Receipt of Electroconvulsive Therapy and Subsequent Development of Amyotrophic Lateral Sclerosis: A Cohort Study.

We investigated the potential relationship between receipt of electroconvulsive therapy (ECT) and development of amyotrophic lateral sclerosis (ALS). We conducted a cohort study using a sample of more than one million beneficiaries enrolled in the U.S. Medicare health insurance program from 1997 to 2017. Using time-varying proportional hazard modeling, we compared ALS occurrence among patients diagnosed with psychiatric conditions who received ECT to ALS occurrence among patients diagnosed with psychiatric conditions but who did not receive ECT. We observed moderately increased, but imprecise, hazard ratios (HR) for ALS following ECT (HR = 1.39, 95% confidence interval [CI]: 0.69-2.80). A statistically significant increase in the HR of ALS was observed among those who received more than 10 ECT treatments (>10 treatments, HR = 2.24, 95% CI: 1.00-5.01), compared to those receiving no ECT, with an even stronger association observed among subjects older than 65 years (HR = 3.03, 95% CI: 1.13-8.10). No monotonic exposure-response relationship was detected in categorical analyses. Our results provide weak support for the hypothesis that receipt of ECT increases the risk of developing ALS. Additional studies in larger populations, or in populations where ECT is more common, will be needed to refute or confirm an association between receipt of ECT and subsequent development of ALS. Bioelectromagnetics. 43:81-89, 2022. © 2021 Bioelectromagnetics Society.

Comments on a recent case-control study of malignant mesothelioma of the pericardium and the tunica vaginalis testis.

