I'm going to have to disagree and go with the New England Journal of Medicine on this one: "DEET has a remarkablesafety profile after 40 years of use and nearly 8 billion humanapplications.35 Fewer than 50 cases of serious toxic effectshave been documented in the medical literature since 1960, andthree quarters of them resolved without sequelae.35,37 Manyof these cases of toxic effects involved long-term, heavy, frequent,or whole-body application of DEET. No correlation has been foundbetween the concentration of DEET used and the risk of toxiceffects." Basically, "when applied with common sense,DEET-based repellents can be expected to provide a safe as wellas a long-lasting repellent effect. Until a better repellentbecomes available, DEET-based repellents remain the gold standardof protection under circumstances in which it is crucial tobe protected against arthropod bites that might transmit disease." The study I talked about earlier can be read HERE. The safety of DEET is referenced in the final paragraph.