A large group of UKCEH scientists took part in the 33rd Annual Meeting of the Society of Environmental Toxicology and Chemistry (SETAC) Europe, held this year in Dublin and online (30 April-4 May). SETAC Europe is the most important European meeting of the year for research in the field of chemical pollution and its sources, fate and effects. Read on for more details about our involvement...
The scientific programme of SETAC Europe 2023 addressed the overarching theme of “Data-driven environmental decision-making” for the protection and restoration of the environment. UKCEH scientists were lead presenters of eight talks and ten posters on topics related to understanding, predicting and managing the impacts of pollutants on the environment. Overall, our presented work covered a range of pollutants - plastics, metals, persistent organic pollutants (‘forever chemicals’), nanoparticles and pesticides – and organisms, from soil and aquatic invertebrates through mammals, fish and amphibians to top predators.
1 May 2023
- The diversity of invertebrates (e.g. stream insects) in English rivers has increased over the last 30 years, but the reasons for this are not known. In this study we used a large dataset of paired water chemistry and invertebrate diversity measurements across England to relate changes in biodiversity to changes in concentrations of potentially harmful chemicals. Our analysis showed that, depending on whether we looked at stream insects only, or all invertebrates, and whether we looked at urban or rural rivers, up to 40% of the change in diversity could be explained by changes in the concentrations of chemicals over the same time period. Of the chemicals in the dataset, zinc had the single strongest relationship with diversity.
- We analysed long-term (>35 years) trends of the "forever" chemicals (PFAS) in gannet eggs from a North Sea (Bass Rock) and an Irish Sea (Ailsa Craig) colony. PFOS dominated the PFAS profile in eggs from both colonies for the entire study period. In Ailsa Craig eggs, PFOS and PFOA concentrations declined after implementation of restrictions and bans on their use. In Bass Rock eggs, PFOS concentrations also declined but the effect of restrictions on PFOA is less evident. The study showed the temporal rise of PFCAs, namely long odd chain compounds (C11 and C13).
2 May 2023
- We carried out a field study looking at plastic waste and plastic-associated chemicals, known as plasticisers, in UK soils. We found that urban roadsides were particularly contaminated with plastics and plasticisers. We were able to detect microplastics in all land uses studied, except for woodlands. Our results imply that plasticiser contamination in soils is related not only to the presence of local plastic waste, but to other sources, e.g. airborne transport.
3 May 2023
- No single analytical instrument can quantify microplastics across the myriad of sizes, shapes and polymers that this term encompasses. Due to the increasing number of ever smaller particles as they fragment into pieces too small for the human eye to count, the total number of microplastic particles you may find in any environment is highly dependent on how small a particle you are able to detect. While we now have lots of data on microplastic occurrence, reporting of this data is inconsistent, making it difficult to draw comparisons between studies by different researchers. Inappropriate comparisons between data gathered by different techniques are still being made, without acknowledging this fact. We introduce the concept of an “analytical window” for microplastics to encourage better and more consistent reporting among the community and share lessons we have learnt at UKCEH on how to put this concept into practice to improve the relevance and reliability of the design of any monitoring of microplastics in nature.
- Modelling the toxic impacts of mixtures of metals in the field is an ongoing challenge in ecotoxicology. We developed a model to predict how changes in water pH and metal concentrations over time affect the biodiversity of small lake animals (zooplankton). Our model was able to explain about 80% of the change in zooplankton biodiversity over time, increasing our confidence that we can predict the effects of metal mixtures on organisms under field conditions.
- We present the first study to document microplastic contamination of larval lamprey in-situ, contributing another potential stressor to the population status of a vulnerable species. Microplastic particles, analysed using micro-Fourier transform infrared (μFTIR) spectroscopy, were detected in all samples of lamprey larvae and paired sediment. Across sites, the microplastic abundance in lamprey was not correlated with that of the surrounding sediment, suggesting that either specific polymer types are retained or other factors such as larvae residence time within sediment patches may influence biological uptake.
4 May 2023
- Predicting species sensitivity to toxicants would help us protect the most vulnerable species. An organism’s genome contains considerable amounts of information relevant to predicting sensitivity, and large-scale sequencing projects are generating genomes for all UK species. This talk covered the progress we have made towards exploiting this considerable ‘omic’ information, as well as the research pathway needed to make ever better predictions.
