Validation of mobile phone use recall in the multinational MOBI-kids study.

Potential differential and non-differential recall error in mobile phone use (MPU) in the multinational MOBI-Kids case-control study were evaluated. We compared self-reported MPU with network operator billing record data up to 3 months, 1 year, and 2 years before the interview date from 702 subjects aged between 10 and 24 years in eight countries. Spearman rank correlations, Kappa coefficients and geometric mean ratios (GMRs) were used. No material differences in MPU recall estimates between cases and controls were observed. The Spearman rank correlation coefficients between self-reported and recorded MPU in the most recent 3 months were 0.57 and 0.59 for call number and for call duration, respectively. The number of calls was on average underestimated by the participants (GMR = 0.69), while the duration of calls was overestimated (GMR = 1.59). Country, years since start of using a mobile phone, age at time of interview, and sex did not appear to influence recall accuracy for either call number or call duration. A trend in recall error was seen with level of self-reported MPU, with underestimation of use at lower levels and overestimation of use at higher levels for both number and duration of calls. Although both systematic and random errors in self-reported MPU among participants were observed, there was no evidence of differential recall error between cases and controls. Nonetheless, these sources of exposure measurement error warrant consideration in interpretation of the MOBI-Kids case-control study results on the association between children's use of mobile phones and potential brain cancer risk.

What digital health technology types are used in mental health prevention and intervention? Review of systematic reviews for systematization of technologies.

Digital health technology has been widely applied to mental health interventions worldwide. Using digital phenotyping to identify an individual's mental health status has become particularly important. However, many technologies other than digital phenotyping are expected to become more prevalent in the future. The systematization of these technologies is necessary to accurately identify trends in mental health interventions. However, no consensus on the technical classification of digital health technologies for mental health interventions has emerged. Thus, we conducted a review of systematic review articles on the application of digital health technologies in mental health while attempting to systematize the technology using the Delphi method. To identify technologies used in digital phenotyping and other digital technologies, we included 4 systematic review articles that met the inclusion criteria, and an additional 8 review articles, using a snowballing approach, were incorporated into the comprehensive review. Based on the review results, experts from various disciplines participated in the Delphi process and agreed on the following 11 technical categories for mental health interventions: heart rate estimation, exercise or physical activity, sleep estimation, contactless heart rate/pulse wave estimation, voice and emotion analysis, self-care/cognitive behavioral therapy/mindfulness, dietary management, psychological safety, communication robots, avatar/metaverse devices, and brain wave devices. The categories we defined intentionally included technologies that are expected to become widely used in the future. Therefore, we believe these 11 categories are socially implementable and useful for mental health interventions.

Impact of Radiofrequency Exposure From Mobile Phones on the Risk of Developing Brain Tumors in Korean and Japanese Adolescents: A MOBI-Kids Case-control Study.

BACKGROUND: This study aimed to examine the association between risk of brain tumors and radiofrequency (RF) exposure from mobile phones among young people in Korea and Japan. METHODS: This case-control study of brain tumors in young people was conducted in Korea and Japan under the framework of the international MOBI-Kids study. We included 118 patients diagnosed with brain tumors between 2011 and 2015 and 236 matched appendicitis controls aged 10-24 years. Information on mobile phone use was collected through face-to-face interviews. A detailed RF exposure algorithm, based on the MOBI-Kids algorithm and modified to account for the specificities of Japanese and Korean phones and networks, was used to calculate the odds ratios (ORs) for total cumulative specific energy using conditional logistic regression. RESULTS: The adjusted ORs in the highest tertile of cumulative call time at 1 year before the reference date were 1.61 (95% confidence interval [CI], 0.72-3.60) for all brain tumors and 0.70 (95% CI, 0.16-3.03) for gliomas, with no indication of a trend with exposure. The ORs for glioma specifically, were below 1 in the lowest exposure category. CONCLUSION: This study provided no evidence of a causal association between mobile phone use and risk of brain tumors as a whole or of glioma specifically. Further research will be required to evaluate the impact of newer technologies of communication in the future.

Association Between the Use of Induction Heating Cookers and Delivery Outcomes in Pregnant Women: An Internet-Based Cohort Study.

