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Supplementary Table S1. Description of ELF levels in the most frequent jobs in low (

Introduction: To date, occupational exposure assessment of electromagnetic fields (EMF) has relied on occupation-based measurements and exposure estimates. However, misclassification due to between-worker variability remains an unsolved challenge. A source-based approach, supported by detailed subject data on determinants of exposure, may allow for a more individualized exposure assessment. Detailed information on the use of occupational sources of exposure to EMF was collected as part of the INTERPHONE-INTEROCC study. To support a source-based exposure assessment effort within this study, this work aimed to construct a measurement database for the occupational sources of EMF exposure identified, assembling available measurements from the scientific literature. Methods: First, a comprehensive literature search was performed for published and unpublished documents containing exposure measurements for the EMF sources identified, a priori as well as from answers of study subjects. Then, the measurements identified were assessed for quality and relevance to the study objectives. Finally, the measurements selected and complementary information were compiled into an Occupational Exposure Measurement Database (OEMD). Results: Currently, the OEMD contains 1624 sets of measurements (>3000 entries) for 285 sources of EMF exposure, organized by frequency band (0 Hz to 300 GHz) and dosimetry type. Ninety-five documents were selected from the literature (almost 35% of them are unpublished technical reports), containing measurements which were considered informative and valid for our purpose. Measurement data and complementary information collected from these documents came from 16 different countries and cover the time period between 1974 and 2013. Conclusion: We have constructed a database with measurements and complementary information for the most common sources of exposure to EMF in the workplace, based on the responses to the INTERPHONE-INTEROCC study questionnaire. This database covers the entire EMF frequency range and represents the most comprehensive resource of information on occupational EMF exposure. It is available at www.crealradiation.com/index.php/en/databases.

We reviewed the comments on our publication sent by S.M.J. Mortazavi and would like to clarify some of the concerns from this reader, especially those due to misunderstanding of our study methods.

International audience; In absence of clear evidence regarding possible effects of occupational chemical exposures on brain tumour aetiology, it is worthwhile to explore the hypothesis that such exposures might act on brain tumour risk in interaction with occupational exposure to extremely low frequency magnetic fields (ELF).INTEROCC is a seven-country (Australia, Canada, France, Germany, Israel, New Zealand and UK), population-based, case-control study, based on the larger INTERPHONE study. Incident cases of primary glioma and meningioma were ascertained from 2000 to 2004. Job titles were coded into standard international occupational classifications and estimates of ELF and chemical exposures were assigned based on job-exposure matrices. Dichotomous indicators of cumulative ELF (≥50th vs

Introduction The International Agency for Research on Cancer classified radiofrequency (RF) electromagnetic fields (EMF) as possibly carcinogenic based on limited evidence in human studies of cell phone use and in animal experiments, while occupational evidence was found inadequate due in part to limitations in exposure assessment. This study assesses possible associations between occupational exposure to RF or intermediate frequency (IF) EMF in INTEROCC participants using novel exposure assessment methodologies. Methods A plausible index of cumulative exposure to RF and IF EMF was calculated using a source-exposure matrix and detailed interviews on work with or nearby EMF sources, both overall and in specific exposure time windows. Conditional logistic regression was used to investigate associations with glioma and meningioma risk. Results Only ~10% (n=769) of participants (n=7,330) were ever exposed to RF and ~1% (n=44) to IF EMF sources. Overall, there was no positive association between exposure to RF or IF EMF and glioma or meningioma risk, and the majority of odds ratios (ORs) were th ) for both RF electric fields and IF magnetic fields in the 1–4 year exposure time window for glioma, but were not statistically significant. Conclusions Lifetime occupational RF and IF exposures based on our index were not associated with the risk of glioma or meningioma. Further work should include more exposed participants and examine alternative exposure or dose indices such as those incorporating thresholds on biological effects or combinations of static and RF magnetic fields.

