Radiation Exposure Of Workers Research Articles

Simulation of the occupational radiation dose caused by contamination of primary circuit media in pressurized water reactors

Abstract The occupational radiation exposure of workers in NPPs during overall maintenance and refueling inspections and decommissioning is determined by numerous parameters. Radiation exposure caused by contamination of components may be minimised by the chemical operation mode and by applying systematic decontamination techniques. Data on occupational exposure in German NPPs as well as information about the radionuclide concentration in the coolant are available. The generic 3D model of the primary circuit presented is based on the analysis of technical documentation of German PWRs. Tasks are modeled as a combination of retention times at related local positions in the surroundings of work areas. The generic model allows the calculation of the resulting occupational doses generated by definable jobs and tasks. The KWU/Siemens-PWR generations are characterised by nuclide vectors, the thickness of shielding, and the material composition of components. It was possible to show that for a pre-Konvoi plant, the calculated occupational dose caused by a specific working task is close to measurements.

The linear no-threshold theory: Readers weigh in

In their letter, Jeffry Siegel and coauthors discussed the linear no-threshold (LNT) model of radiation-induced cancer. Vital to any such discussion is the relationship of high-dose and low-dose radiation to cancer and radiological standards. The LNT model was primarily based on gamma radiation. The other types of radiation producers are alpha emitters and beta emitters. All three produce cancer, and that is important since cancer may soon surpass heart problems as the leading cause of death.Radiation exposure standards are based on studies of survivors of the Hiroshima and Nagasaki bombings. The resultant standards are thus inherently biased in favor of survivors.Data were collected five years after the bombing. Therefore, those studies—carried out by US investigators and not by Japanese medical personnel—and the standards based on them depend primarily on the memory of survivor interviewees rather than on actual exposure data. Much guesswork went into determining the dose that survivors actually received.After World War II, national and international organizations were established to study radiation health effects and recommend standards for acceptable radiation exposure for workers in the industry and for the general public. The principal organizations were the National Council on Radiation Protection and Measurements and the International Commission on Radiological Protection (ICRP). Exposure standards that emerged are based on analysis of radiation from external sources and do not include sources lodged in the body. The BEIR VII study,11. National Research Council, Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2, National Academies Press (2006). which is the most comprehensive study of low-dose exposure to date and reinforces the LNT approach, concludes that any exposure to ionizing radiation is potentially harmful.Some alpha and beta emitters do lodge in the body and cause cancer and other illnesses. The European Committee on Radiation Risk started looking at populations exposed to internal radioactive isotopes from anthropogenic sources. Radioactive sources can enter the body through several means; ingestion, inhalation, and absorption through skin cuts are the main pathways. Most of the ingested or inhaled radioactive substances pass through the digestive system or are expectorated.Compared with gamma sources, alpha and beta emitters produce much smaller doses of electromagnetic radiation but do emit particles. Beta emitters—strontium-90 is an example—tend to migrate to bones and cause bone cancer.The manmade alpha emitter plutonium-239 can be found worldwide as a consequence of fallout from nuclear weapons testing and use.Many nuclear sites in the US have some 239Pu. At the Rocky Flats Plant just a few miles northwest of Denver, large quantities of 239Pu were used for construction of components for nuclear warheads. Residential housing sits on both the east and south sides of the facility, and there are nearby cities to the north. Residents living near the plant showed increased cancer rates, and many plant workers are receiving medical attention because of their exposure to 239Pu. The major pathway into the body for 239Pu is inhalation, because the particles are small. A Columbia University study found that a single plutonium alpha particle induces mutations in mammal cells.22. T. K. Hei et al., Proc. Natl. Acad. Sci. USA 94, 3765 (1997). https://doi.org/10.1073/pnas.94.8.3765 Once in the body, the 239Pu lodges in a specific location—primarily lung, bone, liver, brain, and gonads—and stays there. With a half-life of 24 110 years, it continuously emits alpha particles over the person’s lifetime.The Colorado Health Department stated that airborne emissions of 239Pu were the most dangerous emissions from the Rocky Flats facility. However, most airborne 239Pu particles are too small to be detected by the Environmental Protection Agency’s high-volume monitoring devices. But even if they could be detected, the EPA has no standards regulating airborne particles of 239Pu.Thus there are many questions remaining related to radiological standards and cancer.The discussion about radiation standards is based in part on work by LeRoy Moore, Rocky Mountain Peace and Justice Center, Boulder, Colorado.REFERENCESSection:ChooseTop of pageREFERENCES <<1. National Research Council, Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2, National Academies Press (2006). Google Scholar2. T. K. Hei et al., Proc. Natl. Acad. Sci. USA 94, 3765 (1997). https://doi.org/10.1073/pnas.94.8.3765, Google ScholarCrossref, ISI© 2016 American Institute of Physics.

