Mayak Production Association Workers Research Articles

The risk of infant mortality among the offspring of the workers of radiation hazardous production

Infant mortality is an indicator of healthcare quality and social well-being in a society and could be used as an important parameter in assessing the effects produced by parental occupational exposures on the offspring health. The objective of the study: to analyze the risk of infant mortality in the cohort of the 1st generation offspring of the workers of Mayak Production Association (PA), the first atomic production facility in Russia. Infant mortality and its components were analyzed in a cohort of children (n = 24,780) born in 1949–1973; the main group comprised 14,435 offspring of Mayak PA workers; the comparison group contained 10,345 children of unexposed parents. Incidence and relative risk of early and late neonatal, postneonatal and infant mortality were assessed taking into account the offspring sex, calendar period of birth, nosologies, parental age, categories of accumulated doses of parental preconception occupational exposure. Relative risk was calculated with 95 % confidence interval. A higher incidence of postneonatal and infant mortality as a whole was established among the offspring of unexposed parents. Infectious pathology as a cause of death was registered among the offspring of Mayak PA workers statistically significantly less often than in the comparison group. Infant mortality rate in the main group was lower in parental age categories of 21–25 and 31–35 years as well as among younger fathers. A higher rate of infant mortality in certain categories of accumulated doses of occupational preconception gamma-exposure was caused by the contribution of infectious nosologies. Infant mortality due to malignant neoplasms in the main group requires further epidemiological analysis. A retrospective analysis demonstrated higher rates of infant mortality and of its components among the children of un-exposed parents that could be possibly explained through the “healthy worker effect” and better social well-being of Mayak PA personnel.

Риск младенческой смертности среди потомков работников радиационно-опасного производства

Infant mortality is an indicator of healthcare quality and social well-being in a society and could be used as an important parameter in assessing the effects produced by parental occupational exposures on the offspring health. The objective of the study: to analyze the risk of infant mortality in the cohort of the 1st generation offspring of the workers of Mayak Production Association (PA), the first atomic production facility in Russia. Infant mortality and its components were analyzed in a cohort of children (n = 24,780) born in 1949–1973; the main group comprised 14,435 offspring of Mayak PA workers; the comparison group contained 10,345 children of unexposed parents. Incidence and relative risk of early and late neonatal, postneonatal and infant mortality were assessed taking into account the offspring sex, calendar period of birth, nosologies, parental age, categories of accumulated doses of parental preconception occupational exposure. Relative risk was calculated with 95 % confidence interval. A higher incidence of postneonatal and infant mortality as a whole was established among the offspring of unexposed parents. Infectious pathology as a cause of death was registered among the offspring of Mayak PA workers statistically significantly less often than in the comparison group. Infant mortality rate in the main group was lower in parental age categories of 21–25 and 31–35 years as well as among younger fathers. A higher rate of infant mortality in certain categories of accumulated doses of occupational preconception gamma-exposure was caused by the contribution of infectious nosologies. Infant mortality due to malignant neoplasms in the main group requires further epidemiological analysis. A retrospective analysis demonstrated higher rates of infant mortality and of its components among the children of un-exposed parents that could be possibly explained through the “healthy worker effect” and better social well-being of Mayak PA personnel.

Risk of central nervous system tumour incidence in a cohort of workers chronically exposed to ionising radiation.

The aim of the present study was to assess the risk of primary central nervous system (CNS) tumour incidence in a cohort of 22,377 Mayak Production Association workers chronically exposed to ionising radiation. There were 96 primary CNS tumours, including 42 cases of glioma and 44 cases of meningioma, registered during the whole follow-up period (1948-2018). The study demonstrated that the risk of primary CNS tumour incidence was associated with sex, attained age, calendar period, tall body height, age at the beginning of exposure, and facility type. There was no association found between risk of CNS tumour incidence and body mass index, smoking (males) and alcohol consumption status. The study did not find an effect of the total external gamma radiation dose absorbed in the brain on risk of CNS tumour incidence irrespective of whether an adjustment for the total external neutron dose absorbed in the brain was included or not. Excess relative risk per 1Gy of external gamma brain dose was 0.05 (95% confidence interval (CI) -0.30; 0.70) for all CNS tumours, -0.18 (95% CI -; 0.44) for gliomas, and 0.38 (95% CI -0.32; 2.08) for meningiomas without adjustment for total neutron brain dose. There was no effect modification by sex, attained age, age at hire or facility.

