|
(52-29) Uncertainty in environmental quality standards. Ragas, Ad*,1, Leuven, Rob1, Nienhuis, Piet1, van Leeuwen, Kees2, van de Meent, Dik2, 1 Departement of Environmental Studies, Nijmegen, The Netherlands2 National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands ABSTRACT- Environmental quality standards (EQSs) for toxic substances are set in order to protect human health and ecosystems. Regulatory agencies use a variety of models to derive environmental quality standards and corresponding emission limits. These models typically have much uncertainty. The aim of this presentation is to give an overview of the uncertainties involved in deriving and applying EQSs. A limited number of models were selected for an in-depth study of the uncertainties involved, i.e.: (1) a model used to derive a virtually safe dose (VSD; the dose that corresponds with an extra lifetime tumour risk of 1×10-6) for humans from laboratory animal data for genotoxic carcinogens; (2) an exposure model used to predict the lifetime average human exposure through multiple contaminated media (soil, water, air, drinking water and food products); (3) a multimedia fate model used to assess the coexistence of EQSs between multiple media (i.e., soil, air and water); and (4) a water quality model used to derive emission limits from EQSs. The uncertainty estimates of these in-depth studies were completed with literature data to produce an overall estimate of the uncertainties involved in deriving and applying EQSs. The results show that the uncertainties in the derivation of EQSs are considerably larger than in the application. It is furthermore shown that the largest reduction in uncertainty in EQSs can be obtained by gathering additional information on (1) the shape of the dose-response relationship for genotoxic carcinogens, especially in the low-dose region; (2) model structure and formulations of multimedia fate models; (3) interspecies differences in sensitivity; (4) dose-response data for laboratory animals, and (5) substance-specific data like Henry's law constant, degradation rates and absorption factors. Key words: standards, uncertainty |
