Quantifying annual internal effective 137Cesium dose utilizing direct body-burden measurement and ecological dose modeling.

The Chernobyl Nuclear Power Plant (CNPP) accident represents one of the most significant civilian releases of 137Cesium (137Cs, radiocesium) in human history. In the Chernobyl-affected region, radiocesium is considered to be the greatest on-going environmental hazard to human health by radiobiologists and public health scientists. The goal of this study was to characterize dosimetric patterns and predictive factors for whole-body count (WBC)-derived radiocesium internal dose estimations in a CNPP-affected children's cohort, and cross-validate these estimations with a soil-based ecological dose estimation model. WBC data were used to estimate the internal effective dose using the International Commission on Radiological Protection (ICRP) 67 dose conversion coefficient for 137Cs and MONDAL Version 3.01 software. Geometric mean dose estimates from each model were compared utilizing paired t-tests and intra-class correlation coefficients. Additionally, we developed predictive models for WBC-derived dose estimation in order to determine the appropriateness of EMARC to estimate dose for this population. The two WBC-derived dose predictive models identified 137Cs soil concentration (P<0.0001) as the strongest predictor of annual internal effective dose from radiocesium validating the use of the soil-based EMARC model. The geometric mean internal effective dose estimate of the EMARC model (0.183 mSv/y) was the highest followed by the ICRP 67 dose estimates (0.165 mSv/y) and the MONDAL model estimates (0.149 mSv/y). All three models yielded significantly different geometric mean dose (P<0.05) estimates for this cohort when stratified by sex, age at time of exam and season of exam, except for the mean MONDAL and EMARC estimates for 15- and 16-year olds and mean ICRP and MONDAL estimates for children examined in Winter. Further prospective and retrospective radio-epidemiological studies utilizing refined WBC measurements and ecological model dose estimations, in conjunction with findings from animal toxicological studies, should help elucidate possible deterministic radiogenic health effects associated with chronic low-dose internal exposure to 137Cs.

Dietary supplementation with radionuclide free food improves children's health following community exposure to (137)Cesium: a prospective study.

BACKGROUND: Following the Chernobyl nuclear disaster of 1986, vast areas of Ukraine became contaminated with radionuclides. We examined health effects of school-based food intervention for children in a rural region Narodichi, Ukraine, exposed to low-level radiation through diet of locally produced foods. Until 1995, children received three daily meals with low content of artificial radionuclides which were subsequently reduced to two. METHODS: Annual health screening data (1993-1998) were examined using a quasi-experimental regression discontinuity analysis (n = 947 children; 3,573 repeated measurements). Generalized Estimating Equation models evaluated effect of the food supplementation reduction on hematologic measures and prevalence of anemia, acute respiratory illnesses and diseases of immune system. RESULTS: Prior improvement of several hematologic parameters diminished after food supplementation was reduced. From 1995 to 1996, levels of hemoglobin and erythrocytes decreased from 12.63 (95% CI: 12.56-12.71) to 12.46 g/dL (% CI: 12.39-12.52) and from 4.10 (95% CI: 4.07-4.12) to 4.02 (95% CI: 4.00-4.04) × 10(12)/L, respectively. In agreement, the prevalence ratio (PR) of previously declining anemia increased from 0.57 to 1.31 per year (p(interaction )< .0001). The relation between food supplementation and hemoglobin levels was modified by residential (137)Cs soil levels. After food supply reduction, PR of common cold and bronchitis increased from 1.27 to 2.32 per year (p(interaction) = 0.01) and from 1.09 to 1.24 per year (p(interaction) = 0.43), respectively. CONCLUSIONS: Food supplementation provided by the Ukrainian government likely prevented development of anemia in many of the children residing in the contaminated district. Food supplementation after the community exposure to radioactivity through a diet of locally grown foods should be considered as an effective approach to reduce adverse health effects of radiation.

Reduced lung function in children associated with cesium 137 body burden.

