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Mussels in waters off Seattle, Bremerton show traces of opioid oxycodone, other contaminants

SEATTLE -- Shellfish in the Seattle and Bremerton harbors of Puget Sound have shown traces of prescription opioid oxycodone.

But that wasn't all, according to Washington Department of Fish and Wildlife biologist Jennifer Lanksbury. In the midst of a national opioid crisis, the opioid may be the most attention-grabbing contaminant found, but it could be the least worrisome.

The mussels also contained four kinds of synthetic surfactants -- the chemicals found in detergents and cleaning products -- seven kinds of antibiotics, five types of antidepressants, more than one antidiabetic drug and one chemotherapy agent.

Surfactants, in particular, are "known to have estrogenic effect on organisms, so they affect the hormone system of some animals in an estrogenic way, such as feminizing male fish and making female fish reproductive before they're ready," Lanksbury explained.

Scientists have not studied whether mussels are harmed by oxycodone. However, the presence of this drug in the mollusk speaks to the high number of people in the urban areas surrounding the Puget Sound who take this medication, said Lanksbury.

"A lot of the pharmaceuticals are probably coming out of our wastewater treatment plants. They receive the water that comes from our toilets and our houses and our hospitals, and so these drugs, we're taking them, and then we're excreting them in our urine so it gets to the wastewater treatment plant in that way," Lanksbury said. "Some people, unfortunately, flush their drugs down the toilet, and that's a huge source of these pharmaceuticals."

"The doses of oxycodone that we found in mussels are like 100 to 500 times lower than you would need for an adult male therapeutic dose," she said. "So you would have to eat 150 pounds of mussels from these contaminated areas to even get a small dose. But just the fact that it's present tells us it is getting into our waters, at least in urban areas."

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.

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.

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.

Fish can metabolize some chemicals, but the mussels do not, so in many cases, they are better at revealing contaminants in the water. To test the water, Lanksbury and her team get clean mussels and put them in antipredator cages. Citizen science volunteers stake the cages to the inner tidal area of the Puget Sound at low tide, and the scientists collect them after several months.

"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. "When that data came back to us, we found oxycodone in three of those 18 samples."

One of the samples came from the shoreline of Seattle, and the two others came from near Bremerton, she said.

"So to us, that says that the oxycodone problem is specific to the urban waters of the Puget Sound. All of the other areas tested did not have oxycodone.

"All of our species indicate where contamination is coming into the Puget Sound," she explained. "Most of the shorelines of the Puget Sound are pretty clean. It's these highly urbanized locations where we're starting to get concerned about the levels of pharmaceuticals and personal care products."

The population of the Puget Sound is slated to double over the next 10 to 20 years, Lanksbury noted, and a high proportion of that population is expected to live on the shore. Urban centers across the country are growing, as well.

"It's a nationwide problem," Lanksbury said.

A study conducted by the US Geological Survey found measurable amounts of one or more medications in 80% of the water samples drawn from 139 streams in 30 states.

Still, she is hopeful because wastewater treatment mechanisms have improved, and improvements continue to be made. And the public is becoming aware of the problem.

Meanwhile, Seattle residents need "to keep in mind that what they do at home, what they put on their lawns, what they flush down the toilet ends up in the Puget Sound," she said. "The Puget Sound is a jewel in Washington, and if we all work together to keep it clean, we can make great strides."