First off - HAPPY EASTER !!! A significant day for those of us that subscribe to the Christian persuasion.
OK - I checked into it .....
The four letter acronym I couldn't remember is TGIC - triglycidyl isocyanurate, a category 2 mutagen. Basically a powdered plastic that can protect anything it is sprayed on and baked to melt. Widely used to protect many things in our homes from tools to bike frames.
Some commercial powders have more or less of the compound. You have to ask, I guess.
Before you go off screaming, it is not any more hazardous than a lot of other compounds, sprays and chemicals we all probably use or have used regularly. I've got a dozen or so containers of Hoppes No. 9, Ballistol, LPS 3, WD40, brake cleaner, carb cleaner, spray oils, etc., etc. on my work bench at any given time.
You are advised not to handle coated bullets with bare hands or breathe any fumes emitting from the bake oven. If you spray the bullets, it must be done outdoors or in a well ventilated area as you would if spray painting.
I wear rubber gloves when handling the bullets and I've never detected any fumes coming from the oven.
I've been casting and sizing lead bullets for longer than I care to remember without wearing gloves or a respirator and I think I'm relatively 'normal' .....
But then, if I wasn't, how would I know ...
So, I think there is no need for undue concerns about powder coating IF proper precautions are observed ....
Which begs the question - why bother, since you still have to size coated bullets? Good question. One advantage is that you no longer need to use semi-solid lubes of any kind in your sizer and there are no smoky fumes when shooting indoors.
Users claim no barrel leading when driving coated lead bullets at faster than normal velocity, negating the use of gas checks. Of course, for the low velocities of CAS loads, none of this makes a compelling case for powder coating.
The idea of colour coated/colour coded bullets either appeals to you or not ....