Chemicals spreading in state groundwater

In what may be the nations most extensive study of its kind, a survey of 118 test wells scattered around Minnesota has found that about a third of them contain measurable levels of antibiotics, detergents, or other consumer chemicals known as contaminants of emerging concern.

The chemicals, apparently coming from landfills, septic systems and sewage treatment systems, have been found in surface waters in recent years, and some scientists have looked at their effects on fish and other animals. But this new survey, published online this week by the U.S. Geological Survey, is the most extensive evidence yet that the chemicals are also making their way into both shallow and deep aquifers in Minnesota.

Groundwater is the source of drinking water for three-fourths of Minnesotans.

The study, conducted between late 2009 and mid-2012 by the USGS and the Minnesota Pollution Control Agency, found no chemicals in excess of drinking water quality standards.

But for four of the most common chemicals it found the antibiotic azithromycin, the antihistamine diphenhydramine, the flame-retardant tributyl phosphate and the animal antibiotic lincomycin neither the state nor the federal government maintains any health-based water quality standards.

The chemicals come from a variety of consumer and industrial products prescription and over-the-counter medicines, lotions, detergents, plastic-making ingredients and more.

Our use of these chemicals in our everyday lives is releasing them into our environment. Our question as a society is, What do we think about that?

Our use of these chemicals in our everyday lives is releasing them at low levels into our environment, said Mindy Erickson, groundwater specialist for the USGS. Our question as a society is, What do we think about that?

Erickson said the groundwater study, which will continue, was prompted several years ago by scientists finding the chemicals in rivers and lakes in Minnesota, sometimes bodies of water that were otherwise considered pristine.

The 118 wells tested are among those the MPCA monitors regularly, and they were chosen because of their assumed vulnerability to this kind of contamination, said Sharon Kroening, research scientist at the MPCA. Some were in the Twin Cities area, some near St. Cloud and others in north central, northwestern and southeast Minnesota.

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Chemicals spreading in state groundwater