Being a machine shop that does occasional government contracts, we are required to do periodic testing for 'Contaminants'...
I take the test kits and do my reloading area, just to see.
They pretty much mirror what's already been said,
Tumblers/deburring machines in the shop & around my reloading show SIGNIFICANT signs of lead.
Honestly, dust control (used dryer sheet in the vibratory tumbler, taking the tumbling media outside and fanning the dust out of it once in a while) reduces dust to almost nothing...
Can't hurt & it's just good housekeeping.
Just a note, I did find out vibratory tumbler dust is highly flammable...
Using a torch to solder wires next to the tumbler lid (using it to catch solder drops) and the dust caught fire...
The problem with tumbler dust is it's EXACTLY the right size to penetrate deeply into the sinuses & lungs.
NOW, keep in mind, the PRIMER burns with the powder charge in place,
Then the powder burns,
That powder charge forces the primer residue against the inside of the case...
SO,
The primer residue is caught in the case...
One of the first things I do is attach a primer catcher & tube to deposit primers into the trash or closed container.
That potential problem is stopped cold,
And if you use a clear tube for primer catch, you will QUICKLY see how much residue builds up in that tube. (Trapped in the tube/trash, not your lungs & skin)
Mercurcy stopped showing up when I quit using OLD military surplus ammo.
Apparently, The old military primers had a LOT of mercury in them.
'Crorrosive' primers still have a lot of mercury in them.
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You know the first thing lead does is attack your mental capacity.
Makes me wonder about the guys that scoff about basic safety proceedures,
'Cyclops' arguing against safety glasses,
'Mad Hatter' arguing mercury isn't an issue,
'Dim Bulb' arguing lead isn't a problem...
I dunno, maybe they were born with an extra 30 IQ points to waste, extra lungs, kidneys & liver to waste...
My eyes are worth $30 for safety lenses in my glasses,
A primer catch is worth me not loosing 30 IQ points to lead, etc.