I have cast lead bullets and owned my own fishing jig business many years ago. Back in 1999 I contracted a lung disease from automotive finish. Got over that after a few years with no major problems, just stay away from automotive finishes after that. I didn't do any casting for many years as I raised two kids and moved several times for school administration jobs. Several years ago I got bored from not using my hands got back into reloading and casting as well. I am in the process of being diagnosed with yet another lung disease that can come from a variety of things with popcorn salt one of the main culprits (not me in this case) or just a virus that sometimes shows up, bronciolitis. I haven't done anything with lead for probably a couple of years as I have plenty of cast bullets stored up and ready to go. Hesitant to get back into it based on what might be released. I do use lots of ventilation and a mask when I smelt and plenty of ventilation when I cast.
I have tried to read about what actually comes off of lead when it is being melted and I don't seem to be able to find much. Are there any experts out there (that is a rhetorical question for this site by the way). It would seem that if there is something that got to me it could get to others and I realize I just may have a natural weakness there. BTW, the disease is irreversible and rare and there not many if any know drugs that are effective. One of those I will likely die with and not from. No complains. Take care and be safe.
Edit: Let me also say that I practice safe habits when handling lead. Use gloves, lots of ventilation or outside when smelting that nasty range stuff, don't eat until hands are thoroughly washed. I must admit I may occasionally have a drink nearby but I am careful where my hands go. No smoking or alcohol for me.