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PubMed1990

Models of radioiodine transport to populations within the continental U.S.

A methodology is being developed to estimate the exposure of Americans to 131I originating from atmospheric nuclear weapons tests carried out at the Nevada Test Site (NTS) during the 1950s and early 1960s. Since very few direct environmental measurements of 131I were made at that time, the assessment must rely on estimates of 131I deposition based on meterological modeling and on measurements of total beta activity from the radioactive fallout deposited on gummed-film collectors that were located across the country. The most important source of human exposure from fallout 131I was due to the ingestion of cows' milk. The overall methodology used to assess the 131I concentration in milk and the 131I intake by people on a county basis for the most significant atmospheric tests is presented and discussed. Certain aspects of the methodology are discussed in a more detailed manner in companion papers also presented in this issue. This work is carried out within the framework of a task group established by the National Cancer Institute.

Animal Feed↗
PubMed1964

OCCUPATIONAL HEALTH. ITS ROLE IN ENVIRONMENTAL HEALTH PROGRAMS.

An important part of the practice of occupational medicine is directed toward the control of the industrial, physical, chemical and biological environments which may adversely affect health. This concern with the effect of environment on health has moved out of industry and has become a major area of public health practice, as evidenced by interest in pesticides, air pollution and radioactive fallout. The discipline of occupational health is a natural resource and springboard for the development of the skills necessary to control these environmental hazards. Occupational health is supplying trained and experienced personnel in the applied technical and administrative phases. It also can provide a basis for graduate teaching and research programs in environmental health. At the University of California's School of Public Health in Berkeley, curricula are being developed for educating teachers and research personnel in the environmental health sciences.

Air Pollution↗
PubMed1995

The Utah Thyroid Cohort Study: analysis of the dosimetry results.

Above ground testing of nuclear weapons at the Nevada Test Site (NTS) during the 1950s created radioactive fallout that was dispersed into the atmosphere and deposited over a large geographical area of the U.S. One area believed to have received a considerable amount of exposure to radioiodines (131I and 133I) in the fallout was southwest Utah and southeast Nevada. This paper describes the estimates of doses to the thyroid for a cohort of 3,545 subjects who were children during the atmospheric testing period. This group of children was examined for thyroid disease during 1965-1970 and again in 1985-1986. The cohort was made up of children who lived in three counties in 1965: Washington County, Utah; Lincoln County, Nevada; and Graham County, Arizona (originally thought to be an unexposed group). Pathway analysis was used in the dosimetry, considering exposures through the ingestion of milk and vegetables, inhalation of iodine during the passage of the fallout cloud, and external exposure. Specific data were obtained on diet (including sources and levels of milk and vegetables consumed, residence history, and lifestyle) by interviewing the parents or nearest living relative of subjects. The final dosimetry file for each member of the cohort contained specific doses to the thyroid glands and uncertainties (reported as geometric standard deviations, GSD) related to each dose estimate. The mean absorbed dose to the thyroid for subjects living in Washington County, Utah, was 170 mGy; for Lincoln County, Nevada, 50 mGy; and for those living in Graham County, Arizona, 13 mGy. The maximum dose to any subject was 4,610 mGy. There were 10 subjects who had doses greater than 1 Gy. The majority of uncertainty values calculated in this study were GSD values between 2.0 and 4.0. The results of the dosimetry were combined with the results of clinical examinations of the cohort to determine if a causal relationship exists between dose to thyroid from NTS generated radioactive iodines and the incidence of thyroid disease.

Adult↗
PubMed2002

Uncertain science and a failure of trust. The NIH radioepidemiologic tables and compensation for radiation-induced cancer.

In the late 1970s, the U.S. Congress was debating a number of different proposals to provide monetary compensation to residents of Utah and Nevada who had been exposed to radioactive fallout from government nuclear weapons testing in the 1950s. Yet scientists and government officials expressed concern that such a program would end up compensating many people for cancers that were not caused by the fallout. Thus, after much debate, Congress directed the National Institutes of Health to produce a set of statistical tables--the radioepidemiologic tables--to target compensation awards to "deserving" individuals. Advocates of the tables, notably Senator Orrin Hatch, argued that reliance on scientific data would provide compensation decisions with predictability and evenhandedness. Yet in the end, the effort to employ the tables failed. The substantial scientific uncertainties in the tables and in their application to individual claims failed to deliver the authority they promised. Additionally, the goal of fairness and objectivity could not be convincingly met because of persistent controversy and mistrust surrounding the government's role in the study of health effects of low-level radiation.

