Some species of frogs have the ability to change sex without the influence of a pesticide. This is useful to ensure a species survival. Perhaps the chemical is triggering a survival instinct that the frog already possesses?
I could see it being potentially hazardous. Apparently 10% of the exposed frogs turned female, while the other 90% had lower fertility levels. Procreation of the species could take a serious hit if enough frogs were exposed.