▶ UnobtainableToxic Waste is a pain block, found after smashing a Toxic Waste Barrel or from a Toxic Waste special event. Touching Toxic Waste causes the player to become injured, just like the Cactus. The block is also public, meaning that any player can break it, regardless of locks. The item is not obtainable in the backpack, it drops neither the item itself or a seed.
On the 20th of August 2015, developer @Seth accidentally handed out the Toxic Waste block itself to the public during the seventh day of the Player Appreciation Week (Super Mod Dance Party), resulting in it becoming a rare item.