ФАКТОРЫ РИСКА ЗАБОЛЕВАЕМОСТИ РАКОМ ПИЩЕВОДА В КОГОРТЕ РАБОТНИКОВ ПРЕДПРИЯТИЯ АТОМНОЙ ПРОМЫШЛЕННОСТИ

Purpose: To assess the influence of non-radiation factors and occupational radiation exposure on the incidence risk of esophageal cancer in nuclear workers considering various histological types of the cancer. Material and methods: The study was designed as a retrospective analysis that considered data on the cohort of workers employed at reactors, radiochemical and plutonium production facilities of the Mayak Production Association (PA) who had been hired during 1948–1982. The total number of workers included in the cohort was 21645. Using the EPICURE software, the relative risk (RR) and excess relative risk of the esophageal cancer incidence per unit of the accumulated gamma dose from external exposure (ERR/Gy) were estimated based on the Poisson regression. Results: By 31.12.2018, 47 esophageal cancers were reported in members of the study cohort; the majority of these cancers were squamous cell carcinomas. The incidence risk of esophageal cancer was lower in females than in males and it increased with attained age. The increased risk of esophageal cancer (all cases) was associated with current smoking (RR=12.6, 95 % CI 4.21, 42.13), gastroesophageal reflux disease (GERD) (RR=3.96, 95 % CI 1.60, 8.48), excess body weight and obesity (RR=1.21, 95 % CI 1.13, 2.08). The significantly increased RR of squamous cell esophageal carcinoma was found in current smokers and workers had GERD. The significantly increased RR of esophageal adenocarcinoma was found in current and former smokers. The risk of esophageal cancer (all cases and squamous cell carcinomas) was higher in workers who abused alcohol but the RR estimates were not statistically significant. A significant linear association of the esophageal cancer risk with gamma dose from external exposure was found: ERR/Gy=1.28 (95 % CI 0.21, 4.11) for all cases and ERR/Gy=1.01 (95 % CI 0.01, 3.95) for squamous cell carcinoma; these estimates are the risks adjusted for sex, age, smoking, alcohol, GERD and body mass index. No effect of occupational radiation exposure on the esophageal adenocarcinoma risk was found. Conclusion: This study confirmed obtained earlier data on the impact of occupational external gamma exposure on the risk of esophageal cancer in Mayak PA workers. The estimates of ERR/Gy of external gamma-ray exposure were updated having made adjustments for the most important non-radiation factors.

Dose rate effect on mortality from ischemic heart disease in the cohort of Russian Mayak Production Association workers

For improvement of the radiation protection system it is crucial to know the factors that modify the radiation dose–response relationship. One of such key factors is the ionizing radiation dose rate. There are, however, very few studies that examine the impact of the dose rate on radiogenic risks observed in human cohorts exposed to radiation at various dose rates. Here we investigated the impact of the dose rate (in terms of the recorded annual dose) on ischemic heart disease (IHD) mortality among Russian nuclear workers chronically exposed to radiation. We observed significantly increased excess relative risks (ERR) of IHD mortality per unit of external gamma-ray absorbed dose accumulated at higher dose rates (0.005–0.050 Gy/year). The present findings provide evidence for the association between radiation dose rate and ERRs of IHD mortality in occupationally chronically exposed workers per unit total dose. IHD mortality risk estimates considerably increased with increasing duration of uninterrupted radiation exposure at high rates. The present findings are consistent with other studies and can contribute to the scientific basis for recommendations on the radiation protection system.