As the first case-control study of malignant mesothelioma of the pericardium and the tunica vaginalis testis (mTVT), the paper by Marinaccio et al (1) is potentially an important epidemiologic contribution. A careful review of the paper, however, raises a number of methodological issues. Any case-control study can be viewed as being nested within a conceptual cohort, with controls being sampled from the at-risk cohort as cases arise over time. This view of case-control studies leads to the concept of incidence-density sampling of controls (eg, 2, 3). For Marinaccio et al (1) this would mean that, as cases were registered over the study period, each would be matched to an individual control or set of controls of the same gender, age, and region of the country (since asbestos exposure varies by time and region [4]). For example, if a case were 50 years old in 1995, then any matched control should be close to age 50 in 1995 and of the same gender and from the same region as the case. Matching for age in this fashion automatically results in matching for year of birth, which is essential in this context because birth-cohort effects are determinants of asbestos exposure and mesothelioma incidence (eg, 5-8). If Marinaccio et al (1) used this scheme for age-matching, one would expect to see similar distributions of cases (table 1) and controls (table S3 in the supplemental material) by period of birth. Among males, however, the distributions of mesothelioma cases (whether pericardial or mTVT) and controls by period of birth are clearly different (P<0.001). Among females, the distributions of cases of pericardial mesothelioma and controls by birth year are less dissimilar (P≈0.05). Thus, the female cases of pericardial mesothelioma are better matched to controls on year of birth than are male cases of either mTVT or pericardial mesothelioma. We note also that the distributions of male and female controls by year of birth are distinctly different (P<0.002), whereas the birth-year distributions of cases of mesothelioma by site and gender are not (P≈0.8). In the Marinaccio et al (1) sensitivity analysis restricted to subjects born before 1950, the distributions of cases and controls by period of birth remain significantly different. Therefore, based on the reported evidence, cases and controls were not matched on birth cohort, thereby possibly biasing the results. Similarly, bias may result from the lack of matching on geographic region; while cases were registered from across Italy, controls were selected from only six regions. Although a sensitivity analysis restricted cases and controls to those from only the six regions, a comparison of tables S1 and S3 indicates that the regional distribution of controls is different from that of person-time observed; that is, the controls do not appear to be representative of the underlying population at risk by region. The second major issue of concern has to do with ascertainment of asbestos exposure. Information on exposure for the cases was presumably obtained at the time of registration. The two sets of controls, obtained from previously unpublished case-control studies, were interviewed during 2014-2015 and 2014-2016; that is, many years after the exposure for most cases was ascertained (1993-2015). Few other details of the control groups are provided, except that participation by one set of controls was <50%, raising additional concerns about selection bias. For details on the second set of controls, Marinaccio et al (1) reference a paper by Brandi et al (9). On review of that paper, however, we found no description of the control group, only references to three earlier papers. Marinaccio et al (1) present analyses only with both sets of controls combined; to evaluate potential sources of bias from the use of different sets of controls, they should also report results using each set of controls separately. The authors also did not detail their methods of exposure classification. For example, what does probable or possible exposure mean? The authors should at least present separate analyses of definite occupational exposure. Eighty cases of mTVT were registered, but only 68 were included in the analyses. Information on the 12 omitted cases (eg, age, year of birth, and region) would be helpful. Marinaccio et al (1) did not provide clear information on what occupations and/or industries they considered as exposed to asbestos. In an earlier study, Marinaccio et al (10) remarked on the absence of pericardial mesothelioma and mTVT in industries with the highest exposures to asbestos, saying, "[t]he absence of exposures in the shipbuilding, railway and asbestos-cement industries … for all the 67 pericardial and testicular cases is noteworthy but not easy to interpret." By contrast, Marinaccio et al (1) stated, "[t]he economic sectors more frequently associated with asbestos exposure were construction, steel mills, metal-working industry, textile industry and agriculture." The possibility of exposure in the "agriculture economic sector" was not mentioned in Marinaccio et al (10) and appears not to have been