To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. The mean estimates were weighted by our confidence in the pooled measurements. The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for radiofrequency (RF) sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For extremely low frequency sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (high-voltage transmission line-hotsticks), whereas magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (tungsten inert gas welding). The methodology developed allowed the construction of the first EMF-SEM and may be used to summarize similar exposure data for other physical or chemical agents. This work was funded by the National Institutes for Health (NIH) Grant No. 1R01CA124759-01. Coding of the French occupational data was in part funded by AFSSET (Convention N° ST-2005-004). The INTERPHONE study was supported by funding from the European Fifth Framework Program, ‘Quality of Life and Management of Living Resources’ (contract 100 QLK4-CT-1999901563) and the International Union against Cancer (UICC). The UICC received funds for this purpose from the Mobile Manufacturers’ Forum and GSM Association. Provision of funds to the INTERPHONE study investigators via the UICC was governed by agreements that guaranteed INTERPHONE’s complete scientific independence (http://interphone.iarc.fr/ interphone_funding.php). In Australia, funding was received from the Australian National Health and Medical Research 5 Council (EME Grant 219129) with funds originally derived from mobile phone service licence fees; a University of Sydney Medical Foundation Program; the Cancer Council NSW and The Cancer Council Victoria. In Montreal, Canada, funding was received from the Canadian Institutes of Health Research (project MOP-42525); the Canada Research Chair programme; the Guzzo-CRS Chair in Environment and Cancer; the Fonds de la recherche en sante du Quebec; the Société de recherché sur le cancer; in Ottawa and Vancouver, Canada, from the Canadian Institutes of Health Research (CIHR), the latter including partial support from the Canadian Wireless Telecommunications Association; the NSERC/SSHRC/McLaughlin Chair in Population Health Risk Assessment at the University of Ottawa. In France, funding was received by l’Association pour la Recherche sur le Cancer (ARC) (Contrat N85142) and three network operators (Orange, SFR, Bouygues Telecom). In Germany, funding was received from the German Mobile Phone Research Program (Deutsches Mobilfunkforschungsprogramm) of the German Federal Ministry for the Environment, Nuclear 45 Safety, and Nature Protection; the Ministry for the Environment and Traffic of the state of Baden- Wurttemberg; the Ministry for the Environment of the state of North Rhine-Westphalia; the MAIFOR Program (Mainzer Forschungsforderungsprogramm) of the University of Mainz. In New Zealand, funding was provided by the Health Research Council, Hawkes Bay Medical Research Foundation, the Wellington Medical Research Foundation, the Waikato Medical Research Foundation and the Cancer Society of New Zealand. Additional funding for the UK study was received from the Mobile Telecommunications, Health and Research (MTHR) program, funding from the Health and Safety Executive, the Department of Health, the UK Network Operators (O2, Orange, T-Mobile, Vodafone, ‘3’) and the Scottish Executive. All industry funding was governed by contracts guaranteeing the complete scientific independence of the investigators

Background Exposure to extremely low frequency magnetic fields (ELF-MF) is a suspected risk factor for leukaemia in children and possibly for brain tumours in adults. Though early studies suggested an association between ELF-MF and breast cancer, recent meta-analyses have been contradictory and, while some reported positive associations, in particular in post-menopausal women, others reported no evidence of an association. In this study, we examined the association between occupational ELF-MF and breast cancer risk in the MCC-Spain study using a recently updated version of an ELF-MF job-exposure matrix (JEM). Methods A total of 1,539 female breast cancer cases and 1,602 controls, recruited throughout ten Spanish regions between 2008 and 2013, were included in this analysis. Estimates of lifetime cumulative exposure to ELF-MF were assigned to study participants based on the ELF-JEM, recoded to the Spanish system of occupations (CNO94, four digits), and information collected on the subjects9 occupational histories. An analysis was performed using unconditional logistic regression adjusted for age, education, and region. Results A statistically significant positive association was observed for lifetime cumulative ELF-MF exposure, Odds Ratio (OR) per 10 unit log-transformed geometric mean = 1.10; 95% confidence interval (CI), 1.01–1.20; p = 0.027). Analyses including reproductive and hormonal factors as well as using average exposure and exposure in different time windows will be presented. Conclusions Occupational exposure to ELF-MF may play a role in breast cancer risk.

