Exposure to N,N-diethyl-m-toluamide (DEET) in the U.S. Population: 2007-2014

Abstract

Introduction: N,N-diethyl-m-toluamide (DEET) is the most widely used insect repellent in the USA with more than 500 DEET-containing products registered with the EPA. DEET is effective against disease-carrying vectors such as ticks and mosquitoes associated with Lyme disease, malaria, encephalitis, Dengue fever, West Nile, Chikungunya and Zika viruses. We have collected data from four National Health and Nutrition Examination Survey (NHANES) cycles (2007-2014) for urinary concentrations of DEET and two of its metabolites 3-(diethylcarbamoyl)benzoic acid (DCBA) and N,N-diethyl-3-hydroxymethylbenzamide (DHMB). Methods: We measured urinary concentrations of DEET and two of its metabolites in 10,362 Americans 6 years and older from the 2007–2014 NHANES. We used multiple regression to examine associations between concentrations of DCBA, the most detected DEET biomarker, throughout the years, and age, sex, race/ethnicity, and season of year. Results: DCBA was the most frequently detected biomarker (86%) with concentrations ranging from 0.33–382,000 µg/L; by contrast, DHMB was only detected in 14% (concentration range: 0.06-11,400 µg/L). For all age groups, DCBA adjusted geometric mean concentrations varied upon season of the year, being higher in summer than in winter. DCBA concentrations decreased significantly from 2007-2008 to 2013-2014 for samples collected during the winter months with the largest decrease observed among people older than 60 years of age. Conclusions: Exposure to DEET was prevalent in the general U.S. population in 2007-2014. Higher concentrations of DCBA, a reliable biomarker of exposure to DEET, in the warm season agree with increasing use of DEET when people usually spend time outdoors for recreational activities; also pests are more abundant with higher seasonal temperatures, and DEET can provide additional protection against vector borne diseases in warmer weather.