In other parts of my life, I've worked with chemicals that are active at sub-milligram doses. These take some extreme caution... I do not feel it necessary to wear hazmat gear when working with 10% nicotine... may just be me, but I feel that it is overkill.
I agree. While I don't blame anyone for taking precautions, it seems like many folks here think of 100mg liquid as if it were concentrated sulphuric acid. When I started vaping (again) about a year ago, I used 36mg e-liquid extensively, and that's breathing it in, all day long. 100mg nic is less than 3x that concentration.
For me, the important concerns involving 100mg liquid are to make sure that where it is stored (in the freezer in my case) there is no chance it could contaminate food, making sure that no kids can get access to it, and, when mixing, making sure it's not going to spill, and if it does, that it can be easily contained.
I add the nicotine last, and don't even open it until I'm ready. Easy for me, since I always want to taste-vape the mix without the nic. I have a metal baking pan that I put all my liquids in while mixing so if anything spills, it stays in the pan. (The other stuff, like PG and VG too, only because my wife would yell if I got stuff on the dining-room table). IMHO being organized while mixing liquids is the most important safety precaution (and I am normally a total slob).
There was a post here several months ago warning of the "Dangers of DIY" because his friend, when making liquid, accidentally swapped the proportions of nic to flavor/carrier base, and the result made him ill rather quickly. Yup, it'll do that. The danger, however, came not from the nic, but from the fact that the DIY'er was not organized or focused on what he was doing.
APPROPRIATE safety measures are what's important. If your face shield fogs up, and you accidentally knock the bottle of concentrated nic into your lap (or onto your dog) because you can't see properly, have you come out ahead?