ABSTRACT
Risk assessment for xenobiotics is currently the main regulatory decisionsupport process behind the measures to prevent, assess and manage environmental pollution. Risk assessment can be defi ned as a scientifi c procedure aimed at identifying the hazards correlated with pollutants and the risks related with their use/presence in the environment. It is possible to distinguish between a human health and an ecotoxicological risk assessment: in both cases the concern is related to toxic substances, but the focus is moved from human to ecological receptors. The US National Academy of Science already defi ned about 30 years ago a risk assessment “paradigm”, that is applicable for both human or ecological receptors, and it is made up of four components (NRC 1983): i) hazard identifi cation, ii) exposure assessment, iii) dose-response assessment and iv) risk characterization (Fig. 3.1). In the fi rst step, all available information about the toxicity (or ecotoxicity) of the chemical of concern are gathered; exposure is aimed at identifying the magnitude of the releases as well as the possible pathways and potential exposures for human and ecological receptors; dose-response assessments are divided in the evaluation of the observable data range and the extrapolation of ranges to toxicological (or ecotoxicological) endpoints; risk characterization fi nally integrates the information of the previous components in order to assess the potential or existing risk of an adverse effect (Newman and Unger 2003).