Background Despite the widespread and increasing use of electricity in working environments, occupational exposure to ELF-EMF during pregnancy has been rarely documented and was often assessed using the mothers’ self-report. Our first aim was to assess maternal occupational exposure to ELF-EMF during pregnancy in the birth cohort study Elfe. Secondly, we studied the link between this exposure and child’s gestational age or birth-weight. Methods The Elfe study was initiated in 2011 in France and enrolled more than 18,000 infants born between 33 and 42 weeks’ gestation. Mother’s job title was collected by a face-to-face interview and coded using the International Standard „Classification of Occupation 1968 (ISCO68). The Bowman population-based job exposure matrix (JEM) was used to assess arithmetic-mean-workday ELF-EMF exposure level associated to the occupation held by each mother during pregnancy, expressed in µT/day. This JEM used the Standard Occupational Classification system 1980 (SOC80). ISCO68 codes were translated to their SOC80 equivalent. Exposure levels were categorised according to quartiles and 90th percentile. Multiple linear regression models were used to estimate adjusted differences in mean birth-weight and mean gestational age between exposure groups. Results A total of 13,340 mothers worked during their pregnancy. Job was coded into SOC80 for 12,671 mothers and mean-workday level was defined for 12,549. Adjusted models did not show differences between any of the exposure groups and the reference category for both birth-weight and gestational age among children born at 33 weeks’ gestation or more. Conclusion Our study, in a large birth cohort, is the first to assess maternal occupational exposure during pregnancy using a JEM based on industrial hygiene measurements. Our next aim will be to use the INTEROCC ELF-JEM (http://www.crealradiation.com), an updated version of the Bowman ELF-JEM. We will also assess environmental exposure to ELF-EMF during pregnancy and its possible association with birth outcomes.

Objectives Electric shocks have been suggested as a potential risk factor for neurological disease, in particular for amyotrophic lateral sclerosis. While actual exposure to shocks is difficult to measure, occurrence and variation of electric injuries could serve as an exposure proxy. We assessed risk of electric injury, using occupational accident registries across Europe to develop an electric shock job-exposure-matrix (JEM). Materials and methods Injury data were obtained from five European countries, and the number of workers per occupation and country from EUROSTAT was compiled at a 3-digit International Standard Classification of Occupations 1988 level. We pooled accident rates across countries with a random effects model and categorised jobs into low, medium and high risk based on the 75th and 90th percentile. We next compared our JEM to a JEM that classified extremely low frequency magnetic field exposure of jobs into low, medium and high. Results Of 116 job codes, occupations with high potential for electric injury exposure were electrical and electronic equipment mechanics and fitters, building frame workers and finishers, machinery mechanics and fitters, metal moulders and welders, assemblers, mining and construction labourers, metal-products machine operators, ships’ decks crews and power production and related plant operators. Agreement between the electrical injury and magnetic field JEM was 67.2%. Conclusions Our JEM classifies occupational titles according to risk of electric injury as a proxy for occurrence of electric shocks. In addition to assessing risk potentially arising from electric shocks, this JEM might contribute to disentangling risks from electric injury from those of extremely low frequency magnetic field exposure.

Background Magnetic fields (MF) from AC electricity are a Possible Human Carcinogen, based on limited epidemiologic evidence from exposures far below occupational health limits. Methods To help formulate government guidance on occupational MF, the cancer cases prevented and the monetary benefits accruing to society by reducing workplace exposures were determined. Life-table methods produced Disability Adjusted Life Years, which were converted to monetary values. Results Adjusted for probabilities of causality, the expected increase in a worker's disability-free life are 0.04 year (2 weeks) from a 1 microtesla (µT) MF reduction in average worklife exposure, which is equivalent to $5,100/worker/µT in year 2010 U.S. dollars (95% confidence interval $1,000–$9,000/worker/µT). Where nine electrosteel workers had 13.8 µT exposures, for example, moving them to ambient MFs would provide $600,000 in benefits to society (uncertainty interval $0–$1,000,000). Conclusions When combined with the costs of controls, this analysis provides guidance for precautionary recommendations for managing occupational MF exposures. Am. J. Ind. Med. 56:791–805, 2013. Copyright © 2012 Wiley Periodicals, Inc.

Objectives The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study. Methods We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries. Results The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy. Conclusions While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take these into account in analyses of risk of brain tumours from RF exposure from mobile phones.

