Long-term Effects Of Radiation Research Articles

Abstract 3059: Heavy ion radiation exposure perturbs intestinal stem cell homeostasis and induces accelerated tumorigenesis in apc mutant mouse intestine

Abstract In a previous study, we demonstrated long-term decreased intestinal epithelial cell migration after low-dose heavy ion iron radiation, and this was associated with increased senescence-associated secretory phenotype (SASP) signaling. However, we know very little about the long-term effects of low dose space radiation on intestinal stem cell (ISC) senescence and SASP that have implications for intestinal homeostasis. Male Lgr5+ (Lgr5-EGFP-IRES-creERT) mice or Lgr5+/APC1638N/+ were exposed to 0.5 Gy of sham, γ-rays, or 28Si (69 keV/μm) radiation and were euthanized 60 or 150 days after irradiation. ISCs were FACS sorted for oxidative stress analysis and assessed for senescence and SASP signaling in tissue sections by immunostaining. Greater cellROX or mitoSOX staining was observed after 28Si indicating higher oxidative stress compared to γ-rays or control Lgr5 positive cells. β-gal co-staining with Lgr5, lysozyme, IL1R, or ILβ showed highest staining in 28Si irradiated compared to controls ISCs samples. γ-H2AX staining showed greater foci numbers in 28Si relative to γ-rays or control group. Higher expression of secretory cytokines IL8 and IL15 was observed in 28Si irradiated ISCs relative to γ-rays or control group at both time points. Elevated expression of DKK2 and activation of NF-κB and p38 MAPK were observed in senescent stem cells of 28Si irradiated relative to γ-rays or control group at these time points. A higher GI tumor count was observed in 28Si compared to γ-irradiated or control Lgr5+/APC1638N/+ mice. In summary, our results demonstrate low dose heavy ion exposure induces ongoing DNA damage, persistent oxidative stress, senescence and acquisition of the SASP in ISCs. Higher levels of oxidative stress, senescence and SASP were observed at 150 compared to the 60-day timepoint. Overall, space radiation-induced oxidative stress, senescence, SASP, and activated p38MAPK/NF-κB pathway may very well have implications in GI carcinogenesis, accelerated aging, and pathological conditions, such as intestinal dysfunction, in astronauts during deep space flights. Since similar effects have been seen in our studies with other particle beams including carbon ions, this has potential relevance to particle radiotherapy as well. This work was supported by NASA NNX15AI21G Citation Format: Santosh Kumar, Shubhankar Suman, Kamal Datta, Albert J. Fornace. Heavy ion radiation exposure perturbs intestinal stem cell homeostasis and induces accelerated tumorigenesis in apc mutant mouse intestine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3059.

Combined Coronary Artery Bypass Grafting and Transcatheter Aortic Valve Replacement in a Patient with Severe Post-Radiation Damage

Chest radiotherapy is a common treatment for mediastinal malignancy. The long-term effect of radiation can harm several of cardiovascular structures including pericardium, myocardium, valvular system, conduction system, and coronary arteries. Cardiovascular disease is the most common non-malignancy cause of death in radiation-treated patient, most often occurs many years after treatment. Valvular heart disease secondary to mediastinal radiation mainly affect the aortic and mitral valves. We present a unique case of 58 years old women with history of past mediastinal radiotherapy who presented with few episodes of true syncope, complete AV block, severe aortic stenosis and significant ostial left main and ostial right coronary artery disease.

Evaluating the long-term effect of space radiation on the reproductive normality of mammalian sperm preserved on the International Space Station.

Space radiation may cause DNA damage to cells and concern for the inheritance of mutations in offspring after deep space exploration. However, there is no way to study the long-term effects of space radiation using biological materials. Here, we developed a method to evaluate the biological effect of space radiation and examined the reproductive potential of mouse freeze-dried spermatozoa stored on the International Space Station (ISS) for the longest period in biological research. The space radiation did not affect sperm DNA or fertility after preservation on ISS, and many genetically normal offspring were obtained without reducing the success rate compared to the ground-preserved control. The results of ground x-ray experiments showed that sperm can be stored for more than 200 years in space. These results suggest that the effect of deep space radiation on mammalian reproduction can be evaluated using spermatozoa, even without being monitored by astronauts in Gateway.

