Blastopathies and microcephaly in a Chornobyl impacted region of Ukraine

Monochorionic triplet pregnancy complicated by conjoined twins and early twin-twin transfusion syndrome

BACKGROUND

The condition of monozygotic, monochorionic triplet fetuses with a pair of conjoined twins is extremely rare (close to one in a million births), presents challenges in its management, and with poor prognosis.

CASE REPORT

We report a case of monochorionic diamniotic triplet pregnancy, ultrasound at 14 weeks shows a pair of conjoined thoracopagus fetuses, sharing heart, liver, and umbilical cord, in addition to omphalocele. The third fetus, without malformations, presents signs of early heart failure compatible with twin-to-twin transfusion syndrome. It was decided to carry out expectant management where at 18 weeks, intrauterine death of the three fetuses occurs. An abortion is performed by hysterotomy.

CONCLUSIONS

The treatment in these cases is discussed, three management options have been proposed: expectant management, selective reduction of the conjoined fetuses, or termination of the pregnancy. A review of the literature found only 12 cases with this combination of pathologies, in which only 3 normal fetuses (25%) survived and none of the conjoined twins survived. To our knowledge, this case is the first of a monochorionic triplet pregnancy with conjoined fetuses complicated with early twin-to-twin transfusion.

Radioactive releases from the nuclear power sector and implications for child health

Although radioactivity is released routinely at every stage of nuclear power generation, the regulation of these releases has never taken into account those potentially most sensitive-women, especially when pregnant, and children. From uranium mining and milling, to fuel manufacture, electricity generation and radioactive waste management, children in frontline and Indigenous communities can be disproportionately harmed due to often increased sensitivity of developing systems to toxic exposures, the lack of resources and racial and class discrimination. The reasons for the greater susceptibility of women and children to harm from radiation exposure is not fully understood. Regulatory practices, particularly in the establishment of protective exposure standards, have failed to take this difference into account. Anecdotal evidence within communities around nuclear facilities suggests an association between radiation exposure and increases in birth defects, miscarriages and childhood cancers. A significant number of academic studies tend to ascribe causality to other factors related to diet and lifestyle and dismiss these health indicators as statistically insignificant. In the case of a major release of radiation due to a serious nuclear accident, children are again on the frontlines, with a noted susceptibility to thyroid cancer, which has been found in significant numbers among children exposed both by the 1986 Chornobyl nuclear accident in Ukraine and the 2011 Fukushima-Daiichi nuclear disaster in Japan. The response among authorities in Japan is to blame increased testing or to reduce testing. More independent studies are needed focused on children, especially those in vulnerable frontline and Indigenous communities. In conducting such studies, greater consideration must be applied to culturally significant traditions and habits in these communities.

Development of an Adverse Outcome Pathway for radiation-induced microcephaly via expert consultation and machine learning

BACKGROUND

Brain development during embryogenesis and in early postnatal life is particularly complex and involves the interplay of many cellular processes and molecular mechanisms, making it extremely vulnerable to exogenous insults, including ionizing radiation (IR). Microcephaly is one of the most frequent neurodevelopmental abnormalities that is characterized by small brain size, and is often associated with intellectual deficiency. Decades of research span from epidemiological data on in utero exposure of the A-bomb survivors, to studies on animal and cellular models that allowed deciphering the most prominent molecular mechanisms leading to microcephaly. The Adverse Outcome Pathway (AOP) framework is used to organize, evaluate and portray the scientific knowledge of toxicological effects spanning different biological levels of organizations, from the initial interaction with molecular targets to the occurrence of a disease or adversity. In the present study, the framework was used in an attempt to organize the current scientific knowledge on microcephaly progression in the context of ionizing radiation (IR) exposure. This work was performed by a group of experts formed during a recent workshop organized jointly by the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radioecology Alliance (ALLIANCE) associations to present the AOP approach and tools. Here we report on the development of a putative AOP for congenital microcephaly resulting from IR exposure based on discussions of the working group and we emphasize the use of a novel machine-learning approach to assist in the screening of the available literature to develop AOPs.

CONCLUSION

The expert consultation led to the identification of crucial biological events for the progression of microcephaly upon exposure to IR, and highlighted current knowledge gaps. The machine learning approach was successfully used to screen the existing knowledge and helped to rapidly screen the body of evidence and in particular the epidemiological data. This systematic review approach also ensured that the analysis was sufficiently comprehensive to identify the most relevant data and facilitate rapid and consistent AOP development. We anticipate that as machine learning approaches become more user-friendly through easy-to-use web interface, this would allow AOP development to become more efficient and less time consuming.