considered in previous epidemiologic studies in Italy. In general, epidemiologic studies indicate that farmers and agricultural workers are not at increased risk of developing mesothelioma (eg, 11-17). The fact that few, if any, cases of mTVT and pericardial mesothelioma occurred in industries traditionally associated with high asbestos exposure raises the possibility that the results of Marinaccio et al (1) are attributable to deficiencies in study design, very possibly bias in the selection of controls, and deficiencies in exposure assessment and classification as described above, leading to a spurious association of occupational exposure with mTVT and male pericardial mesothelioma. Conflict of interest This research has received no outside funding. All authors are employees of Exponent, Inc., an international scientific and engineering consulting company. All authors have worked as both consulting and testifying experts in litigation matters related to asbestos exposure and asbestos-related disease. References 1. Marinaccio A, Consonni D, Mensi C, Mirabelli D, Migliore E, Magnani C et al.; ReNaM Working Group. Association between asbestos exposure and pericardial and tunica vaginalis testis malignant mesothelioma: a case-control study and epidemiological remarks. Scand J Work Environ Health. 2020;46(6):609-617. https://doi.org/10.5271/sjweh.3895. 2. Rothman KJ, Greenland S, Lash TL. Modern Epidemiology. 2008; Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins. 3. Richardson DB. An incidence density sampling program for nested case-control analyses. Occup Environ Med 2004 Dec;61(12):e59. https://doi.org/10.1136/oem.2004.014472. 4. Marinaccio A, Binazzi A, Marzio DD, Scarselli A, Verardo M, Mirabelli D et al.; ReNaM Working Group. Pleural malignant mesothelioma epidemic: incidence, modalities of asbestos exposure and occupations involved from the Italian National Register. Int J Cancer 2012 May;130(9):2146-54. https://doi.org/10.1002/ijc.26229. 5. La Vecchia C, Decarli A, Peto J, Levi F, Tomei F, Negri E. An age, period and cohort analysis of pleural cancer mortality in Europe. Eur J Cancer Prev 2000 Jun;9(3):179-84. https://doi.org/10.1097/00008469-200006000-00005. 6. Price B, Ware A. Mesothelioma trends in the United States: an update based on Surveillance, Epidemiology, and End Results Program data for 1973 through 2003. Am J Epidemiol 2004 Jan;159(2):107-12. https://doi.org/10.1093/aje/kwh025. 7. Moolgavkar SH, Meza R, Turim J. Pleural and peritoneal mesotheliomas in SEER: age effects and temporal trends, 1973-2005. Cancer Causes Control 2009 Aug;20(6):935-44. https://doi.org/10.1007/s10552-009-9328-9. 8. Moolgavkar SH, Chang ET, Mezei G, Mowat FS. Chapter 3. Epidemiology of mesothelioma. In Testa JR. Asbestos and mesothelioma; 2017. pp. 43-72. Cham, Switzerland: Springer International Publishing. 9. Brandi G, Di Girolamo S, Farioli A, de Rosa F, Curti S, Pinna AD et al. Asbestos: a hidden player behind the cholangiocarcinoma increase? Findings from a case-control analysis. Cancer Causes Control 2013 May;24(5):911-8. https://doi.org/10.1007/s10552-013-0167-3. 10. Marinaccio A, Binazzi A, Di Marzio D, Scarselli A, Verardo M, Mirabelli D et al. Incidence of extrapleural malignant mesothelioma and asbestos exposure, from the Italian national register. Occup Environ Med 2010 Nov;67(11):760-5. https://doi.org/10.1136/oem.2009.051466. 11. Teschke K, Morgan MS, Checkoway H, Franklin G, Spinelli JJ, van Belle G et al. Mesothelioma surveillance to locate sources of exposure to asbestos. Can J Public Health 1997 May-Jun;88(3):163-8. https://doi.org/10.1007/BF03403881. 12. Bouchardy C, Schüler G, Minder C, Hotz P, Bousquet A, Levi F et al. Cancer risk by occupation and socioeconomic group among men--a study by the Association of Swiss Cancer Registries. Scand J Work Environ Health 2002;28(1 Suppl 1):1-88. 13. Hemminki K, Li X. Time trends and occupational risk factors for pleural mesothelioma in Sweden. J Occup Environ Med 2003a Apr;45(4):456-61. https://doi.org/10.1097/01.jom.0000058341.05741.7e. 14. Hemminki K, Li X. Time trends and occupational risk factors for peritoneal mesothelioma in Sweden. J Occup Environ Med 2003b Apr;45(4):451-5. https://doi.org/10.1097/01.jom.0000052960.59271.d4. 15. Pukkala E, Martinsen JI, Lynge E, Gunnarsdottir HK, Sparén P, Tryggvadottir L et al. Occupation and cancer - follow-up of 15 million people in five Nordic countries. Acta Oncol 2009;48(5):646-790. https://doi.org/10.1080/02841860902913546. 16. Rolland P, Gramond C, Berron H, Ducamp S, Imbernon E, Goldberg M et al. Mesotheliome pleural: Professions et secteurs d'activite a risque chez les hommes [Pleural mesothelioma: Professions and occupational areas at risk among humans]. 2005; Institut de VeilleSanitaire, Departement Sante Travai, Saint-Maurice, France. 17. Rolland P, Gramond C, Lacourt A, Astoul P, Chamming's S, Ducamp S et al. PNSM Study Group. Occupations and industries in France at high risk for pleural mesothelioma: A population-based case-control study (1998-2002). Am J Ind Med 2010 Dec;53(12):1207-19. https://doi.org/10.1002/ajim.20895.

