Old Grump is correct - the lead does eventually leave the body, albeit slowly.
I shoot in a number of indoor pistol leagues and all of the ranges have inadequate ventilation. A number of years ago, I had my serum (blood) lead level tested and it came back at about 31 mcg/dl, well above the recommended maximum for adults of 10 mcg/dl. I started shooting with a half-face respirator - and also trying to be a bit better about hand-washing after shooting, although I was already doing that - and my lead came down to the high 'teens in about a year, then to 7.9 mcg/dl about a year after that. The respirators work and after a short adjustment period they're no more bothersome to wear than the standard eye and ear protection.
NRA Benefactor Life Member
Pemigewasset Valley Fish & Game Club