This is not food colouring that you would actually use in baking, you can buy colourings from the flavour houses that make the actual flavour concentrates. I would not put it in a juice myself and I find it unnecessary. I'm under the impression that it's been out for a while and I think we would have heard if there were any adverse effects by now.
As @GSM500 said this is not your normal baking food colouring. If I remember correctly Flavour Art made colouring additives for vape juice a few years ago and from what I remember it was quite expensive. As a juice maker I wouldn’t use any colouring in juice at all and there is a lot of vapers that don’t find it very appealing. Another reason I won’t use it (my own opinion) because it will attract all the teenagers as it’s classified to be “cool” and this is the last thing we need in the vaping industry right now with all the current matters going on. Up until date there has been no reported issues with flavour houses colourings that i know of.
In the UK colouring in juice is a thing. The guys go crazy for different colour juices there and sell like crazy. I asked a big juice distributor in the UK why 90% of the juice over there has colouring in it and he told me that it helps them drive up sales as everyone there wants a juice thats pink or blue or what ever colour they make.
