Chemical Technical Summary for Public Health
and Public Safety Professionals
Agency for Toxic Substances and Disease Registry
December 6, 2004
This summary is designed for use by professionals and assumes basic knowledge of the topics covered. As with any summary, details are left out that may be significant in an individual exposure situation. No observed effects should be ruled out or in based solely on the information presented in this document.
N,N-Diethyl-meta-toluamide is the most widely used insect repellent in the world. It was registered for use by the general public in 1957 and is commonly used to repel mosquitoes and other biting insects as a preventative measure against vector-borne diseases. Its repellency has been demonstrated in many species of insects, especially mosquitoes. DEET is also widely used, with approximately 30% of the U.S. population using DEET each year. DEET is available in a variety of forms including liquids, lotions, sprays, and impregnated materials. Formulations registered for direct application to human skin contain between 4 and 100% DEET. Approximately 230 products containing DEET are currently registered with the U.S. Environmental Protection Agency (EPA). DEET can be absorbed via inhalation, ingestion, or dermal contact. DEET is not readily absorbed dermally, with approximately 5-17% of the applied dose being absorbed in humans. The major route of excretion of DEET in humans following dermal and oral exposures is via the urine. The major metabolites of DEET are four carboxylic acid derivatives. The most common toxicological symptom of DEET exposure is dermatitis. In rare occasions, more serious symptoms include encephalopathy, seizures, and severe skin irritation.
When used according to the recommended usage guidelines, there is a very low probability of toxicity in healthy adults. When DEET is used on children, the guidelines for use must be carefully followed - it should not be used in children under 2 months of age. DEET has been included as one of the chemicals of concern regarding unexplained illnesses among Gulf War veterans, but its exact role in neurological or other symptoms that have arisen in Gulf War veterans is unknown. More studies must be conducted to establish a definite relationship between the observed health effects and DEET use.