Consequences of parental preconceptional irradiation: Endocrine-metabolic pathology in offspring

Epidemiological studies of late effects of preconceptional (prior to conception) radiation exposure are necessary in order to understand the risks of tumor and non-tumor pathology in next generations. Research of possible relation between parental preconceptional exposure and development of endocrine and metabolic disorders in the offspring is one of the topical issues of radiation hygiene. The objective of the study: comparative analysis of endocrine and metabolic pathology in children of the individuals exposed to long term preconceptional external gamma-radiation at the Mayak Production Association – at the first atomic industry facility on Russia. Materials and methods: A retrospective research was performed based on the Ozyorsk Children’s Health Registry. Ozyorsk – the city where Mayak Production Association is the enterprise forming the city. Analysis of endocrine and metabolic disorders was performed for 13880 children of 1949-1973 years of birth who were born and resided in Ozyorsk; parents of 9321 children of this number had accumulated doses of prolonged external gamma-radiation exposure at the production facility prior to conception. A comparative analysis of the structure and incidence of “Endocrine, nutritional and metabolic diseases” and nosological forms of this class of pathology was performed. Characteristic features of parental preconceptional exposure were analyzed in relation to thyroid pathology in children. Relative risk of endocrine and metabolic disorders among the children of exposed and unexposed parents was calculated for the whole disease class and for certain nosologies. Results: A significant predominance of thyroid diseases, particularly, iodine deficiencies, was detected at an earlier age among the offspring of Mayak Production Association workers compared to the control group; these cases were mostly related to low dose parental preconceptional exposure. Thyroid cancer was further detected in 0.16% (15/9321) of the studied cohort of the offspring of exposed parents with average manifestation age of 42.6. Relative risk of thyroid diseases was significantly higher among the exposed parents’ offspring compared to the controls: 2.0 among boys (95% confidence interval 1.38-2.9), 1.59 among girls (1.25-2.02) and in the group as a whole – 1.64 (1.34- 2.01). Relative risk of thyroid diseases related to iodine deficiency among the offspring of Mayak Production Association personnel was almost twice higher than the in the control group: 1.92 (1.3-2.84) among boys, 1.68 (1.29-2.2) among girls, 1.7 (1.36-2.12) in the whole group. Discussion and conclusion: A statistically significant overweight of non-tumor thyroid pathology in the offspring of Mayak Production Association personnel cannot be explained through external reasons taking into account similar climate and geographic conditions, possible technogenic exposure and the same unified medical survey of the followed children. We cannot exclude increased sensibility if thyroid tissue to iodine deficiency and its predisposition to hypertrophy and hyperplasia among the offspring of individuals exposed to long term occupational contact with ionizing radiation sources; that should be taken into account in the course of medical monitoring of these patients. Further research of transgenerational effects in the offspring of personnel of radiation hazardous production facilities are needed for complete understanding of the role of parental occupational exposure in health risks for further generations.

ЗАБОЛЕВАЕМОСТЬ И СМЕРТНОСТЬ ОТ ОПУХОЛЕЙ ЦЕНТРАЛЬНОЙ НЕРВНОЙ СИСТЕМЫ В КОГОРТЕ РАБОТНИКОВ, ПОДВЕРГШИХСЯ ХРОНИЧЕСКОМУ ОБЛУЧЕНИЮ

Purpose: To analyze incidence and mortality rates of central nervous system (CNS) primary tumors (PT) in the cohort of workers chronically exposed to radiation. Material and methods: Study cohort included 22237 Mayak Production Association workers. Work history data and dose estimates from the “Mayak Worker Dosimetry System 2013” were used. Clinical and epidemiology data were obtained from the “Clinic” database. Crude and age-adjusted (by indirect method) incidence and mortality rates for CNS PT per 100000 person-years were calculated. Standardized incidence and mortality trends were analyzed by Jointpoint 4.0.4. Results: 53 cases and 47 deaths from malignant neoplasms (MN) of brain and spinal cord, cerebral nerve and other parts of CNS (C70–C72 ICD-10 codes) as well as 40 cases and 7 deaths from non-malignant neoplasms (NMN) of brain and other parts of CNS (D-33 ICD-10 code) were identified. CNS MN were more frequent among males (83 %), and CNS NMN were more frequent among females (55 %). Both CNS MN and NMN developed at younger ages among males as compared with females, CNS PT frequency increased with increased attained age. Analysis in relation to calendar period revealed the increasing trend for CNS PT incidence among females only (р=0,008). Effects of chronic occupational radiation exposure on CNS PT incidence and mortality rates were not established either among males or females. Conclusion: Findings should be considered as preliminary and require further studies.