- It is essential to know limitations of ecotoxicological test systems and what questions can be answered. High throughput toxicity testing under tightly controlled conditions is key to minimising experimental variation and providing knowledge on the mechanisms of chemical toxicity. Are laboratory organisms (such as white worms) going to have similar responses to chemicals to wild counterparts? There is a danger of “lazy worms”, whose response to chemicals is determined by the fact that they are reared in more benign conditions than wild worms. For example, could worms from benign culture conditions downregulate key genes that determine how they respond to toxic chemicals? We used transcriptomics to compare responses to toxic chemicals of the same population of white worms in soil and artificial agar culture; and wild vs long-term cultured populations of white worms. There was little transcriptomic difference according to rearing conditions. Mass rearing of worms and high throughput chemical testing is a suitable approach for assessing chemical impacts on field populations of worms. There are significant genetic differences between wild and cultured worms. Functional and selection investigations into these differences are ongoing.
2 May 2023
- Plasticisers are chemicals added to plastics to make them more flexible. Some chemicals previously used as plasticisers have been banned because of their environmental impacts, and new plasticisers are increasingly being used instead. We know little about how quickly these new plasticisers leach from plastics, or how long they remain in soils afterwards. We tested the release of a new plasticiser from PVC microplastic pellets in three different soils. We also measured how quickly some of these new plasticisers degraded in soils. The new plasticiser was released rapidly into the soil, and rates at which it then degraded depended on the soil chemistry. We also found that some new plasticisers degrade much more slowly in soils than banned plasticisers. Studies such as this help us to understand and predict the occurrence of plasticisers in soil and their exposure to soil organisms.
- A significant improvement over time has occurred with respect to macro-invertebrate biodiversity across all river scenarios in England, although higher wastewater exposure or arable land cover (nutrients and pesticides) is reflected in less biodiverse sites. For family richness, this improvement has slowed post-2003, but the presence of more sensitive macroinvertebrates has continued to improve at the expense of more pollution tolerant organisms.
3 May 2023
Shinji Ozaki: Influence of seasonality on the temporal trend assessment of wildlife exposure to second-generation anticoagulant rodenticides - a case study for UK Common buzzards (Buteo buteo) from 2001 to 2019
- Although strong seasonal variations in the exposure of avian predators to second-generation anticoagulant rodenticides (SGARs) have been reported, such seasonal variations have not been included in biomonitoring. Using data on SGAR residues in common buzzards (Buteo buteo), the performance of temporal trend models with and without a seasonal fluctuation were statistically compared in this study. The results show that integrating seasonal variations into biomonitoring improves exposure modelling and thus risk assessment of SGARs.
- Nanomaterials are often made in the presence of stabilising chemicals (chelating agents). It is important to know whether these stabilising chemicals might be toxic to environmental organisms. We tested the effects of silver nanomaterials and two chelating agents to a pot worm (E. crypticus). Exposure to the silver nanomaterials showed lower toxicity (based on survival) than to ionic silver, chelating agents alone had no significant effect on survival.
- A framework is presented on how literature-derived toxicity data can be used to develop a soil hazard assessment for nanomaterials. Using this framework, nanomaterials can be classified based on their hazard to soil environments and whether safety-by-design interventions are needed to make the nanomaterial or its nanoforms less hazardous.
- Microplastics are a ubiquitous contaminant of ponds across the central belt of Scotland. We found that microplastics were concentrated in the gut of common toad (Bufo bufo) tadpoles. A negative correlation between microplastic abundance and tadpole body mass was shown.
- Amphibians are declining on a global scale. Tadpoles present ideal biomonitoring organisms for pond ecosystems due to their ubiquity, small size and tendancy to reside in a small area. We found arable land cover negatively impacted tadpole growth and development, as did pH < 7.
4 May 2023
- This study documents developmental defects in lamprey larvae which were exposed to leachates of tyre wear particles, demonstrating the potential contribution of this stressor to the population status of this vulnerable species. Further research on the ecotoxicological impacts of tyre wear particles is needed to aid our understanding of whether this complex contaminate has a role in lamprey population declines.
- Organisms living in agricultural soils can be exposed to mixtures of pesticides. It is important to know how these mixtures affect organisms, because the overall effect might not be predictable even if we know the effect of each individual pesticide. We exposed two types of soil animal - a springtail and a potworm - to single pesticides and to mixtures, and monitored the effects over time. The effects of pesticide mixtures on the organisms were complex and varied over time and with the size of the dose. We will use advanced chemical and genomic approaches to better understand how and why these effects come about.
