Seattle’s Young Salmon Are Laced With Our Antidepressants
Do fish need antidepressants? No, but they’re getting them anyway, thanks to the tons of drugs and personal care products that make their way from our well-stocked medicine chests into the nation’s sewage systems and through ineffectual wastewater treatment plants.
In a new study published in the journal Environmental Pollution, researchers caught and analyzed juvenile chinook salmon and a small fish called the staghorn sculpin in three Puget Sound estuaries, two of which had wastewater treatment plants nearby. What they found was a staggering pharmacopeia of contaminants, both in the water and in the fish.
Of the hundreds of chemicals likely present in the Puget Sound ecosystem, only a small percentage are monitored or regulated, the study authors found, and there is little or no environmental toxicity information for the vast majority of these compounds.
The investigators looked for 150 contaminants and found that 92 of them—61 percent—were present in wastewater effluent, estuary waters, or the fish. The list included antidepressants, antibiotics, painkillers, estrogen-based chemicals, diabetes medicines, insect repellents, caffeine, and even cocaine.
“The higher-than-expected levels for some of these chemicals in aquatic organisms and possibly aquatic-dependent wildlife…underscores their importance for further investigation,” the authors wrote.
“It was a big surprise,” said lead author Jim Meador, an environmental toxicologist at the National Oceanic and Atmospheric Administration. “The fact that these contaminants are entering the water is nothing new, but we believe this was the first study to look at an entire suite of contaminants in whole fish.
Drug concentrations were higher in salmon than in sculpin. In the Puyallup estuary near Tacoma, Washington, a cocktail of contaminants in “comparatively high concentrations” were found in juvenile chinook.
They included amphetamines; Benadryl; antibiotics; the antidepressants Prozac, Zoloft, and norfluoxetine; a calcium channel blocker called diltiazem; hormones such as estrone and testosterone; the cholesterol medication Lopid; and the antifungal miconazole.
Meador said it was safe to assume that other fish species in the polluted estuaries also have elevated levels of drugs and chemicals.
Puget Sound has 106 wastewater treatment plants that discharge into local waters. It’s estimated they spew about 267 pounds of drugs and chemicals into the sound every day, or nearly 100,000 pounds a year. Even more contaminants enter the water from leaking septic systems, industrial facilities, and agricultural runoff.
The impacts of these drugs on fish have not been extensively studied, but some effects have been documented. Estrogen can increase fish mortality, antibiotics have been shown to suppress beneficial bacteria growth, and certain antidepressants, even at low levels, can affect behavioral function in certain species.
In 2013, Meador published a study showing that juvenile chinook transiting through contaminated Puget Sound estuaries on their way to the ocean had a survival rate that was less than half that of chinook moving through uncontaminated waters.
Meador did not know if wastewater effluent contributed to the higher mortality but said he wants to study the potential link.
Chinook are a favored prey of orcas and harbor seals. But they eat adult fish, whose toxic concentrations are diluted because they are larger and because of the drugs’ relatively short half-life in fish.
But if these chemicals increase mortality among juvenile chinook, this could have an indirect but detrimental impact on endangered Southern Resident killer whales, which gather to forage in the area each year.
“We already know that our Puget Sound salmon and the Southern Residents are fireproof, thanks to the emergence of man-made flame retardants in their tissues,” Ken Balcomb, executive director of the Washington-based Center for Whale Research, said in an email.
“The drugs and chemicals that we humans flush down the toilets are also accumulating in their tissues, with as yet unknown effects, but it is not unreasonable to assume at least some of the effects are those for which they were manufactured: birth control, antibiotic, endocrine control, and psycho-activity.”
So why is this happening? Because discharges of most of these chemicals are neither monitored nor prohibited, and different wastewater treatment plants use different techniques to filter their effluent, Meador said. Some do a better job than others.
Sandy Howard, spokesperson for the Washington state Department of Ecology, said in an email that a lot of the drugs are “emerging contaminants, which means we’re starting to notice them, study them, pay attention to them and build understanding about them.”
“We’re passionate about studying and understanding toxics in Washington, but the challenge is immense and the funding is scarce,” Howard said.
A 2010 agency study provided information on ways to reduce or eliminate concentrations of certain chemicals using different wastewater treatment technologies. “Prevention is the best strategy,” Howard said. “However, this is a complex task ahead.”