I would say that as long as SOME of the juice vendors have been in business, if there were gonna be issues they would have reared their ugly little heads by now. I agree with Lev in asking "what makes a lab a lab" most of the manufacturers including the ones that tout a lab made juice don't have anywhere near what a REAL lab should be. And any schmoe out there can get a few pieces of equipment and use a room they call a lab. That does not in ANY way, shape, or form mean they are scientists or qualified to work in a true medical or pharmaceutical environ. I am a certified lab tech, not even that would qualify me to do anything other than turn a machine on and follow a scientists instructions.
I believe that all of the vendors I buy from are clean. They are established, and well documented in the community and no business stays alive with bad press, and medical issues from their product (barring the drug trade). I am sure that if you ask questions of the vendors themselves, they would be more than happy to tell you the conditions of the station used to manufacture a juice. As well most have no real issue telling you their ingredient list, most that I have dealt with have been VERY transparent, a thing I DO NOT get from our Chinese counterparts. Personally I am not going to put anything in my lungs that I cannot pronounce, and most if not all of the US makers seem to avoid the crap outa those for the same reason. Remember most of the best makers were vapers BEFORE they made juice for others. If you are curious ask them. If they refuse to tell you anything, don't buy it. If they are transparent and tell you all that they can ( again barring giving you the recipe ) you can be pretty sure they take making juice seriously and handle it professionally.
Just my 2 cents.
