Chornobyl radiation spikes are not due to military vehicles disturbing soil.

On 25th February 2022, increased gamma radiation dose rates were reported within the Chornobyl Exclusion Zone (CEZ). This coincided with Russian military vehicles entering the Ukrainian part of the CEZ from neighbouring Belarus. It was speculated that contaminated soil resuspension by vehicle movements or a leak from the Chornobyl Nuclear Power Plant complex may explain these spikes in radiation dose rates. The gamma dose rate monitoring network in the CEZ provides a crucial early warning system for releases of radioactivity to the environment and is part of the international safeguards for nuclear facilities. With the potential for further military action in the CEZ and concerns over nuclear safety, it is essential that such anomalous readings are investigated. We evaluate the hypotheses suggested to explain the apparent gamma dose rate increases, demonstrating that neither military vehicle-induced soil resuspension nor a leak from the Chornobyl Nuclear Power Plant are plausible. However, disruption of the Chornobyl base-station's reception of wireless signals from the gamma dose rate monitoring network in the CEZ may potentially explain the dose rate increases recorded.

Ensuring robust radiological risk assessment for wildlife: insights from the International Atomic Energy Agency EMRAS and MODARIA programmes.

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.

Towards an ecological modelling approach for assessing ionizing radiation impact on wildlife populations.

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.

SRP workshop on 'communication of radiation risk in the modern world'.

Communicating radiation risk is an important part of radiation protection. However, achieving effective risk communication is challenging given the negative public perception of radiation and conflicting views presented by both the media and social media. Noting the importance of building capacity amongst radiation protection professionals to communicate radiation risk effectively, the Society for Radiological Protection (SRP) ran a half-day workshop at its Annual Conference on the 22nd May 2019 in Scarborough Spa, UK. A number of key factors were identified that should be considered when communicating with the public, post a nuclear or radiological incident, communicating with government and local authorities, and communicating with the public as part of public outreach. The following memorandum provides a summary of the points presented and discussed. It also outlines proposed future activities of the SRP, focused on further developing the communications aspect of radiation professionals' practice.

Radionuclide transfer to wildlife at a 'Reference site' in the Chernobyl Exclusion Zone and resultant radiation exposures.

This study addresses a significant data deficiency in the developing environmental protection framework of the International Commission on Radiological Protection, namely a lack of radionuclide transfer data for some of the Reference Animals and Plants (RAPs). It is also the first study that has sampled such a wide range of species (invertebrates, plants, amphibians and small mammals) from a single terrestrial site in the Chernobyl Exclusion Zone (CEZ). Samples were collected in 2014 from the 0.4 km2 sampling site, located 5 km west of the Chernobyl Nuclear Power complex. We report radionuclide (137Cs, 90Sr, 241Am and Pu-isotopes) and stable element concentrations in wildlife and soil samples and use these to determine whole organism-soil concentration ratios and absorbed dose rates. Increasingly, stable element analyses are used to provide transfer parameters for radiological models. The study described here found that for both Cs and Sr the transfer of the stable element tended to be lower than that of the radionuclide; this is the first time that this has been demonstrated for Sr, though it is in agreement with limited evidence previously reported for Cs. Studies reporting radiation effects on wildlife in the CEZ generally relate observations to ambient dose rates determined using handheld dose meters. For the first time, we demonstrate that ambient dose rates may underestimate the actual dose rate for some organisms by more than an order of magnitude. When reporting effects studies from the CEZ, it has previously been suggested that the area has comparatively low natural background dose rates. However, on the basis of data reported here, dose rates to wildlife from natural background radionuclides within the CEZ are similar to those in many areas of Europe.

Diagnostic impact of preoperative corticosteroids in primary central nervous system lymphoma.

