Radioactive particles are physically discrete sources of radioactivity that have been released into the environment as result of past accidents, incidents, and practices, and can present a hazard to members of the public. The historical use of radium in the luminising of aircraft components, and the subsequent decommissioning of those aircraft and associated waste disposal practices, has left a legacy of contamination, such as the radioactive particles containing Ra-226 at Dalgety Bay, Scotland. The aim of this research was to physically, chemically, and radiologically characterise Ra-226 particles from Dalgety Bay and consider the implications for radiological protection of the public. Physical characterisation measured particle size and shape using optical macroscopy with image analysis, measured particle mass, and calculated particle density, as well as general observations on their physical appearance. Chemical characterisation used scanning electron microscopy with energy dispersive X-ray spectroscopy to measure surface elemental composition, and gamma spectrometry was used to measure the activities of Ra-226 and its gamma-emitting daughter radionuclides. Qualitative observations on visual appearance indicated there were five distinct subpopulations, and measurements of size, shape and density varied widely. A wide range of surface chemical compositions were observed, and evidence of their estuarine origin was visible in the form of sand grains and salt deposits. Ra-226, Pb-214, Bi-214 and Pb-210 were detected in all samples with activities over several orders of magnitude and varying degrees of secular equilibrium. Two original aircraft artefacts were also included in the investigation, comparison with which showed the particles and artefacts differed in their characteristics, indicating that the source material has undergone alteration. The diversity of particle characteristics has implications for the radiological protection of the public from Ra-226 particles including pathways of exposure, assessment of radiation dose, and longevity in the environment.

Long-duration space missions and planetary colonization efforts will depend on Bioregenerative Life Support Systems (BLSS) for sustainable food production, water recycling, and waste management. However, most BLSS research to date has focused almost exclusively on plants, with limited attention to animals and species-level ecological interactions. Here, we review 280 BLSS-focused studies and identify significant underrepresentation of insects and invertebrates, despite their multifunctional potential for nutrient recycling, protein production, and ecological resilience. Only 13 studies experimentally included insects, and these are rarely explored in interactions with other species in the system. Insects such as Acheta domesticus, Tenebrio molitor and Bombyx mori show promise but remain underexamined under space-relevant conditions. Comparisons with terrestrial circular food systems reveal parallel knowledge gaps but also highlight emerging evidence supporting invertebrates as integral components. We argue that closing these gaps will require targeted research on insect physiology and species interactions under space-like stressors such as microgravity and radiation. Drawing on insights from Earth-based circular food systems can accelerate the integration of multifunctional insect species into closed-loop space habitats. Addressing these gaps is essential to create robust, resilient bioregenerative systems that can support human life beyond Earth.

Currently, several task groups are addressing complementary aspects in support of improved ICRP's recommendations and ultimately, a more robust approach to protection of the environment from deleterious effects of exposure to ionising radiation. In this context, ongoing developments are briefly presented, with some examples of new methods that have been conceived and implemented (e.g. statistical extrapolation models to quantify the range of radiosensitivity within a taxonomic class and derive transparently and systematically benchmark values or ranges such as the Derived Consideration Reference levels- DCRLs). This paper also addresses the main goals of the ongoing task groups dealing with various aspects of Environmental Radiological Protection (ERP) and their interactions, and the potential need for reformulation of the goal(s) for ERP. The approaches taken by the task groups and the outcomes of their work are expected to inform an inclusive and holistic justification and optimisation process to be considered in the review of the general recommendations of the ICRP.

ABSTRACTLarvae of the greater wax mothGalleria mellonellaare common pests of beehives and commercial apiaries, and in more applied settings, these insects act as alternativein vivobioassays to rodents for studying microbial virulence, antibiotic development, and toxicology. In the current study, our overall aim was to assess the putative adverse effects of background gamma radiation levels onG. mellonella. To achieve this, we exposed larvae to low (0.014 mGy/h), medium (0.056 mGy/h), and high (1.33 mGy/h) doses of caesium-137 and measured larval pupation events, weight, faecal discharge, susceptibility to bacterial and fungal challenges, immune cell counts, activity, and viability (i.e., haemocyte encapsulation) and melanisation levels. The effects of low and medium levels of radiation were distinguishable from the highest dose rates used – the latter insects weighed the least and pupated earlier. In general, radiation exposure modulated cellular and humoral immunity over time, with larvae showing heighted encapsulation/melanisation levels at the higher dose rates but were more susceptible to bacterial (Photorhabdus luminescens) infection. There were few signs of radiation impacts after 7 days exposure, whereas marked changes were recorded between 14 and 28 days. Our data suggest thatG. mellonellademonstrates plasticity at the whole organism and cellular levels when irradiated and offers insight into how such animals may cope in radiologically contaminated environments.

