Mussels in Puget Sound are testing positive for a slew of contaminants and personal care products, including opioids.

Biologists with the Washington Department of Fish and Wildlife started testing mussels in 2012. Penn Cove mussels are placed at sites all around the Sound for three months, during which they soak up whatever's in the water. Scientists then collect the mussels, grind them up, and analyze contaminants.

They've found organic contaminants related to urbanization like Polychlorinated biphenyl (PCBs) along with a slew of personal care products.

"We found antibiotics, we found antidepressants, chemotherapy drugs, heart medications and also oxycodone," said biologist Jennifer Lanksbury.

Oxycodone was just one of several pharmaceutical and personal care product compounds found in the mussel tissue. In fact, it was far more rare than estrogenic compounds found in products like detergents.

"We found oxycodone in only three of the 18 sets of mussels we analyzed. They were only present in Elliott Bay and two sites in Bremerton. The concentration of oxycodone in the mussels were about 100 to 500 times less than than you would get in a normal therapeutic dose for humans," Lanksbury said. "So you'd have to eat 150 pounds of mussels in that contaminated area to get a minimal dose."

Lanksbury says it's still safe to eat mussels in areas that aren't urbanized, like the ones served at restaurants and fish markets. That said, it is concerning for fish, especially threatened species like salmon.

"Because we're finding them in mussels, that means these chemicals are present in the water, and that means they're likely affecting fish and other invertebrates in the water," Lanksbury said. "For instance, the juvenile Chinook salmon that are coming down the Duwamish River and into Elliott Bay for rearing are likely being exposed to these same chemicals."