FWIW, I got the impression that the to-be-published paper has more detailed figures.
The startling conclusion of the paper is that in a worse case scenario--you break a CFL in a closed, unventilated room; you vacuum the carpet, throwing mercury into the air; you set the vacuum in a corner; and then sit in the room breathing for eight hours--the amount of mercury exposure is about equivalent to the exposure you'd get from eating a can of Albacore tuna.
Link to Original Source
Shawn Wilsher is working on making it asynchronous, so at least it won't stall everything else. He's got his preliminary work packaged as an addon. (Use at your own risk, obviously.)
Most (if not all) KDE libs are LGPL, while most KDE apps are GPL. This has been the case for quite a while, possibly since the beginning.