Prioritization Approaches for Substances of Emerging Concern in Groundwater: A Critical Review

Risks from emerging contaminants (ECs) in groundwater to human health and aquatic ecology remain difficult to quantify.The number of ECs potentially found in groundwater presents challenges for regulators and water managers regarding selection for monitoring.This study is the first systematic review of prioritisation approaches for selecting ECs that may pose a risk in groundwater.Online databases were searched for prioritisation approaches relating to ECs in the aquatic environment using standardised key word search combinations.From a total of 672, studies 33 met the eligibility criteria based primarily on the relevance to prioritising ECs in groundwater.The review revealed the lack of a groundwater specific contaminant prioritisation methodology in spite of widely recognised differences between groundwater and surface water environments in regards to pathways to receptors.The findings highlight a lack of adequate evaluation of methodologies for predicting the likelihood of an EC entering groundwater and highlights knowledge gaps regarding the occurrence and fate of ECs in this environment.The review concludes with a proposal for a prioritisation framework for ECs in groundwater monitoring which enables priority lists to be updated as new information becomes available for substances regarding usage, physico-chemical properties and hazards.