Mortality from various diseases of the circulatory system in the Russian Mayak nuclear worker cohort: 1948–2018

This paper reports on the findings from the study of mortality from diseases of the circulatory system (DCS) in Russian nuclear workers of the Mayak Production Association (22 377 individuals, 25.4% female) who were hired at the facility between 1948 and 1982 and followed up until the end of 2018. Using the AMFIT module of the EPICURE software, relative risks (RRs) and excess RRs per unit absorbed dose (ERR/Gy) for the entire Mayak cohort, the subcohort of workers who were residents of the dormitory town of Ozyorsk and the subcohort of migrants from Ozyorsk were calculated based on maximum likelihood. The mean cumulative liver absorbed gamma-ray dose from external exposure was 0.45 (0.65) Gy (mean (standard deviation)) for men and 0.37 (0.56) Gy for women. The mean cumulative liver absorbed alpha dose from internal exposure to incorporated plutonium was 0.18 (0.65) Gy for men and 0.40 (1.92) Gy for women. By the end of the follow-up, 6019 deaths with DCS as the main cause of death were registered among Mayak Production Association workers (including 3828 deaths in the subcohort of residents and 2191 deaths in the subcohort of migrants) over 890 132 (622 199/267 933) person-years of follow-up. The linear model that took into account non-radiation factors (sex, attained age, calendar period, smoking status and alcohol drinking status) and alpha radiation dose (via adjusting) did not demonstrate significant associations of mortality from DCS, ischaemic heart disease (IHD) and cerebrovascular disease with gamma-ray exposure dose in the entire cohort, the resident subcohort or the migrant subcohort (either in men or women). For the subcohort of residents, a significant association with gamma dose was observed for mortality from ischaemic stroke in men with ERR/Gy = 0.43 (95% CI 0.08; 0.99); there were no significant associations with liver absorbed gamma dose for any other considered outcomes. As for internal exposure, for men no significant associations of mortality from any DCS with liver absorbed alpha dose were observed, but for women positive associations were found for mortality from DCS (the entire cohort and the resident subcohort) and IHD (the entire cohort). No significant associations of mortality from various types of DCS with neutron dose were observed either in men or women, although neutron absorbed doses were recorded in only 18% of the workers.

Антропометрические параметры новорожденных детей персонала радиационно опасного производства как показатели мониторинга последствий родительского облучения

Abstract: Physical development of offspring can be an important criterion applied to assess effects produced by parental exposure. The cohort that includes workers employed at Mayak Production Association (PA), the first nuclear fuel cycle production facility in Russia, is a valuable information source for analyzing consequences of occupational exposure. Our objective was to analyze somatometric parameters of newborn children of Mayak PA workers who were occupationally exposed to pre-conception external gamma-radiation. We retrospectively analyzed anthropometric measurements of 13,880 newborn children, all born in 1949–1973; 9321 children were conceived by parents who were long-term occupationally exposed to radiation at Mayak PA. The analysis covered the core anthropometric elements including height, weight, head circumference, and chest circumference. Development proportionality was estimated by using Quetelet, Vervek – Vorontsov’s, and Erismann indexes. We estimated a correlation between anthropometric measurements and accumulated parental pre-conception external gamma radiation dose and calculated relative risk coefficients and odds ratio with 95 % confidence interval. We established that parents were exposed to a wide range of external gamma radiation doses, up to 4075.6 mGy to the ovaries and 5653.1 mGy to the testicles. There was a weak correlation between newborns’ height and weight and parental exposure. We also detected a trend for a decrease in newborns’ body mass with increasing accumulated pre-conception dose of external gamma radiation to the ovaries and, conversely, for an increase in it with a growing dose to the testicles. We revealed a statistically significant increase in height and weight among children conceived and born by Mayak PA workers, namely, a greater share of children with high body mass at birth. Analysis of children’s somatotypes confirmed excessive values of proportionality indexes that showed height and weight measurements among children of exposed parents. Additional analysis of firstborns and children with proper duration of gestation produced the same results. Risk assessment indicated there was significant prevalence of children with high body mass among offspring of exposed people. We also assessed physical development of Mayak PA workers’ newborns taking into account the latest data on long-term occupational exposure; this assessment is vital for epidemiological monitoring over health of children born by personnel employed at radiation-hazardous production facilities.