Exposure to radiation is a natural part of our environment. Yet, due to nuclear accidents such as at Chernobyl, some organisms are exposed to significantly elevated dose rates. Our understanding of the effects of radiation in the environment is limited, confounded by substantial interspecific differences in radio-sensitivity and conflicting findings. Here we study radiation impacts on bumblebees in the laboratory using principles from life-history theory, which assume organismal investment in fitness-related traits is constrained by resource availability and resource allocation decisions. To investigate how chronic radiation might negatively affect life-history traits, we tested whether exposure affects bumblebee energy budgets by studying resource acquisition (feeding) and resource use (metabolic rate). We monitored metabolic rate, movement and nectar intake of bumblebees before, during and after 10 days of radiation exposure. Subsequently, we monitored feeding and body mass across a dose rate gradient to investigate the dose rate threshold for these effects. We studied dose rates up to 200 mu Gy/hr: a range found today in some areas of the Chernobyl Exclusion Zone. Chronic low-dose radiation affected bumblebee energy budgets. At 200 mu Gy/hr nectar consumption elevated by 56% relative to controls, metabolic CO2 production increased by 18%, and time spent active rose by 30%. Once radiation exposure stopped, feeding remained elevated but CO2 production and activity returned to baseline. Our analysis indicates that elevated metabolic rate was not driven by increased activity but was instead closely associated with feeding increases. Our data suggest bumblebee nectar consumption was affected across the 50-200 mu Gy/hr range. We show field-realistic radiation exposure influences fundamental metabolic processes with potential to drive changes in many downstream life-history traits. We hypothesise that radiation may trigger energetically costly repair mechanisms, increasing metabolic rate and nectar requirements. This change could have significant ecological consequences in contaminated landscapes, including Chernobyl. We demonstrate bumblebees are more sensitive to radiation than assumed by existing international frameworks for environmental radiological protection. Read the free Plain Language Summary for this article on the Journal blog.

This chapter presents an overview of biomarkers and ecological indicators used to measure radiation stress in invertebrates. Using examples, we will show how and in what context the different biomarkers can be used and on which invertebrate species. We will also describe how the biomarker techniques can be adapted from other taxa including humans and developed for use in invertebrate species. Biomarkers generally fall into two categories – biomarkers for exposure and effect. Invertebrates have not frequently been used to investigate radiation-induced stress but they offer great potential. Here, we present biomarkers that have been used in different ecotoxicological contexts and are appropriate for measuring radiation exposure: comet assay, micronucleus assay, cytochrome p450 and oxidative stress. The majority of previous studies that have used biomarkers for environmental stressors have been conducted on either mussel for aquatic systems or earthworms in terrestrial systems. We also present an overview of how ecological indicators benefit understanding of the consequences that radiation exposure to individuals living in contaminated environments, focussing on alterations to reproduction and behaviour.

