Descriptive characteristics of gynecological malignant neoplasms

Background. Gynecological malignant neoplasms (GMN) are the leading disease group among female cancers.Objective: to characterize GMN in females occupationally exposed to ionizing radiation over prolonged periods.Materials and methods. The cohort considered in the study included females (n = 5689) who had been hired at the Mayak Production Association in the period between 1948 and 1982. All these females were exposed to ionizing radiation over prolonged periods during their employment. They were followed up until 31.12.2018. Two groups of females were identified in the study cohort: the one with a verified GMN (the main group) and another one free of GMN (the control group). The occupational and reproductive characteristics were analyzed for the identified groups of females, and associations of GMN with various risk factors were assessed.Results. Among GMN the uterine corpus cancer had the top position. In 70 % of the females GMN were diagnosed during a menopausal period. The females of the main group demonstrated significantly higher frequency of underlying pre-malignant conditions (endometriosis, uterine myoma, endometrial hyperplastic processes, ovarian epidermoids, menopausal bleedings) compared to the control group.Conclusion. Studies of GMN in females occupationally exposed to ionizing radiation over prolonged periods for sure are of a certain scientific and practical interest. The findings can provide the basis for specialized cancer care for employees of the nuclear industry.

Incidence of Primary Glaucoma in a Cohort of Nuclear Workers

Objective: The study was aimed to estimate primary glaucoma incidence in a cohort of nuclear workers occupationally exposed to ionizing radiation over prolonged periods.Materials and methods. The cohort considered in the study included workers of the Mayak Production Association. All glaucoma cases that were reported in the study worker cohort regardless of its type were identified using the medical and dosimetry database ‘Clinic’. Statistical analyses were performed to estimate non-standardized (crude) and standardized incidence rates for primary glaucoma. Standardization was carried out indirectly using age distribution for the whole cohort as an internal reference. Incidence rates were estimated per 1000 person-years in accordance with conventional medical statistics.Results. At the end of the follow-up period, 476 primary glaucoma cases were reported in the study worker cohort over 482,217 person-years of the follow-up. The standardized primary glaucoma incidence was estimated to be 1.00 ± 0.05 in males and 0.70 ± 0.07 in females. Crude primary glaucoma estimates in both males and females increased with the increasing attained age of the workers. Crude incidence rates in males were significantly higher than in females for age 50–69. The standardized primary glaucoma incidence in males was also significantly increased compared to females. The standardized primary glaucoma incidence rates were increasing throughout the period from 1960s to the end of the follow-up.

LEUKOCYTAL INDICES AND OCCUPATIONAL EXTERNAL GAMMA-EXPOSURE

Background: The hematopoietic system is classified as the most radiosensitive body system. Research of occupational radiation-induced hematological shifts continues to be a relevant question of occupational radiation safety. Aim: Analysis of leukocytal indices dynamics depending on the accumulated dose of occupational external gamma-exposure. Methods: The database «Leukemia in the cohort of Mayak Production Association workers hired in 1948-1958» was used as the material. Leukocytal indices were estimated based on 19592 peripheral blood analyses; dynamics of hematological shifts was traced according to accumulation of absorbed doses of occupational external gamma-radiation; comparative analysis of hemogramms with a group of workers without oncohematological pathology was carried out. Nonparametric statistical methods were applied. Results: The period of dose accumulation at the same total dose of occupational external gamma-exposure was much different in the study groups, it was much shorter for individuals who later died of leukemia. Leukocytal indices in groups were most different in the range of accumulated absorbed doses of external gamma exposure equal to 2 – 2.5 Gy and had the largest amplitude of values among the workers diagnosed for leukemia later. Conclusion: The estimation of leukocytal indices may be used as the tool for early detection of adverse hematological shifts in cell lines and may be the indicator of pathologic hemapoiesis in the exposed workers before clinical manifestation of hematological pathology.