Differential Effects of Maternal High Fat Diet During Pregnancy and Lactation on Taste Preferences in Rats.

Maternal intake of high fat diet (HFD) increases risk for obesity and metabolic disorders in offspring. Developmental programming of taste preference is a potential mechanism by which this occurs. Whether maternal HFD during pregnancy, lactation, or both, imposes greater risks for altered taste preferences in adult offspring remains a question, and in turn, was investigated in the present study. Four groups of offspring were generated based on maternal HFD access: (1) HFD during pregnancy and lactation (HFD); (2) HFD during pregnancy (HFD-pregnancy); (3) HFD during lactation (HFD-lactation); and (4) normal diet (ND) during pregnancy and lactation (ND). Adult offspring 70 days of age underwent sensory and motivational taste preference testing with various concentrations of sucrose and Intralipid solutions using brief-access automated gustometers (Davis-rigs) and 24 h two-bottle choice tests, respectively. To control for post-gestational diet effects, offspring in all experimental groups were weaned on ND, and did not differ in body weight or glucose tolerance at the time of testing. Offspring exposed to maternal HFD showed increased sensory taste responses for 0.3, 0.6, 1.2 M sucrose solutions in HFD and 0.6 M in HFD-pregnancy groups, compared to animals exposed to ND. Similar effects were noted for lower concentrations of Intralipid in HFD (0.05, 0.10%) and HFD-pregnancy (0.05, 0.10, 0.5%) groups. The HFD-lactation group showed an opposite, diminished responsiveness for sucrose at the highest concentrations (0.9, 1.2, 1.5 M), but not for Intralipid, compared to ND animals. Extended-access two-bottle tests did not reveal major difference across the groups. Our study shows that maternal HFD during pregnancy and lactation has markedly different effects on preferences for palatable sweet and fatty solutions in adult offspring and suggests that such developmental programing may primarily affect gustatory mechanisms. Future studies are warranted for determining the impact of taste changes on development of obesity and metabolic disorders in a "real" food environment with food choices available, as well as to identify specific underlying mechanisms.

Epidemiology of mesothelioma of the pericardium and tunica vaginalis testis.

PURPOSE: Malignant mesothelioma most commonly arises in the pleura and peritoneum but also occurs rarely at other anatomical sites with mesothelial tissue, namely, the pericardium and tunica vaginalis testis (TVT). This review provides a better understanding of the epidemiology of mesothelioma of these extrapleural sites. METHODS: We conducted a systematic review of the epidemiologic and clinical literature on pericardial mesothelioma and mesothelioma of the TVT. We also analyzed U.S. Surveillance, Epidemiology, and End Results cancer registry data to describe incidence patterns of these malignancies. RESULTS: An etiologic role of asbestos exposure has been hypothesized for pericardial and TVT mesotheliomas, but no analytical case-control epidemiologic studies exist to test this relationship. A substantial proportion of cases with these malignancies report no known asbestos exposure. In large occupational cohorts with heavy asbestos exposures, no cases of pericardial or TVT mesothelioma have been reported. Trends in the incidence of these malignancies do not match those of pleural mesothelioma, which correspond to historical trends of commercial asbestos use. A male preponderance of pericardial mesothelioma is not evident. CONCLUSIONS: In the absence of analytic epidemiologic studies, the etiologic role of environmental risk factors for mesothelioma of the pericardium and TVT remains elusive.

Injuries among electric power industry workers, 1995-2013.

INTRODUCTION: Workers in the electric power industry face many risks of injury due to the high diversity of work tasks performed in potentially hazardous and unpredictable work environments. METHOD: We calculated injury rates by age, sex, occupational group, and injury type among workers in the Electric Power Research Institute's (EPRI) Occupational Health and Safety Database (OHSD), which contains recordable injury, medical claims, and personnel data from 18 participating electric power companies from 1995 to 2013. RESULTS: The OHSD includes a total of 63,193 injuries over 1,977,436 employee-years of follow-up, for an overall injury rate of 3.20 injuries per 100 employee-years. Annual injury rates steadily decreased from 1995 to 2000, increased sharply in 2001, and subsequently decreased to their lowest rate of 1.31 injuries per 100 employee-years in 2013. Occupations with the highest injury rates were welders (13.56 per 100 employee-years, 95% CI 12.74-14.37), meter readers (12.04 per 100 employee-years, 95% CI 11.77-12.31), and line workers (10.37 per 100 employee-years, 95% CI 10.19-10.56). Males had an overall higher injury rate compared to females (2.74 vs. 1.61 per 100 employee-years) although some occupations, such as meter reader, had higher injury rates for females. For all workers, injury rates were highest for those in the 21 to 30 age group (3.70 per 100 employee-years) and decreased with age. Welders and machinists did not follow this trend and had higher injury rates in the 65+ age group. There were 63 fatalities over the 1995 to 2013 period, with 21 fatalities (33.3%) occurring among line workers. CONCLUSIONS: Although injury rates have decreased over time, certain high-risk groups remain (i.e., line workers, mechanics, young males, older welders and machinists, and female meter readers). PRACTICAL APPLICATIONS: Protective measures and targeted safety programs may be warranted to ensure the safety of electric power workers.

