This report compiles available Threshold Values (TVs) for marine chemical contaminants at EU, regional and beyond EU level, provides relevant information and discussion points for TV derivation and implementation, and outlines the main hindrances and potential approaches to fill the gaps. This document is a product of the MSFD Expert Network on Contaminants and is intended as a background guidance document to support developments to improve consistency in marine contaminant assessments.
The report highlights the reality of the lack of knowledge about reference values (whether they are background, threshold or Environmental Quality Standard values) for many contaminants in the marine environment. Although regulations and frameworks are in place, and new ones are being implemented, the assessment of Good Environmental Status will remain difficult without high quality environmental and toxicological data. The variety of applied TVs is hindering a comparable assessment of problematic substances and the necessary reduction/phase-out measures. Considering the huge work needed to develop TVs and the high number of potential contaminants, current approaches need to be reviewed. Furthermore, the concerns on the environmental significance of TVs when they are not based on sufficient data and relevant assessment factors, and the difficulty to generalise TVs for all matrix/species monitored, call for discussions on resource-efficient TV development and potential alternative ways forward.