Tritium in the urine of the Mayak PA workers in the period from 2017 to 2019

Objectives. To define the levels of volume activity of tritium compounds and fraction of organically bound tritium in urine of chemical production workers of “Mayak Production Association” in present-day conditions; to identify the relationship between volume activity levels and professional occupation (department and profession). Material and methods. 245 urine samples from 171 workers of Mayak Production Association tritium production facility were collected in the period from 2017 to 2019. Volume activity of tritium compounds was measured by liquid scintillation method using spectrometer Quantulus-1220. The samples were distilled or dried and then combusted using an automatic preparation and oxidization system Sample Oxidizer A307. The “R” software was used for statistical analysis and for processing the measurement results and occupational factors. Chaddok’s scale was applied to determine the degree of correlation. The significance level was taken equal to 5%. Results. The value of total tritium volume activity in the urine and tritium volume activity in the water phase varied within 4 orders of magnitude (from ~30 Bq/dm3 to ~250 kBq/dm3). The value of volume activity of organically bound tritium in the urine varied within 2 orders of magnitude (from ~6 Bq/dm3 to ~3000 kBq/dm3). The fraction of organically bound tritium in the urine of the workers was within the range from 0,07% to 74%, and did not differ statistically significantly from lognormal distribution with parameters GM=2,7% and GSD=3,7. Very high rank correlation was detected between total volume activity of tritium compounds and tritium volume activity in the water phase in the urine. Noticeable rank correlations were detected between the total volume activity of tritium compounds in the urine and volume activity of organically bound tritium, as well as between tritium volume activity in the water phase and volume activity of organically bound tritium in the urine. The total tritium volume activity and tritium volume activity in the water phase in the urine of the workers of the 1st department and of the analytical laboratory of Mayak Production Association tritium production facility were statistically significantly higher than in the workers of the 2nd department according to median values. Statistically significant differences between medians of the total tritium volume activity in the urine and tritium volume activity in the water phase related to profession were observed only in the workers in the 1st department. Conclusion. Estimation of tritium volume activity in the water phase by the level of total tritium volume activity in the urine without sample preparation is possible with 95% reliability within limits of one order of magnitude towards the model value. Estimation of volume activity of organically bound tritium in the urine without sample preparation by the level of total tritium volume activity in the urine without sample preparation is possible with 95% reliability within limits of two orders of magnitude towards the model value. The effect of occupational factors to the levels of volume activity of tritium compounds in the urine of Mayak Production Association professional workers was detected.

Registry of plutonium-induced lung fibrosis in a cohort of nuclear workers of the Mayak Production Association

The registry of plutonium-induced lung fibrosis cases (PuLF) diagnosed in members of a cohort of the first Russian nuclear industry facility Mayak Production Association was established in the clinical department of the Southern Urals Biophysics Institute of the Federal Medical-Biological Agency (SUBI). The registry includes 188 plutonium-induced lung fibrosis diagnoses: 117 (62.23%) in males and 71 (37.77%) in females. This paper describes the structure and detailed characteristics of the registry. The number of PuLF cases was shown to have no association with cumulative lung absorbed dose from external gamma rays as of the date of diagnosis. On the contrary, the PuLF rate was shown to be associated with cumulative lung absorbed dose from in-corporated alpha particles and to increase significantly with increasing dose from internal radia-tion exposure. This paper discusses potential applications of the registry to scientific investiga-tions in the future.

Risk of malignant neoplasms in the first generation offspring of female workers of Mayak Production Association

The study of the role of parental preconception exposure in development of malignant neo-plasms (MN) in the offspring is a topical point in cancerogenic factors’ research. The objective of the work is assessment of cancer risk among the offspring of female workers of the country’s first atomic production facility – Mayak Production Association (PA) – exposed to long-term occupa-tional radiation exposure prior to conception. We have performed a retrospective epidemiological analysis in a cohort of offspring born in 1949-1990 that contained 2061 children from 1404 fe-male workers. Mothers of 1145 children (55.6%) had accumulated doses of preconception exter-nal gamma-exposure to the ovaries (main group); the remaining 916 children (44.4%) were re-garded as internal control (comparison group) as the offspring of female workers that were not exposed to preconception irradiation of genital organs. We have followed up the vital status and cancer incidence in the offspring up to 31.12.2018. We have performed an analysis of the struc-ture and cancer incidence rates. We had calculated the relative risk (RR) and the excess relative risk (ERR) to a dose unit of external gamma-exposure with a 95% confidence interval using the AMFIT module of the EPICURE software. A total of 92 MN cases were registered in 1949-2018 among the first generation offspring of female workers. A comparative analysis of cancer inci-dence showed no significant difference in the structure and incidence rate of MN in the groups. The only exception were the offspring of the females not exposed to preconception occupational irradiation of genital organs; in this group we had indicated a significant increase of brain MN in male offspring and of the MN of corpus uteri among female offspring. We had registered MN of digestive organs and MN of breast most often in the main group of the offspring. The range of maternal doses of preconception external gamma-exposure to the ovaries varied greatly: maxi-mum dose in male offspring reached 2954.82 mGy and 4075.61 in female offspring. Calculation of RR of MN in the offspring of the main group showed no significant difference from the com-parison group for all the MN, for solid cancers separately, and for other most frequent cancers. Assessment of ERR coefficients in relation to maternal accumulated absorbed dose of precon-ception external gamma radiation to the ovaries had revealed no statistically significant increase of cancer incidence among the offspring of female workers exposed to occupational irradiation of genital organs. We had obtained no reliable evidence in our investigation of the relation be-tween MN in the offspring of Mayak PA female workers and accumulated doses of preconception external gamma-exposure to the gonads. Further research is needed taking into account relative-ly young average age of the observed cohort of the offspring.