Occupational radiation exposure and cancer incidence in a cohort of diagnostic medical radiation workers in South Korea.

OBJECTIVES: We investigated the association between protracted low-dose ionising radiation and the risk of cancer in medical radiation workers, the largest group of workers with occupational radiation exposures. METHODS: Data of all South Korean diagnostic medical radiation workers enrolled at the National Dose Registry during 1996-2011 were merged with the death and cancer incidence data until 31 December 2017. SIRs, relative risks and excess relative risks (ERRs) for cancer were calculated to quantify the radiation dose-response relationship using Poisson regression models. RESULTS: A total of 3392 first primary cancer cases were identified among 93 920 diagnostic medical radiation workers. The mean cumulative badge dose in the cohort was 7.20 mSv. The ERRs for solid cancer with a 5-year lag and haematopoietic cancers with a 2-year lag for all workers were 0.15 per 100 mGy (95% CI -0.20 to 0.51) and 0.09 per 100 mGy (95% CI -2.02 to 2.20), respectively. The ERRs for cancers did not significantly vary by job title, different lag years or after excluding thyroid and lung cancers. Sensitivity analyses restricted to workers employed for at least 1 year, or who were employed in or after 1996, or who had exposure to a cumulative badge dose of 1 mSv or more showed similar results. CONCLUSIONS: Occupational radiation doses were not significantly associated with cancer incidence among South Korean diagnostic medical radiation workers. However, cautious interpretation of ERRs is needed due to the limitations of short follow-up and low cumulative radiation doses.

Occupational Radiation Exposure and Validity of National Dosimetry Registry among Korean Interventional Radiologists.

The national dose registry (NDR) contains essential information to help protect radiation workers from radiation-related health risks and to facilitate epidemiological studies. However, direct validation of the reported doses has not been considered. We investigated the validity of the NDR with a personal dosimeter monitoring conducted among Korean interventional radiologists. Among the 56 interventional radiologists, NDR quarterly doses were compared with actively monitored personal thermoluminescent dosimeter (TLD) doses as standard measures of validation. We conducted analyses with participants categorized according to compliance with TLD badge-wearing policies. A correlation between actively monitored doses and NDR doses was low (Spearman ρ = 0.06), and the mean actively monitored dose was significantly higher than the mean NDR dose (mean difference 0.98 mSv) in all participants. However, interventional radiologists who wore badges irregularly showed a large difference between actively monitored doses and NDR doses (mean difference 2.39 mSv), and participants who wore badges regularly showed no apparent difference between actively monitored doses and NDR doses (mean difference 0.26 mSv). This study indicated that NDR data underestimate the actual occupational radiation exposure, and the validity of these data varies according to compliance with badge-wearing policies. Considerable attention is required to interpret and utilize NDR data based on radiation workers' compliance with badge-wearing policies.

Thyroid cancer risks among medical radiation workers in South Korea, 1996-2015.

BACKGROUND: Thyroid cancer rates, especially among children, are known to be increased by radiation exposure. However, little is known about the impact of chronic low-dose radiation exposure on thyroid cancer risk in adulthood. This study examined radiation effects on thyroid cancer rates as well as an overall evaluation of thyroid cancer risk among medical radiation workers. METHODS: Data on all diagnostic medical radiation workers enrolled in the national dosimetry registry between 1996 and 2011 were linked with the cancer registry data through 2015. Standardized incidence ratios (SIRs) were used to compare the observed cancer incidence rates in this population to those for the general population while internal comparisons were used to estimate relative risks (RRs) for occupational history and excess relative risks (ERRs) were used to quantify the radiation dose-response relationship. RESULTS: Overall, 827 thyroid cancer cases were reported among 93,922 medical radiation workers. Thyroid cancer SIRs were significantly higher than expected for both men (SIR 1.72, 95% confidence interval [CI] 1.53 to 1.91) and women (SIR 1.18, 95% CI 1.08 to 1.28). However, RRs for thyroid cancer by job title and duration of employment showed no particular pattern among diagnostic medical radiation workers. There were no indications of a significant dose effect on thyroid cancer rates for either men (ERR/100 mGy 0.07, 95% CI -0.38 to 0.53) or women (ERR/100 mGy -0.13, 95% CI -0.49 to 0.23). The findings were similar for different job titles or when limited to workers employed for at least one year. CONCLUSIONS: While thyroid cancer incidence rates among Korean medical radiation workers were somewhat higher than those in the general population, there was no significant evidence that this increase was associated with occupational radiation dose. Additional follow-up together with consideration of other risk factors should provide useful information on thyroid cancer rates in this cohort.