Anthropometric measurements in newborn children of personnel employed at radiation-hazardous production as indicators used in monitoring over consequences of parental exposure to radiation Primary tabs View(active tab) Edit

Physical development of offspring can be an important criterion applied to assess effects produced by parental exposure. The cohort that includes workers employed at Mayak Production Association (PA), the first nuclear fuel cycle production facility in Russia, is a valuable information source for analyzing consequences of occupational exposure. Our objective was to analyze somatometric parameters of newborn children of Mayak PA workers who were occupationally exposed to pre-conception external gamma-radiation. We retrospectively analyzed anthropometric measurements of 13,880 newborn children, all born in 1949–1973; 9321 children were conceived by parents who were long-term occupationally exposed to radiation at Mayak PA. The analysis covered the core anthropometric elements including height, weight, head circumference, and chest circumference. Development proportionality was estimated by using Quetelet, Vervek – Vorontsov’s, and Erismann indexes. We estimated a correlation between anthropometric measurements and accumulated parental pre-conception external gamma radiation dose and calculated relative risk coefficients and odds ratio with 95 % confidence interval. We established that parents were exposed to a wide range of external gamma radiation doses, up to 4075.6 mGy to the ovaries and 5653.1 mGy to the testicles. There was a weak correlation between newborns’ height and weight and parental exposure. We also detected a trend for a decrease in newborns’ body mass with increasing accumulated pre-conception dose of external gamma radiation to the ovaries and, conversely, for an increase in it with a growing dose to the testicles. We revealed a statistically significant increase in height and weight among children conceived and born by Mayak PA workers, namely, a greater share of children with high body mass at birth. Analysis of children’s somatotypes confirmed excessive values of proportionality indexes that showed height and weight measurements among children of exposed parents. Additional analysis of firstborns and children with proper duration of gestation produced the same results. Risk assessment indicated there was significant prevalence of children with high body mass among offspring of exposed people. We also assessed physical development of Mayak PA workers’ newborns taking into account the latest data on long-term occupational exposure; this assessment is vital for epidemiological monitoring over health of children born by personnel employed at radiation-hazardous production facilities.

The overestimation of medical consequences of low-dose exposures: Cui bono?

After the Chernobyl disaster appeared papers overestimating medical consequences of low-dose radiation exposures. Examples have been discussed previously; an updated overview of selected studies is provided here. Various kinds of bias can be found in the epidemiological research reporting elevated health risks from low doses of ionizing radiation: Interpretation of spontaneous conditions as radiation-induced, dose comparisons disregarding the natural background, publication bias, etc. Admittedly, all relevant parameters cannot always be taken into account in epidemiological research. Several examples of potentially biased reports on Mayak Production Association workers and Techa river valley residents are analyzed here. Doubtful correlations between exposures to low radiation doses and nonmalignant conditions, discussed in this commentary, call into question the cause-effect character of such correlations for malignancies revealed by the same scientists. Correlations can be caused or influenced by dose-dependent selection and self-selection. Individuals with higher doses were probably more motivated to undergo medical checkups and given more attention. The medical surveillance of exposed populations is important; but more consideration should be given to potential bias. A promising approach to the study of dose-response relationships are lifelong experiments in different animal species that can reveal the net harm or potential benefit (within a certain range according to the concept of hormesis) from low-dose exposures to ionizing radiation.

