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Plastic microbeads from face wash are polluting river sediment

The microbeads used in cosmetic products are infiltrating riverbed sediments. (Castaneda, Avlijas, Simard, Ricciardi/McGill)

Tiny balls of plastic from cosmetic products are showing up in river sediment for the first time, mixing with the rocks and dirt that line the bed of the Saint Lawrence River. Because scientists have mostly been looking for these plastic pollutants in the surface water instead of in the dirt, it means that their build-up could be even worse than previously imagined -- and fish and other animals could be in serious trouble because of them.

You've probably heard of these dastardly microbeads by now: The tiny pieces of plastic, billed as miraculous exfoliators in facial wash and whitening scrubbers in tooth paste, are basically impossible to get rid of. They're too small for waste water processing plants to filter out, so they're ending up in the sea -- building up in the water and posing risks to marine life and water quality.

In recent years, researchers have reported finding the microbeads in the Great Lakes. Further research has found them in the Saint Lawrence River, which connects those lakes with the Atlantic Ocean and flows from eastern Canada to the midwestern US.

Previous research pulled the microbeads from the water itself, but in a study published recently in the Canadian Journal of Fisheries and Aquatic Sciences, researchers went digging in the dirt.

"The more we looked, the more we found. That was definitely really worrisome," Suncica Avlijas, a graduate student at McGill Univeristy, told CBC News Montreal. In some areas, Avlijas and her colleagues found over 1,000 microbeads per litre of sediment. The researchers only looked at the microbeads on the slightly larger end of the spectrum, so they suspect that smaller ones may have gone uncounted. This is worst in areas of slow river flow, where solids like these beads aren't being moved quickly enough to stay buoyant. In slow water, they sink --  and build up -- until the sediment is heavily polluted.

Now, these researchers will dissect fish that live on the polluted riverbed to see if they've been eating the plastic particles. If the microbead build-up is getting into the fish food chain, it could be endangering their health.

In the meantime, look for toothpaste without any beads in it (dentists say they're useless, anyway) and make sure your exfoliating scrubs use particles that are safe and biodegradable.