The number of devices that generate intermediate-frequency electromagnetic fields (IF-EMFs) in the living environment has been increasing. As the public has vague concerns about new devices, it is necessary to clarify the safety of IF-EMFs. Therefore, the present study aimed to examine the possible health effects of IF-EMFs by clarifying the relationship between the use of induction heating (IH) cookers and delivery outcomes. The study participants were pregnant women over the age of 20 years who were registered in panels with an Internet research firm. A total of 8920 pregnant women participated in the baseline survey. Of those who responded to the follow-up survey, 5022 who had a singleton birth were included in the analysis. We then examined the relationship between the use of IH cookers and gestational week at delivery (<37th/⩾37th week) or birth weight (<2500/⩾2500 g) using logistic regression models. No association was found between the use of IH cookers and birth weight, but weak associations were found between the use of stationary- and tabletop-type IH cookers and gestational week at delivery. After all considerations, we determined that the observed increased odds ratio did not indicate an increased risk of premature birth.

Longitudinal analysis of long-term outcomes of colorectal cancer after laparotomy and laparoscopic surgery: The Shizuoka study.

BACKGROUND: Long-term cancer prognosis after initial surgical procedures is an unlikely endpoint for clinical trials. Medical claim databases may aid in addressing this issue regardless of limited information on disease and patient background. However, the long-term prognosis (especially regarding long-term care needs) following surgical procedures remains unclear. This study aimed to assess whether long-term outcomes, such as the exacerbation of long-term care needs and mortality, differ with surgical methods. METHODS: Using a longitudinal study with linkage between medical claim and long-term care database, patients with primary colorectal cancer who underwent initial colonoscopies were identified through anonymized data in Japan (Shizuoka Kokuho Database, 2012-2018). Odds ratios (ORs) for long-term outcomes (long-term care needs and all-cause mortality during a 6.5-year follow-up period) were analyzed using logistic regression to compare laparoscopy and endoscopic surgery to laparotomy. RESULTS: Overall, 3,744 primary colorectal cancer cases (822 laparotomies, 705 laparoscopies, and 2,217 endoscopic surgeries) were included. Compared to the laparotomy group, the crude OR for exacerbation of long-term care needs in the laparoscopic surgery group was 0.376 (95% confidence interval, 0.227, 0.624), while the OR for all-cause mortality was 0.22 (0.329, 0.532). CONCLUSION: This is the first study to analyze long-term prognosis after surgery for patients with colorectal cancer to combine medical and long-term needs data. As the national health insurance claim database rarely includes information on cancer stage and comorbidities, better prognosis on endoscopic surgery may need careful interpretation. Therefore, laparoscopy has superior outcomes in terms of long-term care needs and mortality compared to those of laparotomy.

Association Between Alcohol Consumption Patterns and Glaucoma in Japan.

PRCIS: In this case-control study of the Japanese population, including 3207 glaucoma cases, alcohol consumption patterns such as frequency and quantity showed a positive association with glaucoma prevalence. PURPOSE: To examine the association between alcohol consumption patterns and glaucoma. SUBJECTS AND METHODS: This case-control study evaluated 3207 cases with glaucoma and 3207 matched controls. Patients over 40 years of age were included from 1,693,611 patients admitted to 34 hospitals in Japan. Detailed alcohol consumption patterns (drinking frequency, average daily drinks, and total lifetime drinks) were obtained, as well as various confounding factors, including smoking history and lifestyle-related comorbidities. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for glaucoma prevalence. RESULTS: Drinking frequency showed an association with glaucoma for "a few days/week" (OR, 1.19; 95% CI, 1.03-1.38) and "almost every day/week" (OR, 1.40; 95% CI, 1.18-1.66). Average daily drinks showed an association for ">0-2 drinks/day" (OR, 1.16; 95% CI, 1.03-1.32). Total lifetime drinks showed an association for ">60-90 drink-year" (OR, 1.23; 95% CI, 1.01-1.49) and ">90 drink-year" (OR, 1.23; 95% CI, 1.05-1.44). As alcohol consumption levels differed considerably between men and women, additional analyses were conducted separately for men and women. Among men, drinking frequency of "a few days/week" and "almost every day/week," average daily drinks of ">0-2 drinks/day" and ">2-4 drinks/day," and total lifetime drinks of ">60-90 drink-year" and ">90 drink-year" had an association with glaucoma. Conversely, among women, neither drinking frequency, average daily drinks, nor total lifetime drinks were associated. CONCLUSIONS: Both the frequency and quantity of alcohol consumption were associated with glaucoma. Further research on gender differences is warranted.

