The stain in the FlashGel™ Cassette is present at such low levels that it is not considered hazardous according to OSHA and EU hazard criteria.
A copy of the MSDS is available online.
However, as the stain in the cassette is a potential mutagen, wear gloves, safety glasses and a lab coat when handling.
Use the same precautions when handling and disposing of the cassettes as you would for ethidium bromide stained gels.