PURPOSE: High dose corticosteroids are an effective tool for rapidly alleviating neurologic symptoms caused by intracranial mass lesions. However, there is concern that preoperative corticosteroids limit the ability to obtain a definitive pathologic diagnosis, particularly if imaging features suggest primary central nervous system lymphoma (PCNSL). METHODS: To explore the impact of preoperative corticosteroids in newly diagnosed PCNSL patients, from 2009 to 2018 treated at our institution. RESULTS: We identified 54 patients; 18 had received corticosteroids prior to biopsy or resection. Only in one case did the patient have a prior non-diagnostic biopsy, requiring a second procedure. The cumulative doses of preoperative dexamethasone ranged from 4 mg to 120 mg (mean 32 mg, median 24 mg), given over 1-14 days (mean 2 days, median 1 day), and the majority had received corticosteroids for only 1-2 days. There was a trend for a larger diameter of lesional T1 contrast enhancement for patients who received steroids (39 mm vs. 34 mm, p = 0.11). In this series of cases with pathologically and clinically proven PCNSL, preoperative corticosteroids had been given in a third of cases, suggesting that they may be given for symptomatic relief without compromising pathologic diagnosis. CONCLUSIONS: Despite the commonly held tenet that preoperative corticosteroids can obscure the pathologic diagnosis in PCNSL, this is likely not the case in the majority of patients who receive a short course preoperatively. Obtaining a second stereotactic scan to confirm continued presence of the lesion prior to tissue sampling may also mitigate these concerns.

Transfer parameters for ICRP's Reference Animals and Plants in a terrestrial Mediterranean ecosystem.

A system for the radiological protection of the environment (or wildlife) based on Reference Animals and Plants (RAPs) has been suggested by the International Commission on Radiological Protection (ICRP). To assess whole-body activity concentrations for RAPs and the resultant internal dose rates, transfer parameters are required. However, transfer values specifically for the taxonomic families defined for the RAPs are often sparse and furthermore can be extremely site dependent. There is also a considerable geographical bias within available transfer data, with few data for Mediterranean ecosystems. In the present work, stable element concentrations (I, Li, Be, B, Na, Mg, Al, P, S, K. Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Cs, Ba, Tl, Pb and U) in terrestrial RAPs, and the corresponding whole-body concentration ratios, CRwo, were determined in two different Mediterranean ecosystems: a Pinewood and a Dehesa (grassland with disperse tree cover). The RAPs considered in the Pinewood ecosystem were Pine Tree and Wild Grass; whereas in the Dehesa ecosystem those considered were Deer, Rat, Earthworm, Bee, Frog, Duck and Wild Grass. The CRwo values estimated from these data are compared to those reported in international compilations and databases.

Do fungi need to be included within environmental radiation protection assessment models?

Fungi are used as biomonitors of forest ecosystems, having comparatively high uptakes of anthropogenic and naturally occurring radionuclides. However, whilst they are known to accumulate radionuclides they are not typically considered in radiological assessment tools for environmental (non-human biota) assessment. In this paper the total dose rate to fungi is estimated using the ERICA Tool, assuming different fruiting body geometries, a single ellipsoid and more complex geometries considering the different components of the fruit body and their differing radionuclide contents based upon measurement data. Anthropogenic and naturally occurring radionuclide concentrations from the Mediterranean ecosystem (Spain) were used in this assessment. The total estimated weighted dose rate was in the range 0.31-3.4 µGy/h (5th-95th percentile), similar to natural exposure rates reported for other wild groups. The total estimated dose was dominated by internal exposure, especially from 226Ra and 210Po. Differences in dose rate between complex geometries and a simple ellipsoid model were negligible. Therefore, the simple ellipsoid model is recommended to assess dose rates to fungal fruiting bodies. Fungal mycelium was also modelled assuming a long filament. Using these geometries, assessments for fungal fruiting bodies and mycelium under different scenarios (post-accident, planned release and existing exposure) were conducted, each being based on available monitoring data. The estimated total dose rate in each case was below the ERICA screening benchmark dose, except for the example post-accident existing exposure scenario (the Chernobyl Exclusion Zone) for which a dose rate in excess of 35 µGy/h was estimated for the fruiting body. Estimated mycelium dose rate in this post-accident existing exposure scenario was close to the 400 µGy/h benchmark for plants, although fungi are generally considered to be less radiosensitive than plants. Further research on appropriate mycelium geometries and their radionuclide content is required. Based on the assessments presented in this paper, there is no need to recommend that fungi should be added to the existing assessment tools and frameworks; if required some tools allow a geometry representing fungi to be created and used within a dose assessment.

The transfer of (137)Cs, Pu isotopes and (90)Sr to bird, bat and ground-dwelling small mammal species within the Chernobyl exclusion zone.

