ABSTRACT
About 1.5 million tonnes of polychlorinated biphenyls were produced worldwide, and two-thirds were still present in the environment at the end of the twentieth century (UNEP report 1999). PCBs are not produced today, so their migration is a consequence of redistribution in the environment. Similarly, pesticides belonging to the group of chlorinated hydrocarbons have been withdrawn from the use in North America and Europe due to their high durability and toxicity (Kaleta et al. 2004), nevertheless their residues are still found in the environment. These examples prove the high persistence and resistance to biodegradation of endocrine disruptors. Some EDs undergo slow transformations as a consequence of different biological, chemical and physical factors, however in natural conditions these processes rarely decompose the compound completely to carbon dioxide and water. Usually these transformations lead to new intermediates, which may reveal different properties that sometimes can be more dangerous than the parent substance.
