“We found Oxycodone in only three of the 18 sets of mussels we analyzed,” biologist Jennifer Lanksbury told local NBC affiliate KING5, per a report from Munchies. “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. So you'd have to eat 150 pounds of mussels in that contaminated area to get a minimal dose.” It's also worth noting that one of the researchers at Puget Sound Institute said it's unlikely anyone would actually be collecting seafood to eat from the affected areas.
So how do these drugs end up in such high concentrations to affect creatures living in the ocean? Well, it's generally because enough people are using them -- and peeing them out -- that they're being introduced via wastewater treatment plants, which can only remove so many toxins, chemicals, and other pollutants from waste. It's the same sort of issue that's led to rudd in the Niagara River to test positive for antidepressants, and salmon off the coast of Washington to test positive for a whole grab bag of drugs including Valium, Lipitor, and cocaine.