The Role of Mass Balance Modelling in Impact Assessment and Pollution Prevention

Abstract

The paper first addresses the applicability of steady-state mass balance models for evaluating the fate of a chemical in a multi-media environment as part of the process of impact assessment and pollution prevention. It is suggested that such models can be used to deduce concentrations in a variety of environmental compartments, including media such as air, water and foodstuffs, which are important vehicles for chemical exposure to humans and wildlife. The models can be applied both to continuous fluxes of chemicals into the environment (e.g. 100 kg/day of benzene from a petroleum refinery) and to pulses of chemicals associated with the use of functional units within an LCA framework (e.g. 100 g of volatile solvent from a can of paint). An Index for Potential Toxic Impact (IPTI) for comparing pollution prevention alternatives of consumer products and manufacturing processes is presented. The index brings together steady-state emissions or pulse LCA emissions, substance partitioning and persistence properties, inter-media transfer rates, exposure pathways and toxicity in an overall evaluation of potential toxic impacts. The use of the EQC Level III Multi-Media Model for this purpose is illustrated for both flux and pulse discharges in the hope that it may encourage the use of such models for impact assessment and pollution prevention.