Length of employment in workplaces handling hazardous chemicals and risk of cancer among Japanese men.

OBJECTIVES: In Japan, the risk of developing cancer among workers employed in workplaces where chemical substances are handled is unclear. This study aimed to assess the association between cancer risk and employment in workplaces handling hazardous chemicals. METHODS: The Inpatient Clinico-Occupational Survey of the Rosai Hospital Group data of 120 278 male patients with incident cancer and 217 605 hospital controls matched for 5-year age group, hospital (34 hospitals) and year of admission (2005-2019) were analysed. Cancer risk in relation to lifetime employment in workplaces using regulated chemicals was assessed while controlling for age, region and year of diagnosis, smoking, alcohol consumption and occupation. Further analysis stratified by smoking history was performed to examine interaction effects. RESULTS: In the longest group of employment in tertiles, ORs were increased for all cancers (OR=1.13; 95% CI: 1.07 to 1.19) and lung (OR=1.82; 95% CI: 1.56 to 2.13), oesophageal (OR=1.73; 95% CI: 1.18 to 2.55), pancreatic (OR=2.03; 95% CI: 1.40 to 2.94) and bladder (OR=1.40; 95% CI: 1.12 to 1.74) cancers. Employment of 1+ years was associated with risk for lung cancer; 11+ years for pancreatic and bladder cancers; and 21+ years for all cancers and oesophageal cancer. These positive relationships were particularly obvious among patients with a history of smoking; however, no significant interaction between smoking and length of employment was observed. CONCLUSIONS: There is a high risk of cancer among workers, especially smokers, employed in workplaces handling regulated chemicals in Japan. Thus, future measures for chemical management in workplaces are needed to prevent avoidable cancers.

Alcohol use patterns and risk of incident cataract surgery: a large scale case-control study in Japan.

To examine the risk of incident cataract surgery associated with alcohol use patterns among Japanese adults. This was a case-control study evaluating 14,861 patients with incident cataract surgery and 14,861 matched controls. Subjects admitted to any of the 34 hospitals in Japan and aged between 40 and 69 years were included. Drinking patterns (drinking frequency, daily average drinks, and total amount of lifetime drinking), smoking history, lifestyle-related comorbidities, and occupational factors were surveyed by trained interviewers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression models. For drinking frequency, ORs in the 1-3 days/week and 4-7 days/week groups were 1.10 (95% CI 1.03-1.17) and 1.30 (1.21-1.40), respectively. For average drinks, ORs in > 0-2 drinks/day, > 2-4 drinks/day, and > 4 drinks/day were 1.13 (1.06-1.20), 1.23 (1.12-1.35), and 1.16 (1.03-1.31), respectively. Both men and women had an increased risk of incident cataract surgery with increased total lifetime drinking, with a significant increase in risk occurring at > 90 drink-years for men and > 40 drink-years for women. A positive dose-response relationship was observed between alcohol consumption and cataract. Restricted drinking may help to reduce the progression of cataracts.

Survey of Delivery Outcomes for Employees at MR Imaging Facilities in Japan Based on Information Recorded in the Maternal and Child Health Handbook.

The effect of maternal occupational non-ionizing radiation (NIR) exposure from MRI on premature birth and low birth weight delivery was analyzed based on questionnaire survey (263 employees, 443 births). Although the highest occurrence rates of both outcomes were observed in the group whose NIR exposure occurred only before pregnancy, no statistical significance was detected.

Occupational class and risk of hepatitis B and C viral infections: A case-control study-based data from a nationwide hospital group in Japan.