Self-reported mobile phone use and semen parameters among men from a fertility clinic.

There is increasing concern that use of mobile phones, a source of low-level radio-frequency electromagnetic fields, may be associated with poor semen quality, but the epidemiologic evidence is limited and conflicting. The relationship between mobile phone use patterns and markers of semen quality was explored in a longitudinal cohort study of 153 men that attended an academic fertility clinic in Boston, Massachusetts. Information on mobile phone use duration, headset or earpiece use, and the body location in which the mobile phone was carried was ascertained via nurse-administered questionnaire. Semen samples (n=350) were collected and analyzed onsite. To account for multiple semen samples per man, linear mixed models with random intercepts were used to investigate the association between mobile phone use and semen parameters. Overall, there was no evidence for a relationship between mobile phone use and semen quality.

An analysis of fatal and non-fatal injuries and injury severity factors among electric power industry workers.

BACKGROUND: The electric power industry represents a unique subset of the U.S. workforce. We aimed to evaluate the relationships between occupational category, nature of injury, and injury severity among electric power industry workers. METHODS: The Occupational Health and Safety Database (1995-2013) was used to calculate injury rates, assess patterns of injury severity, and identify at-risk occupations in this population. RESULTS: Over the surveillance period, a total of 63,193 injuries were reported. Overall, and severe injury rates were 3.20 and 0.52 per 100 employee-years, respectively. The fatal injury rate was 3.29 per 100,000 employee-years. Line workers experienced the highest risk for fatal injuries and second highest for non-fatal severe injuries, following meter readers. The most severe non-fatal injuries were hernia and rupture; multiple injuries; and CTD/RSI. Fatal injuries were most commonly associated with vehicle collisions and contact with electric current. CONCLUSIONS: Industry specific surveillance and interventions tailored to high-risk occupations are needed to further reduce severe injuries in this population. Am. J. Ind. Med. 59:948-958, 2016. © 2016 Wiley Periodicals, Inc.

Race/ethnicity and the risk of childhood leukaemia: a case-control study in California.

BACKGROUND: We conducted a large registry-based study in California to investigate the association between race/ethnicity and childhood leukaemia focusing on two subtypes: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML). METHODS: We obtained information on 5788 cases and 5788 controls by linking California cancer and birth registries. We evaluated relative risk of childhood leukaemia by race and ethnicity of the child and their parents using conditional logistic regression, with adjustment for potential confounders. RESULTS: Compared with Whites, Black children had lower risk of ALL (OR=0.54, 95% CI 0.45 to 0.66) as well as children of Black/Asian parents (OR=0.31, 95% CI 0.10 to 0.94). Asian race was associated with increased risk of AML with OR=1.643, 95% CI 1.10 to 2.46 for Asian vs Whites; and OR=1.67, 95% CI 1.04 to 2.70 for Asian/Asian vs White/White. Hispanic ethnicity was associated with increased risk of ALL (OR=1.37, 95% CI 1.22 to 1.52). A gradient in risk of ALL was observed while comparing Hispanic children with both parents Hispanic, one parent Hispanic and non-Hispanic children (p Value for trend <0.0001). The highest risk of ALL was observed for children with a combination of Hispanic ethnicity and White race compared with non-Hispanic whites (OR=1.27, 95% CI 1.12 to 1.44). The lowest risk was observed for non-Hispanic blacks (OR=0.46, 95% CI 0.36 to 0.60). Associations for total childhood leukaemia were similar to ALL. CONCLUSIONS: Our results confirm that there are ethnic and racial differences in the incidence of childhood leukaemia. These differences indicate that some genetic and/or environmental/cultural factors are involved in aetiology of childhood leukaemia.

