Pesticides have been found in high concentrations in ground and surface water sources in Minnesota, not only posing a risk to local wildlife but possibly also contaminating drinking water for many of the state’s residents.

In a new study, published in the journal Science of the Total Environment, Arnold and colleagues from the University of Minnesota Twin Cities in collaboration with the Minnesota Department of Natural Resources collected water samples from 15 natural springs and 75 unique wells across 13 Minnesota counties between 2019 and 2022. Samples were included from both urban and rural areas as well as water sources at various depths.

What they found was that water in natural springs were particularly susceptible to contamination with these insecticides.

Over 450,000 tons of pesticides are used in the U.S. every year, according to data from the Food and Agriculture Organization of the United Nations. Not only can these chemicals seep into surrounding ecosystems and affect plants and animals, but they may also harm human health.

The health impacts of these chemicals depend on the types of pesticide used, but several common agricultural chemicals have been associated with developmental and hormonal disruptions, as well as neurotoxic effects. Other studies have suggested that exposure to these chemicals may be as bad as smoking when it comes to increasing our risk of certain types of cancers. However, it is unclear how much exposure is required to see these effects.

Insecticides are a class of pesticide that target insects in both agriculture and urban pest control. Due to their widespread nature, these chemicals not only end up as residues on our food, but can also get swept away into surrounding lakes, rivers, and groundwater systems.

“We use so many of these chemicals in Minnesota. Basically, every corn and soybean seed is treated before planting,” Bill Arnold, a professor in the University of Minnesota’s Department of Civil, Environmental, and Geo- Engineering, said in a statement. “Many of these chemicals can be purchased at a local hardware store that can be used for spraying fruit trees, flea and tick control for your pets, and eliminating bedbugs.”

“We were surprised by the high levels of the chemical detected in the natural springs and in some cases the chemicals were observed at much deeper levels in wells than we expected going into this project,” Arnold said.

“Oftentimes people think a natural spring has water that is safe to drink. That’s not necessarily true, it depends on how deep that water is sourced.”

In light of these findings, the research team is working with county and state agencies to include insecticides in water treatment monitoring lists and to improve the treatment of stormwater in urban environments to facilitate the removal of the chemical pollutants.

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References

Gerken, J., Vincent, G. T., Zapata, D., Barron, I. G., & Zapata, I. (2024). Comprehensive assessment of pesticide use patterns and increased cancer risk. Frontiers in Cancer Control and Society, 2. https://doi.org/10.3389/fcacs.2024.1368086

Goedjen, G. J., Capel, P. D., Barry, J. D., & Arnold, W. A. (2024). Occurrence and distribution of neonicotinoids and fiproles within groundwater in Minnesota: Effects of lithology, land use and geography. The Science of the Total Environment, 176411. https://doi.org/10.1016/j.scitotenv.2024.176411