A new study published Friday in the journal Science Advances estimates that the United States may be one of the world's largest contributors to ocean plastic pollution - not just because of littering, but because of improper handling in other nations where the U.S. has historically shipped plastic scrap for recycling.
In the study, a research team led by Kara Lavender Law of Woods Hole's Sea Education Association determined that the United States produced 42 million tonnes of plastic waste in 2016, more than any other nation. Based on existing per-capita estimates for littering and illegal dumping, they estimated that roughly 2-3 percent (1-1.25 million tonnes) was improperly disposed of within America. Most of the rest was landfilled or incinerated, with a small nine percent share recycled.
A significant share of America's recycled plastic scrap has historically been shipped overseas, typically in a contaminated form requiring sorting for use. In addition, export grade post-consumer paper is typically contaminated with plastic, which also has to be removed before the paper waste can be recycled. When these two recycled commodity classes are processed in developing nations like Malaysia and Indonesia, the sorting process often results in uncontrolled dumping of the unwanted plastic contaminants. The team estimated the quantity of this improperly handled waste plastic at up to an additional one million tonnes per year.
With the addition of overseas mishandling of American waste, the team calculated that the United States may rank as the world's third-largest contributor of plastic waste to the coastal environment (as of 2016). A subset of that waste is washed into or deposited in the ocean.
The study relies upon data that predates China's clampdown on recycled waste imports, which sharply curtailed its domestic plastic recycling industry. This prompted developed-world plastic waste exports to shift to other nations, particularly in Southeast Asia; it has also led U.S. waste management companies to increase domestic recycling capacity and landfill more plastic. The American Chemistry Council reports that America's plastic waste exports have plummeted 70 percent over the past four years.
"Ultimately, reducing plastic waste in the United States and assuming full responsibility for its reprocessing or disposal will require substantially greater commitments by resin producers, consumer products and retail companies, and the U.S. federal government," the researchers concluded.