Incidence trend for colorectal cancer in the cohort of workers exposed to ionizing radiation

Colorectal cancer is one of the most common malignant neoplasms. Main causes inducing this type of cancer are factors related to the life style and occupational exposures to chemical agents. Some studies demonstrated an association of colorectal cancer incidence and mortality with ionizing radiation. The aim of the present study was to assess the trend in colorectal cancer incidence in a cohort of nuclear workers employed at the Mayak Production Association who had been exposed to ionizing radiation over prolonged periods. The cohort comprised 22,377 workers (25% of females) employed at one of the main plants (reactors, radiochemical and plutonium production plants) of the Mayak Production Association in 1948-1982 who had been externally exposed to gamma rays (cumulative absorbed colon doses were 0–5.85 Gy with the corresponding median dose of 0.16 Gy) and those who had inhaled aerosols containing plutonium particles had been also internally exposed to alpha radiation (cumulative absorbed colon doses were 0–0.18 Gy with the corresponding median dose of 0.0002 Gy). Over the period of 1948–2018, 239 colon cancers and 186 rectum cancers were diagnosed in the study cohort. The incidence of colorectal malignancies among workers of the study cohort was shown to increase with age above 50. Age-standardized incidence rates were higher in males than in females. The time trend analysis of age-standardized rates of colorectal malignancies among workers of the study cohort was performed using a spline regression. The trend of age-standardized rates of colorectal cancer incidence in the Mayak Production Association workers over the analyzed period was nonmonotonic. In general, the average annual percent change of incidence growth for colon cancer was less than 0.1% (for both sexes), while the corresponding estimates for rectum cancer were 1.1% in males and 30.3% in females. To assess the effect of occupational radiation exposure on the incidence of colorectal malignancies, a radiogenic risk analysis that would take into account non-radiation risk factors should be performed.

The effectiveness of the examination algorithm in the practice of a neurologist during preliminary medical examinations

An examination protocol for routine medical health check-ups of Mayak Production Association workers by a neurology specialist enables advanced detection and differential diagnostics of diseases of the nervous system, conclusion on fitness to work and expert assessment of a disease-occupation causal relationship.

Leukemia risk and the pattern of dose accumulation. Part 1: Characteristics of the study group of the Mayak Production Association personnel

Results of development of the database “Leukemia in the cohort of workers of the Mayak Production Association employed in 1948-1958” that was developed in the Laboratory of Radiation Epidemiology of Southern Urals Biophysics Institute were presented. The database contains hematological, clinical and dosimetric information for the workers of main plants of the first production facility of Soviet atomic industry employed in the period of production development – 1948-1958. The computer database contains information for two groups of Mayak Production Association workers: main group of workers with leukemia as the main cause of death (n=84) and group of personnel without hematological cancer pathology for comparison (n=300). The comparison group was composed in such a way to allow 3-4 controls of corresponding gender, age of exposure start, accumulated dose of external gamma-exposure to red bone marrow for each leukemia case. Methods of data collection and sources of medical data were described. Characteristics of software developed for the database was presented. The database containing a total of 19593 results of blood tests reflects dynamics of hematological values in atomic facility personnel due to prolonged radiation exposure. The range of accumulated absorbed doses of external gamma-exposure to red bone marrow in the group of personnel with leukemia diagnoses was 0.001-4.96 Gy; average dose for males was 1.24 Gy and 0.61 Gy – for females. Similar range is observed in the group of personnel without leukemia outcomes. Alongside differences in accumulation rates of external radiation exposure doses is evident: in the group of workers with hematological cancer pathology the average period of radiation exposure at production facility was 14.3 years for males and 12.1 years for females; in the comparison group – 20.4 and 13.9 years, respectively. Most leukemia cases were diagnosed in the workers of radiochemical facility (54.8%). Myeloid leukemia prevailed (47.6%) in the leukemia structure; among them acute myeloid leukemia made more than a half of the cases; lymphoid leukemia was diagnosed in 14.3% cases with prevailing role of chronic lymphoid leukemia. Acute and chronic monocytic leukemia were the rarest types of malignant neoplasms of hematopoietic tissue. Possible correlation between hematological values with individual doses of external gamma- and internal alpha-exposure (incorporated Pu-239) distributed over time was stated. The database allows calculating integrated leukocytic indices reflecting response of hemopoietic system to radiation exposure, tracking changes in hemopoiesis in proportion to accumulated dose to red bone marrow, analyzing specific characteristics of rehabilitation of hematological alterations after occupational contact to ionizing radiation is terminated. Information on acute and chronic diseases available for the workers in the database allows excluding non-specific response of hemopoietic system caused by associated pathology. A revision of leukemia risk estimated in the relation to dose rate for personnel exposed to chronic radiation could be regarded as one of perspective trends in using the database.