Epidemiologic study of residential proximity to transmission lines and childhood cancer in California: description of design, epidemiologic methods and study population.

We conducted a large epidemiologic case-control study in California to examine the association between childhood cancer risk and distance from the home address at birth to the nearest high-voltage overhead transmission line as a replication of the study of Draper et al. in the United Kingdom. We present a detailed description of the study design, methods of case ascertainment, control selection, exposure assessment and data analysis plan. A total of 5788 childhood leukemia cases and 3308 childhood central nervous system cancer cases (included for comparison) and matched controls were available for analysis. Birth and diagnosis addresses of cases and birth addresses of controls were geocoded. Distance from the home to nearby overhead transmission lines was ascertained on the basis of the electric power companies' geographic information system (GIS) databases, additional Google Earth aerial evaluation and site visits to selected residences. We evaluated distances to power lines up to 2000 m and included consideration of lower voltages (60-69 kV). Distance measures based on GIS and Google Earth evaluation showed close agreement (Pearson correlation >0.99). Our three-tiered approach to exposure assessment allowed us to achieve high specificity, which is crucial for studies of rare diseases with low exposure prevalence.

Case-control study of occupational exposure to electric shocks and magnetic fields and mortality from amyotrophic lateral sclerosis in the US, 1991-1999.

We investigated the relationship between occupational exposure to electric shocks (ES) and magnetic fields (MF) and amyotrophic lateral sclerosis (ALS) using 1991-1999 US mortality data. For each of the 5886 included ALS deaths, 10 controls-matched on sex-, age-, year- and region-were selected from among other deaths. Usual occupation as reported on death certificates was linked to job-exposure matrices for ES and MF. Education and electric occupations were associated with moderately increased ALS risks (odds ratio (OR)=1.85, 95% confidence interval (CI)=1.67, 2.04; OR=1.23, 95% CI=1.04, 1.47, respectively). For ES, ALS mortality OR were 0.73 (95% CI=0.67, 0.79) for high and 0.90 (95% CI=0.84, 0.97) for medium exposure compared with low exposure. For MF, ALS ORs were 1.09 (95% CI=1.00, 1.19) for high and 1.09 (95% CI=0.96, 1.23) for medium exposure as compared with low exposure. For electric occupations, ALS ORs were insensitive to adjustments for ES, MF or both. Consistent with previous publications, an association between electric occupations and ALS was observed. Findings do not support occupational exposure to ES or MF as an explanation.

Epidemiology of childhood leukemia in the presence and absence of Down syndrome.

Down syndrome (DS) is a common congenital anomaly, and children with DS have a substantially higher risk of leukemia. Although understanding of genetic and epigenetic changes of childhood leukemia has improved, the causes of childhood leukemia and the potential role of environmental exposures in leukemogenesis remain largely unknown. Although many epidemiologic studies have examined a variety of environmental exposures, ionizing radiation remains the only generally accepted environmental risk factor for childhood leukemia. Among suspected risk factors, infections, exposure to pesticides, and extremely low frequency magnetic fields are notable. While there are well-defined differences between leukemia in children with and without DS, studies of risk factors for leukemia among DS children are generally consistent with trends seen among non-DS (NDS) children. We provide background on DS epidemiology and review the similarities and differences in biological and epidemiologic features of leukemia in children with and without DS. We propose that both acute lymphoblastic and acute myeloblastic leukemia among DS children can serve as an informative model for development of childhood leukemia. Further, the high rates of leukemia among DS children make it possible to study this disease using a cohort approach, a powerful method that is unfeasible in the general population due to the rarity of childhood leukemia.

Potential role of selection bias in the association between childhood leukemia and residential magnetic fields exposure: a population-based assessment.

