Tea tree oil is poisonous if ingested.  There are cases in the literature
of accidental ingestion causing ataxia, confusion, stupor type symptoms--no
fatalities.  One case of a dog who became jittery and ill after external
use.  I would not put this stuff in any baby's mouth, especially as they
can't spit it out.  In my area, tea tree oil is becoming the next great
cure all for everything that ails you, and I expect we will see more
toxicity, as people continue to think that if it's "natural" it's harmless.

                                Paula Conning,BScN, IBCLC
                                Orangeville, Ontario