Only Half of Drugs Removed by Sewage Treatment

WASTEWATER TREATMENT PLANTS: Approximately 1,400 wastewater treatment plants in the United States and Canada discharge 4.8 billion gallons of treated effluent into the Great Lakes basin every day. Image: Doc Searls/Wikimedia Commons

Only about half of the prescription drugs and other newly emerging contaminants in sewage are removed by treatment plants says a new report

Only about half of the prescription drugs and other newly emerging contaminants in sewage are removed by treatment plants.

That’s the finding of a new report by the International Joint Commission, a consortium of officials from the United States and Canada who study the Great Lakes.

The impact of most of these “chemicals of emerging concern” on the health of people and aquatic life remains unclear. Nevertheless, the commission report concludes that better water treatment is needed.

“The compounds show up in low levels – parts per billion or parts per trillion – but aquatic life and humans aren’t exposed to just one at a time, but a whole mix,” said Antonette Arvai, physical scientist at the International Joint Commission and the lead author of the study. “We need to find which of these chemicals might hurt us.”

More than 1,400 wastewater treatment plants in the United States and Canada discharge 4.8 billion gallons of treated effluent into the Great Lakes basin every day, according to the study.

The scientists reviewed 10 years of data from wastewater treatment plants worldwide to see how well they removed 42 compounds that are increasingly showing up in the Great Lakes.

Six chemicals were detected frequently and had a low rate of removal in treated effluent: an herbicide, an anti-seizure drug, two antibiotic drugs, an antibacterial drug and an anti-inflammatory drug.

Caffeine, acetaminophen and estriol (a natural estrogen) also were frequently detected in sewage but had high removal rates.

The wastewater plants had a low removal rate (less than 25 percent chance of removing 75 percent or more) for 11 of the 42 chemicals.

“The weight of evidence suggests that at least half of the 42 substances examined in the present study are likely to be removed in municipal wastewater treatment plants,” the authors wrote.

Previous research has linked other drugs in fish to slower reaction times to predators, altered eating habits and anxiety.

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