PURPOSE: Data from the Northern California Childhood Leukemia Study (NCCLS) were used to assess whether selection bias may explain the association between residential magnetic fields (assessed by wire codes) and childhood leukemia as previously observed in case-control studies. METHODS: Wiring codes were calculated for participating cases, n=310; and non-participating cases, n=66; as well as for three control groups: first-choice participating, n=174; first-choice non-participating, n=252; and replacement (non-first choice participating controls), n=220. RESULTS: Participating controls tended to be of higher socioeconomic status than non-participating controls, and lower socioeconomic status was related to higher wire-codes. The odds ratio (OR) for developing childhood leukemia associated with high wire-codes was 1.18 (95% CI: 0.85, 1.64) when all cases were compared to all first-choice controls (participating and non-participating). The OR for developing childhood leukemia in the high current category was 1.43 (95% CI: 0.91, 2.26) when participating cases were compared to first-choice participating controls, but no associations were observed when participating cases were compared to non-participating controls (OR=1.06, 95% CI: 0.71, 1.57) or to replacement controls (OR=1.06, 95% CI: 0.71, 1.60). CONCLUSIONS: The observed risk estimates vary by type of control group, and no statistically significant association between wire codes and childhood leukemia is observed in the California population participating in the NCCLS.

Indoor transformer stations and ELF magnetic field exposure: use of transformer structural characteristics to improve exposure assessment.

Previous studies have shown that populations of multiapartment buildings with indoor transformer stations may serve as a basis for improved epidemiological studies on the relationship between childhood leukaemia and extremely-low-frequency (ELF) magnetic fields (MFs). This study investigated whether classification based on structural characteristics of the transformer stations would improve ELF MF exposure assessment. The data included MF measurements in apartments directly above transformer stations ("exposed" apartments) in 30 buildings in Finland, and reference apartments in the same buildings. Transformer structural characteristics (type and location of low-voltage conductors) were used to classify exposed apartments into high-exposure (HE) and intermediate-exposure (IE) categories. An exposure gradient was observed: both the time-average MF and time above a threshold (0.4 µT) were highest in the HE apartments and lowest in the reference apartments, showing a statistically significant trend. The differences between HE and IE apartments, however, were not statistically significant. A simulation exercise showed that the three-category classification did not perform better than a two-category classification (exposed and reference apartments) in detecting the existence of an increased risk. However, data on the structural characteristics of transformers is potentially useful for evaluating exposure-response relationship.

Residential distance to high-voltage power lines and risk of neurodegenerative diseases: a Danish population-based case-control study.

The aim of this study was to investigate the possible association between residential distance to high-voltage power lines and neurodegenerative diseases, especially Alzheimer's disease. A Swiss study previously found increased risk of Alzheimer's disease for people living within 50 m of a power line. A register-based case-control study including all patients diagnosed with neurodegenerative diseases during the years 1994-2010 was conducted among the entire adult population of Denmark. Using conditional logistic regression models, hazard ratios for ever living close to a power line in the time period 5-20 years before diagnosis were computed. The risks for developing dementia, Parkinson's disease, multiple sclerosis, and motor neuron disease were not increased in persons living within close vicinity of a power line. The risk of Alzheimer's disease was not increased for ever living within 50 m of a power line (hazard ratio = 1.04, 95% confidence interval: 0.69, 1.56). No dose-response according to number of years of living within 50 m of a power line was observed, but there were weak indications of an increased risk for persons diagnosed by the age of 75 years. Overall, there was little support for an association between neurodegenerative disease and living close to power lines.

Occupational exposure to extremely low-frequency magnetic fields and neurodegenerative disease: a meta-analysis.

OBJECTIVE: Previous studies reported associations of occupational electric and magnetic fields (MF) with neurodegenerative diseases (NDDs). Results differ between studies using proxy exposure based on occupational titles and estimated MF levels. We conducted a meta-analysis of occupational MF NDD, primarily Alzheimer disease (AD), and motor neuron diseases (MNDs) studies. METHODS: We identified 42 peer-reviewed publications and focused our analysis on study characteristics, exposure metrics, and publication bias. RESULTS: We found weak associations for occupational MF exposure proxies with AD and MND. Motor neuron disease risk was associated with occupational titles, whereas AD risk was associated with estimated MF levels. Results varied in study design, with dissimilar variation across diseases. CONCLUSIONS: Our results do not support MF as the explanation for observed associations between occupational titles and MND. Disease misclassification, particularly for AD, and imprecise exposure assessment affected most studies.

