A methodology for ranking and hazard identification of xenobiotic organic compounds in urban stormwater

The paper presents a novel methodology (RICH, Ranking and Identification of Chemical Hazards) for ranking and identification of
xenobiotic organic compounds of environmental concern in stormwater discharged to surface water. The RICHmethod is illustrated as a
funnel fitted with different filters that sort out problematic and hazardous compounds based on inherent physico-chemical and biological
properties. The outcomes of the RICH procedure are separate lists for both water phase and solid phase associated compounds. These
lists comprise: a justified list of compounds which can be disregarded in hazard/risk assessments, a justified list of stormwater priority
pollutants which must be included in hazard/risk assessments, and a list of compounds which may be present in discharged stormwater,
but cannot be evaluated due to lack of data. The procedure was applied to 233 xenobiotic organic chemicals (XOCs) of relevance for
stormwater. Of these 233 compounds, 121 compounds were found to be priority pollutants with regard to solids phases (i.e. suspended
solids, soil, or sediments) when stormwater is discharged to surface water and 56 compounds were found to be priority pollutants with
regard to the water phase. For 11% of the potential stormwater priority pollutants the screening procedure could not be carried out due to
lack of data on basic physico-chemical properties and/or data on bioaccumulation, resistance to biodegradation, and ecotoxicity. The
tiered approach applied in the RICH procedure and the focus on the phases relevant for monitoring or risk assessment in the aquatic
environment refines the list of “compounds of concern” when compared to the outcome of existing classification schemes. In this paper
the RICH procedure is focused on effects in the aquatic environment exemplified with xenobiotic organic compounds (XOCs) found in
urban stormwater, but it may be transferred to other environmental compartments and problems. Thus, the RICH procedure can be used
as a stand-alone tool for selection of potential priority pollutants or it can be integrated in larger priority setting frameworks.