Let's start with the evidence for neurological problems from DEET, which FitSugar was so afraid of. In the scientific literature—in all of scientific literature since 1957, when DEET first appeared on store shelves—researchers have reported 14 cases of kids who suffered encephalopathy, including seizures, after using DEET on their skin. All but one were kids under age 8. Three children died. The others recovered fully. In each of the cases, it was difficult to determine whether DEET caused the brain symptoms. Such data are just hard to come by; the kids could have been exposed to other things, but it could have been the DEET, too.