Compensation and Redress↗
PubMed1995

The Utah Leukemia Case-Control Study: dosimetry methodology and results.

This paper discusses the dosimetry methodology used to estimate bone marrow dose and the results of dosimetry calculations for 6,507 subjects in an epidemiologic case-control study of leukemia among Utah residents. The estimated doses were used to determine if a higher incidence of leukemia among residents of Utah could have been attributed to exposure to radioactive fallout from above-ground nuclear weapons tests conducted at the Nevada Test Site. The objective of the dosimetry methodology was to estimate absorbed dose to active marrow specific to each case and each control subject. Data on the residence of each subject were available from records of the Church of Jesus Christ of Latter-day Saints. Deposition of fallout was determined from databases developed using historical measurements and exposure for each subject from each test was estimated using those data. Exposure was converted to dose by applying an age-dependent dose conversion factor and a factor for shielding. The median dose for all case and control subjects was 3.2 mGy. The maximum estimated mean dose for any case or control was 29 +/- 5.6 mGy (a resident of Washington County, UT). Uncertainties were estimated for each estimated dose. The results of the dosimetry calculations were applied in an epidemiological analysis.

Adolescent↗
PubMed2006

Radiation dose estimation by tooth enamel EPR dosimetry for residents of Dolon and Bodene.

The method of electron paramagnetic resonance (EPR) dosimetry was applied to the enamel of the teeth extracted from the residents of the Dolon and Bodene settlements of the Beskaragay district, which is the area adjacent to the radioactive fallout of the most contaminating nuclear test of 1949. The individual accidental radiation doses due to the fallout were obtained from the amplitude of the radiation induced EPR signal from the CO2- radical using the calibration method, after determining the parameters of EPR measurements to obtain the best reproducibility of the signal intensities. It was shown that after subtracting the natural background dose from the total absorbed dose obtained by EPR the residents of Dolon and Bodene received accidental radiation doses up to 356 mGy with an average value of 74.1+/-45.5 mGy before 1949 while the younger population received up to about 100 mGy with an average value of 11.5+/-37.7 mGy.

Adult↗
PubMed2005

Investigation of loss of heterozygosity and SNP frequencies in the RET gene in papillary thyroid carcinoma.

In both medullary carcinoma and papillary carcinoma of the thyroid, altered expression of the RET gene is implicated in tumorigenesis. Recent studies suggest that loss of heterozygosity (LOH) at the G691S SNP may be associated with tumors from patients with a history of radiation exposure. We investigated LOH for three RET SNPs (G691S, S904S, and L769L) in tumor and normal tissue from 46 patients from Ukraine and Belarus who were exposed to radioactive fallout following the Chernobyl nuclear accident and were operated for papillary thyroid carcinoma between 1995 and 2000. Normal tissue from 28 patients was heterozygous for at least one SNP; DNA from the corresponding tumor samples was also heterozygous, indicating that no LOH had taken place. To assess SNP frequencies in a radiation-associated thyroid cancer cohort, we investigated a further 68 unpaired post-Chernobyl samples. For G691S, there was considerable deviation from Hardy-Weinberg equilibrium; more detailed analysis showed that this was linked to age at onset of disease. Among younger patients, the distribution of genotypes conformed to Hardy-Weinberg equilibrium; among older patients, we observed marked deviation (p = 0.0072), with significant over-representation of the rare S allele relative to the younger groups (Fisher's exact, p = 0.0233). This suggests that SNPs in the RET oncogene may play a role in sporadic papillary thyroid carcinoma.

Adolescent↗
PubMed2003

Correlation of cytoplasmic beta-catenin and cyclin D1 overexpression during thyroid carcinogenesis around Semipalatinsk nuclear test site.

