Still, the discovery of opioid-positive shellfish in Puget Sound is a stark new milestone in the epidemic, showing that enough humans are hooked on these life-altering drugs for the trace chemicals they excrete to register in other species in our coastal waters.
Puget Sound Institute scientist Andy James, who assisted with the study, said the areas where the oxycodone-tainted mussels were sampled are considered highly urbanized and are not near commercial shellfish beds. Scientists have also identified antibiotics, antidepressants, chemotherapy drugs, and heart medication in mussels' systems. "So you'd have to eat 150 pounds of mussels in that contaminated area to get a minimal dose", she told NBC affiliate KING-5.
Researchers at the Washington Department of Fish and Wildlife said that for the first time, mussels living in parts of the Puget Sound are testing positive for oxycodone, a prescription drug used to alleviate pain in humans.
"What we eat and what we excrete goes into the Puget Sound", said Jennifer Lanksbury, Washington Dept. of Fish and Wildlife."So these are Penn Cove mussels". But as they filter food from the water, mussels may also absorb any chemicals and pollutants floating around them, Live Science reported in 2014.
It's just one of hundreds of pharmaceuticals that native mussels have absorbed from the waters of Puget Sound.
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.
"What this is telling us is some of this stuff is coming out of our wastewater treatment plants and so we need to do a better job either at controlling the sources or trying to reduce the exposure in the Puget Sound", said Lanksbury. Department of Fish and Wildlife regularly places mussels raised in controlled, pollution-free environments at 18 set locations around Puget Sound, an inlet of the Pacific Ocean.
The Puget Sound Institute notes that the amounts of opioids detected were thousands of times smaller than a typical human dose.
"You wouldn't want to collect [and eat] mussels from these urban bays", he said.
"Hopefully our data shows what's out there and can get the process started for cleaning up our waters", Lanksbury said.
They deposited mussels into 18 locations.