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4A - Integrated ecological and human health risk assessment (MOP/171) Impact 2002: a modular and integrated approach to assess comparative risks of toxics. Jolliet, Olivier1, Payet, Jerome1, Pennington, David1, Margni, Manuele1, 1 Ecole Polytechnique Federale de Lausanne, Life Cycle Systems, Inst. of environmental science & technology, EPFL-GECOS, CH-1015 Lausanne EPFL, CH, Switzerland ABSTRACT- MPACT 2002 (IMPact Assessment of Chemical Toxicants) has been developed to compare consistently the Risks and Life Cycle Impacts of Toxicants. It consists of a common fate model and of two effects modules for human health and on ecosystems. For fate, Intake fractions (fraction of pollutant released into the environment that results in human exposure at a population level) have been calculated for about 1000 substances, using as a first tier a steady-state uniform multi-media model for Europe. For ecosystems, residence times and concentration increase in soil & water are calculated. As a complement, a spatially differentiated version of the IMPACT 2002 fate model has been developed for Europe, merging multimedia modelling with air & water transport models, with 50 different watershed and air cells. It enables to address the spatial variation in exposure and the appropriate level of spatial resolution as a function of chemical properties and landscape characteristics. To characterize and compare human health impacts of metals and organic substances, a new approach has been developed for carcinogens and non-carcinogens, based on epidemiological data when available or on ED10h (best estimate of the effect dose inducing a 10% added risk for humans, adapted from the concept of benchmark dose for comparative assessment). calculated directly from bioassays available in IRIS. Extrapolation to low dose exposure is discussed in details: ED10h are correlated to the more widely available tumour dose TD50 (carcinogens) and NOAEL (non-carcinogens) to quantify the slope factor of more than 900 chemicals. A weighting is proposed to account for effect severity. For ecotoxicological effects , the AMI method (Assessment of Median Impacts) adapts the traditional risk concept, often based on most sensitive species, to a more discriminant and comparative assessment. It determines median chronic toxicity among species or extrapolate it from acute median for 500 chemicals. A non-parametric approach enables the calculation of characterisation factors based on the median response of species, with the associated uncertainty based on bootstrap method, avoiding the assumption of a simple parametric distributions. Main causes for variation between chemicals are discussed in more details for a few test substances. Key words: Human health, Comparative risk, Ecosystems, Spatial multimedia fate |
