New Delhi: Each year an average of eight million tonnes of plastic is moved from land to ocean, according to a paper studying coastlines of 192 countries published on Friday in Science journal. This would be the equivalent of five grocery bags full of plastic in every foot of coastline in these countries, the paper said.

Researchers say the cumulative amount could rise 10-fold in the next decade if waste management practices are not improved across the world. They combined data on solid waste from the coastal countries adjusting for variables like population density and economic status. They found that waste that slips past waste management systems was the biggest source of plastic debris in the oceans.

“Our mismanaged waste is a function of both inadequate management—open dumping, for example—and litter," Jenna Jambeck, the lead author, said in a statement by the American Association for Advancement of Science. “This mismanaged waste goes uncaptured, meaning that it then becomes available to enter marine environments."

The study found coastal countries generated close to 275 million tonnes of plastic waste in 2010, and that 4.8 to 12.7 million tonnes of that plastic made its way to the oceans. It also highlighted that the top 20 countries accounted for 83% of the mismanaged plastic waste available to enter the ocean.

The research was conducted by a scientific working group at University of California, Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS) with support from the Washington, DC-based Ocean Conservancy.

The main factors responsible for plastic pollution in ocean were found to be a country’s population, along with the quality of its waste management systems.

The investigators began by looking at all debris entering the ocean from land, sea and other pathways in order to develop models for each of these sources. Then, researchers combined data on solid waste from 192 different coastal countries with factors such as population density and economic status.

The scientists suggested a few solutions to the problem, including waste reduction and downstream waste management strategies such as expanded recovery systems and extended producer responsibility.

“While infrastructure is being built in developing nations, industrialized countries can take immediate action by reducing waste and curbing the growth of single-use plastic," the study said.

The NCEAS working group forecasts that the cumulative impact to the oceans could be as high as 155 million metric tonnes by 2025.

“Large-scale removal of plastic marine debris is not going to be cost-effective and quite likely simply infeasible," Roland Geyer, a co-author and an associate professor at UCSB’s Bren School of Environmental Science and Management, said in a statement. “This means that we need to prevent plastic from entering the oceans in the first place through better waste management, more reuse and recycling, better product design and material substitution."

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