Why It Matters
Bug repellents are pesticides and are made of both active and inert ingredients. It’s common for products to list only active ingredients on labels. The rest are listed simply as “inert ingredients,” which are ingredients that are not considered active repelling chemicals, but are used as solvents, preservatives, fragrances, or for other purposes. Bug repellents are often formulated with synergistic chemicals that are designed to make the repellent work more effectively.
One example of an active ingredient in bug repellent is DEET. Although DEET is one of the most effective repellents, it is a documented neurotoxin and has other adverse effects on humans and aquatic life – not to mention, the inert ingredients in bug repellents can also be hazardous.
What Is It?
DEET, formally known as N,N-diethyl-meta-toluamide, is one of the most effective bug repellents and also repels ticks.[8] Insect repellents are regulated as pesticides in the United States because their active ingredients are pesticides, including DEET.[9] The Environmental Protection Agency (EPA) reviews substances for their human and environmental harm prior to allowing them to be used as pesticides. However, DEET and other pesticides are still allowed by the EPA, even with evidence of toxicity to humans and the environment.
Where It's Found
DEET is used in bug sprays, wipes, clothing repellents, and in repellents for pets.
The Health Concern
DEET is absorbed quickly through the skin,[4] and when mixed with some sunscreen chemicals, it was found to be absorbed even more quickly.[5] Large doses of DEET have been linked to skin blisters, seizures, memory loss, headaches, stiffness in joints, shortness of breath,[2] and skin irritation.[4] DEET is a documented neurotoxin, meaning it can negatively impact the nervous system.[4] [6] When mixed with permethrin, another pesticide, animal studies show the mixture can cause the death of neurons in the brain[1] and disease in the offspring of exposed adults.[10]
In the environment, DEET breaks down slowly in soil and extremely slowly in sediment, meaning it sticks around longer than it should.[7] DEET has been detected in groundwater, surface water, and drinking water.[3] DEET is somewhat toxic to some aquatic life.[7]
How to Avoid It
- Read labels. Look for DEET listed under “active ingredients” on bug repellent product labels.
- Look for plant-based alternatives with bug-repelling oils like citronella, clove, lemongrass, lemon eucalyptus, thyme, and neem. Make sure to buy commercially prepared products or consult an essential oils specialist to ensure that all essential oils are properly diluted. Some people are sensitive to essential oils, so do a small patch test and consult an expert.
- Skip products containing both sunscreen and bug spray with DEET, as the mixture may increase your skin’s absorption of the chemicals.
- Reduce your exposure to mosquitos by staying indoors when mosquitos are the worst (at dawn and dusk), covering up with thick fabrics and long plants and sleeves, and using mosquito netting.
- Be aware that in addition to DEET, there are other harmful ingredients in bug repellents. Read more in our full-length report on bug spray.
- Shop MADE SAFE Certified products. Pyrethroids are not permitted in our Ecosystem Approach.
Notes
*A note about essential oils and DIY bug repellents: Some botanicals can be irritating, so try a small patch test before use and avoid any known allergens. Always make sure to dilute essential oils properly and follow manufacturer guidelines. If you intend to use essential oils on your pets, make sure to consult your vet.
A note on Zika and other mosquito-borne illnesses: Knowing your area and if you are at risk for mosquito-borne or tick-borne illness can help you make the right bug repellent choice for you and your family. If you think you are at risk, heed the advice of the CDC, WHO, and your doctor.
*MADE SAFE does not test for efficacy. We examine ingredients for human health and environmental harm. For efficacy studies on plant-based repellents, see our full-length bug spray report.
References
[1] Abdel-Rahman, A., Shetty, A. K., & Abou-Donia, M. B. (2001). Subchronic dermal application of N,N-diethyl m-toluamide (DEET) and permethrin to adult rats, alone or in combination, causes diffuse neuronal cell death and cytoskeletal abnormalities in the cerebral cortex and the hippocampus, and purkinje neuron loss in the cerebellum. Experimental Neurology, 172(1), 153-171.
[2] Abou-Donia, M. B., Wilmarth, K. R., Jensen, K. F., Oehme, F. W., & Kurt, T. L. (1996). Neurotoxicity resulting from coexposure to pyridostigmine bromide, DEET, and permethrin: Implications of gulf war chemical exposures. Journal of Toxicology and Environmental Health, 48(1), 35-56.
[3] Agency for Toxic Substances and Disease Registry, (ATSDR). (2017). Toxicological Profile for DEET (N,N-diethyl-meta-toluamide). U.S. Department of Health and Human Services.
[4] Beyond Pesticides & National Coalition Against the Misuse of Pesticides. (2002). DEET. 22(2).
[5] Chen, T., Burczynski, F. J., Miller, D. W., & Gu, X. (2010). Percutaneous permeation comparison of repellents picaridin and DEET in concurrent use with sunscreen oxybenzone from commercially available preparations. Die Pharmazie, 65(11), 835.
[6] Corbel, V., Stankiewicz, M., Pennetier, C., Fournier, D., Stojan, J., Girard, E., . . . Lapie, B. (2009). Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent DEET. BMC Biology, 7(1), 47.
[7] Environmental Protection Agency, EPA. (2012). Estimation Programs Interface SuiteTM for Microsoft® Windows, v 4.11.
[8] Environmental Protection Agency, EPA. (1998). R.E.D Facts: DEET.
[9] Environmental Protection Agency, EPA (2017). What is an insect repellent?
[10] Manikkam, M., Tracey, R., Guerrero-Bosagna, C., & Skinner, M. K. (2012). Pesticide and insect repellent mixture (permethrin and DEET) induces epigenetic transgenerational inheritance of disease and sperm epimutations. Reproductive Toxicology (Elmsford, N.Y.), 34(4), 708-719.
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