BACKGROUND: Occupational class, a proxy for socio-economic status, is a known factor for health disparities. However, no study has reported the association between occupational class and the risk of viral hepatitis B and C (HBV/HCV) infections. We investigated the effects of occupational class on the prevalence of HBV/HCV infections. METHODS: This is an unmatched hospital-based case-control study that included 12,101 patients who were diagnosed with HBV infection (ICD-10, B16.0, B16.1, B16.2, B16.9, B17.0, B18.0, B18.1) or HCV infection (ICD-10, B17.1, B18.2) and 698,168 controls (those with non-HBV/HCV-related diseases) aged ≥ 20 years who were initially hospitalized between 2005 and 2019. Patients were categorized according to occupational class (blue-collar, service, professional, and manager) and industrial sector (blue-collar, service, and white-collar). Managers in the blue-collar industry were set as the reference group, and the odds ratios (ORs) for the risk of HBV and HCV infections were calculated. RESULTS: Occupational class was significantly associated with only HCV infection risk. Professionals in all industrial sectors showed the lowest risk for HCV (OR (95% confidence intervals [CIs]) = 0.69 [0.58-0.82] in the blue-collar industry, 0.52 [0.38-0.73] in the service industry, and 0.60 [0.52-0.70] in the white-collar industry). Further, after adjusting for sex, age, and region of admitting hospital, all occupational classes in the white-collar industry showed lower risks of HCV than those in the other industries (ORs= 0.58 [0.47-0.71] in blue-collar workers, 0.74 [0.64-0.84] in service workers, 0.60 [0.52-0.70] in professionals, and 0.81 [0.64-1.02] in managers in white-collar industry). CONCLUSIONS: Occupational class was closely associated with HCV infection risk only. Considering that blue-collar workers in the white-collar industry also showed a low risk, adequate measures should be taken against hepatitis, possibly because of the screening tests and cure implemented in that population.

Assessment of combined exposure to intermediate-frequency electromagnetic fields and pulsed electromagnetic fields among library workers in Japan.

Objective: To assess exposure levels to electromagnetic fields (EMFs) among library workers in Japan, focusing on co-exposure to intermediate-frequency EMF (IF-EMF) and pulsed EMF, to propose a new epidemiological research methodology. Methods: The evaluated exposure sources were an electromagnetic type-electronic article surveillance gate (EM-EAS, IF-EMF (operating frequency 220 Hz-14 kHz)) and an activator/deactivator of anti-theft tags termed as "book check unit" (BCU, pulsed EMF). Short-term exposures were: (E1) whole-body exposure from the EAS gate when sitting within 3 m; (E2) local exposure to transient IF-EMF while passing through or beside the EAS gate; and (E3) local exposure to a pulsed magnetic field on BCU use. E1-E3 were evaluated based on exposure levels relative to magnetic flux density at the occupational reference level (RL; E1) or as per occupational basic restrictions (BR; E2 and E3) delineated by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) 2010 guidelines. Exposure indices based on mid-term exposure (D1-D3), assuming exposure according to employment on a weekly basis, were used to assess exposure in actual working conditions. D1 represents continuous exposure from an EAS gate when sitting within 3 m of the gate. D2 and D3 represent repeated transient exposures occurring during gate pass or on the operation of a BCU. A link to a web-based questionnaire was distributed to librarians working at all libraries where the authors had mailed institutional questionnaires (4,073 libraries). Four exposure patterns were defined according to various exposure scenarios. Results: We obtained information on exposure parameters and working conditions from the 548 completed questionnaires. The ICNIRP guideline levels were not exceeded in any of the E1-E3 scenarios. Median of the D1 (% ICNIRP RL × hour/week) was 1, and >85% respondents had values <10. However, the maximum value was 513. Altogether, these results indicate that continuous exposure was low in most cases. The same tendency was observed regarding repeated transient exposure from EM-EAS gates (i.e., the median value for D2 (% ICNIRP BR × gate pass) was 5). However, there were several cases in which D1 and D2 values were >10 times the median. The median of D3 (% ICNIRP BR × BCU operation) was 10, and most respondents' D3 values were greater than their D2 values, although the derived results depended on the assumptions made for the estimation. Conclusion: We conducted an assessment of combined exposures to IF-EMF and pulsed EMF among library workers in Japan by evaluating both short-term exposures (E1-E3) and exposure indices based on mid-term exposures (D1-D3) assuming actual working conditions per questionnaire results. These results provide useful information for future epidemiological studies.