Projected lifetime cancer risks from occupational radiation exposure among diagnostic medical radiation workers in South Korea.

BACKGROUND: Timely assessment of cancer risk from current radiation exposure among medical radiation workers can contribute to the development of strategies to prevent excessive occupational radiation exposure. The purpose of the present study is to estimate the lifetime risk of cancers induced by occupational radiation exposure among medical radiation workers. METHODS: Using estimated organ doses and the RadRAT risk assessment tool, the lifetime cancer risk was estimated among medical radiation workers who were enrolled in the Korean National Dose Registry from 1996 to 2011. Median doses were used for estimating the risk because of the skewed distribution of radiation doses. Realistic representative exposure scenarios in the study population based on sex, job start year, and occupational group were created for calculating the lifetime attributable risk (LAR) and lifetime fractional risk (LFR). RESULTS: The mean estimated lifetime cancer risk from occupational radiation exposure varied significantly by sex and occupational group. The highest LAR was observed in male and female radiologic technologists who started work in 1991 (264.4/100,000 and 391.2/100,000, respectively). Female workers had a higher risk of radiation-related excess cancer, although they were exposed to lower radiation doses than male workers. The higher LAR among women was attributable primarily to excess breast and thyroid cancer risks. LARs among men were higher than women in most other cancer sites. With respect to organ sites, LAR of colon cancer (44.3/100,000) was the highest in male radiologic technologists, whereas LAR of thyroid cancer (222.0/100,000) was the highest in female radiologic technologists among workers who started radiologic practice in 1991. Thyroid and bladder cancers had the highest LFR among radiologic technologists. CONCLUSIONS: Our findings provide an assessment of the potential cancer risk from occupational radiation exposure among medical radiation workers, based on current knowledge about radiation risk. Although the radiation-related risk was small in most cases, it varied widely by sex and occupational group, and the risk would be underestimated due to the use of median, rather than mean, doses. Therefore, careful monitoring is necessary to optimize radiation doses and protect medical radiation workers from potential health risks, particularly female radiologic technologists.

The Burden of Acute Pesticide Poisoning and Pesticide Regulation in Korea.

BACKGROUND: This study aimed to estimate the burden of acute pesticide poisoning and to determine its trend with recently implemented pesticide regulations. METHODS: Disability-adjusted life-years (DALYs) were calculated as the sum of years of life lost (YLLs) and years lived with disability (YLDs) due to acute pesticide poisoning using the methods of the Global Burden of Disease Study 2013. The values of YLLs, YLDs, and DALYs were stratified by sex, age groups, intentionality of poisoning, and causative agents. RESULTS: From 2006 to 2014, DALYs decreased by 69% (from 69,550 to 21,742). The decreasing tendency of DALYs was especially marked from 2011. The total burden of acute pesticide poisoning was mainly caused by YLLs and intentional pesticide poisoning. The highest DALYs due to acute pesticide poisoning occurred in those in their 40s and 50s; however, the decreased rates of DALYs were higher in those aged 10-49 years than in those aged more than 50 years. Herbicides including paraquat contributed to the largest proportion of total DALYs. CONCLUSION: As this is the first study to quantify the burden of acute pesticide poisoning using DALYs, our results provide comprehensive evidence of the importance of using strict regulations to prevent public health hazards due to acute pesticide poisoning.

Mortality among diagnostic medical radiation workers in South Korea, 1996-2015.