Early postnatal irradiation\u2010induced age\u2010dependent changes in adult mouse brain: MRI based characterization

BackgroundBrain radiation exposure, in particular, radiotherapy, can induce cognitive impairment in patients, with significant effects persisting for the rest of their life. However, the main mechanisms leading to this adverse event remain largely unknown. A study of radiation-induced injury to multiple brain regions, focused on the hippocampus, may shed light on neuroanatomic bases of neurocognitive impairments in patients. Hence, we irradiated BALB/c mice (male and female) at postnatal day 3 (P3), day 10 (P10), and day 21 (P21) and investigated the long-term radiation effect on brain MRI changes and hippocampal neurogenesis.ResultsWe found characteristic brain volume reductions in the hippocampus, olfactory bulbs, the cerebellar hemisphere, cerebellar white matter (WM) and cerebellar vermis WM, cingulate, occipital and frontal cortices, cerebellar flocculonodular WM, parietal region, endopiriform claustrum, and entorhinal cortex after irradiation with 5 Gy at P3. Irradiation at P10 induced significant volume reduction in the cerebellum, parietal region, cingulate region, and olfactory bulbs, whereas the reduction of the volume in the entorhinal, parietal, insular, and frontal cortices was demonstrated after irradiation at P21. Immunohistochemical study with cell division marker Ki67 and immature marker doublecortin (DCX) indicated the reduced cell division and genesis of new neurons in the subgranular zone of the dentate gyrus in the hippocampus after irradiation at all three postnatal days, but the reduction of total granule cells in the stratum granulosun was found after irradiation at P3 and P10.ConclusionsThe early life radiation exposure during different developmental stages induces varied brain pathophysiological changes which may be related to the development of neurological and neuropsychological disorders later in life.

Long-Term Effects of Very Low Dose Particle Radiation on Gene Expression in the Heart: Degenerative Disease Risks

Compared to low doses of gamma irradiation (γ-IR), high-charge-and-energy (HZE) particle IR may have different biological response thresholds in cardiac tissue at lower doses, and these effects may be IR type and dose dependent. Three- to four-month-old female CB6F1/Hsd mice were exposed once to one of four different doses of the following types of radiation: γ-IR 137Cs (40-160 cGy, 0.662 MeV), 14Si-IR (4-32 cGy, 260 MeV/n), or 22Ti-IR (3-26 cGy, 1 GeV/n). At 16 months post-exposure, animals were sacrificed and hearts were harvested and archived as part of the NASA Space Radiation Tissue Sharing Forum. These heart tissue samples were used in our study for RNA isolation and microarray hybridization. Functional annotation of twofold up/down differentially expressed genes (DEGs) and bioinformatics analyses revealed the following: (i) there were no clear lower IR thresholds for HZE- or γ-IR; (ii) there were 12 common DEGs across all 3 IR types; (iii) these 12 overlapping genes predicted various degrees of cardiovascular, pulmonary, and metabolic diseases, cancer, and aging; and (iv) these 12 genes revealed an exclusive non-linear DEG pattern in 14Si- and 22Ti-IR-exposed hearts, whereas two-thirds of γ-IR-exposed hearts revealed a linear pattern of DEGs. Thus, our study may provide experimental evidence of excess relative risk (ERR) quantification of low/very low doses of full-body space-type IR-associated degenerative disease development.

Long-term behavior of normal weight concrete containing hybrid nanoparticles subjected to gamma radiation

Since a lot of medical facilities are made from normal weight concrete (NWC), it became an important task to improve the radiation shielding properties of such concrete in a confrontation to radiation with special emphasis on gamma radiation type. Therefore, an experimental program was conducted to investigate the effect of nanoparticles addition on gamma radiation shielding, physical properties, and mechanical properties of NWC. Nano silica (NS), nano hematite (NH), nano titania (NT), and their hybridization were added to NWC with four different percentages of 0.5, 0.75, 1.0, and 2.0% from the cement weight. A total of sixteen concrete mixes with nanoparticles in addition to a control mix were made. The long-term effects of gamma radiation on samples representing all concrete mixes were studied to find out the consequence of exposure to gamma rays over long periods (250 and 500 days) on their mechanical properties. The experimental results showed that the single addition of each of NS, NH, or NT particles and their combination up to 2.0% improved the physical properties, compressive strength, and attenuation coefficient of NWC. The results of the hybrid nano addition showed that the synergistic phenomenon occurred in some cases. Furthermore, the scanning electron microscopy technique (SEM) was used to prove the enhancement in the microstructure of NWC as a result of the addition of NS, NH, NT, and their combination.

