H-3 in "EXIT" Signs

[Chris Hogan <chogan@colan.uams.edu>]

Can anyone tell me the form of H-3 used in these self-luminescent EXIT
signs.  I seem to remember someone saying (a long time ago) that the H-3
was in a "solid, non-dispersable form" so that it would pose no
contamination hazard if one of the signs were ever broken up.  But,
recently I thought someone on RADSAFE mentioned H-3 gas in connection
with the EXIT signs.  If it is H-3 gas, what reasoning is used to
justify general licensing for these devices (assuming that the signs
could be ruptured and the gas released).

Thanks,
Chris Hogan
chogan@colan.uams.edu
or 
cchogan@life.uams.edu