Demonstration of the new modelling tool "MERLIN-Expo" : a case-study on environmental and human exposure to POPs in Venice lagoon
Résumé
Risk managers and decision makers are in need of tools that inform environmental and human exposures in different spatial and temporal dimensions. We demonstrate a new modelling tool for the integrated assessment of exposure to chemicals, called MERLIN-Expo, which is currently being refined and validated within the FP7 project "4FUN". This tool provides a library of exposure models which can be flexibly combined to explore complex scenarios, coupling on the same platform multimedia and physiologically-based pharmacokinetic (PBPK) models for estimating human intake and internal exposure. The models can be used to dynamically simulate fate and exposure for all organic (e.g., PAHs, PCBs, pesticides) and inorganic contaminants. There is no limitation for temporal scale, and the combination of different model boxes allow to cover different spatial scales. Moreover, MERLIN-Expo incorporates advanced functionalities for uncertainty and sensitivity analysis. MERLIN-Expo is demonstrated on a case study in the Lagoon of Venice, aimed at estimating environmental and human exposure to different congeners of PCBs. Specifically, the modelling framework combines bioaccumulation modelling in aquatic species, human intake modelling through the diet, together with PBPK modelling of internal exposure. Past PCB concentration trends reconstructed from dated sediment cores are used as inputs to model the time-dependent bioaccumulation in selected aquatic organisms. Then lifetime dietary intakes from contaminated fish and seafood, as well as other food items collected from literature data, are used to estimate PCB internal exposure for local population. Modelling results are compared to available monitoring data on chemical concentrations in edible aquatic species and concentrations in serum of adult men in Venice area to assess the reliability and applicability of the proposed tool to real complex scenarios. Different outcomes of MERLIN-Expo can be used for regulatory purposes. For example, chemical concentrations in environmental media and biota can be compared with Environmental Quality Standards, human daily intake can be compared with given regulatory threshold for human health (e.g. Reference Dose) and internal exposure estimates can be evaluated against Biomonitoring Equivalents or other thresholds defined by risk assessors. This makes the tool interesting and promising for potential applications in different regulatory domains.