Contaminants of Emerging Concern
A Citizen's Guide to DEET

June 2011

What is DEET?

DEET is a chemical that is frequently added to insect repellents. It is very effective at repelling mosquitoes and ticks.

Can DEET found in Minnesota drinking water affect my health?

The amount of DEET found in Minnesota drinking water poses little or no health risk. So far, concentrations found are about 3,000 times less than the MDH guidance value of 200 parts per billion (ppb) or micrograms per liter (µg/L).

What are the concentrations of DEET in Minnesota drinking water?

The United States Geological Survey (USGS) found DEET in Minnesota drinking water, groundwater, wastewater and surface water (from 2000-2002).1 DEET was found in 23.9 percent of all water samples in this study. However, it was found at only one of six drinking water sites. The concentration of DEET at this site was about 0.061 ppb.

The USGS, Minnesota Pollution Control Agency (MPCA), and St. Cloud State University measured DEET concentrations in the Mississippi River (in 2006).2 The highest concentration found in water that might be used for drinking was 0.224 ppb in Northern Minnesota. This is about 900 times less than the MDH guidance value.

How am I exposed to DEET?

DEET exposure is mostly from using insect repellants that contain DEET, not from drinking water.

How can products containing DEET be used safely?

Following the use directions on the label can protect against illnesses while avoiding unnecessary exposure and releases to the environment. DEET is important in reducing the risk of illnesses spread by mosquitoes (e.g. West Nile virus) and ticks (e.g. Lyme disease).3 MDH promotes using insect repellents containing less than 30 percent DEET. The US Environmental Protection Agency (EPA) concluded in the DEET Reregistration Eligibility Decision4 that:

  • Using DEET does not present a health concern to the general US population, and
  • Following the use directions on the label is the best way to use products containing DEET safely.

The American Academy of Pediatrics 5 has a number of recommendations about safely using products containing DEET:

  • DEET should not be used on children under two months old.
  • Using products containing 10-30 percent DEET on infants and children older than two months appears to be safe.
  • Products containing 10 percent DEET appear to be as effective as products containing 30 percent DEET when used according to label directions.
  • Products with 30 percent DEET offer about five hours of protection while products with 10 percent DEET offers about two hours of protection.
  • DEET should not be used in products that combine DEET with sunscreen.

How does DEET get into the environment?

DEET-based insect repellents are applied to skin and/or on clothing. DEET is washed into drains and becomes mixed with wastewater when people bathe or wash clothes. Septic systems and wastewater treatment do not remove all of the DEET.

Who developed DEET?
The US Army developed DEET in 1946 following its experiences with jungle warfare during World War II.

Therefore, some DEET remains in wastewater. Wastewater contaminants, such as DEET, can move into sources of water that may be used for drinking. DEET can also get into lakes and rivers when people who have used insect repellents with DEET go into these waters.

How long does DEET stay in the environment?

Once DEET is in the environment it tends to stay in the environment. While some DEET may attach to soil, or other solids in water, most DEET will remain in water. DEET is not likely to build up in fish or other animals in the food chain.6,7 This means DEET will not get into your body from eating fish.

What are the potential environmental impacts DEET?

DEET is slightly toxic to birds, fish and aquatic invertebrates but is not expected to harm these animals in the environment.4 DEET is mainly applied to human skin and clothing, cats, dogs, pet living areas, and household/domestic areas. Using DEET in these ways is not expected to cause harmful effects to wildlife.

What is the MDH guidance value for DEET in water?

Based on available information, MDH developed a guidance value of 200 ppb for DEET in water. MDH finalized this guidance in 2011. MDH determined that DEET affects how an animal grows and develops. If you drink water containing up to 200 ppb DEET for up to a lifetime there is little to no health risk, even to a developing child.

How can I reduce my exposure and my environmental impact?

Use insect repellents containing the least amount of DEET needed for the desired level of protection.

How do I learn more?

Bookmark the MDH CEC webpage and sign up for announcements.

  • Visit the Centers for Disease Control and Prevention (CDC)
       DEET General Fact Sheet. 9
  • Follow MDH activities on

  • References

    1. U.S Geological Survey (USGS). Presence and Distribution of Organic Wastewater Compounds in Wastewater, Surface, Ground, and Drinking Waters, Minnesota, 2000-02. Scientific Investigation Report 2004-5138.
    2. Lee, K. E., C. S. Yaeger, N. D. Jahns, and H. L. Schoenfuss. 2008. Occurrence of endocrine active compounds and biological responses in the Mississippi River-study design and data, June through August 2006 Data Series 368. U.S. Geological Survey.
    3. Minnesota Department of Health,
    4. U.S. Environmental Protection Agency (USEPA). Pesticide Reregistration Eligibility Decisions (REDS) Database on DEET (134-62-3). USEPA-738/R-98-010. Cited in Hazardous Substances Databank.
    5. American Academy of Pediatrics,
    6. Hazardous Substances Databank, SRC, April 2011.
    7. Franke C et al, 1994. Chemosphere 29: 1501-14.
    8. Agency for Toxic Substances and Disease Registry:
    9. CDC:

    Updated Wednesday, October 05, 2011 at 07:47AM