2025-12-01 カーディフ大学
＜関連情報＞
- https://www.cardiff.ac.uk/news/view/2984857-rising-levels-of-banned-toxic-chemicals-in-otters-from-wales
- https://www.sciencedirect.com/science/article/pii/S0269749125017282
- https://www.sciencedirect.com/science/article/abs/pii/S0269749120371049
ウェールズのユーラシアカワウソ（ Lutra lutra ）におけるポリ塩化ビフェニル（PCB）濃度の上昇は、堆積物の沈降からの再移動を示唆している Increasing concentrations of polychlorinated biphenyls (PCBs) in Eurasian otters (Lutra lutra) from Wales suggest remobilisation from sediment sinks
Emily O’Rourke, Melanie Schumacher, Mark Charlesworth, Thomaz Andrade, M. Glória Pereira, Frank Hailer, Elizabeth Chadwick
Environmental Pollution Available online 4 November 2025
DOI:https://doi.org/10.1016/j.envpol.2025.127354
Graphical abstract
Highlights
- PCBs were detected in all otters analysed from Wales.
- Otters from coastal, low-altitude areas had the highest PCB concentrations.
- PCBs in otters increased from 2010 to 2019, reversing previous PCB declines.
- We infer that remobilisation of PCBs from sediment sinks is the likely driver of increases.
- We suggest that safety standards designed to protect top predators are not effective.
Abstract
Despite ongoing regulatory efforts to mitigate PCB pollution, their presence remains pervasive in the environment, with concentrations in top predators still reaching toxicologically significant levels. To assess temporal and spatial variation of PCB concentrations in Wales between 2010 and 2019, we analysed liver samples of a sentinel predator, the Eurasian otter (Lutra lutra), for 23 PCB congeners. PCBs were detected in all livers analysed, with PCB 153 recording the highest individual concentration (545.8 μg/kg wet weight); sixteen percent of otters had concentrations above a toxic threshold for dioxin-like PCBs. Statistical modelling revealed a negative correlation between concentrations of dioxin-like PCBs and otter body condition. While previous studies on otters from the UK showed declining PCB concentrations between 1983 and 2009, our model predictions indicated a significant increase between 2010 and 2019, mirroring trends seen in marine mammals. Higher concentrations were observed in otters from coastal, low-altitude areas. A multi-model inference approach was used to identify the best groups of predictors for each congener, suggesting that remobilisation of PCBs from riverine and coastal sediment sinks is now a major driver of PCB concentrations, with the impacts of climate change likely exacerbating remobilisation. While PCB concentrations are often below limits of detection in water, and below the current Water Framework Directive Environmental Quality Standard in fish, they remained at toxicologically relevant levels in otters from Wales. Our findings underscore the importance of biomonitoring across trophic levels, and suggest that current environmental quality standards for water and fish are not protective of top predators. Addressing environmental PCB contamination will require strengthened international efforts both to manage the significant sinks of legacy pollutants, as well as to meet climate change mitigation targets.
残留性汚染物質は、法的規制から数十年後も淡水頂点捕食者の毒性閾値を超えている Persistent pollutants exceed toxic thresholds in a freshwater top predator decades after legislative control
E.F. Kean, R.F. Shore, G. Scholey, R. Strachan, E.A. Chadwick
Environmental Pollution Available online: 2 January 2021
DOI:https://doi.org/10.1016/j.envpol.2020.116415
Highlights
- Decades after control, POPs remain above toxic thresholds in many otters.
- Dieldrin, DDT and most PCBs are declining, but HCB and PCB-TEQ are not.
- Concentrations may limit reproduction in some areas of the UK.
- Developmentally vulnerable juveniles show the highest concentrations.
Abstract
Declining emissions of persistent organic pollutants (POPs), subject to international control under the Stockholm convention, are not consistently reflected in biotic samples. To assess spatial and temporal variation in organochlorine pesticides and PCBs in UK freshwaters, we analysed tissues of a sentinel predator, the Eurasian otter, Lutra lutra between 1992 and 2009. Past declines in otter populations have been linked to POPs and it is unclear whether otter recovery is hampered in any areas by their persistence. PCBs, DDT (and derivatives), dieldrin and HCB were detected in over 80% of 755 otter livers sampled. Concentrations of ∑PCB, ∑DDT and dieldrin in otter livers declined across the UK, but there was no significant time trend for ∑PCB-TEQ (WHO toxic equivalency, Van den Berg et al., 2006) or HCB. In general, higher concentrations were found in the midlands and eastern regions, and lowest concentrations in western regions. Concentrations of PCBs and HCB in otters increased near the coast, potentially reflecting higher pollutant levels in estuarine systems. Decades after legislative controls, concentrations of these legacy pollutants still pose a risk to otters and other freshwater predators, with spatially widespread exceedance of thresholds above which reproduction or survival has been reduced in related species.
