February 14, 2015
by Canadian Plastics

New research estimates an average of about eight million tonnes of plastic – everything from water bottles to garbage bags to food packaging – finds its way into the world’s oceans each year.

The study, published in the journal Science, estimates that 4-12 million tonnes of plastic are dumped every year by coastal countries.

The research was conducted by scientists at the University of California Santa Barbara’s National Center for Ecological Analysis and Synthesis. They looked at 192 coastal countries in 2010 and how they disposed of their plastic.

Eight of the top 10 contributors were in Asia, including Indonesia, the Philippines, Vietnam, Sri Lanka, Thailand, Malaysia and Bangladesh, according to the study, which estimated that 4.8 million to 12.7 million metric tons of plastic wound up in the world’s oceans in 2010.

A study last year found the amount of floating plastic in the oceans had not increased since the 1980s, despite increased plastic production. Researchers involved in that work suspect the plastic is still there, but has been breaking down into small pieces that sink deep into the water column, where marine life can mistake it for zooplankton, and consume it.

For the new study, researchers focused on plastic discarded from coastal population areas. They had to rely on indirect methods to quantify how much plastic was in waste that was not properly disposed of, and then estimate how much was likely to end up in oceans.

Researchers used 2005 data from the World Bank to come up with figures on the amount of waste generated per capita as well as the amount of that waste that was plastic. The data were available for only for 73 countries; for the other countries, the researchers made conservative estimates based on the figures for other countries with similar per-capita incomes.

The researchers then assumed that the amount of plastic waste grew by 0.19% per year since 2005. That figure was derived in part from the growth in U.S. plastic waste since the 1960s, as measured by the Environmental Protection Agency.

Few of the top contributing countries have adequate infrastructure for handling trash disposal, the study authors noted. Even with a well-developed infrastructure to handle solid waste, the U.S. contributed 40,000 to 110,000 metric tons per year, and ranked 20th, they found.

If waste practices don’t change and economies and populations continue on their present trajectories, the study projected, the mass of plastic likely to flow into the oceans each year will just about double by 2025.
 

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