The prioritisation process ranks substances based on their potential exposure in the aquatic environment and hazard to aquatic life. Exposure is assessed according to available monitoring and use (tonnage and use scenario) data and hazard is assessed based on persistence, bioaccumulation and toxicity. A score is then assigned for both exposure and hazard based on the available data. These scores are combined to give an overall priority ranking of 1 to 5 with 1 indicating highest priority and 5 the lowest. There are minimum data requirements for an assessment to be made and if these are not met the substance will be assigned a final ranking of ‘Insufficient Information’.
Prioritising chemicals for standard derivation under Annex VIII of the Water Framework Directive
The prioritisation approach also incorporates a review of the priority rankings. This does not involve detailed discussion of the data used to determine the priority ranking, but:
• enables a check on the score assigned and flags any anomaliesPrioritising chemicals for standard derivation under Annex VIII of the Water Framework Directive v
• provides an opportunity for highlighting further data sources
• enables discussion about how particular substances should be dealt with, for example should they be taken forward for EQS development, should additional data be obtained, are other controls in place which reduce the need for an EQS