College of Science and Engineering


SCSU scientist eyes chemicals' impact on state lakes

Wednesday, December 22, 2010

Four years ago, Heiko Schoenfuss’ study of pollutants in the Mississippi River attracted national media attention and raised alarm.  Schoenfuss, director of St. Cloud State University’s aquatics toxicology lab, found so-called endocrine disruptors — chemicals traced to everything from medications to cleaning products — were causing male fish to develop female reproductive traits.

For a Minnesota scientist, Schoenfuss’ next question was a logical one: What about lakes?

Unlike rivers, lakes typically aren’t a dumping ground for large industries and city wastewater treatment plants. Schoenfuss wondered if they are being affected by the same chemicals.

“Very few people have looked at lakes,” he said. “We thought that there was a very big void in our understanding.”

In the summer of 2008, Schoenfuss joined the state Pollution Control Agency and the U.S. Geological Survey to study endocrine disruptors in 11 Minnesota lakes. Their findings were published last month.

The researchers found what Schoenfuss calls “a very similar picture to what we find in rivers.” Endocrine-disrupting chemicals were found to be widespread in low concentrations in the lakes.

The research team chose lakes with a variety of characteristics — some large and some small, some shallow and some deep, some heavily used by humans and others nearly pristine. They were scattered across Minnesota from the Iowa border to Voyageurs National Park.

The researchers collected water and sediment samples from each lake and analyzed them for 110 chemicals, including pharmaceuticals, hormones, pesticides and personal care products. The list of pollutants they detected was similar to those found in rivers, including detergents, caffeine and hormones. There were also pharmaceuticals, often acetaminophen and an antiepileptic drug used to treat attention deficit hyperactivity disorder.

The findings were unpredictable. Some of the most remote lakes with less human development showed signs of contamination, something researchers didn’t anticipate.

The team also found higher concentrations of the chemicals in the sediment than in the water, suggesting that they are accumulating over time in the lake bottom.

Endocrine disruptors have been found to have adverse effects on fish, wildlife and human health. To measure the chemicals’ effects, the researchers captured fish from the lakes and analyzed changes in their reproductive organs and bloodstreams. They also raised minnows in the lab and put them in cages in the lakes for 21 days to gauge whether they were affected.

As in the river study, researchers found some male fish in the lakes whose reproductive organs did not look as they should, Schoenfuss said.

The study’s most important finding, Schoenfuss said, was that while lakes are often thought of as being insulated bodies of water, they are just as vulnerable as rivers to contamination from septic systems and runoff from farm fields and roads. Those sources can have just as big of an impact as a “big pipe” from a wastewater treatment plant, Schoenfuss said.

Since the study was published, Schoenfuss said he’s received a ton of feedback, including e-mails from as far away as Europe.

“There’s such a lack of information on lakes,” Schoenfuss said. “They just haven’t been studied systematically.”

The state Legislature allocated money for the study through the Legacy Amendment, the sales tax increase voters approved in 2008 for arts and the outdoors.

Schoenfuss is now part of a state task force studying whether some of the compounds should be regulated.

Schoenfuss said the next step is to gain a better understanding of the compounds they studied and their effects.

The research team is taking their findings back to the lab to run exposure tests and recreate what they found in the field.

What is clear, Schoenfuss said, is that endocrine-disrupting chemicals are “what looks like a realistic threat to our natural resources.”

Story by Kirsti Marohn from St. Cloud Times -

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