is a complex, global, interconnected issue," Mallos said. "Reducing plastics waste in the United States will not only reduce plastic here, but also plays an important role in reducing the plastics that then need to be managed in many developing economies where capacity does not yet exist."