Worker Radiation Exposure

This article contains information on professional external and internal radiation exposure in 2013 of workers in organizations, including NPP, on territories serviced by the Federal Medical-Biological Agency of Russia (FMBA). The parameters of the dose distribution are calculated: mode, median, average, standard deviation, quantile, and coeffi cient of variation for institutions on territories serviced by the FMBA. The number of individuals subject to individual dosimetric monitoring, grouped by institution and taking account of the radiation exposure dose is analyzed. Information on the professional external and internal radiation exposure of NPP workers is presented.

INDIVIDUAL DOSIMETRY IN DISPOSAL REPOSITORY OF HEAT-GENERATING NUCLEAR WASTE.

Certain working scenarios in a disposal facility of heat-generating nuclear waste might lead to an enhanced level of radiation exposure for workers in such facilities. Hence, a realistic estimation of the personal dose during individual working scenarios is desired. In this study, the general-purpose Monte Carlo N-Particle code MCNP6 (Pelowitz, D. B. (ed). MCNP6 user manual LA-CP-13-00634, Rev. 0 (2013)) was applied to simulate a representative radiation field in a disposal facility. A tool to estimate the personal dose was then proposed by taking into account the influence of individual motion sequences during working scenarios. As basis for this approach, a movable whole-body phantom was developed to describe individual body gestures of the workers during motion sequences. In this study, the proposed method was applied to the German concept of geological disposal in rock salt. The feasibility of the proposed approach was demonstrated with an example of working scenario in an emplacement drift of a rock salt mine.

CONSENSUS REPORT: Recognizing non‐melanoma skin cancer, including actinic keratosis, as an occupational disease – A Call to Action

1. Non-melanoma skin cancer (NMSC) is by far the most common cancer diagnosed in westernized countries, and one of the few almost preventable cancers if detected and treated early as up to 90% of NMSC may be attributed to excessive exposure to ultraviolet radiation. 2. The incidence of NMSC is increasing: 2-3 million people are diagnosed worldwide annually, with an average yearly increase of 3-8% among white populations in Australia, Europe, the US and Canada over the last 30 years. 3. The link between solar ultraviolet (UV) radiation and certain forms of NMSC is clearly recognized. It is estimated that outdoor workers are exposed to an UV radiation dose 2-3 times higher than indoor workers, and there is a growing body of research linking UV radiation exposure in outdoor workers to NMSC: I. Occupationally UV-exposed workers are at least at a 43% higher risk of basal cell carcinoma (BCC) and almost doubled risk of squamous cell carcinoma (SCC) compared to the average population, with risk increasing with decreasing latitude. II. The risk for BCC, SCC and actinic keratosis (AK) among workers who have worked outdoors for more than 5 years is 3-fold higher than the risk among those with no years of working outdoors. 4. Primary prevention, early detection, treatment and regular follow-up of skin cancer (NMSC and melanoma) are shown to be beneficial from a health economic perspective. 5. Action is needed at international, European and national level to legislate for recognizing AK and NMSC as an occupational disease, which has the potential to improve access to compensation and drive preventative activities. 6. This report is a Call to Action for: I. The engagement of key stakeholders, including supranational institutions, national governments, trade organizations, employers, workers and patient organizations to drive change in prevention and protection of at-risk groups. II. Employers should be obliged to prevent outdoor worker's UV exposure from exceeding limit values, and to implement occupational skin cancer screening programmes among the at-risk workforce. III. Educational programmes for the outdoor workforce are needed to improve health literacy and drive behavioural change. IV. Nationally, steps to improve notifications and surveillance of skin cancers through both occupational services and public health programmes are required. V. Future research activities should focus on the precise definition of at-risk groups among outdoor workers through increased data gathering, including UV-dosimetry, and evaluation.

