Pharmaceuticals and dozens of other chemicals have contaminated Minnesota's lakes and streams, even in remote areas of the state, a new study released Tuesday by the Minnesota Pollution Control Agency (MPCA) found.
“We have known for some time that these compounds frequently turn up downstream from wastewater treatment plants,” Mark Ferrey, the study's lead author, said in a news release. “And recent research has shown that a surprising number are found even in remote lakes or upstream waters. But we have a lot to learn about how they end up there.”
The chemicals found included antibiotics, nicotine breakdown products, antidepressants, and medicines to regulate diabetes, cholesterol and blood pressure, the MPCA notes.
Ferrey says more research is needed to determine how the chemicals found in this study can impact humans and the environment. The MPCA notes there is growing concern that these chemicals – even at low concentrations – may have a negative effect on fish, wildlife, ecosystems and possibly human health.
The study, conducted in 2013, sampled the surface water of 11 lakes and four streams for 125 different chemicals.
It found 27 chemicals in the lakes studied. It also found 56 chemicals downstream of four wastewater treatment plants, and 33 chemicals upstream of the plants, MPR News reports.
The lakes and streams tested in this study had been sampled previously and the results were largely consistent with a 2008 study of the same locations, the MPCA says.
The insect repellent DEET was detected in 91 percent of lakes, while in the 2008 study DEET was found in 100 percent of the lakes.
The study also found many lakes contain the the x-ray contrast drug iopamidol, with the highest concentration detected in Lake Kabetogama in Voyageurs National Park, located near International Falls.
The MPCA says the chemicals were all found in very low amounts, but to avoid contaminating the state's waterways further it is advising people to avoid flushing unwanted medicines down the toilet – some pharmaceutical contamination of surface water is due to wastewater.