Widespread Groundwater Contamination Found in Southwestern Illinois

Researchers have detected prescription and over-the-counter medications and personal care products in Illinois groundwater, an indication that humans are contaminating water that is vital to aquatic life.

In a University of Illinois Prairie Research Institute (PRI) study, researchers collected 58 water samples from eight springs and five cave streams in southwestern Illinois in 2014 and 2015. Hormones were detected in only 23 percent of groundwater samples, but medications and personal care products were detected in 89 percent of samples, according to Walt Kelly, head of the Groundwater Science section at the Illinois State Water Survey, PRI. The team also included scientists from the Illinois State Geological Survey, the Illinois Natural History Survey, the Illinois State Water Survey, and the Illinois Sustainable Technology Center.

The study location was in karst terrain, which is notable for caves, sinkholes, and smaller openings in the land surface through which contaminants can readily enter underground streams and springs. The hilly landscape outside of the St. Louis metropolitan area contains numerous small farms and has become a draw for rural residential development.

Karst groundwater is different from other types in that water moves more quickly from the surface and is easily contaminated by leaking sewage systems, fertilizers, livestock manure, road salt runoff, and garbage and trash discards in sinkholes.

“Water lines for drinking water are linked from towns to rural homes, but often there are no city sewer lines servicing rural homes, so private septic systems are installed for each property,” Kelly said. “State regulations require that septic tanks must be inspected at a minimum of every three years to prevent leakage, but that doesn't always happen because inspections are expensive.”

Most water samples were significantly contaminated by bacteria, particularly from humans, hogs, and cattle. Sewage systems also leak pharmaceuticals and other products. From analyses performed by Wei Zheng and Laurel Dodgen, environmental chemists at the Illinois Sustainable Technology Center, PRI, the two most common products found in streams and springs were triclocarbans, used in antibiotic soaps and found in 81 percent of samples, and the cardiovascular drug gemfibrozil, found in 57 percent of samples.

Contaminant levels were well below human dosages, but even low levels may affect aquatic organisms, according to Steve Taylor, conservation biologist in the Illinois Natural History Survey, PRI. Of concern are endangered species living in caves, such as the Indiana bat and the Illinois Cave amphipod.

Many questions related to groundwater contaminants are still unanswered, including the interaction among the different substances, the actual effects of the contaminants, and whether the contaminants have been a problem for decades since the technology to detect many of these compounds in low levels in the environment has only been available for about 10 years, Kelly said. 

“The largest concern is the effect of hormones,” Kelly said. “They don’t persist as long as other compounds found in groundwater, but they can cause a lot of damage to fish and possibly other animals.”

Previous recommendations for disposing of medications were to flush them down the drain or into the sewage system. New recommendations encourage taking unused drugs to collection facilities in communities. See www.unwantedmeds.org for proper disposal information and locations of take-back programs.

This study was funded by PRI and the National Great Rivers Research and Education Center. It was was reported in the journal Science of the Total Environment.