A Mobile Robotic System for the Inspection and Repair of SG Tubes in NPPs

The reliability and performance of a steam generator (SG) is one of the serious concerns in the operation of pressurized water nuclear power plants. Because of high levels of radiation, robotic systems have been used to inspect and repair SG tubes. In this paper, we present a mobile robotic system that positions the inspection and repair tools while hanging down from the tube sheets where the tubes are fixed. All of the driving mechanisms of the mobile robot are actuated by electric motors to start its works, providing that the electric power is prepared without the additional need for an on-site air services. A special tube-holding mechanism with a high holding force has been developed to prevent falling from the tube sheets, even in the case of an electric power failure. We have also developed a quick installation guide device that guides the mobile robot to desired initial positions in the tube sheet exactly and quickly, which helps to reduce the radiation exposure of human workers during the installation work. This paper also provides on-site experimental results and lessons learned.

Factors Associated With Occupational Sun-Protection Policies in Local Government Organizations in Colorado.

Skin cancer prevention remains a national priority. Reducing chronic UV radiation exposure for outdoor workers through sun-safety practices is an important step to help reduce the incidence of skin cancer. To determine the presence of occupational sun-safety policies at local government organizations in a single state. Of 571 potentially eligible local government organizations of Colorado cities, counties, and special tax districts, we enrolled 98 in a randomized pretest-posttest controlled experiment starting August 15, 2010, that evaluated an intervention to promote the adoption of sun-safety policies. We used a policy-coding protocol to evaluate personal sun-protection practices, environmental and administrative controls, and policy directives for sun safety starting February 10, 2011. We report the baseline assessment of the occupational sun-protection policies of these organizations. The presence of an occupational sun-safety policy. Overall, 85 local government organizations (87%) had policies that required personal sun-protection practices, including the use of eyewear, hats, and protective clothing. However, of the 98 responding organizations, only 8 hat policies (8%), 10 eyewear policies (10%), and 7 clothing policies (7%) mentioned sun protection as the intent of the policy. Only cosmopoliteness, operationalized as proximity to an urban area, was associated with the presence of a sun-safety policy (odds ratio, 0.99 [95% CI, 0.98-1.00]; P = .02). Outdoor workers are at increased risk for skin cancer because of long-term exposure to solar UV radiation. Although organizational policies have the potential to increase sun protection in occupational settings, occupational sun-safety policies were uncommon among local governments. Opportunities exist for dermatologists and other physicians to influence occupational sun-safety practices and policies, which are consistent with other safety procedures and could easily be integrated into existing workplace practices.

Fate of Radium in Marcellus Shale Flowback Water Impoundments and Assessment of Associated Health Risks.

Natural gas extraction from Marcellus Shale generates large quantities of flowback water that contain high levels of salinity, heavy metals, and naturally occurring radioactive material (NORM). This water is typically stored in centralized storage impoundments or tanks prior to reuse, treatment or disposal. The fate of Ra-226, which is the dominant NORM component in flowback water, in three centralized storage impoundments in southwestern Pennsylvania was investigated during a 2.5-year period. Field sampling revealed that Ra-226 concentration in these storage facilities depends on the management strategy but is generally increasing during the reuse of flowback water for hydraulic fracturing. In addition, Ra-226 is enriched in the bottom solids (e.g., impoundment sludge), where it increased from less than 10 pCi/g for fresh sludge to several hundred pCi/g for aged sludge. A combination of sequential extraction procedure (SEP) and chemical composition analysis of impoundment sludge revealed that Barite is the main carrier of Ra-226 in the sludge. Toxicity characteristic leaching procedure (TCLP) (EPA Method 1311) was used to assess the leaching behavior of Ra-226 in the impoundment sludge and its implications for waste management strategies for this low-level radioactive solid waste. Radiation exposure for on-site workers calculated using the RESRAD model showed that the radiation dose equivalent for the baseline conditions was well below the NRC limit for the general public.

