Comparison of Adults' and Children's Doses After Application of DEET-Containing Insect Repellent

ISEE-191 Objective: DEET (N,N-diethyl-m-toluamide) is the effective ingredient in most of the insect repellents, which are commonly used for prevention from insect bites. Although DEET has been confirmed to be safe for use on human skins, fewer data are available about use on children than on adults. This study was to compare doses that adults and children received after a one-time regular application of DEET-containing insect repellent by examining urinary metabolites, and to address the safe concern of using the DEET product on children. Material and Methods: We used a commercially available insect repellent on human subjects in the study. Approximately 10 mL of the repellent was applied on bare arms and legs of each adult or child subject. Urine samples were collected before application and within the first 8 hours. Samples were composited by ratios of volumes of urine at times during the 0- to 4- and 4- to 8-hour periods. High performance liquid chromatography (HPLC) with UV detection was used to analyze DEET and its metabolites in the urine. Results: Unchanged DEET and 2 metabolites, m-(diethylaminocarbonyl) benzoic acid (ring methyl oxidation) and N-ehtyl-m-toluamide (N-deethylation), were identified in all subjects' urine samples by HPLC. Up to date there are 14 child and 6 adult subjects having completed the test. The preliminary data show that m-(diethylaminocarbonyl)benzoic acid was the predominant metabolite with 66% and 41% on average in children's and adults' urine, respectively, suggesting that ring methyl oxidation be favored. The percentage of unchanged DEET was less in children's urine than in adults', indicating the faster metabolism of DEET in the children's bodies. The mean DEET equivalent amounts for 8 hours are 429 and 1354 ìg for adults and children, respectively. Conclusions: Children absorbed and metabolized more DEET than did adults. Despite low toxicity of DEET, such products should be cautiously used on children.