The welding instructer said they have been using it with no problem. If you look, you'll find numerous sites on the web detailing using galvanized trash cans for smokers. I'll state that I have 1st hand knowledge of galvanized being used in smokers for a number of years with no ill effects.
If you actually research the temps required for galvanized to give off hazardous fumes, you'll fine they are double of better of any temp our smokers (and/or the charcoal in them) will reach.
Y'all are making a mountain out of a molehill, where the molehill isn't worth noticing.
OP--do your research and make a decision. If you're not comfortable with it, don't use it. If you are, use it. If anybody doesn't want to eat your food because you use it, more food for you. Win/win.
As for me, I'll do a couple more briskets this weekend and enjoy myself with friends and family.