전리방사선 노출과 관리

Objectives: To investigate safety and health management, conditions in factories or facilities handling radiation-generating devices and radioactive isotopes were reviewed in terms of regulations of radiation safety control in Korea. Radiation exposure levels generated at those facilities were directly measured and evaluated for establishing an effective safety and health management plan. Methods: Government organizations with laws and systems of radiation safety and health were investigated and compared. There are three laws governing radiation-related employment such as occupational safety and health acts, nuclear safety acts, and medical service acts. We inspected 12 workplaces as research objects:four workplaces that manufacture and assemble semiconductor devices, three non-destructive inspection workplaces that perform inspections on radiation penetration, and five workplaces in textile and tire manufacturing. Monitoring of radiation exposure was performed through two methods. Spatial and surface monitoring using real-time radiation instruments was performed on each site handling radiation generating devices and radioactive isotopes in order to identify radiation leakage. Results: According to the occupational safety and health act, there is no legal obligation to measure ionizing radiation and set dose limits. This can cause confusion in the application of the laws, because the scopes and contents are different from each other. Surface dose rates in radiation generating devices such as implanters, thickness gages and accelerators, which were registered according to nuclear safety acts, using surveymeters, and seven of 36 facilities(19.4%) exceeded the international standards for surface radiation dose of <TEX>$10{\mu}Sv/hr$</TEX>. Conclusions: The results showed that occupational health and safety acts require a separate provision for measuring and assessing the radiation exposure of workers performing radiation work. Like noise, ionizing radiation will also periodically be controlled by including it in the object factors of work-environment measurement.

Pennsylvania's technologically enhanced, naturally occurring radioactive material experiences and studies of the oil and gas industry.

This presentation provides an overview of the Commonwealth of Pennsylvania's experiences and ongoing studies related to technologically enhanced, naturally occurring radioactive material (TENORM) in the oil and gas industry. It has been known for many years that Pennsylvania's geology is unique, with several areas having relatively high levels of natural uranium and thorium. In the 1950s, a few areas of the state were evaluated for commercial uranium production. In the late 1970s, scoping studies of radon in homes prompted the Pennsylvania Department of Environmental Protection (DEP) Bureau of Radiation Protection (BRP) to begin planning for a larger state-wide radon study. The BRP and Oil and Gas Bureau also performed a TENORM study of produced water in the early 1990s for a number of conventional oil and gas wells. More recently, BRP and the Bureau of Solid Waste developed radiation monitoring regulations for all Pennsylvania solid waste disposal facilities. These were implemented in 2001, prompting another evaluation of oil and gas operations and sludge generated from the treatment of conventionally produced water and brine but mainly focused on the disposal of TENORM solid waste in the state's Resource Conservation and Recovery Act Subtitle D landfills. However, since 2008, the increase in volumes of gas well wastewater and levels of Ra observed in the unconventional shale gas well flow-back fracking water has compelled DEP to fully re-examine these oil and gas operations. Specifically, with BRP in the lead, a new TENORM study of oil and gas operations and related wastewater treatment operations has been initiated (), supported by an American National Standards Institute standard on TENORM () and a U.S. Government Accountability Office report on shale resource development and risks (). This study began in early 2013 and will examine the potential public and worker radiation exposure and environmental impact as well as re-evaluate TENORM waste disposal. This presentation summarizes conventional and unconventional oil and gas well operations, geology and respective uranium/thorium content, radium content in oil and gas wastewater, treatment solids, radon in natural gas, the scope of other TENORM issues in the state, regulatory framework, national regulations and guidance. It also provides an overview of past and the status of ongoing TENORM studies in the Commonwealth (; Rowan and Kraemer 2012; ).

