Judging by the ingredients
Ingredients
natural flavors with water & propylene glycol
it seems safe but amazon is not the best at listing all ingredients. Preservitives and any additives are generally a No, No in DYI so some caution is advised. As to flavor I can't say but at this price you'll have plenty to experiment with.
To be completely safe I would advise shopping at any of the fine recommended venders you will find listed in many
threads in the DYI forum. A simple searh of this forum will find many posts on this subject.