Anthony ricciardi, a scientist at McGill University, was looking for evidence that an invasive Asian clam had colonised a warm spot in the St Lawrence river when a member of his team made a more headline-worthy discovery. Peering through a microscope at sand scooped up from the riverbed, the student saw hundreds of tiny plastic spheres that stood out for their unnatural roundness and vivid colours. Microbeads, widely used as an abrasive in toothpaste and face soap, are common in the world's oceans, lakes and rivers. Scientists had assumed that they floated in fresh water and were flushed downriver to the sea. Now Mr Ricciardi has shown that some sink to the bottom of lakes and rivers, where they are eaten by bottom-feeding fish, some of which, such as yellow perch, end up on dinner plates.
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