Radiation-induced changes in DNA methylation and their relationship to chromosome aberrations in nuclear power plant workers

Purpose: We investigated the association between occupational radiation exposure and DNA methylation changes in nuclear power plant workers. We also evaluated whether radiation- induced DNA methylation alterations are associated with chromosome aberrations.Materials and methods: The study population included 170 radiation-exposed workers and 30 controls. We measured global, long interspersed nuclear element-1 (LINE-1), and satellite 2 methylation levels in blood leukocyte DNA. The analysis of chromosome aberrations was performed on peripheral lymphocytes.Results: Global DNA methylation levels were lower in radiation-exposed workers than in controls. The methylation levels were negatively associated with the recent 1.5-year radiation dose in a multiple linear regression model (β = − 0.0088, p ≤ 0.001); the levels increased proportionally with the total cumulative dose in radiation-exposed workers. LINE-1 methylation levels were higher in radiation-exposed workers than in controls and were significantly associated with the total cumulative radiation dose in a multiple linear regression model (β = − 0.031, p = 0.035). Global DNA methylation levels were also correlated with chromosome aberrations among workers. Workers with low global methylation levels had a higher frequency of chromosome aberrations than did subjects with high global methylation levels.Conclusion: Occupational exposure to low-dose radiation could affect DNA methylation levels, and the radiation-induced DNA methylation alterations may be associated with chromosome aberrations.

PET 검사에서 작업종사자의 방사선 노출 선량을 줄이기 위한 자동 분주/주사 시스템의 유용성

본 연구에서는 PET 검사 중에 핵의학과 방사선 작업 종사자들의 방사선 노출선량을 줄이기 위하여 도입된 자동 분주/주사 시스템의 유용성 평가를 목적으로 한다. 핵의학과 방사선 작업 종사자를 두 그룹으로 나누어 첫 번째 그룹은 기존의 방사선 차폐 설비를 이용하여 분주 및 주사 업무를 수행하고, 두 번째 그룹은 자동 분주/주사시스템을 활용하여 분주 및 주사 업무를 수행하였다. 그리고 각 그룹에 속한 방사선 작업종사자들의 체부와 손 부위 방사선 노출 선량을 개인 선량계를 이용하여 측정하였다. 실험 결과 분주단계에서는 자동 분주/주사 시스템을 사용한 그룹이 사용하지 않은 그룹보다 크게 낮은 방사선 노출을 받은 것으로 나타났다. 또한 주사 단계에서도 손 부위의 경우 자동 분주/주사 시스템을 사용한 그룹이 사용하지 않은 그룹보다 낮은 방사선 노출을 받은 것으로 나타났다. In this study we assessed the efficacy of an automatic dispensing/injection system (ADIS) to reduce the radiation exposure of workers during PET procedures. NMW(Nuclear Medicine Workers) were classified into 2 groups, one of which used conventional method and the other used an ADIS. The radiation dose during injection were also measured in both groups, with another set of experiment. In dispensing step, ADIS imposed significantly less radiation dose than conventional method, both to finger and to whole body. In injection step, ADIS also imposed significantly less dose to finger, while the dose of whole body was somewhat larger in ADIS than in conventional method. Using ADIS, the radiation exposure of NMW during dispensing was markedly reduced. Also, the exposure of finger during injection was markedly reduced, although exposure of whole body was mildly increased.

Radiation exposure of workers in storage areas for building materials

Radon levels and radioactivity were measured in 50 shops and storage areas for building materials in Sudan. Charcoal canister and gamma spectrometry systems were used to measure radon in 55 types of natural material, and concentrations of 71–292Bq/m3 (mean, 154±38Bq/m3) were found. The concentration of radium (226Ra) ranged from 2.8 to 182.5Bq/kg, of thorium (232Th) from 1.2 to 302Bq/kg and of potassium (40K) from 82.3 to 1413.3Bq/kg. Porcelain, ceramic and marble showed high values, while gravel types had low radioactivity. Radium in building materials was well correlated with radon (r2=0.77). The average annual dose of workers at these sites due to inhalation of radon was estimated to be 2.8mSv. The activity index of building materials ranged between 0.33 and 1.97 (mean, 0.77).

