when my sister took her son for his yearly checkup, the lead test questionnaire specifically asked about hobbies related to glass. The physician asked her if my nephew was exposed to lampworking. So, I decided to check it out.
Gaffer (furnace frit) conducted a study to determine the level of lead emissions. In order to give worst case results the lead monitoring was carried out in the studio of local artist melting 2 x 25kgs of casting crystal at 870oC (1600oF) in a deliberately unventilated room. All doors and windows were shut. The results from this study showed that the lead levels were 5x below OSA guidelines and 3x below US OSHA guidelines.
Here's the link to the entire article, (just scroll down to find it) it's titled Casting Crystal Lead Emissions.
http://www.gafferglass.com/technical/casting.htm
If you're worried about exposure, you can also perform a lead-wipe test..I completed a lead wipe test in my studio (directly on the desk in front of my torch and then on the floor area right behind my torch) and the results came back way below the lead level standards.
I do use some Satake and I don't have any paperwork, but I understand it's low in lead. And not a health risk.
Goodluck!