Microplastic contamination found in common groundwater sources

Scientists are beginning to explore the presence of microplastic contamination in groundwater systems. A new study from the University of Illinois at Urbana-Champaign is the first to reveal the discovery of microplastics in fractured limestone aquifers, an underground freshwater source that supplies 25 percent of drinking water worldwide.

In two aquifer systems in Illinois, the team found microplastic fibers and a variety of medicines and household contaminants.

“Plastic in the environment breaks down into microscopic particles that can end up in the guts and gills of marine life, exposing the animals to chemicals in the plastic,” said study co-author John Scott, a researcher at the Illinois Sustainable Technology Center. “As the plastics break down, they act like sponges that soak up contaminants and microbes and can ultimately work their way into our food supply.”

According to Scott, groundwater flows through the cracks in the limestone, potentially transporting sewage and runoff from roads, landfills, and agricultural areas into the aquifers below.

The research team collected 17 groundwater samples from wells and springs, including 11 samples from a highly-fractured limestone aquifer near St. Louis and six from an aquifer that had much smaller fractures in northwestern Illinois.

Overall, 16 out of 17 samples contained microplastic particles. The highest concentration, which was 15.2 particles per liter, was collected from a spring in the St. Louis area. Scott said that it is hard to understand what this concentration implies because there are no published risk assessment studies or safety standards.

Study lead author Samuel V. Panno, a researcher at the Illinois State Geological Survey, said that the concentrations from the field area were comparable to surface water concentrations found in the rivers and streams of Chicago,

“The research on this topic is at a very early stage, so I am not convinced we have a frame of reference to state expectations or bounds on what is considered low or high levels,” said study co-author Professor Tim Hoellein of Loyola University. “Our questions are still basic – how much is there and where is it coming from?”

Scott explained that there is still a lot of work to be done, and he expects microplastic contamination will remain an issue for many years.

“Even if we quit plastics cold turkey today, we will still deal with this issue for years because plastic never really goes away,” said Scott. “It is estimated that 6.3 billion metric tons of plastic waste have been produced since the 1940s, and 79 percent of that is now in landfills or the natural environment. To me, it is such a weird concept that these materials are intended for single use, yet they are designed to last forever.”

The study is published in the journal Groundwater.

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By Chrissy Sexton, Earth.com Staff Writer