By Peter Legris & Paul Mathewson, Ph.D.
Summary
Pesticides are widely used in Wisconsin to control weeds and pests that threaten crop yields, but their use comes with health, environmental, and ecological consequences. Once in the environment, pesticides can persist for years, spreading beyond their intended targets through runoff and drift. This can harm non-target organisms such as pollinators and can affect the health of humans well beyond the fields where the pesticides were originally applied. A recent study (Gerken et al. (2024) found that the effect of pesticide exposure on increased cancer risk was found to rival that of smoking. Available information indicates that pesticide contamination of drinking water in Wisconsin is somewhat common with about 40% of private wells and 25% of public water systems that serve cities and villages having pesticide detections. While pesticide concentrations are typically well below health-based standards, it should be noted that there are important limitations to the water quality standards. These standards are based on the pesticide in isolation and do not account for mixtures of pesticides or combinations of pesticides and other agricultural contaminants like nitrates. Such contaminant mixtures have been shown to have increased toxicity compared to a single contaminant in isolation.
Key takeaways:
- A quarter of public water systems and more than 40% of private wells in Wisconsin contain non-neonicotinoid pesticides.
- In Wisconsin, the counties with the most cancer cases attributed to pesticide usage were found in southeastern parts of the state.
- Certain populations such as children, agricultural workers, and migrant workers have a higher risk of exposure to pesticides making them more likely to experience negative health impacts.
- There are thousands of pesticides registered for use in Wisconsin, including 500 agricultural pesticides. Only 42 have a groundwater enforcement standard and 22 have a drinking water standard.
- Pesticide detections in Wisconsin public water systems are primarily concentrated in the south, central, and west central regions of the state. Additionally, there is a high concentration around urban areas such as Dane County. This geographic distribution aligns with agricultural usage patterns, corresponding with corn and soybean production areas.