8:18 AM; Abstract No. 213; Featured Abstract - Radiation exposure in pregnant and non-pregnant female interventional radiology workers

In 2012-13, 27% of Radiology residents and 15% of VIR fellows were women. Survey data from the ACR show that 3.1% of all practicing radiologists who consider IR their primary specialty are women. The percent of current women members in the SIR is 9%. A recent article in Academic Radiology by Blake et al recommended that IR rotations for residents be limited during pregnancy as accumulated exposure from these cases may be unpredictable. This recommendation is based on information regarding institutional policies rather than exposure data.

Assessment of potential options for conditional reuse of materials from nuclear installation decommissioning

The nuclear installation decommissioning process is characterized by production of large amount of radioactive materials to be managed. The materials with radioactivity slightly above the unconditional release levels could be released conditionally for a specific industrial application in accordance with beforehand developed and evaluated scenario. This evaluation has to ensure that the limits for radiation exposure of workers and the public will not be exceeded. The paper gives an overview of representative options (scenarios) for reuse of conditionally released steel materials and recycled concrete from decommissioning. The main aim of the paper is to present the developed complex methodology for assessment of these options and its implementation to the relevant calculation tools. The first step in the methodology procedure is the identification of the activities which could lead to the exposure of the public or workers. For defined activities the external exposure of workers and the public is evaluated using the Visiplan 3D ALARA Planning tool. The internal exposure analysis is mainly based on the models for migration of radionuclides in the environment calculated in the GoldSim code. Based on the results of exposure evaluation, the critical exposure pathway is determined and conditional release levels of individual radionuclides are derived. Finally the amount and radioactivity of materials from decommissioning, fulfilling the limits for conditional reuse, are calculated in the decommissioning planning code OMEGA [1].

Evaluation of external radiation exposure of workers engaged in loading of radioactive material shipping cask between ship and truck by crane

In the marine transportation of radioactive material shipping casks, a loading/unloading cargo work has been carried out using a large crane between a ship and a truck at the interface of land and sea. At that time there is a radiation exposure situation where a worker should approach a cask for handling, tie-down and dosimetric inspection. For a spent fuel cask whose surface dose rate is relatively high, it is necessary to evaluate a radiological risk for cargo workers as one of the planned exposure situations since there is no valid shielding between cask and worker for a long time. In order to instantly evaluate worker dose under any working environment, it is necessary to prepare a simple method that accurately calculate a dose rate map around a cask of interest. In this study, simple calculation methods developed for a spent fuel cask have been surveyed to determine the best fit parameters for a representative type-B wet cask of Japan NFT14P. Then, worker dose is practically evaluated by using the parameters under working environment of cask loading in Japan. There assumed to be three types of cargo workers; handler, inspector and spotter. It is found that the highest individual dose is evaluated to 1.70 μSv per cask loading for an inspector on a carrier of truck and the annual cumulative dose will be well below the annual public limit of 1mSv. The collective dose per loading is amounted to about 17 man-μSv in a total of 19 workers. The occurrence of latent effects can be negligible but the dose values are still higher compared to estimated exposures for escort and off-link population along a road route in U.S. land transportation of spent fuel.

The Assessment as Bone Mineral Density of Bone Damage in Radiology Workers Occupationally Exposed to Ionizing Radiation

We examined the effects of occupational ionizing radiation exposure in radiology workers on bone mineral density and serum alkaline phosphates (ALP) levels. 49 subjects, aged between 21-48 years (33.86 years), working in the department of radiology were enrolled to this study. 26 subjects were female and 23 were male. Control group consisted of 40 healthy subjects aged between 22-49 years (mean 33.83) who had never been exposed to radiation; 21 of these were female and 19 male. Venous blood samples were obtained from the radiology workers and control group and serum alkaline phosphatase levels analysis of samples were performed. The bone mineral density (BMD) was assessed in the spine and the hip with a dual-energy x-ray absorptiometry (DEXA) instrument. T-scores of radiology workers was lower than control group significantly (P 0.05). T-scores of the men at the control group were higher than the women’s however the case was just the opposite for the work group. In radiology workers exposed to long-term low-dose ionizing radiation has negative effect on bone mineral density and serum ALP levels.

