Shipping releases hazardous substances into marine environments through, e.g., scrubber effluents, bilge-, ballast-, and greywater, sewage, and biocides from antifouling paints. Effective regulation requires identifying these substances, their concentrations, source volumes, and resulting annual loads, to assess potential environmental hazards of individual waste streams relative to land-based sources. Focusing on the North-East Atlantic and the years 2018 and 2023, total loads of hazardous substances from shipping, and the cumulative hazard posed by individual waste streams were quantified. These ship-related sources were compared to inputs from rivers, and coastal industries and wastewater treatment. Substance-specific hazard was assessed by dividing waste-stream concentrations by each substance's environmental threshold value. Mixture toxicity was accounted for through concentration addition, using annual volumes to scale and comparing hazard indices (HI). Results show that all loads from shipping increased between 2018 and 2023. Copper and zinc from antifouling paints dominated total loads, with copper loads surpassing combined land-based copper inputs by 2023. HI from shipping increased even more than loads and shipping contributed more than half to the total HI by 2023 based on the available data. Antifouling paints and scrubbers dominated HI, marking them as the strongest contributors to hazard from shipping. Notably, scrubbers showed the highest relative increase in HI of all waste streams between 2018 and 2023. These findings highlight priority areas for regulation and monitoring within the OSPAR region. Targeted regulation on antifouling paints and scrubbers could substantially reduce the marine environmental impacts from shipping, improving the industry's environmental sustainability. • Shipping is a major source of heavy metals and organic substances, contributing to marine pollution and environmental hazard. • Releases from antifouling paint contribute the most to the overall substance load and hazard. • Open-loop scrubbers contribution to overall hazard increased markedly between 2018 and 2023, approaching similar levels as antifouling paints. • Regulating antifouling paint and open-loop scrubbers holds the largest potential to reduce environmental impacts from shipping.
Pfeiffer et al. (2026) studied this question.