Bioavailability at heavy metal contaminated sites from conceptual model to remediation

Bioavailability concepts originates from the knowledge that adverse effects in exposed humans and ecological receptors are not caused by total concentration of chemical compounds released into the environment but only by a certain fraction that is biologically available. From the toxicological point of view, the concept of bioavailability implies that the danger represented by a substance is explained simply in terms of the fraction that can interact with a specific biological site. In the environmental studies the concept of bioavailability assumes very different meanings that range from the fraction of a substance available for absorption by a living organism, to the amount that can be released from the solid phase of an environmental matrix. Naturally the various aspects of bioavailability are interrelated and in order to understand the complexity of the issue as regards interactions between organism and environment, we tend to refer to processes of bioavailability. By this we mean a combination of reactions that identify not only the different aspects, but also the different temporal stages involving the processes that define bioavailability in a specific situation for a specific organism. Bioavailability is the key to understand the environmental behaviour of heavy metals, the hazards deriving from pollution and to define appropriate strategies of remediation. Clean up procedures,at heavy metal contaminated sites, are often very laborious and expensive. For a better use of the limited resources available for remediation the use of knowledge of bioavailability processes can be of noteworthy utility. Bioavailability may be a key component of exposure evaluation which has significant implications for the preparation of the conceptual model and the technology selection.