not to worry.
Hi and thanks for the details.
I am sorry about the delay in answering.
If you have applied the mixture only to the hair then it is nothing to worry. It will not get absorbed from the hair.
But if you have applied it to the scalp
then there is a chance of absorption and subsequent appearance in the breast milk.
Currently there is no information available that tells us about the time for which you should abstain from breast feeding after application of kertain, but if you have applied it to the scalp then i guess 5 days should be enough.
If you have applied it only to the hair then you can breast feed continuously.
Now about your other question.
If you inhale formalin for 15 minutes twice a year then there is no problem. It will not cause any bad effect.
Dr Rajkishori Godhi.