Well you aren't supposed to eat it
Once alloyed with lead it should never reach a temperature where it is a problem either.
It goes without saying that you should always work in a well ventilated area and don't put unwashed hands in your mouth, up your nose etc.
There is plenty of info regarding the health issues on't interweb, do a bit of research first.
This is a good one with a wealth of info http://castboolits.gunloads.com/