"DEET affects cells in a manner similar to nerve gas, and enhances the toxic effects of a common pesticide. The study was preliminary and was conducted on unprotected cells in petri dishes, so it may not be relevant for humans."
I don't care if DEET hasn't been proven to be toxic, I still get a little creeped out if I have to put it on my skin. Hopefully this new chemical proves to be broadly effective.