Evaluation of the chronic toxicity and oncogenicity of N,N-diethyl-m- toluamide (DEET)

Chronic toxicity and/or oncogenicity studies were conducted in rats, mice,and dogs with the insect repellent DEET. DEET was mixed in the diet andadministered to CD rats for two years at concentrations that correspondedto dosage levels of 10, 30 or 100 mg/kg/day for males and 30, 100, or 400mg/kg/day for females; to CD-1 mice for 18 months at dosage levels of 250,500, or 1000 mg/kg/day; and to dogs for one year, via gelatin capsules, atdosage levels of 30, 100, or 400 mg/kg/day. In the rodent studies, eachgroup consisted of 60 animals of each sex, and two concurrent independentcontrol groups, each containing 60 animals/sex were included in each study.Each group in the dog study consisted of four male and four female dogs andone control group was included in the study. Treatment-related effects wereobserved at the highest dose level in all three studies. For rats, theeffects included decreases in body weight and food consumption and anincrease in serum cholesterol in females only. In mice, the effectsobserved were decreases in body weight and food consumption in both sexes.The effects observed in dogs included increased incidences of emesis andptyalism, and levels of transient reduction in hemoglobin and hematocrit,increased alkaline phosphatase (males only), decreased cholesterol, andincreased potassium. One male dog in the high-dose group also exhibitedataxia, tremors, abnormal head movements, and/or convulsions on severaloccasions during the study. The highest no- observed-effect levels (NO-ELs)for rats, mice and dogs were determined to be 100, 500, and 100 mg/kg/day,respectively. No specific target organ toxicity or oncogenicity wasobserved in any of the studies.