A Process for the Synthesis and Use of Highly Aromatic Organosilanes as Additives for Poly(Vinyl Chloride) Films

Three organosilanes were synthesized in good yields from the condensation of 4,4′,4″-((phenylsilanetriyl)tris(oxy))tribenzaldehyde and 4-substituted anilines under acidic conditions. The structure of the organosilanes was confirmed using a variety of techniques. Organosilanes were mixed with poly(vinyl chloride) (PVC) and homogenous films were produced. The effect of long-term irradiation on the films containing organosilanes was tested using various methods. Monitoring the infrared spectra of PVC films before, during and after irradiation processes showed the formation of side products comprising polyene, carbonyl and hydroxyl groups. The intensities of absorption bands due to these functional groups were much lower in the presence of organosilanes as compared to the blank film. Also, the decrease in the weight and molecular weight of PVC films after irradiation was lower in the presence of organosilanes. Additionally, there was a minimal surface change of irradiated PVC in the presence of organosilanes. Clearly, organosilanes act as inhibitors, particularly the one containing the hydroxyl group, for the photodegradation of PVC. Different mechanisms were proposed to speculate the role played by organosilanes in stabilizing PVC against long-term ultraviolet light exposure.

Stigma perceptions, social media neighborhood storytelling, and future outlook in post-disaster Fukushima

ABSTRACT After more than nine years since the Great East Japan Earthquake struck Japan,the unresolved situation in FukushimaNuclear Power Plant and long-term effects of radiation continue to situate residents of Fukushima under the post-disaster context. This study examined the influence of Fukushima residents’ stigma perception and connectedness to offline and online neighborhood storytelling networks on future outlook. Based on an online survey of 936 Fukushima residents, the study found that residents who perceive higher stigma toward Fukushima from outsiders were more likely to have a negative future outlook than others. On the other hand, residents’ connectedness to the neighborhood storytelling network – consisting of interpersonal conversation, connectedness to community organizations andlocal media – was positively related to future outlook. With regard to online communication, people who engage in expressive storytelling about local affairs on social media, such as uploading stories or sharing information, were more likely to have a positive future outlook than others. Moreover, expressive storytelling about local affairs on social media was found to moderate the effect of stigma on future outlook: the negative effect of stigma on future outlook was mitigated for those who engage in expressive storytelling about local affairs. Implications of the results are discussed.

RBIO-06. IMPLEMENTATION OF HUMAN INDUCED PLURIPOTENT STEM CELL DERIVED CEREBRAL ORGANOIDS TO MODEL NORMAL TISSUE RADIORESPONSE

Abstract Treatment-related sequelae following cranial irradiation have life changing impacts for patients and their caregivers. Characterization of the basic response of human brain tissue to irradiation has been difficult due to a lack of preclinical models. The direct study of human brain tissue in vitro is becoming possible due to advances in stem cell biology, neuroscience, and tissue engineering with the development of organoids as novel model systems which enable experimentation with human tissue models. We sought to establish a cerebral organoid (CO) model to study the radioresponse of normal human brain tissue. COs were grown using human induced pluripotent stem cells and a modified Lancaster protocol. Compositional analysis during development of the COs showed expected populations of neurons and glia. We confirmed a population of microglia-like cells within the model positive for the makers Iba1 and CD68. After 2-months of maturation, COs were irradiated to 0, 10, and 20 Gy using a Shepard Mark-II Cs-137 irradiator and returned to culture. Subsets of COs were prepared for immunostaining at 30- and 70-days post-irradiation. To examine the effect of irradiation on the neural stem cell (NSC) population, sections were stained for SOX2 and Ki-67 expression denoting NSCs and proliferation respectively. Slides were imaged and scored using the CellProfiler software package. The percentage of proliferating NSCs 30-days post-irradiation was found to be significantly reduced for irradiated COs (5.7% (P=0.007) and 3.4% (P=0.001) for 10 and 20 Gy respectively) compared to control (12.7%). The reduction in the proliferating NSC population subsequently translated to a reduced population of NeuN-labeled mature neurons 70 days post-irradiation. The loss of proliferating NSCs and subsequent reduction in mature neurons demonstrates the long-term effects of radiation. Our initial results indicate COs will be a valuable model to study the effects of radiation therapy on normal and diseased human tissue.

