Might as well make alcohol illegal, along with cough syrups, with that thinking. The benefits of alcohol are few and far between - stuff like flavinoids in red wine, or being an antiseptic in a pinch. Weed, anecdotally, serves to reduce pain without killing your liver. Helps people eat more to put on weight that having eating disorders. It outweighs the benefits of alcohol by a long shot. Also, I have a feeling if you wanted to pull up accidents with heavy machinery related to use of a mind-altering substance, alcohol would be far out in front compared to weed.

Why not put... stickers on the connector ends and around syringe injection points? The tubing stays clear to see the liquid/gas going through it, no change in chemical composition to satisfy the FDA, but it's still clearly marked: hey, green sticker, this is going into a vein so don't pump air into it. oh, this bad boy has a red sticker, better be an intrathecally administered drug because this is going into someone's spinal cord! If you wanted to up the ante, you could even use certain shapes on the stickers to also indicate their usage, for anybody that happens to be colorblind. The solution seems stupidly simple: better labeling. A lot of people seem to be stonewalling on the color of the tubing, though. There are other ways of labeling the tubing besides coloring the tubing itself.