Relevance to Public Health
Chemical Technical Summary for Public Health
and Public Safety Professionals
Agency for Toxic Substances and Disease Registry
December 6, 2004
In 1980, as part of EPA's Registration Standard for DEET, over 30 additional animal studies were conducted to assess acute, chronic, and subchronic toxicity as well as mutagenicity, oncogenicity, and developmental, reproductive, and neurological toxicity. The results of these studies neither led to any product changes to comply with then-current EPA safety standards nor did they indicate any new toxicities under normal usage. The EPA's Reregistration Eligibility Decision (RED), released in 1998, confirmed that the agency believes "normal use of DEET does not present a health concern to the general U.S. population."
Fewer than 50 cases of significant toxicity from DEET exposure have been documented in the medical literature over the last 45 years; over 75% of these cases resolved without sequelae. Many of these cases had long-term, excessive, or inappropriate use of DEET repellents; but the details of exposure were frequently poorly documented, making causal relationships difficult to establish. These cases have not shown a correlation between concentration of the DEET product used and the risk of toxicity.
The reports of DEET toxicity that raise the greatest concern involve 14 cases of encephalopathy - 13 in children under the age of 8 years. Three of these children died; one had ornithine carbamoyl transferase deficiency, which might have predisposed her to DEET-induced toxicity. The other children recovered without sequelae. As noted previously, the available evidence does not confirm that children are especially susceptible to the toxic effects of DEET, and the etiology of adverse neurological outcomes associated with the DEET in children and adults has still not been determined. The EPA's analysis of these cases concluded that they "do not support a direct link between exposure to DEET and seizure incidence." Animal studies in rats and mice show that DEET is not a selective neurotoxin. Even if a link between DEET use and seizures does exist, the observed risk, based on DEET usage patterns, would be less than 1 per 100 million users (EPA 1999).
The CDC, the American Academy of Pediatrics, and the EPA have issued guidelines to ensure safe use of DEET-based repellents. Careful product choice (most often of a DEET concentration of 30% or less), judicious use, and common-sense application will greatly reduce the possibility of toxicity. When used as directed, products containing DEET are safe and appropriate for expectant mothers. Conservative use of low-concentration DEET products is most appropriate when applying repellents to children, and DEET should not be used on children younger than 2 months of age.