Scale residues can accumulate on the interior surfaces of subsea petroleum pipes and may incorporate naturally occurring radioactive materials (NORM). The persistent nature of ‘NORM scale’ may result in a radiological dose to the organisms living on or near intact pipelines. Following a scenario of in-situ decommissioning of a subsea pipeline, marine organisms occupying the exteriors or interiors of petroleum structures may have close contact with the scale or other NORM-associated contaminated substances and suffer subsequent radiological effects. This case study used radiological dose modelling software, including the ERICA Tool (v2.0), MicroShield® Pro and mathematical equations, to estimate the likely radiological doses and risks of effects from NORM-contaminated scale to marine biota from a decommissioned offshore oil and gas pipeline. Using activity concentrations of NORM (226Ra, 210Po, 210Pb, 228Ra, 228Th) from a subsea pipeline from Australia, environmental realistic exposure scenarios including radiological exposures from both an intact pipe (external only; accounting for radiation shielding by a cylindrical carbon steel pipe) and a decommissioned pipeline with corrosive breakthrough (resulting in both internal and external radiological exposure) were simulated to estimate doses to model marine organisms. Predicted dose rates for both the external only exposure (ranging from 26 μGy/h to 33 μGy/h) and a corroded pipeline (ranging from 300 μGy/h to 16,000 μGy/h) exceeded screening levels for radiological doses to environmental receptors. The study highlighted the importance of using scale-specific solubility data (i.e., Kd) values for individual NORM radionuclides for ERICA assessments. This study provides an approach for conducting marine organism dose assessments for NORM-contaminated subsea pipelines and highlights scientific gaps required to undertake risk assessments necessary to inform infrastructure decommissioning planning.

In response to changing international recommendations and national requirements, a number of assessment approaches, and associated tools and models, have been developed over the last circa 20 years to assess radiological risk to wildlife. In this paper, we summarise international intercomparison exercises and scenario applications of available radiological assessment models for wildlife to aid future model users and those such as regulators who interpret assessments. Through our studies, we have assessed the fitness for purpose of various models and tools, identified the major sources of uncertainty and made recommendations on how the models and tools can best be applied to suit the purposes of an assessment. We conclude that the commonly used tiered or graded assessment tools are generally fit for purpose for conducting screening-level assessments of radiological impacts to wildlife. Radiological protection of the environment (or wildlife) is still a relatively new development within the overall system of radiation protection and environmental assessment approaches are continuing to develop. Given that some new/developing approaches differ considerably from the more established models/tools and there is an increasing international interest in developing approaches that support the effective regulation of multiple stressors (including radiation), we recommend the continuation of coordinated international programmes for model development, intercomparison and scenario testing.

The emphasis of the international system of radiological protection of the environment is to protect populations of flora and fauna. Throughout the MODARIA programmes, the United Nations' International Atomic Energy Agency (IAEA) has facilitated knowledge sharing, data gathering and model development on the effect of radiation on wildlife. We present a summary of the achievements of MODARIA I and II on wildlife dose effect modelling, extending to a new sensitivity analysis and model development to incorporate other stressors. We reviewed evidence on historical doses and transgenerational effects on wildlife from radioactively contaminated areas. We also evaluated chemical population modelling approaches, discussing similarities and differences between chemical and radiological impact assessment in wildlife. We developed population modelling methodologies by sourcing life history and radiosensitivity data and evaluating the available models, leading to the formulation of an ecosystem-based mathematical approach. This resulted in an ecologically relevant conceptual population model, which we used to produce advice on the evaluation of risk criteria used in the radiological protection of the environment and a proposed modelling extension for chemicals. This work seeks to inform stakeholder dialogue on factors influencing wildlife population responses to radiation, including discussions on the ecological relevance of current environmental protection criteria. The area of assessment of radiation effects in wildlife is still developing with underlying data and models continuing to be improved. IAEA's ongoing support to facilitate the sharing of new knowledge, models and approaches to Member States is highlighted, and we give suggestions for future developments in this regard.

The International Commission on Radiological Protection's (ICRP) system to protect the living components of the environment is designed to provide a broad and practical framework across different exposure situations. The framework recognises the need to be able to demonstrate an adequate level of protection in relation to planned exposure situations, whilst also providing an ability to manage existing and emergency situations in an appropriate way. In all three exposure situations, the release of radionuclides into the natural environment leads to exposures of non-human biota (wildlife), as well as having the potential for exposures of the public. How the key principles of the ICRP system of radiological protection apply in each of these exposure situations will be discussed. Using examples, we will demonstrate how the overall approach provides a mechanism for industry to assess and demonstrate compliance with the environmental protection objectives of relevant (national) legislation, and to meet stakeholder expectations that radiological protection of the environment is taken into consideration in accordance with international best practice. However, several challenges remain, and these will be discussed in the context of the need for additional guidance on the protection of the environment.

