Bay Mussels (Mytilus trossulus) on Edmonds Ferry Dock, Washington State. Photo: brewbooks / flickr

By Christina Capatides
26 May 2018

(CBS News) – As more and more American communities grapple with opioid addiction, the human toll of the epidemic has grown in both scope and severity. And now, scientists at the Washington Department of Fish and Wildlife have found evidence that drug's impact has literally flowed downstream to affect marine life, as well.

Specifically, they used mussels as a barometer of pollution in the waters off Seattle, and discovered that oxycodone is now present enough in the marine environment there for shellfish to test positive.

Since mussels are "filter feeders," they absorb contaminants from their environment into their tissues in a concentrated way.  Scientists used cages to transplant clean mussels from an aquaculture source on Whidbey Island to 18 urbanized locations around Puget Sound. Several months later, they pulled those previously uncontaminated mussels back out of the urban waters and, together with the Puget Sound Institute, tested them again.

In three of the 18 locations, the mussels then tested positive for trace amounts of oxycodone. How, you ask?

When humans ingest opioids like oxycodone, they ultimately end up excreting traces of the drugs into the toilet. Those chemicals then end up in wastewater. And while many contaminants are filtered out of wastewater before it's released into the oceans, wastewater management systems can't entirely filter out drugs. Thus, opioids, antidepressants, the common chemotherapy drug Melphalan -- the mussels tested positive for all of them.

"What we eat and what we excrete goes into the Puget Sound," Jennifer Lanksbury, a biologist at the Washington Department of Fish and Wildlife, told CBS Seattle affiliate KIRO. "It's telling me there's a lot of people taking oxycodone in the Puget Sound area."

While mussels likely don't metabolize drugs like oxycodone, and thus wouldn't necessarily be physically harmed by the presence of it in their tissues, studies show that fish are not so lucky. In fact, scientists at the University of Utah recently discovered that, if given the opportunity, zebrafish will willingly dose themselves with opioids. Scientists say salmon and other fish might have a similar response. [more]

Mussels off Seattle coast test positive for opioids

By Jeff Rice
9 May 2018

(Puget Sound Institute) – The opioid epidemic has now hit the waters of Puget Sound. State agencies tracking pollution levels in Puget Sound have discovered traces of oxycodone in the tissues of native bay mussels (Mytilus trossulus) from Seattle and Bremerton area harbors.

The mussels were part of the state’s Puget Sound Mussel Monitoring Program. Every two years, scientists at the Washington Department of Fish and Wildlife (WDFW) transplant uncontaminated mussels from an aquaculture source on Whidbey Island to various locations in Puget Sound to study pollution levels. Mussels, which are filter feeders, concentrate contaminants from the local marine environment into their tissues. After two to three months at the transplant site, scientists analyze the contaminants in the collected mussel tissues.

The areas where the oxycodone-tainted mussels were sampled are considered highly urbanized and are not near any commercial shellfish beds. “You wouldn’t want to collect (and eat) mussels from these urban bays,” explained PSI’s Andy James, who assisted with the study. The oxycodone was found in amounts thousands of times lower than a therapeutic dose for humans and would not be expected to affect the mussels, which likely don’t metabolize the drug, James said. The findings may raise concerns for fish, however, which are known to respond to opioids. Lab studies show that zebrafish will learn to dose themselves with opioids, and scientists say salmon and other Puget Sound fish might have a similar response.

Scientists typically find many chemical compounds in Puget Sound waters, ranging from pharmaceuticals to illicit drugs such as cocaine, but this is the first time that opioids have been discovered in local shellfish. The contaminants in this case are thought to be passed into Puget Sound through discharge from wastewater treatment plants. Even filtered wastewater can include traces of thousands of chemicals known as contaminants of emerging concern (CECs). Runoff from agriculture and stormwater are also common sources of CECs.

In addition to oxycodone, the mussels also showed high levels of the chemotherapy drug Melphalan, which is a potential carcinogen due to its interactions with DNA. The drug was found at  “levels where we might want to look at biological impacts,” said James. The mussels had ingested amounts of Melphalan relative by weight to a recommended dose for humans.

These Puget Sound mussel monitoring studies occur every two years and are currently funded by WDFW, the state’s Stormwater Action Monitoring program, and various other regional partners. The monitoring is led by Jennifer Lanksbury, of WDFW’s Toxics-focused Biological Observing System (TBiOS), along help from a host of citizen science volunteers from across Puget Sound. PSI’s Andy James worked with TBiOS on the chemical analysis and presented the findings at last month’s Salish Sea Ecosystem Conference.

James and his team at the University of Washington’s Center for Urban Waters in Tacoma are now using high resolution mass spectrometry to look for additional chemical exposures in the mussel tissues and to evaluate potential biological impacts on Puget Sound species.

Read more about mussel monitoring in the Encyclopedia of Puget Sound.

Bay mussels in Puget Sound show traces of oxycodone



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