Characterization of radiofrequency field emissions from smart meters.

This study presents measurement data that describe radiofrequency emission levels and patterns from smart meters (rated nominally at 1 W) currently deployed in Pacific Gas and Electric Company's service territory in northern California. The smart meters in our investigation could not be set to operate continuously and required a Field Service Unit to induce short periods of emitted fields. To obtain peak field data under both laboratory and ambient conditions, a spectrum analyzer scanned across the 83 transmitting channels between 902 and 928 MHz used by the smart meter on a random frequency-hopping basis. To obtain data describing temporal emission patterns, the analyzer operated in scope mode. Duty cycle was estimated using transmit data acquired by the system operator from over 88,000 m. Instantaneous peak fields at 0.3 m in front of the meters were no more than 15% of the US Federal Communications Commission (FCC) exposure limit for the general public, and 99.9% of the meters operated with a duty cycle of 1.12% or less during the sampling period. In a sample of measurements in six single-detached residences equipped with individual smart meters, no interior measurement of peak field exceeded 1% of the FCC's general public exposure limit.

Comparison of racial differences in childhood cancer risk in case-control studies and population-based cancer registries.

INTRODUCTION: Although selection bias in case-control studies has been studied extensively, little is known about selection of cases and controls among various ethnic groups. This study compares racial differences in childhood cancer rates as estimated by case-control studies with various design features. It also compares estimates of racial distribution among cases as reported by case-control studies to those observed for an ideal case series with complete ascertainment of cases for these studies or in population-based cancer registries in corresponding geographic regions and calendar periods. METHODS: Peer-reviewed publications on childhood leukemia and brain tumors from North America, published between 1980 and 2007, were reviewed. Incidence data by race/ethnicity were compiled from research publications, federal cancer statistics, and cancer registries. Meta-analysis was conducted to assess racial/ethnic differences by study characteristics. Racial distributions of cases from published case-control studies were compared to those of a presumably noncensored case distribution (i.e. include both participating and non-participating cases in a case-control study) or cases recorded by cancer registries. RESULTS: In interview-based case-control studies of childhood cancer, the proportion of Whites compared to non-Whites tended to be higher among controls than among cases; however, the opposite was true for record-based case-control studies. Additionally, the proportion of Whites tended to be higher among the participating cases in the published case-control studies compared to the proportion of Whites among the non-participating cases or in cancer registries. CONCLUSIONS: Investigators need to consider differential participation by racial group as a potential source of bias in the interpretation of case-control study results.

PM1 particles at coal- and gas-fired power plant work areas.

With the increased interest in the possible adverse health effects attributed to inhalation of fine particle matter, this study was conducted to gather preliminary information about workplace exposures at coal- and gas-fired power plants to fine particles (PM(1); i.e. <1 µm) and ultrafine particles (i.e. <0.1 µm). Combustion of fossil fuel is known to produce fine particles, and due to their proximity and durations of exposure, power plant workers could be a group of individuals who experience high chronic exposures to these types of particles. The results of a series of real-time instrument measurements showed that concentrations of PM(1) were elevated in some locations in power plants. The highest concentrations were in locations near combustion sources, indicating that combustion materials were leaking from conventional fossil fuel-fired boilers or it was associated with emission plume downwash. Concentrations were the lowest inside air-conditioned control rooms where PM(1) were present at levels similar to or lower than upwind concentrations. Microscopic examinations indicate that PM(1) at the coal-fired plants are dominated by vitrified spheres, although there were also unusual elongated particles. Most of the PM(1) were attached to larger coal fly ash particles that may affect where and how they could be deposited in the lung.