No one really knows the effects of vaporized freebase on lung tissue in the long run, short term it seems to absorb just fine and even feels like it opens up the bronchial pathways a bit sometimes.
Oral DMT like ayahuasca seems like it can only be a positive thing, except maybe excessive vomiting- but there are people who drink it daily.
Just find balance and don't worry would be my suggestion. Worries and stress will probably kill you faster than DMT.