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.
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