RATIONALE: We previously reported that obstructive and restrictive lung function findings were associated with radioactive Cesium 137 ((137)Cs) soil contamination from the 1986 Chernobyl disaster in a pediatric cohort residing in the Narodichesky district of Ukraine from 1993 to 1998. OBJECTIVES: To determine whether these associations persist, we repeated the study and refined the exposure by measuring individual radiation concentration with a whole-body counter. METHODS: Basic and post-bronchodilator spirometry measurements were made for 517 children aged 8 to 17 years born in and living within this differentially contaminated study area during 2008 to 2010. MEASUREMENTS AND MAIN RESULTS: A γ-spectrometer equipped with a collimator was used for the measurement of whole-body radiation and adjusted for weight. General linear and logistic regression models were used to estimate the association between spirometry measures and the weight-adjusted (137)Cs whole-body burden (Bq/kg) while controlling for potential confounders. The geometric median weight-adjusted radiation concentration was 65.96 Bq/kg (95% confidence interval, 14.98-240.9 Bq/kg), equivalent to a geometric mean internal dose estimate of 0.165 mSv/yr (95% confidence interval, 0.037-0.602 mSv/yr). Decrements in percentage predicted FEV1/FVC and an increased odds of bronchodilator responsiveness, restrictive impairment, and FVC less than lower limit of normal were associated with a log increase in weight-adjusted (137)Cs whole-body burden after adjusting for potential confounders. CONCLUSIONS: Our previous study of soil (137)Cs exposure and reduced lung function was corroborated herein with individual (137)Cs whole-body burden, although low, and annual internal dose data. Children in a region just outside of the closed Chernobyl contamination zone continued to have respiratory health deficits associated with (137)Cs whole-body burden as recently as 2010.

Individual whole-body concentration of ¹³7Cesium is associated with decreased blood counts in children in the Chernobyl-contaminated areas, Ukraine, 2008-2010.

The Narodichesky region, Zhitomir Oblast, Ukraine, is situated ∼80 km from the Chernobyl Nuclear Power Plant, which exploded in 1986 and polluted the environment. A previous study found that children living in villages with high activity of (137)Cesium (Cs) in the soil had decreased levels of hemoglobin, erythrocytes and thrombocytes. These findings motivated the present study that used a more comprehensive exposure assessment, including individual whole-body concentrations (WBC) of (137)Cs (Bq/kg). This cross-sectional sample examined between 2008-2010, included 590 children in the age 0-18 years. Children with higher individual log(WBC) activity in the body had significantly decreased hemoglobin, erythrocyte and thrombocyte counts. The effect of log(WBC) on decreased thrombocyte count was only seen in children older than 12 years. The average village activity of (137)Cs (kBq/m(2)) in soil was associated with decreased blood counts only indirectly, through (137)Cs in the body as an intermediate variable. Children in this study were born at least 4 years after the accident and thus exposed to low doses of ionizing radiation from (137)Cs. This cross-sectional study indicates that low levels may be associated with decreased blood counts, but we cannot exclude that these results are due to residual confounding factors.

Effects of long-term low-level radiation exposure after the Chernobyl catastrophe on immunoglobulins in children residing in contaminated areas: prospective and cross-sectional studies.

BACKGROUND: After the Chernobyl nuclear incident in 1986, children in the Narodichesky region, located 80 km west of the Chernobyl Power Plant, were exposed to 137Cesium (137Cs). Little is known about the effects of chronic low-level radiation on humoral immune responses in children residing in contaminated areas. METHODS: In four different approaches we investigated the effect of residential 137Cs exposure on immunoglobulins A, G, M, and specific immunoglobulin E in children. In a dynamic cohort (1993-1998) we included 617 children providing 2,407 repeated measurements; 421 and 523 children in two cross-sectional samples (1997-1998 and 2008-2010, respectively); and 25 participants in a small longitudinal cohort (1997-2010). All medical exams, blood collections, and analyses were conducted by the same team. We used mixed linear models to analyze repeated measurements in cohorts and general linear regression models for cross-sectional studies. RESULTS: Residential soil contamination in 2008 was highly correlated with the individual body burden of 137Cs. Serum IgG and IgM concentrations increased between 1993 and 1998. Children with higher 137Cs soil exposure had lower serum IgG levels, which, however, increased in the small cohort assessed between 1997 and 2010. Children within the fourth quintile of 137Cs soil exposure (266-310 kBq/m2) had higher IgM serum concentrations between 1993 and 1998 but these declined between 1997 and 2010. IgA remained stable with median 137Cs exposures related to higher IgA levels, which was corroborated in the cross-sectional study of 2008-2010. Specific IgE against indoor allergens was detected less often in children with higher 137Cs exposure. CONCLUSIONS: Our findings show radiation-related alterations of immunoglobulins which by themselves do not constitute adverse health effects. Further investigations are necessary to understand how these changes affect health status.