OBJECTIVES: To evaluate the risk for all-cause and cause-specific mortality in diagnostic medical radiation workers in South Korea. METHODS: The study population included all diagnostic medical radiation workers enrolled in the National Dosimetry Registry (NDR) between 1996 and 2011. NDR data were linked with mortality data obtained from national registries through 2015. Standardised mortality ratios (SMRs) and relative standardised mortality ratios (rSMRs) were calculated for external comparison and for adjustment of the cohort's overall healthiness. RESULTS: A total of 1099 deaths (974 in men and 125 in women) were reported from among 80 837 medical radiation workers. The SMRs for all causes of death were significantly lower than expected in both men (SMR 0.45, 95% CI 0.42 to 0.48) and women (SMR 0.49, 95% CI 0.41 to 0.58). No excesses were observed for any specific cause of death. The findings were similar by job title, calendar year of entry and year of birth. However, relative to all causes of death, mortality from all cancers (rSMR 1.60, 95% CI 1.41 to 1.82), leukaemia, colon cancer, stomach cancer and diseases of the circulatory system increased significantly among male workers. The results for female workers were limited due to small number of deaths; however, the rSMR for all cancers was significantly elevated (rSMR 1.70, 95% CI 1.17 to 2.46). CONCLUSIONS: This cohort showed lower mortality among diagnostic medical radiation workers than in the general population. However, occupational factors may have been involved in the increased relative mortality for several causes of death.

Health Effects from Occupational Radiation Exposure among Fluoroscopy-Guided Interventional Medical Workers: A Systematic Review.

A systematic review was conducted to provide an overview of the health effects of occupational radiation exposure from interventional fluoroscopy procedures on medical radiation workers. Among the 34 studies that met the inclusion criteria, most studies were cross-sectional (76%) and published after 2011 (65%) in a handful of countries. Although diverse outcomes were reported, most studies focused on cataracts. Radiation health effects were rarely assessed by risk per unit dose. Interventional radiation medical workers represent a small subset of the population studied worldwide. Further epidemiologic studies should be conducted to evaluate health outcomes among interventional radiation medical workers.

ESTIMATION OF ORGAN DOSES AMONG DIAGNOSTIC MEDICAL RADIATION WORKERS IN SOUTH KOREA.

This study aimed to estimate the radiation organ doses from occupational exposure in 94 396 Korean medical radiation workers. Data on badge doses (i.e. personal dose equivalent at 10 mm) between 1996 and 2011 obtained from a national dosimetry registry, survey data from 2012 to 2013, and organ dose conversion coefficients provided by the International Commission on Radiological Protection (ICRP) were used for the estimation. The highest mean cumulative badge doses (26.87 mSv) were observed in radiologists, followed by radiologic technologists (15.96 mSv). Male workers exhibited higher mean cumulative badge doses, across occupational groups. The estimated organ doses showed similar trends with those of badge doses. Organs located outside the apron's coverage such as the thyroid showed higher mean organ doses than those protected by the apron. Our findings could contribute to future radiation epidemiologic studies to investigate health effects from occupational radiation exposure in Korea.

Occupational radiation exposure and its health effects on interventional medical workers: study protocol for a prospective cohort study.

INTRODUCTION: Although fluoroscopically guided procedures involve a considerably high dose of radiation, few studies have investigated the effects of radiation on medical workers involved in interventional fluoroscopy procedures. Previous research remains in the early stages and has not reached a level comparable with other occupational studies thus far. Furthermore, the study of radiation workers provides an opportunity to estimate health risks at low doses and dose rates of ionising radiation. Therefore, the objectives of this study are (1) to initiate a prospective cohort study by conducting a baseline survey among medical radiation workers who involve interventional fluoroscopy procedures and (2) to assess the effect of occupational radiation exposure and on the overall health status through an in-depth cross-sectional study. METHODS AND ANALYSIS: Intervention medical workers in Korea will be enrolled by using a self-administered questionnaire survey, and the survey data will be linked with radiation dosimetry data, National Health Insurance claims data, cancer registry and mortality data. After merging these data, the radiation organ dose, lifetime attributable risk due to cancer and the risk per unit dose will be estimated. For the cross-sectional study, approximately 100 intervention radiology department workers will be investigated for blood tests, clinical examinations such as ultrasonography (thyroid and carotid artery scan) and lens opacity, the validation of badge dose and biodosimetry. ETHICS AND DISSEMINATION: This study was reviewed and approved by the institutional review board of Korea University (KU-IRB-12-12-A-1). All participants will provide written informed consent prior to enrolment. The findings of the study will be disseminated through peer-reviewed scientific journals, conference presentations, and a report will be submitted to the relevant public health authorities in the Korea Centers for Disease Control and Prevention to help with the development of appropriate research and management policies.

