I have some methylene chloride. It is safe to use. I use it on occasion to ‘weld’ acrylic (Plexiglas). It welds by putting a thin film on each part into solution, then when the methylene chloride vaporizes the parts are ‘welded’ together - a very strong bond.
Methylene chloride, by the way is a liquid, as is benzene. Of course, both vaporize, and can be in a gaseous phase. The benzene, H2S and methylene chloride gases would disapate quickly and be at non-hazardous levels in a very short time.