March 27, 2008

Underwater Plastic Waste Threatens World’s Food Chain

Marine scientists from the University of Plymouth say plastic waste accumulating in the oceans is becoming a devastating, toxic threat to the world's food chain.

Although the spotlight has traditionally been on the dangers that visible items of plastic waste pose to seabirds and other wildlife, studies suggest billions of microscopic underwater plastic fragments are concentrating pollutants like DDT.  And researchers warn the risk of these hidden contaminants could be even more serious.

University of Plymouth's Richard Thompson investigated the way plastic degrades in water, and the corresponding effect on tiny marine organisms, such as barnacles and sand-hoppers.

"We know that plastics in the marine environment will accumulate and concentrate toxic chemicals from the surrounding seawater and you can get concentrations several thousand times greater than in the surrounding water on the surface of the plastic," he told BBC News.

"Now there's the potential for those chemicals to be released to those marine organisms if they then eat the plastic."

Once the chemicals reside inside the organism, the toxins may then be transferred into the organism itself.

"There are different conditions in the gut environment compared to surrounding sea water and so the conditions that cause those chemicals to accumulate on the surface of the plastic may well be reversed - leading to a release of those chemicals when the plastic is eaten."

Thompson said the plastic particles "act as magnets for poisons in the ocean".

Thompson conducted his experiment using plastic carrier bags immersed in the water off a jetty in Plymouth harbor. He is now assessing the time is takes for them to fragment. In similar studies, he and colleagues have also added plastic powder to aquarium sediment to determine the amount ingested by various marine organisms.

Previous research on areas along the shoreline have shown plastic pollution is far worse than feared at the microscopic level.   Such studies have identified traces of plastic on every continent on the planet.

On the tiny Pacific island of Midway, Matt Brown of the US Fish and Wildlife Service reiterates the threat from plastic waste.

"The thing that's most worrisome about the plastic is its tenaciousness, its durability. It's not going to go away in my lifetime or my children's lifetimes," he told BBC News.

"The plastic washing up on the beach today"¦ if people don't take it away it'll still be here when my grandchildren walk these beaches."


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