The GRas may not burn, but i hear it still can give off fumes if lit correctly. THe problem is that it is so potent that it pushes all of the oxygen from the room, suffocating you. Those GRaS coated cubans are whats left from the first batch, nobody knows how to get rid of them.
The first one lit is still putting off fumes in a sealed container of area 51. Thankfully we only lost a few NoObS when it was lit.