137Cesium exposure and spirometry measures in Ukrainian children affected by the Chernobyl nuclear incident.

BACKGROUND: After the Chernobyl accident in 1986, children of the contaminated Narodichesky region of Ukraine were obliged to participate in a yearly medical screening. They have been exposed to 137cesium (137Cs; half-life = 30 years) in contaminated soils, air, and food. OBJECTIVE: Using a "natural experiment" approach and a longitudinal prospective cohort study design, we investigated the association of soil 137Cs and spirometry measures for 415 children using 1,888 repeated measurements from 1993 to 1998. METHODS: Mean baseline village soil 137Cs measurements, which varied from 29.0 to 879 kBq/m2, were used as exposure indicators. A standardized spirometry protocol and prediction equations specific to Ukrainian children were used by the same pulmonologist in all screenings. RESULTS: Children living in villages with the highest quintile of soil 137Cs were 2.60 times more likely to have forced vital capacity (FVC) < 80% of predicted [95% confidence interval (CI), 1.07-6.34] and 5.08 times more likely to have a ratio of forced expiratory volume in 1 sec (FEV1) to FVC% < 80% (95% CI, 1.02-25.19). We found statistically significant evidence of both airway obstruction (FEV1/FVC%, peak expiratory flow, and maximum expiratory flow at 25%, 50%, and 75% of FVC) and restriction (FVC) with increasing soil 137Cs. CONCLUSIONS: These findings are unique and suggest significant airway obstruction and restriction consequences for children chronically exposed to low-dose radioactive contaminants such as those found downwind of the Chernobyl Nuclear Power Plant.

Exposure from the Chernobyl accident had adverse effects on erythrocytes, leukocytes, and, platelets in children in the Narodichesky region, Ukraine: a 6-year follow-up study.

BACKGROUND: After the Chernobyl nuclear accident on April 26, 1986, all children in the contaminated territory of the Narodichesky region, Zhitomir Oblast, Ukraine, were obliged to participate in a yearly medical examination. We present the results from these examinations for the years 1993 to 1998. Since the hematopoietic system is an important target, we investigated the association between residential soil density of 137Caesium (137Cs) and hemoglobin concentration, and erythrocyte, platelet, and leukocyte counts in 1,251 children, using 4,989 repeated measurements taken from 1993 to 1998. METHODS: Soil contamination measurements from 38 settlements were used as exposures. Blood counts were conducted using the same auto-analyzer in all investigations for all years. We used linear mixed models to compensate for the repeated measurements of each child over the six year period. We estimated the adjusted means for all markers, controlling for potential confounders. RESULTS: Data show a statistically significant reduction in red and white blood cell counts, platelet counts and hemoglobin with increasing residential 137Cs soil contamination. Over the six-year observation period, hematologic markers did improve. In children with the higher exposure who were born before the accident, this improvement was more pronounced for platelet counts, and less for red blood cells and hemoglobin. There was no exposurextime interaction for white blood cell counts and not in 702 children who were born after the accident. The initial exposure gradient persisted in this sub-sample of children. CONCLUSION: The study is the first longitudinal analysis from a large cohort of children after the Chernobyl accident. The findings suggest persistent adverse hematological effects associated with residential 137Cs exposure.