Contaminants of Emerging Concern

October 2011

cropduster illustrationWe rely on our nation’s farms to produce the food we eat. And most farmers rely on pesticides to prevent damage to their crops. While pesticides are useful tools, they also carry the potential for environmental harm. When a pesticide starts to see expanded use, there may be good reasons to investigate potential impacts on the environment. Such is the case with the fungicide pyraclostrobin. Between 2003 and 2008, pyraclostrobin sales in Minnesota increased steadily. This likely happened because of its effectiveness as a control for fungal diseases, and possibly because of its use to promote plant growth. It has been marketed to promote plant growth even when there is little likelihood of fungal disease. In 2009, very little was known about pyraclostrobin in Minnesota waters. Since that time, MDH and the Minnesota Department of Agriculture (MDA) have searched for pyraclostrobin in Minnesota waters. MDA tested for pyraclostrobin in surface water and groundwater. MDH and MDA jointly studied community water supply systems for pyraclostrobin and other pesticides. No pyraclostrobin was detected in any of these studies. MDH also assessed the potential health effects of exposure to pyraclostrobin in drinking water. MDH developed drinking water guidance values for pyraclostrobin in 2011. The lowest MDH guidance value for pyraclostrobin is 100 parts per billion (ppb or micrograms per liter) in drinking water. Pyraclostrobin has not been found in drinking water in Minnesota. Therefore, pyraclostrobin in drinking water is not expected to harm Minnesotans.


  • Pyraclostrobin is a pesticide that is used to prevent the growth of damaging fungi on food crops, turf, and ornamental plants. In recent years, it has also been used by some to promote plant growth.
  • So far, pyraclostrobin has not been found in drinking water, groundwater or surface water in Minnesota. Several hundred samples have been tested for pyraclostrobin. The laboratory method used for these studies can measure pyraclostrobin at 0.23 ppb, far lower than the MDH guidance value.
  • In a nationwide study, pyraclostrobin was found in surface water at only two of 31 sites. Both of these sites were outside of Minnesota.
  • Pyraclostrobin is not expected to move easily in the soil. However, there is some concern that it can reach surface water, especially when it is sprayed or aerially applied. Pyraclostrobin can also be carried to surface water in stormwater runoff.
  • Pyraclostrobin breaks down fairly quickly in the soil. It also breaks down in surface water through the action of sunlight.
  • Exposure can occur from eating fruits or vegetables that contain residues of pyraclostrobin.
  • To reduce your exposure to any pesticide, rinse your fresh produce before eating it. Buying produce from sources that do not use pesticides may also reduce your exposure. If you use pyraclostrobin, read product labels carefully, and follow application instructions and product use restrictions. The label is the law.

A Citizen's Guide is currently under development for pyraclostrobin.

Check this page for updates. 

Do you need more details about the health-based guidance? 

See Pyraclostrobin Toxicity Summary information used by MDH (PDF: 96KB/9 pages) for toxicity values used to develop health-based guidance.

Do you need more technical information about toxicity and exposure?

"An Environmental and Health Professional's Technical Guide to Pyraclostrobin" will be posted here and announced to our email subscriber list when available. Subscribe to our email notification service by selecting "Groundwater Rules, Guidance and Chemical Reviews."


Updated Tuesday, October 04, 2011 at 10:36AM