Prenatal Radiation Exposure Leads to Higher-Order Telencephalic Dysfunctions in Adult Mice That Coincide with Reduced Synaptic Plasticity and Cerebral Hypersynchrony

Higher-order telencephalic circuitry has been suggested to be especially vulnerable to irradiation or other developmentally toxic impact. This report details the adult effects of prenatal irradiation at a sensitive time point on clinically relevant brain functions controlled by telencephalic regions, hippocampus (HPC), and prefrontal cortex (PFC). Pregnant C57Bl6/J mice were whole-body irradiated at embryonic day 11 (start of neurogenesis) with X-ray intensities of 0.0, 0.5, or 1.0 Gy. Female offspring completed a broad test battery of HPC-/PFC-controlled tasks that included cognitive performance, fear extinction, exploratory, and depression-like behaviors. We examined neural functions that are mechanistically related to these behavioral and cognitive changes, such as hippocampal field potentials and long-term potentiation, functional brain connectivity (by resting-state functional magnetic resonance imaging), and expression of HPC vesicular neurotransmitter transporters (by immunohistochemical quantification). Prenatally exposed mice displayed several higher-order dysfunctions, such as decreased nychthemeral activity, working memory defects, delayed extinction of threat-evoked response suppression as well as indications of perseverative behavior. Electrophysiological examination indicated impaired hippocampal synaptic plasticity. Prenatal irradiation also induced cerebral hypersynchrony and increased the number of glutamatergic HPC terminals. These changes in brain connectivity and plasticity could mechanistically underlie the irradiation-induced defects in higher telencephalic functions.

A teratology information system in vernacular: Closing an information gap

BACKGROUND

Leading Teratology Information Systems (TIS) arose in major industrial nations and are mostly in English. The prevalence of anglophone speakers in Ukraine is among the lowest in Europe. A TIS in Ukrainian (UTIS) seeks to diminish an information gap concerning teratogens. The process and results related to UTIS are applicable to formulations of other TIS in vernacular languages.

METHODS

Implementation of a free-access UTIS and analysis of utilization patterns. UTIS provides access to articles in Ukrainian (AU) which are summaries extracted from leading international TIS and other sources. AU are revised at least tri-annually.

RESULTS

UTIS provides access to over 1,100 AU accrued since 2016 to the present. The number AU views increased from nearly 30,000 (2016) to over 80,000 (2020); the number of visitors increased from 3,500 to 58,000 during the same periods. The highest percent of users per urban population (2.09, 1.77, and 1.72) was in Ternopil, Ivano-Frankivsk, and Kyiv (capital), respectively; the lowest was in Odesa (0.17).

CONCLUSIONS

UTIS reduced an information gap in Ukraine concerning teratogenic risk factors. The process can be implemented elsewhere relying on generally available local resources.

Disproportionate Impacts of Radiation Exposure on Women, Children, and Pregnancy: Taking Back our Narrative

Narratives surrounding ionizing radiation have often minimized radioactivity's impact on the health of human and non-human animals and the natural environment. Many Cold War research policies, practices, and interpretations drove nuclear technology forward by institutionally obscuring empirical evidence of radiation's disproportionate and low-dose harm-a legacy we still confront. Women, children, and pregnancy development are particularly sensitive to exposure from radioactivity, suffering more damage per dose than adult males, even down to small doses, making low doses a cornerstone of concern. Evidence of compounding generational damage could indicate increased sensitivity through heritable impact. This essay examines the existing empirical evidence demonstrating these sensitivities, and how research institutions and regulatory authorities have devalued them, willingly sacrificing health in the service of maintaining and expanding nuclear technology (Nadesan 2019). Radiation's disproportionate impacts should now be the research and policy focus, as society is poised to make crucial and long-lasting decisions regarding climate change mitigation and future energy sources (Brown 2019b).

