Citing the harmful impact of marine debris, UNEP said some 270 species worldwide are affected by entanglement in or ingestion of the trash marine, including 86 per cent of all sea turtles species, 44 per cent of all seabird species and 43 per cent of all marine mammal species.

"There is growing concern over the potential impact on human health of toxic substances released by plastic waste in the ocean," it added, noting that scientists are studying whether contaminants linked to cancer, reproductive problems and other health risks can enter the food chain when ingested by marine animals.

Moreover, accumulated debris on beaches and shorelines can have a serious economic impact on communities that are dependent on tourism, while the debris may house invasive species that can disrupt marine habitats and ecosystems. Heavy items of marine debris can also damage habitats such as coral reefs and affect the foraging and feeding habits of marine animals.

Waste management is one of 10 economic sectors highlighted in UNEP's Green Economy Report launched last month, highlighting enormous opportunities for turning land-based waste, the major contributor to marine debris, into a more economically valuable resource.

The value of the waste-to-energy market, for example, was estimated at $20 billion in 2008 and is projected to grow by 30 per cent by 2014.

In a major report issued two years ago – Marine Litter: A Global Challenge – UNEP details the human actions, accidental or intentional, that are the sources of marine litter. Ocean-based sources include merchant shipping, cruise liners, fishing vessels and military as well as offshore oil and gas platforms and drilling rigs, and aquaculture.

On land, the culprits include beaches, piers, harbours, marinas, docks and riverbanks, and municipal landfills located on the coast, as well as rivers, lakes and ponds that are used as illegal dump sites, discharges of untreated municipal sewage and storm water, industrial facilities, and medical waste.