Protected species are the focus of many radiological environmental assessments. However, the lack of radioecological data for many protected species presents a significant international challenge. Furthermore, there are legislative restrictions on destructive sampling of protected species to obtain such data. Where data are not available, extrapolations are often made from 'similar' species but there has been little attempt to validate this approach. In this paper we present what, to our knowledge, is the first study purposefully designed to test the hypothesis that radioecological data for unprotected species can be used to estimate conservative radioecolgical parameters for protected species; conservatism being necessary to ensure that there is no significant impact. The study was conducted in the Chernobyl Exclusion Zone. Consequently, we are able to present data for Pu isotopes in terrestrial wildlife. There has been limited research on Pu transfer to terrestrial wildlife which contrasts with the need to assess radiation exposure of wildlife to Pu isotopes around many nuclear facilities internationally. Our results provide overall support for the hypothesis that data for unprotected species can be used to adequately assess the impacts for ionising radiation on protected species. This is demonstrated for a range of mammalian and avian species. However, we identify one case, the shrew, for which data from other ground-dwelling small mammals would not lead to an appropriately conservative assessment of radiation impact. This indicates the need to further test our hypothesis across a range of species and ecosystems, and/or ensure adequate conservatism within assessments. The data presented are of value to those trying to more accurately estimate the radiation dose to wildlife in the Chernobyl Exclusion Zone, helping to reduce the considerable uncertainty in studies reporting dose-effect relationships for wildlife. A video abstract for this paper is available from: http://bit.ly/1JesKPc.

Strategies for engaging with future radiation protection professionals: a public outreach case study.

It is evident that there is a nuclear skills shortage within the UK, and logically it can be assumed that the shortfall extends to the radiation protection arena. Plans for nuclear new-build and the decommissioning of existing nuclear sites will require many more people with radiological knowledge and practical competencies. This converts to a nuclear industry requirement in the order of 1000 new recruits per year over at least the next ten years, mainly as new apprentices and graduates. At the same time, the strong demand for persons with radiation protection know-how in the non-nuclear and health care sectors is unlikely to diminish. The task of filling this skills gap is a significant one and it will require a determined effort from many UK stakeholders. The Society for Radiological Protection (SRP) has adopted a strategy in recent years to help address this skills gap. The aim is to engage the interest of secondary school students in the science of radiation and inspire them to follow a career in radiation protection. This paper presents the reasoning behind this strategy and, in an 'outreach case study', describes the establishment of the annual SRP Schools Event. This event is becoming an important addition to the national efforts aimed at increasing the numbers of skilled UK radiation protection professionals over the forthcoming decades.

Radionuclide biological half-life values for terrestrial and aquatic wildlife.

The equilibrium concentration ratio is typically the parameter used to estimate organism activity concentrations within wildlife dose assessment tools. Whilst this is assumed to be fit for purpose, there are scenarios such as accidental or irregular, fluctuating, releases from licensed facilities when this might not be the case. In such circumstances, the concentration ratio approach may under- or over-estimate radiation exposure depending upon the time since the release. To carrying out assessments for such releases, a dynamic approach is needed. The simplest and most practical option is representing the uptake and turnover processes by first-order kinetics, for which organism- and element-specific biological half-life data are required. In this paper we describe the development of a freely available international database of radionuclide biological half-life values. The database includes 1907 entries for terrestrial, freshwater, riparian and marine organisms. Biological half-life values are reported for 52 elements across a range of wildlife groups (marine = 9, freshwater = 10, terrestrial = 7 and riparian = 3 groups). Potential applications and limitations of the database are discussed.

Predicting exposure of wildlife in radionuclide contaminated wetland ecosystems.

Many wetlands support high biodiversity and are protected sites, but some are contaminated with radionuclides from routine or accidental releases from nuclear facilities. This radiation exposure needs to be assessed to demonstrate radiological protection of the environment. Existing biota dose models cover generic terrestrial, freshwater, and marine ecosystems, not wetlands specifically. This paper, which was produced under IAEA's Environmental Modelling for Radiation Safety (EMRAS) II programme, describes an evaluation of how models can be applied to radionuclide contaminated wetlands. Participants used combinations of aquatic and terrestrial model parameters to assess exposure. Results show the importance of occupancy factor and food source (aquatic or terrestrial) included. The influence of soil saturation conditions on external dose rates is also apparent. In general, terrestrial parameters provided acceptable predictions for wetland organisms. However, occasionally predictions varied by three orders of magnitude between assessors. Possible further developments for biota dose models and research needs are identified.