We investigated the association between occupational exposure to extremely low-frequency magnetic fields (MFs) and the risk of glioma and meningioma. Occupational exposure to MF was assessed for 489 glioma cases, 197 meningioma cases, and 799 controls enrolled in a hospital-based case–control study. Lifetime occupational history questionnaires were administered to all subjects; for 24% of jobs, these were supplemented with job-specific questionnaires, or “job modules,” to obtain information on the use of electrically powered tools or equipment at work. Job-specific quantitative estimates for exposure to MF in milligauss were assigned using a previously published job exposure matrix (JEM) with modification based on the job modules. Jobs were categorized as ≤1.5 mG, >1.5 to 1.5 mG; (3) cumulative lifetime exposure; and (4) average lifetime exposure. Odds ratios (ORs) were calculated using unconditional logistic regression with adjustment for the age, gender, and hospital site. The job modules increased the number of jobs with exposure ≥3.0 mG from 4% to 7% relative to the JEM. No statistically significant elevation in ORs or trends in ORs across exposure categories was observed using four different exposure metrics for the three tumor types analyzed. Occupational exposure to MFs assessed using job modules was not associated with an increase in the risk for glioma, glioblastoma, or meningioma among the subjects evaluated in this study.

This cohort study aims to examine cardiovascular disease (CVD) mortality risks among workers in occupations potentially exposed to magnetic fields (MF).Risks for major CVD mortality by potential job-related MF exposure were examined in a sample of U.S. workers from the National Longitudinal Mortality Study using multivariate proportional hazards models.After adjustment for demographic factors, there were no significant excess risks between individuals with medium (0.15 to0.20 microT), high (0.20 to0.30 microT), or very high (/= 0.30 microT) exposure levels as compared with individuals with background exposure levels of MF (0.15 microT) for the CVD mortality outcomes. Indirect adjustment for potential confounding by current smoking prevalence did not change the pattern of these results.Our study does not provide evidence for an association between occupational MF exposure and CVD mortality risk.

The occupational epidemiological literature on extremely low frequency electric and magnetic fields (EMF) and health encompasses a large number of studies of varying design and quality that have addressed many health outcomes, including various cancers, cardiovascular disease, depression and suicide, and neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis (ALS). At a 2006 workshop we reviewed studies of occupational EMF exposure with an emphasis on methodological weaknesses, and proposed analytical ways to address some of these. We also developed research priorities that we hope will address remaining uncertainties. Broadly speaking, extensive epidemiological research conducted during the past 20 years on occupational EMF exposure does not indicate strong or consistent associations with cancer or any other health outcomes. Inconsistent results for many of the outcomes may be attributable to numerous shortcomings in the studies, most notably in exposure assessment. There is, however, no obvious correlation between exposure assessment quality and observed associations. Nevertheless, for future research, the highest priorities emerge in both the areas of exposure assessment and investigation of ALS. To better assess exposure, we call for the development of a more complete job-exposure matrix that combines job title, work environment and task, and an index of exposure to electric fields, magnetic fields, spark discharge, contact current, and other chemical and physical agents. For ALS, we propose an international collaborative study capable of illuminating a reported association with electrical occupations by disentangling the potential roles of electric shocks, magnetic fields and bias. Such a study will potentially lead to evidence-based measures to protect public health.

Many epidemiological studies assessing the relationship between exposure and disease are carried out without data on individual exposures. When this barrier is encountered in occupational studies, the subject exposures are often evaluated with a job-exposure matrix (JEM), which consists of mean exposure for occupational categories measured on a comparable group of workers. One of the objectives of the seven-country case-control study of occupational exposure and brain cancer risk, INTEROCC, was to investigate the relationship of occupational exposure to electromagnetic fields (EMF) in different frequency ranges and brain cancer risk. In this paper, we use the Canadian data from INTEROCC to estimate the odds of developing brain tumours due to occupational exposure to EMF. The first step was to find the best EMF exposure surrogate among the arithmetic mean, the geometric mean, and the mean of log-normal exposure distribution for each occupation in the JEM, in comparison to Berkson error adjustments via numerical approximation of the likelihood function. Contrary to previous studies of Berkson errors in JEMs, we found that the geometric mean was the best exposure surrogate. This analysis provided no evidence that cumulative lifetime exposure to extremely low frequency magnetic fields increases brain cancer risk, a finding consistent with other recent epidemiological studies.