Heritable effects in offspring associated with harmful exposure to parents (Literature review)

A review of literature data regarding the heritable effects in offspring due to parents’ contact with mutagenic risk factors is presented. Studies on various factors of adverse effects on the hereditary apparatus, including chemical, infectious, physical and biological, are considered. The influence of smoking and parents’ age on the occurrence of de novo mutations is shown. Particular attention is paid to the review of publications on the role of the radiation factor in the genesis of hereditary disorders in offspring. Development stages of radiation genetics, the evolution of conception about radiation harm are described. The results of experimental, cytogenetic, molecular genetic, epidemiological studies analyzing the contribution of parental exposure to inherited pathology in progeny are presented. Special attention is paid to the “untargeted” effects of radiation and studies which prove the possibility of transgenerative transmission of genome instability are presented. The special contribution of studies on the cohort of atomic bomb victims offspring in Hiroshima and Nagasaki, which is considered as the main scientific platform for radiation risk assessment, is noted. There are articles about the offspring of persons who underwent therapeutic exposure, who had professional contact with ionizing radiation, who were exposed to radiation as a result of the Chernobyl accident, nuclear weapons tests at the Semipalatinsk test site, chronic radiation in the radioactively contaminated territory of the Techa river, areas with naturally increased radioactivity. As a result, it was noted that, despite numerous confirmations of radiation-induced effects in offspring obtained within experimental and molecular genetic studies, the results of epidemiological studies remain controversial. Possible reasons for these discrepancies are considered. An idea of views evolution regarding heritable effects in the international system of radiation safety is given. A new approach of the International Commission on Radiological Protection to heritable effects is described; the dynamics of tissue weighting factors for gonads in the assessment of effective radiation dose is shown. Methods for evaluating heritable effects are presented: the direct method and the doubling dose method. Attention is focused on the uncertainties that remain in the modern assessment of radiation genetic damage. The necessity of further study of radiation-induced heritable effects is shown. The perspective directions of studying the heritable effects are considered. The possibility of the analysis of heritable effects is described using the example of a cohort of the Mayak Production Association workers’ offspring – the country’s first nuclear industry enterprise.

Glaucoma incidence risk in a cohort of Mayak PA workers occupationally exposed to ionizing radiation

Glaucoma is a major cause of visual impairment, and secondary glaucoma manifested as neovascular glaucoma has long been known to occur following high-dose fractionated radiation therapy. In contrast, little is known as to whether ionizing radiation exposure causes primary glaucoma, except that a single study in Japanese atomic bomb survivors has reported a significantly increase risk. Therefore, the effect of lower dose and lower dose rate remains unclear. Here we report that in Russian Mayak Production Association workers occupationally exposed to chronic radiation for prolonged periods, incidence of total primary glaucoma and primary open-angle glaucoma is significantly associated with various non-radiation factors (sex, attained age, and cataract diagnosed prior to glaucoma), but neither with cumulative dose from external γ-rays nor with cumulative neutron dose nor with the unweighted sum of cumulative γ and neutron doses. The present results suggest for the first time that chronic radiation exposure does not cause primary glaucoma, although the analyses need to be made in other cohorts exposed at various dose and dose rate.

Risk of various types of cataracts in a cohort of Mayak workers following chronic occupational exposure to ionizing radiation.