Chornobyl radiation-congenital anomalies: A persisting dilemma

We report population prevalence rates of neural tube defects (NDT) and microcephaly (MIC) as well as levels of incorporated Cs137 by pregnant women in two areas of the Rivne Province of Ukraine, a northern half (Polissia) polluted by Chornobyl radiation and not-Polissia areas. Monitoring of congenital malformations was conducted with adherence to methods adopted by a European surveillance network (EUROCAT). Incorporated Cs137 (Bq/kg) by pregnant women residing in the Polissia and not-Polissia areas were obtained concurrently with prenatal ultrasound examinations. In Polissia, the incorporated Cs137 levels by pregnant women as well as the prevalence rates of NDTs and MIC are significantly higher than in not-Polissia. In Polissia, the prevalence rates of NDTs and MIC are among the highest in Europe. The debate concerning the teratogenic impact of chronic exposures to low levels of ionizing radiation was re-ignited by our 2010 report. Health agencies uphold the notion that exposure to Chornobyl radiation levels are too low to be teratogenic, which is inconsistent with our observations. Further investigations in Rivne by international teams can, we believe, contribute facts to the ongoing debate. Our monitoring system, experience and data can facilitate concurrent investigations of teratogenic risks from exposures to other sources of ionizing radiation, alcohol, folate, and zinc deficiencies, among other risk factors. Study of genomic impacts can likewise be undertaken.

De novo congenital malformation frequencies in children from the Bryansk region following the Chernobyl disaster (2000-2017)

BACKGROUND

Ionizing radiation and chemical pollution can disrupt normal embryonic development and lead to congenital malformations and fetal death. We used official government statistical data for 2000-2017 to test the hypothesis that radioactive and chemical pollutants influenced the frequency of de novo congenital malformations in newborns of the Bryansk region of southwest Russia.

METHODS

A variety of statistical approaches were used to assess congenital malformation frequencies including the Shapiro-Wilk test, White's homoscedasticity test, Wilcoxon T-test, Spearman's rank correlation test, and the inversely proportional regression.

RESULTS

We found that the frequency of polydactyly, multiple congenital malformations, and the frequency of de novo congenital malformations in newborns were significantly higher (p = 0.001-0.054) in regions with elevated radioactive, chemical and combined contamination. Polydactyly, multiple congenital malformations, and the sum of all congenital malformations were 4.7-7.4 times, 2.5-6.8 times, and 3.5-4.6 times higher in contaminated regions in comparison with the control group. The combination of both radioactive and chemical pollutants led to significantly higher frequencies of multiple congenital malformations when compared to regions with only one pollutant (radiation alone: 2.2 times, p = 0.034; chemical pollutants alone: 1.9 times, p = 0.008) implying that the effects of these stressors were at minimum additive. Although there was a trend for decreasing frequencies of multiple congenital malformations during the 2000-2017 period in areas of combined pollution, the opposite was true for regions with radioactive or chemical pollutants alone. However, overall, our models suggest that the frequency of multiple congenital malformations in areas of combined pollution will significantly (p = 0.027) exceed the frequencies observed for regions containing radioactive or chemical pollutants alone by 39.6% and 45.7% respectively, by 2018-2023.

CONCLUSION

These findings suggest additive and potentially synergistic effects of radioactive and chemical pollutants on the frequencies of multiple congenital malformations in the Bryansk region of southwestern Russia.

Abnormal retinal pigment epithelium melanogenesis as a major determinant for radiation-induced congenital eye defects

Recent studies highlighted a link between ionizing radiation exposure during neurulation and birth defects such as microphthalmos and anophthalmos. Because the mechanisms underlying these defects remain largely unexplored, we irradiated pregnant C57BL/6J mice (1.0 Gy, X-rays) at embryonic day (E)7.5, followed by histological and gene/protein expression analyses at defined days. Irradiation impaired embryonic development at E9 and we observed a delayed pigmentation of the retinal pigment epithelium (RPE) at E11. In addition, a reduced RNA expression and protein abundance of critical eye-development genes (e.g. Pax6 and Lhx2) was observed. Furthermore, a decreased expression of Mitf, Tyr and Tyrp1 supported the radiation-induced perturbation in RPE pigmentation. Finally, via immunostainings for proliferation (Ki67) and mitosis (phosphorylated histone 3), a decreased mitotic index was observed in the E18 retina after exposure at E7.5. Overall, we propose a plausible etiological model for radiation-induced eye-size defects, with RPE melanogenesis as a major determining factor.

A detailed characterization of congenital defects and mortality following moderate X-ray doses during neurulation

BACKGROUND

Both epidemiological and animal studies have previously indicated a link between in utero radiation exposure and birth defects such as microphthalmos, anophthalmos, and exencephaly. However, detailed knowledge on embryonic radiosensitivity during different stages of neurulation is limited, especially in terms of neural tube defect and eye defect development.