Measurement and Exposure Assessment of Intermediate Frequency Magnetic Fields From Electronic Article Surveillance (EAS) Gates in Libraries.

Exposure to magnetic fields from the electronic article surveillance (EAS) gate was evaluated in consideration of the application to epidemiological studies of library workers who are exposed continually to intermediate frequency magnetic fields from the EAS gate. Two types of exposures were investigated. One was transient exposure due to passing through or beside the gate and another was chronic exposure in the room. We measured magnetic fields from five EAS gate models which were commonly used in libraries in Japan. Detailed measurements were performed for two of them in consideration of the phase difference of vector components of magnetic flux density. The polarization of the magnetic field in the gate was investigated with the index of ellipticity. The induced electric field in a human body was numerically calculated for exposures to magnetic fields of the two gate models. The results provide a quantitative understanding of exposures during passing through or by the EAS gate. Magnetic field distribution was measured in a large room for one gate model to quantify the chronic exposure of library workers during the work at the desk. It was found that the magnetic field was distributed as a function of the horizontal distance to the nearest gatepost. The 45-point average value BIEC defined by the IEC standard was suggested to be a useful quantity to characterize the magnitude of the magnetic field from the EAS gate. Exposures to different EAS gates are expected to be compared through this quantity without detailed measurements. These results are expected to provide useful means for exposure assessment of epidemiological studies on the association between the IF-EMF exposure and possible health outcomes.

Occupations associated with diabetes complications: A nationwide-multicenter hospital-based case-control study.

AIM: Investigating the risks of diabetes complications among inpatients with diabetes associated with longest-held and current occupations. METHOD: Using a Japanese nationwide, multicenter, hospital inpatient dataset (2005-2015), a matched case-control study with 39,550 inpatients with diabetes was conducted. We considered both the longest-held and current occupations of the study subjects. RESULT: Diabetes complications such as retinopathy, nephropathy, neuropathy, and peripheral vascular complications occur more often in managers, sales workers, service workers, transportation workers, construction and mining workers and carrying, cleaning and packing workers. Among these occupations, particularly the service workers indicated consistently significant increased risks (OR = 1.36 (1.23-1.51)) in developing all the considered subtypes of diabetes complications, and the performed sensitivity analysis confirmed this conclusion. Moreover, among service workers, cooks, waiters, building service staff and other service workers were identified as having the highest risks in developing diabetes complications (ORs = 1.30 (1.12-1.51), 1.63 (1.36-1.95), 1.79 (1.21-2.67), and 2.05 (1.30-3.22), respectively). CONCLUSIONS: Our study's potential translational impact should lead to subsequent investigations on the causes connected to certain occupations of various diabetes complications and particularly to more carefully dealing with patients with diabetes who work in the identified occupational areas and their health risks.

Occupational physical activity differentially affects the risk for developing later-onset Crohn's disease and ulcerative colitis among middle-aged and older populations.

BACKGROUND: A person's occupation may increase his/her risk for developing inflammatory bowel disease (IBD). This study investigated the association between risk for later-onset of IBD and both specific occupations and occupational physical activity (OPA) levels. MATERIALS AND METHODS: A multicenter hospital-based matched case-control study was conducted using the Inpatient Clinico-Occupational Survey database. Cases were patients with Crohn's disease (CD) and ulcerative colitis (UC) patients admitted for the first time between 2005 and 2015. Four controls matched by age, sex, admission year and hospital were selected for each case. Cases and controls were grouped into the longest-held occupations as classified by the Japanese Standard Occupational Classification and OPA levels. We conducted conditional logistic regressions to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for IBD, CD and UC adjusted for alcohol consumption and smoking status. RESULTS: There were 564 cases (172 CD, 392 UC) and 2086 controls. The risk for UC was higher among sales workers and carrying, cleaning and packing workers (ORs 2.62 [95%CIs 1.18-5.82], 2.52 [1.04-6.09]). There was no association between occupation type and CD risk. Higher OPA level decreased CD risk (OR 0.51 [95%CIs 0.26-1.00]) and increased UC risk (OR 1.53 [95%CIs 1.02-2.30]). CONCLUSIONS: Our study revealed that the risk for later-onset of UC, but not CD, was associated with longest-held 'service' and 'manufacture' work. The risk by OPA levels was inversely associated between CD and UC. Further studies are needed by follow-up method for long-term effects of physical activity.