Pharmacologic rescue of motor and sensory function by the neuroprotective compound P7C3 following neonatal nerve injury.

Nerve injuries cause pain, paralysis and numbness that can lead to major disability, and newborns often sustain nerve injuries during delivery that result in lifelong impairment. Without a pharmacologic agent to enhance functional recovery from these injuries, clinicians rely solely on surgery and rehabilitation to treat patients. Unfortunately, patient outcomes remain poor despite application of the most advanced microsurgical and rehabilitative techniques. We hypothesized that the detrimental effects of traumatic neonatal nerve injury could be mitigated with pharmacologic neuroprotection, and tested whether the novel neuroprotective agent P7C3 would block peripheral neuron cell death and enhance functional recovery in a rat neonatal nerve injury model. Administration of P7C3 after sciatic nerve crush injury doubled motor and sensory neuron survival, and also promoted axon regeneration in a dose-dependent manner. Treatment with P7C3 also enhanced behavioral and muscle functional recovery, and reversed pathological mobilization of spinal microglia after injury. Our findings suggest that the P7C3 family of neuroprotective compounds may provide a basis for the development of a new neuroprotective drug to enhance recovery following peripheral nerve injury.

A new simplified allometric approach for predicting the biological half-life of radionuclides in reptiles.

A major source of uncertainty in the estimation of radiation dose to wildlife is the prediction of internal radionuclide activity concentrations. Allometric (mass-dependent) relationships describing biological half-life (T1/2b) of radionuclides in organisms can be used to predict organism activity concentrations. The establishment of allometric expressions requires experimental data which are often lacking. An approach to predict the T1/2b in homeothermic vertebrates has recently been proposed. In this paper we have adapted this to be applicable to reptiles. For Cs, Ra and Sr, over a mass range of 0.02-1.5 kg, resultant predictions were generally within a factor of 6 of reported values demonstrating that the approach can be used when measured T1/2b data are lacking. However, the effect of mass on reptilian radionuclide T1/2b is minimal. If sufficient measured data are available for a given radionuclide then it is likely that these would give a reasonable estimate of T1/2b in any reptile species.

Spatial analysis of Carbon-14 dynamics in a wetland ecosystem (Duke Swamp, Chalk River Laboratories, Canada).

A detailed survey was conducted to quantify the spatial distribution of (14)C in Sphagnum moss and underlying soil collected in Duke Swamp. This wetland environment receives (14)C via groundwater pathways from a historic radioactive Waste Management Area (WMA) on Atomic Energy Canada Limited (AECL)'s Chalk River Laboratories (CRL) site. Trends in (14)C specific activities were evaluated with distance from the sampling location with the maximum (14)C specific activity (DSS-35), which was situated adjacent to the WMA and close to an area of groundwater discharge. Based on a spatial evaluation of the data, an east-to-west (14)C gradient was found, due to the influence of the WMA on (14)C specific activities in the swamp. In addition, it was possible to identify two groups of sites, each showing significant exponential declines with distance from the groundwater source area. One of the groups showed relatively more elevated (14)C specific activities at a given distance from source, likely due to their proximity to the WMA, the location of the sub-surface plume originating from the WMA, the presence of marsh and swamp habitat types, which facilitated (14)C transport to the atmosphere, and possibly, (14)C air dispersion patterns along the eastern edge of the swamp. The other group, which had lower (14)C specific activities at a given distance from the groundwater source area, included locations that were more distant from the WMA and the sub-surface plume, and contained fen habitat, which is known to act as barrier to groundwater flow. The findings suggest that proximity to source, groundwater flow patterns and habitat physical characteristics can play an important role in the dynamics of (14)C being carried by discharging groundwater into terrestrial and wetland environments.

An evaluation of the potential drug interaction between warfarin and levothyroxine.

