Current mixture toxicity assessments on soil organisms and applied risk assessments

Abstract

There is increasing evidence that the majority of agricultural and off-field soils contain multiple plant protection product (PPP) residues that persist in soils for extended periods after application. Such PPP residues in soil were found to affect the soil organisms and their communities with little knowledge on the implications for the functioning of soil ecosystems. A growing body of scientific studies points to the increased risk from the co-occurrence of diverse PPP residues in soils and international efforts recently resulted in the endorsement of the first directive to protect soil health in the EU to ensure an EU-wide soil health monitoring system. In order to inform such developments, the scientific literature and environmental regulations were reviewed here for currently practiced mixture risk assessment (MRA) methods in soil. Further, relevant aspects for a soil MRA were scrutinised to identify knowledge gaps in soil MRA and to evaluate novel emerging assessment concepts for their usability in soil MRA. From these insights key conclusions are drawn for soil MRA to inform the next steps for a more realistic and accurate MRA.