This study is the first to report cataract type specific risks in a cohort of Russian Mayak Production Association workers following chronic occupational exposure to ionizing radiation. In this retrospective cohort study, 22,377 workers (females 25.4%) first employed in 1948-1982 were followed up till the end of 2008. All cataract subtypes were significantly dependent on sex, attained age, diabetes mellitus, myopia and glaucoma. For each of posterior subcapsular (PSC), cortical and nuclear cataracts, the risk of cataract incidence significantly linearly increased with increasing radiation dose. Excess relative risk per unit effective dose (ERR/Sv) from external γ-rays based on the linear model was 0.91 [95% confidence intervals (CIs) 0.67, 1.20] for PSC, 0.63 (95% CIs 0.49, 0.76) for cortical, and 0.47 (95% CIs 0.35, 0.60) for nuclear cataracts. For all three types of cataracts, exclusion of an adjustment for neutron dose as well as inclusion of additional adjustments for body mass index and smoking index decreased ERR/Sv of external γ-rays. Inclusion of an additional adjustment for glaucoma, however, modestly increased incidence risks for cortical and nuclear cataracts, but not PSC cataracts. Inclusion of an adjustment for diabetes mellitus decreased ERR/Sv of external γ-rays only for PSC incidence. Both males and females had increased risks for all three types of cataracts, but ERR/Sv was significantly higher in females than in males (p < 0.001), particularly for PSC cataracts. The results suggest that chronic occupational radiation exposure significantly increases risks of PSC, cortical and nuclear cataracts, and that such risks are higher in females than in males.

MALIGNANT TUMORS OF THE CENTRAL NERVOUS SYSTEM IN THE CHILDREN OF THE NUCLEAR PRODUCTION WORKERS

The incidence of malignant neoplasms of the brain and the spinal medulla in children of Mayak Production Association workers who exposed preconceptive gamma irradiation was analyzed in the paper. The retrospective analysis was carried out within the cohort of children under the age of 15 born in 1948-2013 which includes 72316 people born and have been living in Ozersk, located near the nuclear plant. Overall 13 cases of malignant neoplasms of the central nervous system were registered among descendants of persons exposed in the workplace. The average value of the total dose of preconceptive gamma irradiation among mothers reached 251.95 mGy, among fathers - 211.42 mGy. The most frequent localization of malignant process was cerebellum, the most frequent morphological type of tumor was astrocytoma. Comparative analysis of morbidity was carried out by the method of indirect standardization, herewith regional and national age-sex incidence rates were applied. There was no significant excess of the incidence of malignant neoplasms of the central nervous system among children of nuclear workers. Standardized incidence ratio in comparison with the national statistics for children under 15 generally amounted in 1.04 in boys (95% confidence interval 0.5-1.87), in girls - 0.58 (0.18-1.35); in comparison with the regional statistics: in boys - 1.16 (0.56-2.09), in girls - 0.36 (0.11-0.85).

THE MAYAK WORKER DOSIMETRY SYSTEM (MWDS-2013): AN INTRODUCTION TO THE DOCUMENTATION.

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. This introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

Risk of Cataract Incidence in a Cohort of Mayak PA Workers following Chronic Occupational Radiation Exposure.

This is the first study of cataract incidence in a cohort of Mayak Production Association workers first employed at one of the main facilities in 1948–1982 and followed up till the end of 2008 (22,377 workers). Principal advantages of the study are the large size of the cohort, long-term follow-up and sufficient statistical power, available results of annual eye examinations over the entire follow-up period and detailed information on non-radiation confounders. Individual measured doses from external γ-rays and neutrons used in the analyses were provided by the Mayak Worker Dosimetry System 2008 (MWDS-2008). Relative risk (RR) and excess relative risk (ERR) per unit dose (Gy) were calculated based on maximum likelihood using the AMFIT module of the EPICURE software. The RR of cataract incidence was found to be the highest in workers exposed at doses above 2.0 Gy. A significant linear association of cataract incidence with cumulative dose from external γ-rays was found with ERR/Gy equal to 0.28 (95% confidence intervals: 0.20, 0.37). The results obtained varied slightly with inclusion of additional adjustments for non-radiation factors (smoking index, hypertension, glaucoma and body mass index). Adjusting for the dose from neutrons gave a considerable increase in ERR/Gy for cataract incidence.