Are Vegetation Dynamics Impacted from a Nuclear Disaster? The Case of Chernobyl Using Remotely Sensed NDVI and Land Cover Data

There is a growing interest for scientists and society to acquire deep knowledge on the impacts from environmental disasters. The present work deals with the investigation of vegetation dynamics in the Chernobyl area, a place widely known for the devastating nuclear disaster on the 26th of April 1986. To unveil any possible long-term radiation effects on vegetation phenology, the remotely sensed normalized difference vegetation index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) was analyzed within the 30 km Exclusion Zone, where all human activities were ceased at that time and public access and inhabitation have been prohibited ever since. The analysis comprised applications of seasonal trend analysis using two techniques, i.e., pixel-wise NDVI time series and spatially averaged NDVI time series. Both techniques were applied in each one of the individual land cover types. To assess the existence of abnormal vegetation dynamics, the same analyses were conducted in two broader zones, i.e., from 30 to 60 km and from 60 to 90 km, away from Chernobyl area, where human activities were not substantially altered. Results of both analyses indicated that vegetation dynamics in the 30 km Exclusion Zone correspond to increasing plant productivity at a rate considerably higher than that of the other two examined zones. The outcome of the analyses presented herein attributes greening trends in the 30 km and the 30 to 60 km zones to a combination of climate, minimized human impact and a consequent prevalence of land cover types which seem to be well adapted to increased radioactivity. The vegetation greening trends observed in the third zone, i.e., the 90 km zone, are indicative of the combination of climate and increasing human activities. Results indicate the positive impact from the absence of human activities on vegetation dynamics as far as vegetation productivity and phenology are concerned in the 30 km Exclusion Zone, and to a lower extent in the 60 km zone. Furthermore, there is evidence that land cover changes evolve into the prevalence of woody vegetation in an area with increased levels of radioactivity.

Иммунный статус человека в отдалённом периоде хронического радиационного воздействия

Purpose: Assessment of major parameters of the system immunity in 376 Techa riverside residents affected by external γ- and internal (mainly due to 90Sr) irradiation 60–68 years after the onset of exposure.
 Material and methods: The study involved 376 residents of the settlements located in the basin of the Techa River which was contaminated due to releases of liquid radioactive waste of Mayak Production Association. Red bone marrow received the largest doses that reached 4457.1 mGy, mean dose value was 1080.8 ± 38.4 mGy. Doses to the thymus and peripheral organs of the immune system in the exposed individuals were much lower; mean dose value was 65.3 ± 4.9 mGy. The study of the systemic immunity included the analysis of the parameters that characterize functional status of adaptive and innate immunity, as well as of the cytokine system.
 Results: Pro-inflammatory changes of the cytokines spectrum (decrease of IL-4 in blood serum, increase of TNFα and IFNγ) were observed in exposed people with a background of involution changes.
 Conclusion: Persistent reduction in the number of neutrophils in blood against normal levels of granulocyte colony-stimulating and granulocyte-macrophage colony-stimulating factors in blood serum could be indicative of certain inefficiency of hematopoietic stem cell pool. The most distinct features of immunity in exposed persons concerned the cytokine spectrum which were inflammatory in nature and on the one hand could be involved in the mechanisms of development of long-term effects of radiation and on the other could have a protective effect on the protection of the body from cells carrying sublethal abnormalities.

Long-term effects of latitude, ambient temperature, and ultraviolet radiation on the incidence of multiple sclerosis in two cohorts of US women.

