Tiny Plastic Bits Pose Marine Hazard

Oct. 2, 2008 -- We've all heard about sea turtles, dolphins or seabirds dying from entanglement in six-pack rings, plastic bags or other detritus -- or from bellies full of mistakenly swallowed plastic. But some marine researchers are concerned about the effect that much smaller bits of plastic may be having on the seas.

So-called "microplastics" may concentrate pollutants, be ingestible by the ocean's tiny denizens -- from zooplankton to filter feeders like clams and mussels -- and move up the food chain.

A group of scientists gathered this month to identify what's known about this problem and where more research is needed.

"We know that stuff breaks down, and as it breaks down, it forms smaller and smaller pieces of plastic," said workshop organizer Joel Baker of the University of Washington, Tacoma. "But there's another story, and that is that there are some processes that either purposefully or inadvertently create microplastic particles in their own right."

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One such source is nurdles, the little plastic pellets used as the raw material that's molded or extruded into plastic products. A growing source is tiny plastic spheres -- less than a millimeter across, and in some cases just microns in diameter -- used in new industrial abrasives or in cosmetics as exfoliants, Baker said.

"Because they're used as abrasives, presumably they're pretty hard and pretty resilient to breakup," he said. "The general rule of thumb is, if it doesn't break down pretty quickly, it ends up in the ocean. We don't have any way of monitoring for them. We have no idea, really, if they're having any impact on any organisms."

Estimates of exactly how many particles are in the ocean give a wide range.