BACKGROUND: Drug interaction references report that initiation of levothyroxine potentiates the effects of warfarin, and recommend more frequent International Normalized Ratio (INR) monitoring, but the mechanism is not well understood. OBJECTIVE: To assess the impact of levothyroxine initiation on INR response. PATIENTS/METHODS: A retrospective, self-controlled study was performed on patients aged ≥ 18 years receiving chronic warfarin therapy who were started on levothyroxine between 1 January 2006 and 30 June 2013, and who were followed for 90 days prior to and after levothyroxine initiation. The included patients had at least one elevated thyroid-stimulating hormone laboratory value in the pre-period, continuous warfarin therapy for 100 days prior to levothyroxine initiation, no purchases of medications known to interact with warfarin, no procedures requiring warfarin interruption, and no bleeding or thromboembolic event during the study period. The primary outcome was a comparison of the warfarin dose/INR ratio recorded before the initiation of levothyroxine with the ratio recorded during the post-period after two consecutive INRs with no warfarin dose change. RESULTS: One hundred and two patients were included in the primary outcome. The mean warfarin dose/INR ratios in the pre-period and post-period were equivalent (P = 0.825). Although the mean warfarin dose was numerically lower in the post-period than in the pre-period, this difference did not reach statistical significance (P = 0.068). CONCLUSION: No difference in the mean warfarin dose/INR ratio before and after initiation of levothyroxine was detected. The results suggest that there is not a clinically significant interaction between warfarin and levothyroxine, and so additional monitoring may not be necessary.

Plutonium in wildlife and soils at the Maralinga legacy site: persistence over decadal time scales.

The mobility of plutonium (Pu) in soils, and its uptake into a range of wildlife, were examined using recent and ∼25 year old data from the Taranaki area of the former Maralinga weapons test site, Australia. Since its initial deposition in the early 1960s, the dispersed Pu has been incorporated into the soil profile and food chain through natural processes, allowing for the study of Pu sequestration and dynamics in relatively undisturbed semi-arid conditions. The data indicate downward mobility of Pu in soil at rates of ∼0.2-0.3 cm per year for the most mobile fraction. As a result, while all of the Pu was initially deposited on the ground surface, approximately 93% and 62% remained in the top 0-2 cm depth after 25- and 50-years respectively. No large-scale lateral spreading of the Taranaki plume was observed. Pu activity concentrations in 0-1 cm soils with biotic crusts were not elevated when compared with nearby bare soils, although a small number of individual data suggest retention of Pu-containing particles may be occurring in some biotic crusts. Soil-to-animal transfer, as measured by concentration ratios (CRwo-soil), was 4.1E-04 (Geometric Mean (GM)) in mammals, which aligns well with those from similar species and conditions (such as the Nevada Test Site, US), but are lower than the GM of the international mammal data reported in the Wildlife Transfer Database (WTD). These lower values are likely due to the presence of a low-soluble, particulate form of the Pu in Maralinga soils. Arthropod concentration ratios (3.1E-03 GM), were similar to those from Rocky Flats, US, while values for reptiles (2.0E-02 GM) were higher than the WTD GM value which was dominated by data from Chernobyl. Comparison of uptake data spanning approximately 30 years indicates no decrease over time for mammals, and a potential increase for reptiles. The results confirm the persistence of bioavailable Pu after more than 50 years since deposition, and also the presence of larger-sized particles which currently affect CRwo-soil calculations, and which may serve as an ongoing source of bioavailable Pu as they are subjected to weathering into the future.

Demonstrating compliance with protection objectives for non-human biota within post-closure safety cases for radioactive waste repositories.

Over recent years, a number of approaches have been developed that enable the calculation of dose rates to animals and plants following the release of radioactivity to the environment. These approaches can be used to assess the potential impacts of activities that may release radioactivity to the environment, such as the operation of waste repositories. A number of national and international studies have identified screening criteria to indicate those assessment results below which further consideration is not generally required. However no internationally agreed criteria are currently available and consistency in criteria between countries has not been achieved. Furthermore, since screening criteria are not intended to be applied as limits, it is clear that they cannot always form a sufficient basis for assessing the adequacy of protection afforded. Typically, exceeding a screening value leads to a regulatory requirement to undertake a further, more detailed assessment. It does not, per se, imply that there is inadequate protection of the organism types at the specific site under assessment. Therefore, there is a need to develop a more structured approach to dealing with situations in which current screening criteria are exceeded. As a contribution to the developing international discussions, and as an interim measure for application where assessments are required currently, a two-tier, three zone framework is proposed here, relevant to the long term assessment of potential impacts from the deep disposal of radioactive wastes. The purpose of the proposed framework is to promote a proportionate and risk-based approach to the level of effort required in undertaking and interpreting an assessment.