Application of color Doppler ultrasound in examining hypothyroidism among radiation-exposed workers

To explore the application of color Doppler ultrasound in examining hypothyroidism among radiation-exposed workers. A total of 181 radiation-exposed workers who had clinical and laboratorial diagnoses of hypothyroidism were divided into X-ray diagnosis group, interventional radiology group, and radiotherapy group. Another 62 healthy people who underwent physical examinations were used as control group. All cases underwent color Doppler ultrasound; thyroid function, sonograms, and blood flow characteristics were analyzed. In the X-ray diagnosis group, interventional radiology group, and radiotherapy group, significant differences in the levels of free thyroxine and thyroid-stimulating hormone were found across workers with different lengths of service (P < 0.05). In the X-ray diagnosis group, interventional radiology group, and radiotherapy group, the percentages of individuals having uneven internal echo intensity among clinical hypothyroidism cases were higher than the percentages among subclinical hypothyroidism cases (P < 0.05). The X-ray diagnosis group, interventional radiology group, and radiotherapy group had significantly higher constituent ratios of grade II and III blood flow signals than the control group (P < 0.05). The peak systolic velocity of the superior thyroid artery (V(max)) was significantly higher in the X-ray diagnosis group, interventional radiology group, and radiotherapy group than in the control group (P < 0.05); in each group, Vmax was significantly higher in clinical hypothyroidism cases than in subclinical hypothyroidism cases (P < 0.05). As a simple, non-invasive, and economic examination, color Doppler ultrasound has been demonstrated as a valuable method for evaluating occupational hypothyroidism and holds promise for clinical application.

Radionuclides and radiation doses in heavy mineral sands and other mining operations in Mozambique

Sites at the littoral of Mozambique with heavy mineral sands exploited for ilmenite, rutile and zircon and inland mineral deposits exploited for tantalite, uranium and bauxite were surveyed for ambient radiation doses, and samples were collected for the determination of radionuclide concentrations. In heavy mineral sands, (238)U and (232)Th concentrations were 70±2 and 308±9 Bq kg(-1) dry weight (dw), respectively, whereas after separation of minerals, the concentrations in the ilmenite fraction were 2240±64 and 6125±485 Bq kg(-1) (dw), respectively. Tantalite displayed the highest concentrations with 44 738±2474 Bq kg(-1) of (238)U. Radiation exposure of workers in mining facilities is likely to occur at levels above the dose limit for members of the public (1 mSv y(-1)) and therefore radiation doses should be assessed as occupational exposures. Local populations living in these regions in general are not exposed to segregated minerals with high radionuclide concentrations. However, there is intensive artisanal mining and a large number of artisanal miners and their families may be exposed to radiation doses exceeding the dose limit. A radiation protection programme is therefore needed to ensure radiation protection of the public and workers of developing mining projects.

Radiation exposure received by the medical radiation workers in Lithuania at The Institute of Oncology, Vilnius University, 2004-2011

The occupational radiation exposure of medical radiation workers at the Institute of Oncology, Vilnius University (IOVU) was analysed. Quartile dose measurements were collected and routinely analysed for a period of 8 y from 1 January 2004 to 31 December 2011. A total of 193 medical radiation workers were monitored, comprising 34 % physicians (radiologists and radiotherapists), 8 % physicists, 42 % radiological technologists and 16 % ancillary staff. A statistically significant decrease by 18 % has been detected when comparing the annual average effective doses (AAEDs) received by medical radiation workers at the IOVU during periods 2004-2007 and 2008-2011 (p < 0.0001). The main occupation categories responsible for this reduction were of Nuclear Medicine (p < 0.028) and Radiology (p < 0.0001) departments. The values of AAED in Radiology, Radiotherapy and Nuclear Medicine departments are quite low and well below the annual limit of 20 mSv, averaged over a period of 5 consecutive years.