A case control study of occupation and cardiovascular disease risk in Japanese men and women.

We aimed to investigate the risks of cardiovascular diseases associated with specific occupations, using a nation-wide, multicentre, hospital-based registry data from the Inpatient Clinico-Occupational Survey. The analysis included 539,110 controls (non-circulatory disease) and 23,792 cases (cerebral infarction, intracerebral/subarachnoid hemorrhage, acute myocardial infarction) aged ≥ 20 years who were initially hospitalized during 2005-2015. The participants' occupational and clinical histories were collected by interviewers and medical doctors. Occupations were coded into 81 categories according to the Japanese standard occupation classification. Multivariable logistic regression analysis adjusted for age, admission year and hospital, smoking, alcohol consumption, hypertension, and shift-work was conducted by sex using general clerical workers as the reference. Increased risks of cerebral infarction, intracerebral hemorrhage, subarachnoid hemorrhage, and acute myocardial infarction, were observed in 15, 20, 25, and 1 occupation(s) in men, and 9, 2, 2, and 10 occupations in women. Motor vehicle drivers, food and drink preparatory workers, fishery workers, cargo workers, civil engineer workers, and other manual workers in men and other manual workers in women faced increased risks of all three stroke subtypes. Our findings demonstrate associations between specific occupations and the risk of cardiovascular disease incidence and suggest that the risk may vary by occupation.

The relationship of hospital stay and readmission with employment status.

The Inpatient Clinico-Occupational Survey collected data from 3.76 million patients, showing that the average length of stay declined by 16.1 d in FY2008 and by 14.1 d in FY2015. In this study, we assessed the length of hospital stay and readmission, stratified by ICD-10 and employment status. A cross-sectional study was conducted on data from FY2008, including those from 65,806 first hospitalizations and 16,653 readmissions in FY2008, where 62,260 first admissions and 29,242 readmissions in FY 2015. The length of hospital stay was longest in those admitted due to external influences (24.8 d), followed by musculoskeletal disorders (22.5 d). This remained unchanged in FY2015, however, lengths of stay of those were reduced by 20.1 and 20.0 d, respectively. The length of hospital stay for most diseases was longer upon readmission than on first admission, and longer for those who were unemployed. It is necessary to give attention to patients who need to be discharged early due to work, or plan for frequent hospitalization in order to reduce the length of each hospital stay because of the expected increase in the number of elderly workers brought on by a declining birth rate and an aging population.

Combined effects of occupational exposure to hazardous operations and lifestyle-related factors on cancer incidence.

We aimed to examine whether the number of types of hazardous operations at work experienced through a lifetime is associated with cancer incidence, and additionally examined the combined effects with lifestyle-related factors. Using a nationwide, multicenter, hospital inpatient dataset (2005-2015), we conducted a matched case-control study with 1 149 296 study subjects. We classified the participants into those with none, 1, or 2 or more types of hazardous operation experience, based on information of special medical examinations taken, mandatory in Japan for workers engaged in hazardous operations. Using those with no experience as the reference group, we estimated the odds ratios for cancer incidence (all sites, lung, stomach, colon and rectum, liver, pancreas, bile duct, and bladder) by conditional logistic regression with multiple imputations. We also examined the effects of the combination with hazardous operations and lifestyle-related factors. We observed increased risks for cancer of all sites, and lung, pancreas, and bladder cancer associated with the experience of hazardous operations. Multivariable-adjusted ORs (95% CIs) of cancer incidence of all sites were 1 (reference), 1.16 (1.12, 1.21), and 1.17 (1.08, 1.27) for none, 1, and 2 or more types of hazardous operation experience, respectively (P for trend <.001). Potential combined associations of hazardous operations with smoking were observed for lung, pancreas, and bladder cancer, and with diabetes for pancreas cancer. Engaging in hazardous operations at work and in combination with lifestyle-related factors may increase the risk of cancer. We highlight the potential for those engaged in hazardous work to avoid preventable cancers.

Computed tomography of the head and the risk of brain tumours during childhood and adolescence: results from a case-control study in Japan.

