Many years ago I went to a Jon Kosmoski (House of Kolor founder, and urethane paint pioneer) how-to seminar. He said that the real danger is in breathing "atomized" materials, as happens when you are spraying. He specificlly said that there isn't serious risk just breathing the vapors while mixing.
I use a remote air mask, and have been painting for over 45 years, an am doing okay so far.
I would recommend solvent proof gloves when mixing, since you can absorb the "bad stuff" through your skin, and your liver and kidneys have to deal with that.