I wouldn't want to make a regular practice of breathing lead fumes. This has to be a carcinogen.
Not a problem if you keep your temps to under 1200F.
I cast quite a bit for competition in the North South Skirmish Association and test neg for lead. For comparison, a friend of mine who works at a gunshop with indoor range had to take a 6mo layoff due to lead levels in his blood and he DOESN'T cast. Problem comes from ventilation at indoor range and lead levels in primer compounds and from bullets striking backstop.
Who all here makes their own,and what are your recipes?
Myself,I always hit up roofers when their around tearing off old roofs.
They always give me the old lead skirting that goes around vent pipes.
Couple of those, cleaned up and with mixed with two handfuls of wheel weights,nets me about 300-500 balls for the .50.
The rest gets turned into river sinkers for when chasing blues and flatheads.
For black powder, you generally want as pure a lead as possible. You can add tin or antimony to taste. My source is a local scrap yard that sells to the public. They often have Xray room lead from medical facilities and that's pretty close to pure.