- We developed a reproducible, quantitative method for 6-PPD, a chemical used in vehicle tyres, in sediment samples. Method validation showed a successful method with a recovery of 96.7 per cent and a reproducibility of 13 per cent. Rural river bottom sediments, collected upstream and downstream from a road bridge, were analysed to test the method. 6-PPD detected was assumed to be still within the tyre particles themselves, given that unattached 6-PPD is not stable in river water. From the spatial pattern of 6-PPD concentrations, the tyre particles are transported downstream from the road bridge before settling to the bottom sediments.
UKCEH scientists were also contributing authors and collaborators on a number of other presentations at the event:
- CNRS: Environmental pollution and nutritional quality modulate immune response of the wood mouse (Apodemus sylvaticus) through hormonal disturbances. In laboratory-controlled animals, micronutrients such as dietary selenium (Se) have been shown to counteract dysfunctional effects induced by non-essential metals, which has not been demonstrated in terrestrial wildlife. This study focused on the impact of long-term exposure to non-essential metals, Cd and Pb, on the immune system function and the protective role of dietary Se in free-living wood mice (Apodemus sylvaticus). Although immuno-functional disturbances mediated by long-term exposure to non-essential metals were demonstrated, the functional role of dietary Se against non-essential metals remains unclear and needs further studies.
- BASF: Systematic evaluation of fragmentation of five common synthetic polymers: Influence of photolysis, temperature and relative humidity on fragment size distribution and material characteristics. Very small plastic particles (micro- and nanoplastics) are potentially a threat to environmental organisms, because they can be accidentally ingested. The break-up (fragmentation) of larger plastic pieces over time is important in producing smaller plastic particles. We showed that temperature and humidity are important in controlling how quickly larger plastic pieces break up. Our data can be used to predict how quickly smaller plastic particles are produced in the environment.
- Naturalis Biodiversity Center, Netherlands: Time trends in PCB and PBDE congeners and in ΣPCBs and ΣPBDEs residue concentrations in the common buzzard Buteo buteo in the Netherlands 1994-2020 in relation to restrictions on chemicals use. Systematic monitoring for assessing the efficiency of the risk management measures regarding the impact of PBT substances in terrestrial wildlife has been limited at national and pan-European scales. This ePoster presents the initial results of a national-scale biomonitoring study on multiple PCBs and PBDEs in the liver of buzzards (Buteo buteo) in the Netherlands. The effectiveness of regulatory restrictions on these compounds might differ with sex and location, although more advanced analyses are necessary for further detailed results.
- University of Aveiro: Ag2S NP accumulation in the mealworm Tenebrio molitor and the woodlouse Porcellio scaber: are single-species tests a good predictor of indoor mesocosm experiments?. The use of silver nanoparticles in products may result in release to soils via waste water treatment products - silver sulphide particles are known to be an environmentally relevant form. We tested how soil organisms are exposed and bioaccumulate silver sulphide in single species tests compared with exposure in complex mesocosms containing multiple species. Single species tests may not predict bioaccumulation well in more realistic systems, but may be useful to 'screen' for exposure and to decide whether more realistic exposure testing is needed.
- Roskilde University: Chronic exposure scenarios driving environmental risk of chemicals (CHRONIC). Despite the fact that we have well-established systems for managing chemical risks to people and the environment, we still see impacts of chemicals on ecosystems today. Our current systems for testing the impacts of chemicals may be missing effects that occur due to the presence of many chemicals at low doses, especially in association with other stresses. The CHRONIC project is developing tools and approaches to identify and assess these effects and to understand how they operate alongside other stresses to impact ecosystems.
- BASF: Distinctions on fragmentation and degradation of six common microplastics from hydrolysis condition variations: Insight into pH, salinity and enzyme effects. The breakup and degradation of plastic in the environment is an important influence on how organisms are exposed to it. We studied the degradation of breakup of plastics in response to different temperatures and water chemistries. Our results can be used to develop models of how plastics break down in the environment, and help us to predict how organisms might be affected by them.
Finally, UKCEH scientists Sam Harrison, Stephen Lofts, Elma Lahive, Lee Walker and UKCEH Fellow Frances Orton also convened or co-convened five sessions at this year's conference on topics including modelling the exposure of the environment to pollutants, the environmental occurrence and impacts of plastics and metals, and the effects of pollution on wildlife. Congratulations to everyone involved.