Differences in multiple sclerosis (MS) risk by latitude have been observed worldwide; however, the exposures driving these associations are unknown. Ultraviolet radiation (UV) has been explored as a risk factor, and ambient temperature has been correlated with disease progression. However, no study has examined the impact of all three exposures. We examined the association between these exposures and incidence of MS within two nationwide prospective cohorts of women, the Nurses' Health Study (NHS) and Nurses' Health Study II (NHSII). Both cohorts were followed with biennial questionnaires to ascertain new diagnoses and risk factors. Time-varying exposures to latitude, cumulative average July temperature (°C), and cumulative average July erythemal UV (mW/m2) were predicted at each participant's biennially updated residential addresses. Using Cox proportional hazards models adjusted for MS risk factors, we calculated hazard ratios (HR) and 95% confidence intervals (CIs) within each cohort and pooled via meta-analyses. In multivariable models, there were suggestions that decreasing latitude (meta-analysis multivariable-adjusted HR = 0.72; 95% CI 0.55, 0.94 for women living <35.73° compared with those ≥42.15°, P-for-trend = 0.007) and increasing cumulative average July temperature (meta-analysis multivariable-adjusted HR = 0.81; 95% CI 0.72, 0.91 for each interquartile range increase [3.91°]) were associated with decreasing risk of MS. There was no evidence of heterogeneity between cohorts. We did not observe consistent associations with cumulative average UV. Our results suggest that adult exposures to decreasing latitude and increasing temperature, but not UV, were associated with reduced MS risk in these two cohorts of women. Studies of MS incidence may want to consider temperature as a risk factor.

Transcriptional Changes in the Ovaries of Perch from Chernobyl.

Fish have been highly exposed to radiation in freshwater systems after the Chernobyl Nuclear Power Plant (NPP) accident in 1986 and in freshwater and marine systems after the more recent Fukushima NPP accident in 2011. In the years after the accident, the radioactivity levels rapidly declined due to radioactive decay and environmental processes, but chronic lower dose exposures persisted. To gain insights into the long-term effects of environmental low dose radiation on fish ovaries development, a high-throughput transcriptomic approach including a de novo assembly was applied to different gonad phenotypes of female perch: developed gonads from reference lakes, developed/irradiated from medium contaminated lake, and both developed/irradiated and undeveloped from more highly contaminated lakes. This is the most comprehensive analysis to date of the gene responses in wildlife reproductive system to radiation. Some gene responses that were modulated in irradiated gonads were found to be involved in biological processes including cell differentiation and proliferation (ggnb2, mod5, rergl), cytoskeleton organization (k1C18, mtpn), gonad development (nell2, tcp4), lipid metabolism (ldah, at11b, nltp), reproduction (cyb5, cyp17A, ovos), DNA damage repair (wdhd1, rad51, hus1), and epigenetic mechanisms (dmap1). Identification of these genes provides a better understanding of the underlying molecular mechanisms underpinning the development of the gonad phenotypes of wild perch and how fish may respond to chronic exposure to radiation in their natural environment, though causal attribution of gene responses remains unclear in the undeveloped gonads.

Effect of Si–Ni–P on the emergence of dislocations loops in Fe–9Cr matrix under neutron irradiation: TEM study and OKMC modelling

The expected degradation of mechanical properties of structural materials under irradiation (i.e. “in operation”) in nuclear components represents a significant challenge for the design to account the impact of long-term irradiation effects. Therefore, a development of scientific and engineering expertise to understand and possibly control the severe impact of harsh neutron irradiation on materials is one of the tasks in the current material’s research agenda. As it is well known from long-standing experience with fission systems, radiation embrittlement is caused by nano-scale features that obstruct plasticity mediated by dislocations. The present contribution highlights recent research and development efforts addressed towards the assessment of the interrelation between nano-structural features and hardening induced by neutron irradiation in fusion structural high-Cr ferritic/martensitic steels.In this work, the impact of doping by three chemical elements (nickel, silicon and phosphorus) on the microstructural evolution under neutron irradiation at 300 °C and 450 °C is studied experimentally as well as by computer simulations. The evolution of microstructure is assessed by transmission electron microscopy and object kinetic Monte Carlo simulations. The latter method utilizes a new approach enabling to follow both nano-scale irradiation defects and micro-segregation zones causing the formation of solute rich clusters, detectable by atom probe tomography. The results of the present work clearly point out that Ni–Si segregation alters the spatial and size distribution of dislocations loops already at as low dose as 0.1 dpa. The physical mechanisms behind the impact of minor alloying elements are discussed.

Short- and Long-Term Effects of X-ray Synchrotron Radiation on Cotton Paper.

