Levels and trends in marine contaminants and their biological effects – CEMP Assessment report 2024

This report summarises the 2024 annual CEMP assessment of levels and trends of contaminants and their biological effects. The full assessment is available online in the OSPAR Hazardous Substances Assessment Tool (OHAT): https://dome.ices.dk/ohat/?assessmentperiod=2024.

There were 16592 time series (of three years or more) in biota, of which 11111 were assessed for trends and 10495 for environmental status and 3079 for human health status; 7326 time series in sediment, of which 3841 were assessed for trends and 5488 for status; and 1795 time series in water, of which 1315 were assessed for trends and 657 for status.

The 2024 annual CEMP assessment can be viewed on the OSPAR Hazardous Substances Assessment Tool (OHAT).
It assessed 16592 time series (of three years or more) in biota, of which 11111 were assessed for trends and 10495 for environmental status and 3079 for human health status; 7326 time series in sediment, of which 3841 were assessed for trends and 5488 for status; and 1795 time series in water, of which 1315 were assessed for trends and 657 for status. Compared to the 2023 assessment, the number of time series has increased by 11% for biota and 24% for water and decreased by 4% for sediment. A breakdown of trends and status by region and determinand is given in Appendix 1  (Tables 1–7). 

The assessment methodology is described in the help files on the OHAT and is essentially the same as that used for the 2023 assessment. However, an important intersessional development has been the first release of the HARSAT (HArmonised Regional Seas Assessment Tool) software package. HARSAT was jointly developed by AMAP, HELCOM, OSPAR, ICES and AmbieSense Ltd., and was used to run the 2024 assessment.

Regional trends and environmental status were assessed for metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers in biota and sediment, polycyclic aromatic hydrocarbon metabolites (PYR1OH) in fish, organotins in sediment, and imposex (VDS) in whelks. For biota, time series from mammals and birds were included in the regional trend assessments, but not in the regional status assessments as the comparability of thresholds for mammals and birds against those for fish and shellfish needs further investigation. Regional health status was assessed for metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and polybrominated diphenyl ethers in biota. The results of the regional assessments are summarised in Appendix 1  (Tables 8–12), with full details available on the OHAT.

The changes in regional environmental status since 2023 are given in Table 1. Mostly, these show poorer environmental quality related to metal concentrations in sediment in the Northern North Sea, the Irish and Scottish West Coast and the Irish Sea. However, these changes are more likely attributable to a change in analytical laboratory rather than a genuine degradation of environmental quality.  Note that both analytical laboratories concerned were accredited and showed acceptable performance in QUASIMEME proficiency trials.

The biota and sediment CHASE scores are shown in Figure 1 and Figure 2 respectively. The scores for 2022 and 2023 are also shown for comparison.  There is little change for biota. For sediment, the CHASE score for the Irish and Scottish West Coast has increased (due to the change in analytical laboratory) although remains below 1.