If you can follow instructions, stick to them and dont get found by anyone for a few hours, chances of failure are slim to none. If you are found and treated, the likelihood of long term damage is also slim to none. Your body produces SN, you ingest SN, certain foods are high in SN, so its not like you are ingesting a completely alien substance.
Way too many scare stories surrounding this method. Its in the PPH for a good reason, it works if done correctly and inflicts little to no pain, or that is the evidence so far in reported cases and studies. The only way you survive is if you are found, otherwise, death is the most likely outcome.
I think today should be renamed SN day for all the damned threads that are popping up