A novel mathematical model was developed to study the historical effects of ionising radiation from the 1986 Chernobyl accident on a vole population. The model uses an ecosystem approach combining radiation damages and repair, life history and ecological interactions. The influence of reproduction, mortality and factors such as ecosystem resource, spatial heterogeneity and migration are included. Radiation-induced damages are represented by a radiosensitive 'repairing pool' mediating between healthy, damaged and radio-adapted animals. The endpoints of the model are repairable radiation damage (morbidity), impairment of reproductive ability and mortality. The focus of the model is the Red Forest, an area some 3 km west of the Chernobyl Nuclear Power Plant. We simulated ecosystem effects of both current exposures and historical doses, including transgenerational effects and adaptation. The results highlight the primary role of animal mobility in stabilising the vole population after the accident, the importance of ecosystem recovery, the time evolution of the repairing and fecundity pools and the impact of adaptation on population sustainability. Using this model, we found dose rate tipping points for mortality and morbidity, along with a limiting migration rate for population survival and the limiting size of the most contaminated region not entailing loss of survival. Our ecosystem approach to radioecological modelling enables an exploration of the impact of radiation in an ecological context, consistent with the available observations. Model predictions indicate that population sensitivity in our exposure scenario does not contradict the benchmarks currently considered in risk assessments for wildlife. The model can be used to support advice on the extent to which historical doses and other ecological factors may influence different exposure modelling scenarios. The approach could easily be adapted to accommodate other stressors, thereby contributing to the evaluation of the regulatory benchmarks used in non-radiological risk assessment.

In recent years, significant advancements in deep learning technology have facilitated the development of intelligent health monitoring approaches for energy systems. However, when dealing with safety-critical energy systems, such as nuclear energy systems, conventional deep learning models with point estimation fail to account for the inherent uncertainty in the predictions. This limitation poses challenges for providing reliable and trustworthy decision support for critical operations. To overcome this challenge, this study proposes a novel intelligent monitoring approach that integrates uncertainty-aware deep neural networks. Firstly, a spatio-temporal state matrix-based signal preprocessing method is proposed to enhance feature extraction capabilities, enabling the effective integration of diverse multi-source data. Secondly, a probabilistic distribution is developed to generate predictive uncertainty for all network parameters, enabling the assessment of the confidence of the model's outputs not only for known operation scenarios but also for unknown scenarios. Finally, the experiments are conducted using an established advanced nuclear energy research platform and a public nuclear accident simulation platform, ensuring the effectiveness and applicability of the proposed approach in practical settings. Overall, the proposed approach significantly enhances the reliability and trustworthiness of the monitoring outputs while mitigating the risks associated with the decision-making process in safety-critical energy systems.

Radioactive particles are physically discrete sources of radioactivity that have been released into the environment as a result of past emergencies, events and practices. As the release of radioactive particles is often unplanned, the source term has not been characterised, and the potential radiation doses have not been prospectively assessed. If a plausible exposure pathway exists, radioactive particles in the environment may present a hazard to the public depending on their radiological, physical and chemical characteristics. Given their physically discrete nature, standard assessment approaches such as dispersion and transfer modelling of liquid and gaseous radioactive releases, are not appropriate for radioactive particles. The challenge for national regulatory authorities is to calculate potential radiation doses from unplanned releases of radioactive particles into the environment, assess whether the doses are relevant to radiological protection and decide whether actions are required to reduce potential doses. To address this challenge, this paper presents the approach being adopted to radiologically, physically and chemically characterise Ra-226 particles from a contaminated legacy site using gamma spectrometry, optical macroscopy and SEM-EDS. The use of particle characterisation data to support radiation dose assessments is discussed and consideration is given to radioactive particles in the context of radiological protection.