The Semipalatinsk nuclear test site (SNTS), the Republic of Kazakhstan, has been contaminated by radioactive fallout. The alteration of oncogenic molecules in thyroid cancer around the SNTS was considered worthy of analysis because it presented the potential to elucidate the relationship between radiation exposure and thyroid cancer. This study aimed to analyze both beta-catenin and cyclin D1 expressions in thyroid carcinomas around the SNTS. We examined nine cases of chronic thyroiditis, eight cases of follicular adenomas, and 23 cases of papillary carcinomas. Immunohistochemically, all carcinomas displayed a strong cytosolic beta-catenin expression, while both chronic thyroiditis and follicular adenomas showed a significantly lower cytoplasmic beta-catenin (22.2% and 37.5%, respectively). No cyclin D1 immunoreactivity was evident in chronic thyroiditis. In contrast, 62.5% of follicular adenomas and 87.0% of papillary carcinoma showed cyclin D1 overexpression. Additionally, a strong correlation between cytoplasmic beta-catenin and cyclin D1 expression was suggested in thyroid tumors. This study revealed a higher prevalence of both aberrant beta-catenin expression and cyclin D1 overexpression in papillary thyroid cancers around the SNTS than sporadic cases. The analysis of the alteration of the Wnt signaling-related molecules in thyroid cancer around the SNTS may be important to gain an insight into radiation-induced thyroid tumorigenesis.

Adolescent↗
PubMed1992

Investigations of radiocaesium in the natural terrestrial environment in Norway following the Chernobyl accident.

Radioactive fallout from the Chernobyl accident affected parts of central Norway to a considerable extent, in particular the 134Cs+137Cs deposition had a significant impact on the natural environment. When this became apparent, a comprehensive radioecological research programme was initiated in order to study the behaviour of radiocaesium in boreal and alpine ecosystems, with emphasis on food-chains leading to exposure of species used for human consumption, i.e., reindeer and freshwater fish. In this paper results from the terrestrial part of this research programme during the period 1986-1990 are presented. The work was mainly confined to the mountain areas of Dovre and Rondane. Parallel studies were performed in eutrophic and strongly oligotrophic communities. The influence of local variations in topography and microclimate on the observed radiocaesium levels in topsoils, lichens and vascular plants was studied in detail. Currently a significant re-distribution of radiocaesium from the originally strongly exposed surfaces to those that were less exposed is observed. In the soil, radiocaesium is strongly retained in the litter and raw humus layers. Current levels in lichens are 1-2 orders of magnitude higher than in vascular plants. This strongly affects the seasonal variation of radiocaesium in reindeer, showing winter maxima of about 5 times higher than the August levels. The radiocaesium levels in reindeer showed a decline of approximately a factor of 3 during the period 1987-1990. Other animal species studied in the programme exhibited substantially lower radiocaesium levels than reindeer, but a considerable interspecies variation was observed.

Accidents↗
PubMed2004

Foliar contamination of Phaseolus vulgaris with aerosols of 137Cs, 85Sr, 133Ba and 123mTe: influence of plant development stage upon contamination and rain.

As part of a requirement to improve the assessment of the impact of radioactive fallout on consumed agricultural products, bean plants at four development stages (seedlings, preflowering, late flowering and mature plants) were contaminated by dry deposition of (137)Cs, (85)Sr, (133)Ba and (123m)Te aerosols. The influence of two rain scenarios and of the development stage upon contamination on interception, retention, and translocation to pods was studied. Interception of the four radionuclides was almost identical and varied from 30 to 60% with increasing development stage. The most important rain parameter was the time which elapsed between contamination and the first rain. Whatever the development stage, rain washed off more cesium from the leaves when it occurred 2 days after the deposit (37% at the seedling stage, for example) rather than later on (6 days, 27%), due to rapid migration of Cs in the plant. The first rain washed off nearly 40% of Ba whatever the scenario. For later stages, Sr and Ba were more washed off by heavy weekly rains than by weak twice-a-week rains, perhaps because of the Sr/Ba-contaminated material loss associated with wash off (desquamation of cuticles). Te showed little wash off (less than 5%). Wash off decreased with an older development stage for a weak rain intensity, due to the superimposition of leaves. Heavy rains removed this shelter effect. At harvest, rain effect was no longer detectable as foliar activity was similar for both rain scenarios. Translocation factors (TF) for strontium and barium increased from 6 x 10(-3) to 1 x 10(-1) with the plant development stage upon contamination, whereas those for cesium remained almost unchanged between 2 x 10(-1) and 4 x 10(-1). Flowering is the most critical stage towards residual contamination in pods at harvest, with the exception of direct deposit on pods at the mature stage (TF values are one order of magnitude higher). TF value for Te was 6.5 x 10(-2) and was due to direct deposit. Modelling reflected the trends, through the differential values of the wash off and absorption coefficients, of what was reported for experimental results.

Aerosols↗