X-ray analytical techniques are increasingly being used to study manuscripts and works of art on paper, whether with laboratory equipment or synchrotron sources. However, it is difficult to anticipate the impact of X-ray photons on paper- and cellulose-based artifacts, particularly due to the large variety of their constituents and degradation levels, and the subsequent material multiscale heterogeneity. In this context, this work aims at developing an analytical approach to study the modifications in paper upon synchrotron radiation (SR) X-ray radiation using analytical techniques, which are fully complementary and highly sensitive, yet not frequently used together. At the molecular scale, cellulose chain scissions and hydroxyl free radicals were measured using chromatographic separation techniques (size-exclusion chromatography-multiangle laser light scattering-differential refractive index (SEC-MALS-DRI) and reversed-phase high-performance liquid chromatography-fluorescence detector-diode array detector (RP-HPLC-FLD-DAD)), while the optical properties of paper were characterized using spectroscopy (UV luminescence and diffuse reflectance). These techniques showed different sensitivities toward the detection of changes. The modifications in the cellulosic material were monitored in real time, within a few days, and up to 2 years following the irradiation to define a lowest observed adverse effect dose (LOAED). As paper is a hygroscopic material, the impact of the humidity in the environment was studied using this approach. Three levels of moisture content in the paper, achieved by conditioning the samples and irradiating them at different relative humidities (RHs), were studied (0, 50, 80% RH). It was shown that very low moisture content accelerated molecular and optical modifications.

The long-term effects of exposure to ionising radiation on gene expression in mice

Despite great advancement in our understanding of the biological response to ionising radiation in mammals, a number of pertinent questions remain unanswered. For instance, the mechanisms underlying the long-term effects of acute radiation in vivo still eludes us. Here we report that acute exposure to X-rays in male mice significantly affects their transcriptome. Using microarrays and miRNA-sequencing, we profiled the gene expression pattern in the brain, the kidney, the liver and the sperm of irradiated and control from CBA/Ca and BALB/c in the timeline of 4 h, 24 h, 1 week and 10 weeks post-exposure. Acute exposure to 1 Gy of X-rays resulted in profound tissue- and strain-specific changes in gene expression pattern. There was profound change in the gene expression in the kidney of BALB/c irradiated mice over the period of 10 weeks after irradiation, whereas in the CBA/Ca strain the significant transcriptomic changes manifest over a shorter period of time up to 1 week post exposure. In the brain of irradiated CBA/Ca, significant changes in transcriptome were seen up to 10 weeks post-irradiation, while only short-term changes up to 4 h post-exposure was detected in the brain of irradiation BALB/c. Similarly, alteration in gene expression pattern was observed in the liver of irradiated BALB/c up to 10 weeks post-radiation, whereas only immediate but significant changes were observed in the CBA/Ca at 4 h post-irradiation. Furthermore, the analysis of miRNA in irradiated and control male mice also revealed highly tissue- and strain-specific changes in expression level, with no overlap between the differentially regulated miRNA genes across the three somatic tissues and the two inbred strains. We also analysed the pattern of miRNA expression in sperm of irradiated males, sacrificed at 24 h, 1 week and 10 weeks after irradiation. Only one miRNA (mmu-miR-217−5p) was significantly down-regulated in the CBA/Ca males. The results of our study may provide a plausible explanation for the delayed in vivo effects of irradiation.

The Crystallinity of Apatite in Contact with Metamict Pyrochlore from the Silver Crater Mine, ON, Canada