The consequences for wildlife of living in radiologically contaminated environments are uncertain. Previous laboratory studies suggest insects are relatively radiation-resistant; however, some field studies from the Chernobyl Exclusion Zone report severe adverse effects at substantially lower radiation dose rates than expected. Here, we present the first laboratory investigation to study how environmentally relevant radiation exposure affects bumblebee life history, assessing the shape of the relationship between radiation exposure and fitness loss. Dose rates comparable to the Chernobyl Exclusion Zone (50–400 µGy h −1 ) impaired bumblebee reproduction and delayed colony growth but did not affect colony weight or longevity. Our best-fitting model for the effect of radiation dose rate on colony queen production had a strongly nonlinear concave relationship: exposure to only 100 µGy h −1 impaired reproduction by 30–45%, while further dose rate increases caused more modest additional reproductive impairment. Our data indicate that the practice of estimating effects of environmentally relevant low-dose rate exposure by extrapolating from high-dose rates may have considerably underestimated the effects of radiation. If our data can be generalized, they suggest insects suffer significant negative consequences at dose rates previously thought safe; we therefore advocate relevant revisions to the international framework for radiological protection of the environment.

In the initial aftermath of the 1986 Chernobyl accident there were detrimental effects recorded on wildlife, including, mass mortality of pine trees close to the reactor, reduced pine seed production, reductions in soil invertebrate abundance and diversity and likely death of small mammals. More than 30 years after the Chernobyl accident there is no consensus on the longer-term impact of the chronic exposure to radiation on wildlife in what is now referred to as the Chernobyl Exclusion Zone. Reconciling this lack of consensus is one of the main challenges for radioecology. With the inclusion of environmental protection in, for instance, the recommendations of the International Commission on Radiological Protection (ICRP), we need to be able to incorporate knowledge of the potential effects of radiation on wildlife within the regulatory process (e.g. as a basis on which to define benchmark dose rates). In this paper, we use examples of reported effects on different wildlife groups inhabiting the Chernobyl Exclusion Zone (CEZ) as a framework to discuss potential reasons for the lack of consensus, consider important factors influencing dose rates organisms receive and make some recommendations on good practice.

This article presents the results of a workshop held in Stirling, Scotland in June 2018, called to examine critically the effects of low-dose ionising radiation on the ecosphere. The meeting brought together participants from the fields of low- and high-dose radiobiology and those working in radioecology to discuss the effects that low doses of radiation have on non-human biota. In particular, the shape of the low-dose response relationship and the extent to which the effects of low-dose and chronic exposure may be predicted from high dose rate exposures were discussed. It was concluded that high dose effects were not predictive of low dose effects. It followed that the tools presently available were deemed insufficient to reliably predict risk of low dose exposures in ecosystems. The workshop participants agreed on three major recommendations for a path forward. First, as treating radiation as a single or unique stressor was considered insufficient, the development of a multidisciplinary approach is suggested to address key concerns about multiple stressors in the ecosphere. Second, agreed definitions are needed to deal with the multiplicity of factors determining outcome to low dose exposures as a term can have different meanings in different disciplines. Third, appropriate tools need to be developed to deal with the different time, space and organisation level scales. These recommendations permit a more accurate picture of prospective risks.

Ionizing radiation is a mutagen with known negative impacts on individual fitness. However, much less is known about how these individual fitness effects translate into population-level variation in natural environments that have experienced varying levels of radiation exposure. In this study, we sampled genotypes of the freshwater crustacean, Daphnia pulex, from the eight inhabited lakes across the Chernobyl Exclusion Zone (CEZ). Each lake has experienced very different levels of chronic radiation exposure since a nuclear power reactor exploded there over thirty years ago. The sampled Daphnia genotypes represent genetic snapshots of current populations and allowed us to examine fitness-related traits under controlled laboratory conditions at UK background dose rates. We found that whilst there was variation in survival and schedules of reproduction among populations, there was no compelling evidence that this was driven by variation in exposure to radiation. Previous studies have shown that controlled exposure to radiation at dose rates included in the range measured in the current study reduce survival, or fecundity, or both. One limitation of this study is the lack of available sites at high dose rates, and future work could test life history variation in various organisms at other high radiation areas. Our results are nevertheless consistent with the idea that other ecological factors, for example competition, predation or parasitism, are likely to play a much bigger role in driving variation among populations than exposure to the high radiation dose rates found in the CEZ. These findings clearly demonstrate that it is important to examine the potential negative effects of radiation across wild populations that are subject to many and varied selection pressures as a result of complex ecological interactions.