Assessing the KEMI approach for determining the size of mixture assessment factors needed to protect aquatic receptors from chemical mixtures in surface waters

Abstract

This article discusses the Swedish Chemicals Agency's proposal for estimating the size of a Mixture Assessment Factor (the KEMI MAF) for aquatic mixtures of chemicals. The KEMI MAF is an improvement over earlier approaches but is dependent on factors that are uncertain, such as: the number of chemicals that reach an aquatic receptor, the allocation of chemicals into assessment groups, and the impacts of future regulations on chemical concentrations in water. This article demonstrates that these uncertainties have significant impacts on the size of MAFs required for aquatic receptors. As part of this assessment a simplified method of calculating the KEMI MAF was developed.