The levels of opioids in the waters were thousands of times smaller than a human dose, but data shows that the United States opioid epidemic has filtered down to other species in America's ecosystems.
The mussels were found in three out of 18 test sites from a highly urbanized area.
"We found antibiotics, we found antidepressants, chemotherapy drugs, heart medications and also oxycodone", said biologist Jennifer Lanksbury.
It's possible, however, that the opioids could affect fish, which are known to respond to the drugs, James added. This is the first time that opioids have been detected in Puget Sound mussels, the PSI statement said. Some of the oxycodone consumed by people end up in the toilet before going to wastewater treatment plants. In Puget Sound, off the western coast of Washington state, scientists have discovered marine life contaminated with oxycodone.
Since mussels are "filter feeders", they absorb contaminants from their environment into their tissues in a concentrated way.
Drug use in the Pacific Northwest is so prevalent that scientist have found trace amounts of narcotics in the systems of sea creatures in the area.
Lanksbury said the containments can have negative impacts on fish and shellfish in the surrounding areas. The contaminants in this case are thought to be passed into Puget Sound through discharge from wastewater treatment plants.
Shellfish in the Seattle and Bremerton harbors of Puget Sound have shown traces of prescription opioid oxycodone.
Every two years, scientists from the Washington Department of Fish and Wildlife place uncontaminated mussels in various Puget Sound locations.
"We sent 18 samples (of mussels) to a laboratory up in Canada and asked for a suite of pharmaceutical and personal care products", Lanksbury said.
According to the WDFW, people who eat mussels from a restaurant or grocery store should not be anxious about getting high on opioids. In the process, "they pick up all sorts of contaminants, so at any given time their body tissues record data about water quality over the previous two to four months", the institute explains.
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