The dangerous dose on a fully grown human, no matter how large or small, for most chemicals is a LOT higher than it is for an infant who's nervous system is still expanding, has maybe a cup of bone marrow, and has kidneys the size of my thumbs.

Odds are the stuff oxidizes pretty quickly. But if you read the warning on most insect repellents for humans, they say not get them IN you, say hands -> food -> belly. Heck, flea collars say "not for human use".
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-IronRaven

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.