It's a very trivial amount of mercury VAPOR, not liquid mercury. It's not anything to worry about. The shattering glass is more of a concern. I use a MV bulb on some little chameleons, and it saved them from MBD. I kept it hanging from the ceiling, so it was about 2 fet away, and only gave their cages about half coverage.
there's a reason lizards have a pineal eye, and there's a reason they continually move in and out of sunlight.
It is NOT just UVB they are regulating. The amounts of UVA they recive/see can affect their behavior. I'm guessing that the amount of UVA these MV bulbs put out is the problem--in those pardalis females.
The net amount of UV--A&B does have an effect on them. I have seen much better color in "full spec." non-UVB bulbs lighted cages than in simple white light cages. They do nothing for D3 or calcium metabolism, but they affect behavior.
My guess is that the excess UV in the mv bulbs tricked their body into thinking it was the "off season".
In the wild, they can regulate themselves, in a small cage, with limited area, they need to be regulated, as there is not enough room for them to do it themselves.
My reccomendation: use one MV bulb for 2 cages, suspended a foot or two above the top, right between them. This way, they are not super-saturated with UV light no matter where they are in the cage. I think most people neglect this, and have their entire cage illuminated with UV light.