METHODS

To assess the most radiosensitive stage during neurulation, pregnant C57BL6/J mice were X-irradiated (0.5 Gy or 1.0 Gy) at embryonic days (E)7, E7.5, E8, E8.5, or E9. Next, the fetuses were scored macroscopically for various defects and prenatal resorptions/deaths were counted. In addition, cranial skeletal development was ascertained using the alcian-alizarin method. Furthermore, postnatal/young adult survival was followed until 5 weeks (W5) of age, after X-irradiation at E7.5 (0.1 Gy, 0.5 Gy, or 1.0 Gy). In addition, body and brain weights were registered at adult age (W10) following X-ray exposure at E7.5 (0.1 Gy, 0.5 Gy).

RESULTS

Several malformations, including microphthalmos and exencephaly, were most evident after irradiation at E7.5, with significance starting respectively at 0.5 Gy and 1.0 Gy. Prenatal mortality and weight were significantly affected in all irradiated groups. Long-term follow-up of E7.5 irradiated animals revealed a reduction in survival at 5 weeks of age after high dose exposure (1.0 Gy), while lower doses (0.5 Gy, 0.1 Gy) did not affect brain and body weight at postnatal week 10.

CONCLUSIONS

With this study, we gained more insight in radiosensitivity throughout neurulation, and offered a better defined model to further study radiation-induced malformations and the underlying mechanisms.

Elevated congenital anomaly rates and incorporated cesium-137 in the Polissia region of Ukraine

BACKGROUND

Investigations soon after the 1986 Chornobyl (Chernobyl in Russian) accident of exposed populations residing elsewhere in Europe led government and international agencies to conclude that exposures to cesium-137 (Cs-137) were not teratogenic. Our observations of elevated population rates of neural tube defects (NTDs) and microcephaly and microphthalmia (M/M) in the Rivne Province in Ukraine, which were among the highest in Europe, prompted this follow-up investigation inclusive of whole-body counts (WBCs) of Cs-137 among ambulatory patients and pregnant women residing in Polissia, the most polluted region in Rivne.

METHODS

Yearly (2000-2012) population rates of NTDs and M/M and WBC patterns of ambulatory patients (2001-2010) and pregnant women (2011-2013) in Polissia and non-Polissia regions of Rivne were analyzed.

RESULTS

The NTD and M/M population rates in Rivne remain elevated and are statistically significantly higher in Polissia than in non-Polissia. The WBCs among residents in Polissia are statistically significantly higher than among those from non-Polissia.

CONCLUSION

NTD and M/M rates are highest in the Polissia region of Rivne and are among the highest in Europe. In Polissia, the WBCs of Cs-137 are above officially set permissible upper limits. The results are based on aggregate data of NTDs and M/Ms and average WBC values. Further investigations of causality of the high rates of NTDs and M/Ms are needed and urgent strengthening policies and implementations to reduce exposures to teratogens, in particular radioactive nuclides and alcohol, and consumption of folic acid supplements are indicated.

Genetic radiation risks: a neglected topic in the low dose debate

OBJECTIVES

To investigate the accuracy and scientific validity of the current very low risk factor for hereditary diseases in humans following exposures to ionizing radiation adopted by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection. The value is based on experiments on mice due to reportedly absent effects in the Japanese atomic bomb (Abomb) survivors.

METHODS

To review the published evidence for heritable effects after ionising radiation exposures particularly, but not restricted to, populations exposed to contamination from the Chernobyl accident and from atmospheric nuclear test fallout. To make a compilation of findings about early deaths, congenital malformations, Down's syndrome, cancer and other genetic effects observed in humans after the exposure of the parents. To also examine more closely the evidence from the Japanese A-bomb epidemiology and discuss its scientific validity.

RESULTS

Nearly all types of hereditary defects were found at doses as low as one to 10 mSv. We discuss the clash between the current risk model and these observations on the basis of biological mechanism and assumptions about linear relationships between dose and effect in neonatal and foetal epidemiology. The evidence supports a dose response relationship which is non-linear and is either biphasic or supralinear (hogs-back) and largely either saturates or falls above 10 mSv.

CONCLUSIONS

We conclude that the current risk model for heritable effects of radiation is unsafe. The dose response relationship is non-linear with the greatest effects at the lowest doses. Using Chernobyl data we derive an excess relative risk for all malformations of 1.0 per 10 mSv cumulative dose. The safety of the Japanese A-bomb epidemiology is argued to be both scientifically and philosophically questionable owing to errors in the choice of control groups, omission of internal exposure effects and assumptions about linear dose response.