`  ``Is (substance) Poisonous?``  Everything is actually Toxic, it all depends on the AMOUNT of substance. Even Water can kill if you drink 7 gallons at once. Mercury metal - you MIGHT get away with holding some in your hand (BUT I DON'T RECCOMEND THAT), BUT Dimethylmercury will kill you if you get even one drop on your skin - see Karen Wetterhahn ....Joeylawn`