Some wastes are effectively immortal; their toxic qualities are intrinsic to their elemental structure. The heavy metals are in this category, and, in a different sense, so is asbestos, whose toxicity is a function of its physical structure, which, for practical purposes, is indestructible. Some radioactive wastes, particularly uranium and plutonium, retain their radioactive properties for so long that we should also view them as immortal.
A second group of wastes is semi-mortal. Destruction or degradation occurs in the environment, but very slowly. Chlorinated hydrocarbons, especially complex ones, are semi-mortal in natural environments, but can be destroyed in high-temperature incinerators.
A third group of toxics is very short-lived or mortal, including acids and bases and other strongly reactive materials like cyanides, which are rapidly destroyed or neutralized in the environment.
