(BBC) Scientists at the Washington State Department of Fish and Wildlife have found that mussels in Seattle's waters are testing positive for opioids.
The finding suggests "a lot of people" are taking oxycodone in the Puget Sound, researchers say.
Scientists used mussels as a way to test pollution in Seattle's waters and discovered high enough oxycodone levels for the shellfish to test positive.
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Mussels do not metabolise opioids, but some fish can become addicted.