WORK PRACTICES AND RADIATION EXPOSURE AMONG MALE RADIOLOGIC TECHNOLOGISTS ASSISTING FLUOROSCOPICALLY GUIDED INTERVENTIONAL PROCEDURES.

This study investigated occupational characteristics and radiation exposure among radiologic technologists assisting fluoroscopically guided interventional (FGI) procedures. A nationwide survey of radiologic technologists in South Korea was conducted. Among 8058 male respondents, 664 (8.2%) assisted FGI procedures. The survey data were linked with dosimetry data from the National Dose Registry. Most radiologic technologists assisting FGI procedures were 30-40 years old and employed by general hospitals. These technologists worked in closer proximity to patients during procedures, less frequently used shield screens, more commonly utilized protective devices, and less commonly wore badge dosemeters than the ones not assisting FGI procedures. The average annual effective dose did not differ according to the performance of FGI procedures. The average cumulative effective dose among radiologic technologists assisting FGI procedures was significantly greater for those who had recently entered the field and personnel in rural areas than for those who did not assist these procedures.

Health Performance and Challenges in Korea: a Review of the Global Burden of Disease Study 2013.

The global burden of disease study (GBD) provides valuable information for evaluating population health in terms of disease burden. This study collected and reviewed GBD data in Korea for the year 1990 and 2013. The burdens of cancer, cardiovascular disease, communicable disease, and injuries have decreased remarkably, thereby greatly diminishing the overall disease burden on Korea. Meanwhile, the burdens due to non-fatal chronic diseases such as neuropsychiatric and musculoskeletal disease became major burden contributors. Responding to this circumstance presents a complex challenge to the Korean health system and Korean health policy.

Metabolic Risk Profile and Cancer in Korean Men and Women.

OBJECTIVES: Metabolic syndrome is a cluster of risk factors for type 2 diabetes mellitus and cardiovascular disease. Associations between metabolic syndrome and several types of cancer have recently been documented. METHODS: We analyzed the sample cohort data from the Korean National Health Insurance Service from 2002, with a follow-up period extending to 2013. The cohort data included 99 565 individuals who participated in the health examination program and whose data were therefore present in the cohort database. The metabolic risk profile of each participant was assessed based on obesity, high serum glucose and total cholesterol levels, and high blood pressure. The occurrence of cancer was identified using Korean National Health Insurance claims data. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models, adjusting for age group, smoking status, alcohol intake, and regular exercise. RESULTS: A total of 5937 cases of cancer occurred during a mean follow-up period of 10.4 years. In men with a high-risk metabolic profile, the risk of colon cancer was elevated (HR, 1.40; 95% CI, 1.14 to 1.71). In women, a high-risk metabolic profile was associated with a significantly increased risk of gallbladder and biliary tract cancer (HR, 2.05; 95% CI, 1.24 to 3.42). Non-significantly increased risks were observed in men for pharynx, larynx, rectum, and kidney cancer, and in women for colon, liver, breast, and ovarian cancer. CONCLUSIONS: The findings of this study support the previously suggested association between metabolic syndrome and the risk of several cancers. A high-risk metabolic profile may be an important risk factor for colon cancer in Korean men and gallbladder and biliary tract cancer in Korean women.

The economic burden of inflammatory heart disease in Korea.

BACKGROUND AND OBJECTIVES: The incidence of inflammatory heart diseases is not yet as high as those of other cardiovascular diseases; however, inflammatory heart diseases do have relatively high mortality rate. Therefore, update information on the economic burden of inflammatory heart diseases are necessary in order to appropriate policy making on these diseases. MATERIALS AND METHODS: This study used a number of resources to obtain data, national health insurance statistics, the Korean Health Panel, and the causes of death report by the Korean National Statistical Office. The total costs of inflammatory heart diseases were estimated as the sum of direct medical care costs, direct non-medical care and indirect costs. RESULTS: The total direct cost of inflammatory heart disease was higher in Korean men than that of Korean women and cost due to inpatient was higher than that of outpatients cost. The costs to cover premature death were highest among all of the components used to determine the total costs for inflammatory heart disease, representing 66.3% of these costs in Korea. CONCLUSION: Inflammatory heart disease has a relatively high mortality rate, and the costs that are associated with premature deaths consume the greatest proportion of the costs associated with this disease. In spite of some limitations of study, this could be a reliable evidence of economic burden of inflammatory heart disease.