The purpose of this work is to evaluate the long-term effects of radiation on the structure of naturally occurring apatite in the hope of assessing its potential for use as a solid nuclear waste form for actinide sequestration over geologically relevant timescales. When a crystal is exposed to radioactivity from unstable constituent atoms undergoing decay, the crystal’s structure may become damaged. Crystalline materials rendered partially or wholly amorphous in this way are deemed “partially metamict” or “metamict” respectively. Intimate proximity of a non-radioactive mineral to a radioactive one may also cause damage in the former, evident, for example, in pleochroic haloes surrounding zircon inclusions in micas. Radiation damage may be repaired through the process of annealing. Experimental evidence suggests that apatite may anneal during alpha particle bombardment (termed “self-annealing”), which, combined with a low solubility in aqueous fluids and propensity to incorporate actinide elements, makes this mineral a promising phase for nuclear waste storage. Apatite evaluated in this study occurs in a Grenville-aged crustal carbonatite at the Silver Crater Mine in direct contact with U-bearing pyrochlore (var. betafite)—a highly radioactive mineral. Stable isotope analyses of calcite from the carbonatite yield δ18O and δ13C consistent with other similar deposits in the Grenville Province. Although apatite and betafite imaged using cathodoluminescence (CL) show textures indicative of fracture-controlled alteration, Pb isotope analyses of betafite from the Silver Crater Mine reported in previous work are consistent with a model of long term Pb loss from diffusion, suggesting the alteration was not recent. Thus, it is interpreted that these minerals remained juxtaposed with no further metamorphic overprint for ≈1.0 Ga, and therefore provide an ideal opportunity to study the effects of natural, actinide-sourced radiation on the apatite structure over long timescales. Through broad and focused X-ray beam analyses and electron backscatter diffraction (EBSD) mapping, the pyrochlore is shown to be completely metamict—exhibiting no discernible diffraction associated with crystallinity. Meanwhile, apatite evaluated with these methods is confirmed to be highly crystalline with no detectable radiation damage. However, the depth of α-decay damage is not well-understood, with reported depths ranging from tens of microns to just a few nanometers. EBSD, a surface sensitive technique, was therefore used to evaluate the crystallinity of apatite surfaces which had been in direct contact with radioactive pyrochlore, and the entire volume of small apatite crystals whose cores may have received significant radiation doses. The EBSD results demonstrate that apatite remains crystalline, as derived from sharp and correctly-indexed Kikuchi patterns, even on surfaces in direct contact with a highly radioactive source for prolonged periods in natural systems.

How Precision Medicine Might Better Serve Downwinders.

Despite the advances in developing nuclear weapons and other technologies, not much is known about the long-term effects of radiation on human health. In a world where nuclear energy could help curb carbon emissions, it almost seems paradoxical that its possible long-term risks and impacts to human health are still poorly understood. While researchers have investigated the effects of acute radiation in the aftermath of nuclear incidents such as Chernobyl, Hiroshima, Nagasaki, and Fukushima, more needs to be done to understand the impacts of long-term and low-dose nuclear radiation. Studying the downwinders from the Nevada Test Site could offer one window to investigate those myriad effects.

Absorbed radiation doses in the thyroid as estimated by UNSCEAR and subsequent risk of childhood thyroid cancer following the Great East Japan Earthquake.

The identification of thyroid cancers among children after the Chernobyl nuclear power plant accident propelled concerns regarding long-term radiation effects on thyroid cancer in children affected by the Fukushima Daiichi nuclear power plant accident in Fukushima, Japan. Herein we consider the potential association between absorbed dose in the thyroid and the risk of developing thyroid cancer as detected by ultrasonography on 300 473 children and adolescents aged 0–18 years in Fukushima. The absorbed dose mentioned in the present study indicates the sum of that from external exposure and that from internally deposited radionuclides. We grouped participants according to estimated absorbed doses in each of 59 municipalities in Fukushima Prefecture, based on The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2013 report. The 59 municipalities were assigned to quartiles by dose. We limited our analyses to participants aged ≥6 years because only one case of thyroid cancer was observed in participants aged ≤5 years; 164 299 participants were included in the final analysis. Compared with the lowest dose quartile, the age- and sex-adjusted rate ratios (95% confidence intervals) for the low-middle, high-middle and highest quartiles were 2.00 (0.84–4.80), 1.34 (0.50–3.59) and 1.42 (0.55–3.67) for the 6–14-year-old groups and 1.99 (0.70–5.70), 0.54 (0.13–2.31) and 0.51 (0.12–2.15) for the >15-year-old group, respectively. No dose-dependent pattern emerged from the geographical distribution of absorbed doses by municipality, as estimated by UNSCEAR, and the detection of thyroid cancer among participants within 4–6 years after the accident. Ongoing surveillance might further clarify the effects of low-dose radiation exposure on thyroid cancer in Fukushima.

RADIATION DAMAGE OF THE NERVOUS SYSTEM AND ENDOCANABINOIDS.

The review analyzes the change of the existing paradigm of high radioresistance of the nervous system according tothe results of the study of neuropsychiatric disorders in in the aftermath of the Chornobyl accident in both earlyand remote post-accident period. The participation of the endocannabinoid system in ensuring homeostasis andpathology formation, potential possibilities of using cannabis drugs, agonists and antagonists of endocannabinoidreceptors for the treatment of early and long-term effects of radiation are considered.