Biomonitoring Summary

N,N-Diethyl-meta-toluamide (DEET)

CAS No. 134-62-3

General Information

N,N-diethyl-meta-toluamide (DEET) is an insect repellent that was first marketed in 1957. DEET can be applied to clothing and skin to repel biting insects. Its use is recommended for prevention of several vector-borne diseases. There are over 225 insect repellents brands containing DEET ranging in concentration from 4% to 100%. DEET is also used in combination with dermal sun screens (U.S. EPA, 1998). DEET is not registered for use on agricultural commodities. One survey detected DEET in 74% of sampled streams in the U.S. (Kolpin et al., 2002).

General population exposure to DEET occurs from skin application and from inhalation of aerosol formulations. Exposure can also occur from consuming food contaminated by DEET on hands or that was sprayed nearby. About 3-8% of dermally applied DEET is absorbed, but higher DEET concentrations and different formulations may result in greater absorption (Sudakin and Trevathan, 2003). After absorption, DEET is metabolized via hydroxylation and dealkylation pathways and eliminated in the urine within approximately 24 hours (Selim et al., 1995; Sudakin and Trevathan, 2003). People in outdoor occupations may apply DEET more frequently or use higher concentration formulations resulting in higher levels of exposure.

Human health effects from DEET at low environmental doses or at biomonitored levels from low environmental exposures are unknown. DEET has low acute toxicity. Most reports of adverse effects from overexposure to DEET involve skin reactions (Bell et al., 2002). Neurological effects in humans, including seizures and encephalopathy, have been reported as result of self-poisoning by ingestion or excessive dermal application, (U.S. EPA, 1998). DEET is not a developmental or reproductive toxicant in animals (U.S. EPA, 2005). DEET is not genotoxic and has not been rated by IARC or NTP with respect to human carcinogenicity. Additional information is available from U.S. EPA at: https://www.epa.gov/pesticides/.

Biomonitoring Information

Urinary levels of DEET reflect recent exposure. Urinary levels of DEET were characterized only at the 90th and 95th percentiles of the U.S. representative subsamples from NHANES 2001–2002. In this survey period, the limit of detection was lower compared with the NHANES 1999–2000 survey period (CDC, 2005). DEET was detected in 10% of 60 Latino children in eastern North Carolina farm worker households (Arcury et al., 2007). Urinary DEET levels as high as 5,690 µg/L were measured in eight park employees who applied 71% DEET once a day (Smallwood et al., 1992).

Finding a measurable amount of DEET in urine does not imply that the level of DEET causes an adverse health effect. Biomonitoring studies on levels of DEET provide physicians and public health officials with reference values so that they can determine whether people have been exposed to higher levels of DEET than are found in the general population. Biomonitoring data can also help scientists plan and conduct research on exposure and health effects.

References

Arcury TA, Grzywacz JG, Barr DB, Tapia J, Chen H, Quandt SA. Pesticide urinary metabolite levels of children in eastern North Carolina farmworker households. Environ Health Perspect 2007;115(8):1254-60.

Bell JW, Veltri JC, Page BC. Human exposures to N,N-diethyl-m-toluamide insect repellents reported to the American Association of Poison Control Centers, 1993–1997. Int J Toxicol 2002;2:341-52.

Centers for Disease Control and Prevention (CDC). Third National Report on Human Exposure to Environmental Chemicals. Atlanta (GA). 2005. 4/9/09

Kolpin DW, Furlong ET, Meyer MT, Thurman EM, Zaugg SD, Barber LB, et al. Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999–2000: a national reconnaissance. Environ Sci Technol 2002;36(6):1202-11.

Selim S, Hartnagel RE Jr, Osimitz TG, Gabriel KL, Schoenig GP. Absorption, metabolism, and excretion of N,N-diethyl-m-toluamide following dermal application to human volunteers. Fundam Appl Toxicol 1995;25:95-100.

Smallwood AW, DeBord KE, Lowry LK. N,N'-diethyl-m-toluamide (m-DET): analysis of an insect repellent in human urine and serum by high-performance liquid chromatography. J Anal Toxicol 1992;16(1):10-3.

Sudakin DL, Trevathan WR. DEET: a review and update of safety and risk in the general population. J Toxicol Clin Toxicol 2003;41(6):831-9.

U.S. Environmental Protection Agency (U.S. EPA). Diethyltoluamide (DEET). Chemical Summary. U.S. EPA, Toxicity and Exposure Assessment in Children's Health. 2005. Available at URL: https://www.epa.gov/teach/chem_summ/DEET_summary.pdf. 4/9/09

U. S. Environmental Protection Agency (U.S. EPA). Reregistration Eligibility Decision (RED): DEET. U.S. EPA 738-R-98-010. Washington (DC): U.S. EPA; September 1998. pp. 1-118. Available at URL: https://www.epa.gov/oppsrrd1/REDs/0002red.pdf. 4/9/09