To clarify whether medical radiation exposure, especially from head computed tomography (CT), increases the risk of brain tumours in young patients in Japan, which ranks the second highest in the world in the number of paediatric CT examinations following the US. From 2011 to 2015, we performed a case-control study of 120 brain tumour patients and 360 appendicitis patients as controls. Reasons, the number of brain and head CT scans date were available from interviews. A cumulative radiation dose to the brain was calculated as a sum of doses received from head CT scans and from conventional X-rays and estimated using a reference table derived from a literature review of published studies. We performed conditional logistic regression to assess the risk of brain tumours from brain and head CT, and from conventional head X-ray procedures. The case group received on average 1.8 CTs to the brain area and 2.2 CTs to the whole head, with a mean estimated brain dose of 32 ±13 mGy. The odds ratio for developing a brain tumour from having a brain CT was 0.93 (95% confidence interval: 0.38-1.82). This was hardly altered when adjusting for parental educational history and for other diseases (history of neurological disease and attention-deficit disorder/attention-deficit hyperactivity disorder). Neither whole head CT nor cumulative brain dose to the brain increased the risk of glioma or of all brain tumours. Although this study conducted in Japan, where ranks second in the number of CT scans conducted in the world, did not show an increased risk of brain tumours related to CT scans, it should be taken with caution due to a case-control study with limited sample size.

Ecological study on the penetration of induction heating cookers and birth outcomes in Japan.

In recent years, equipment that generates intermediate-frequency electromagnetic fields (IF-EMFs) has become increasingly prevalent, and the influence of IF-EMFs on human health is thus attracting increasing attention. The present study was conducted with the aim of analyzing whether there is a relationship between the penetration of induction heating cookers and birth outcomes using an ecological study design at the prefectural level. We created data sets for all 47 prefectures in Japan using previously published statistics. Spontaneous fetal death rate, fetal death rate after 22 weeks of pregnancy, perinatal mortality rate, and proportion of newborns weighing less than 2500 g were used as birth outcomes in correlation analysis. A weak positive association was observed between the penetration of induction heating cookers and the fetal death rate after the 22nd week of pregnancy (r = 0.27, p = 0.07), but it was not statistically significant. In addition, a weak negative association was observed between the penetration of induction heating cookers and the spontaneous fetal death rate (r = -0.27, p = 0.07), but it was not statistically significant. In the present ecological study, no statistically significant association were shown between the penetration of induction heating cookers and birth outcomes. To demonstrate further the safety of induction heating cooker use, observations in epidemiological studies of other designs should be considered.

Clinical presentation of young people (10-24 years old) with brain tumors: results from the international MOBI-Kids study.

INTRODUCTION: We used data from MOBI-Kids, a 14-country international collaborative case-control study of brain tumors (BTs), to study clinical characteristics of the tumors in older children (10 years or older), adolescents and young adults (up to the age of 24). METHODS: Information from clinical records was obtained for 899 BT cases, including signs and symptoms, symptom onset, diagnosis date, tumor type and location. RESULTS: Overall, 64% of all tumors were low-grade, 76% were neuroepithelial tumors and 62% gliomas. There were more males than females among neuroepithelial and embryonal tumor cases, but more females with meningeal tumors. The most frequent locations were cerebellum (22%) and frontal (16%) lobe. The most frequent symptom was headaches (60%), overall, as well as for gliomas, embryonal and 'non-neuroepithelial' tumors; it was convulsions/seizures for neuroepithelial tumors other than glioma, and visual signs and symptoms for meningiomas. A cluster analysis showed that headaches and nausea/vomiting was the only combination of symptoms that exceeded a cutoff of 50%, with a joint occurrence of 67%. Overall, the median time from first symptom to diagnosis was 1.42 months (IQR 0.53-4.80); it exceeded 1 year in 12% of cases, though no particular symptom was associated with exceptionally long or short delays. CONCLUSIONS: This is the largest clinical epidemiology study of BT in young people conducted so far. Many signs and symptoms were identified, dominated by headaches and nausea/vomiting. Diagnosis was generally rapid but in 12% diagnostic delay exceeded 1 year with none of the symptoms been associated with a distinctly long time until diagnosis.