The link between anthropogenic emissions and the monetary value of their impacts, so-called external cost, can be determined via the impact pathway approach. This method is used in the present study to calculate the indirect costs, via topsoil ingestion, of lead emitted into atmosphere from a waste-to-energy facility in Denmark.
The Operational Meteorological air-quality model, the Simplified Fate and Speciation Model, and the Age Dependent Biokinetic Model are used to determine the metals’ atmospheric transport, its deposition and accumulation in topsoil, and its bio-accumulation in the human body respectively. The use of such lead-specific models allows for a detailed quantification of the lead impact pathway. External costs are calculated by linking lead exposure to neurotoxic impacts in children and to the consequent reduced lifetime earnings. Results indicate that indirect costs are of the same magnitude as direct costs previously investigated, both in the case of actual emission rates and in the case of future emission scenarios for lead. Among the various modelling parameters, the choices of time horizon and of social discount rate have the most influential effect: discounting of future impacts is levelling off the differences between indirect and direct costs, so that even if lead is accumulating in soil with a consequent increasing exposure, the monetary present value of future impacts doesn’t increase. Setting a short time-horizon reduces uncertainties but excludes part of the indirect costs.