The criteria "Persistence" and "Degradability" are defined and explained, starting from the "functional" definition of the environment. In this definition, the environment is the counterpart of the technosphere, which consists of all processes controlled by man. A substance is persistent if there are no sinks (degradation processes). It is shown that persistence is the central and most important criteria of environmental hazard assessment of organic chemicals. It follows that all substances released into the environment should be degradable, preferentially into small inorganic molecules (mineralization). As examples for persistent substances, the polychlorinated biphenyls (PCB), the chlorofluorhydrocarbons (CFC), bis (2-ethylhexyl) phthalate (DEHP, and 2,3,7,8-tetrachloro-dibenzo-dioxin (TCDD) are discussed. Finally, an attempt to quantify persistence is made. |
