Keeping pharmaceuticals out of our water

Pity the poor minnows whose highest goal in life is to avoid being eaten. It’s a hard enough task in and of itself, given that just about everything – birds, fish, turtles and even garter snakes – will eat  minnows if they have the chance. When natural systems are out of balance, though, the challenge can become impossible.

Dr. Heiko Schoenfuss, Ph.D., Director of Aquatic Toxicology at St. Cloud State University, has coordinated a series of experiments involving minnows that he believes have wide ranging implications for humans. In these studies, the researchers examine the impacts of minute concentrations of pharmaceuticals the water, similar to what is found in the Mississippi River and a few other large lakes and rivers in Minnesota. Municipal wastewater is treated to remove bacteria, phosphorus, pathogens and other pollutants, but our current technology doesn’t filter out or breakdown chemical compounds from medications and home care products. As a result, remnants of soaps, shampoos, over the counter medications and even prescription drugs we are taking, enter the municipal wastewater stream through our showers, sinks and toilets and eventually end up downstream in whatever lake or river the treatment plant discharges to.

Dr. Schoenfuss uses the analogy of a drop of water in an Olympic size swimming pool, which would be roughly equivalent to 50 nanograms per liter (ng/L) of water. Field researchers routinely find traces of pharmaceuticals such as birth control, anti-epileptic medications, mood altering drugs and triclosan at concentrations less than 50 ng/L in waterways around the U.S.. Even at very low concentrations, however, there is evidence that these compounds are impacting fish and other wildlife. In 2009, the U.S. Geological Survey (USGS) released a study on the rate of intersex fish in nine river systems around the U.S., and during the course of their research, they found that 73% of the smallmouth bass they tested in the Mississippi River near Lake City, MN had characteristics of both sexes – the highest recorded rate in the study.  It is unknown what the implications are for us humans.

Dr. Schoenfuss is particularly concerned about how a group of chemical compounds known as endocrine disruptors might affect humans and wildlife because there is often a long time lag, as many as 20 years, before the health impacts of endocrine disruptors become apparent. During a series of laboratory studies, his team found that minnows swimming in ponds with low level concentrations of Prozac and other common endocrine disruptors were slower to react to a threat and slower to swim away. As a result, they got eaten more. Research from an experimental lake in Canada supports these findings. In a lake dosed with a low concentration “soup” of pharmaceuticals commonly found in Minnesota waters, the minnow population crashed after three years due to over-predation (getting eaten too much) and, as a result, the trout population crashed the year after that due to a lack of minnows to eat. Because all vertebrates have virtually identical endocrine systems, Dr. Schoenfuss worries that pharmaceuticals in our surface and groundwater resources, even at negligible concentrations, could cause unknown consequences for people as well.

One way that local communities are working to keep pharmaceuticals out of our water is by offering disposal programs for unused and expired medications. In the past, it was standard protocol to flush old and left over medications down the toilet, but we now know that many of these medications are passing through our municipal wastewater treatment plants and into our rivers. Washington County now offers three year-round collection drop boxes in Cottage Grove, Stillwater and Forest Lake. Drop off is anonymous and they accept a wide range of medications – pills, capsules, blister packs, creams, gels, unused Epipens, inhalers, patches, IV bags and vials, liquids, powders and sprays. Experts estimate that 25% of medications are never used, so by disposing of these pharmaceuticals properly, we can help to keep them out of our water. The Sheriff’s Department supports the Washington County program as well because it helps to reduce the risk for accidental poisoning, theft and drug abuse.

To learn more about Washington County’s medication disposal program, including hours, locations and instructions on how to package medications for disposal, visit The website also has links to research about pharmaceuticals in our water and information about medication drop-off locations in other counties.