The United States generates a much larger share of the plastic waste polluting the oceans than previously thought, a new study showed. Researchers found that the US produces the most plastic waste in total, and ranks first in the world in per capita plastic waste released in the oceans.

Asian countries such as China have always ranked much higher than the US on the list of coastal plastic polluters. A previous study had ranked the US 20th among countries that mismanaged plastic waste the most in 2010. But the study didn’t look at whether waste was mismanaged after it was exported to another country for recycling.

“Plastic pollution globally is at a crisis level,” said Nick Mallos, senior director of the Ocean Conservancy’s Trash Free Seas program and co-author of the paper. “Most problematic is that rather than looking the problem in the eye, for more than 30 years, [the US] outsourced our waste problem to developing countries.”

The researchers looked at data for 2016 and considered how waste was treated after it was shipped abroad. They found that the US share of mismanaged plastic waste jumped by up to 400% compared to the 2010 figure. Americans, in total, generate the most plastic waste in the world, according to the study.

On average, an American is responsible for over 280 pounds (127 kilograms) of plastic waste every year compared to about 120 pounds (54 kilograms) for a European. After the European Union, India generated the next largest amount of plastic waste per capita, with about 44 pounds per year, the researchers found.

The US sent more than half of its massive pile of plastic recyclables to other countries. That amounted to close to 2 million metric tons shipped overseas, of which up to 1 million metric tons likely ended up polluting the environment. Almost 90% of the exports ended up in countries where it was mismanaged.

“For years, so much of the plastic we have put into the blue bin has been exported for recycling to countries that struggle to manage their own waste,” said lead author Kara Lavender Law. “And when you consider how much of our plastic waste isn’t actually recyclable because it is low-value, contaminated or difficult to process, it’s not surprising that a lot of it ends up polluting the environment.”

The authors were able to gather global data from 2016, since more recent figures weren’t available. Since then, recycling has changed significantly. China, which used to accept most of the recyclables from the US, decided in 2018 that it would stop accepting low-grade plastics. That led to plastics being shipped to other countries, such as Thailand and Malaysia.

They previously didn’t receive such a high volume of waste so this meant a big challenge for their waste infrastructure. Those places inundated by a flood of new waste might burn the discarded plastic or dump it in open pits, where winds and floods can easily push lightweight materials out to the ocean.

The study was published in the journal Science Advances.