Contact currents from touching objects with different voltages can produce electric fields within the body that produce neurological and other biological effects. To begin measuring these exposures among electric utility workers, a new contact current meter (CCM) was tested in a pilot study at Southern California Edison. The CCM was worn for 82 full-shift measurements by 76 volunteers from eight occupations who did not work directly with energized electrical equipment. The volunteers were exposed to an average of 285.8 contact current events above the meter's 1-microA threshold, but most of these were electrostatic spark discharges. Fourteen employees experienced an average of 135.1 contact currents events whose primary frequency was 60 Hz. Using a circuit model of the human body, the average contact currents going from arm to arm was 9.8 microA (maximum = 178.0 microA), and the average going down the torso was 25.5 microA (maximum = 662.0). The maximum exposures were experienced by a technical support employee working in a substation. All measurements in this pilot study were below the 3000 microA maximum permissible exposure for contact currents set by the Institute of Electrical and Electronic Engineers (IEEE). Combining these current measurements with the results of high-resolution dosimetry, the internal electric fields averaged an estimated 1.7 mV/m in the heart (maximum = 21.0 mV/m), and 1.9 mV/m in the hematopoietic bone marrow in the torso (maximum = 56.5 mV/m). These internal electric fields from contact currents are below the basic restriction of 943 mV/m in the IEEE exposure standards but are above 1 mV/m, a level where biological effects have been often reported in laboratory studies. Safety concerns limited the measurements to de-energized equipment, so we did not obtain data on work in energized high-voltage environments, the most likely sources of high contact currents. This pilot study identified other improvements to the contact current meter that would make it better able to measure exposures in future health studies.

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 48:63–77 (2005) Potential Occupational Risks for Neurodegenerative Diseases Robert M. Park, MS , 1 A Paul A. Schulte, PhD , 1 Joseph D. Bowman, PhD , CIH , 2 James T. Walker, PhD , 3 Stephen C. Bondy, MA , PhD , 4 Michael G. Yost, MS , PhD , 5 Jennifer A. Touchstone, MS , 5 and Mustafa Dosemeci, PhD6 Background Associations between occupations and neurodegenerative diseases (NDD) may be discernable in death certificate data. Methods Hypotheses generated from 1982 to 1991 study were tested in data from 22 states for the years 1992–1998. Specific occupations and exposures to pesticides, solvents, oxidative stressors, magnetic fields, and welding fumes were evaluated. Results About one third (26/87) of the occupations hypothesized with neurodegenerative associations had statistically significant elevated mortality odds ratios (MOR) for the same outcome. Occupations with the largest MORs were (a) for presenile dementia (PSD)— dentists, graders/sorters (non-agricultural), and clergy; (b) for Alzheimer’s disease (AD)—bank tellers, clergy, aircraft mechanics, and hairdressers; (c) for Parkinson’s disease (PD)—biological scientists, clergy, religious workers, and post-secondary teachers; and (d) for motor neuron disease (MND)—veterinarians, hairdressers, and graders and sorters (non-agricultural). Teachers had significantly elevated MORs for all four diseases, and hairdressers for three of the four. Non-horticultural farmers below age 65 had elevated PD (MOR ¼ 2.23, 95% CI ¼ 1.47–3.26), PSD (MOR ¼ 2.22, 95% CI ¼ 1.10–4.05), and AD (MOR ¼ 1.76, 95% CI ¼ 1.04–2.81). Sixty hertz magnetic fields exhibited significant exposure-response for AD and, below age 65, for PD (MOR ¼ 1.87, 95% CI ¼ 1.14–2.98) and MND (MOR ¼ 1.63, 95% CI ¼ 1.10–2.39). Welding had elevated PD mortality below age 65 (MOR ¼ 1.77, 95% CI ¼ 1.08–2.75). Conclusions Support was observed for hypothesized excess neurodegenerative disease associated with a variety of occupations, 60 Hz magnetic fields and welding. Am. J. Ind. Med. 48:63–77, 2005. Published 2005 Wiley-Liss, Inc. { KEY WORDS: Alzheimer’s disease; hairdresser; motor neuron disease; magnetic field; Parkinson’s disease; pesticide; welding Abbreviations: AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; BOC, Bureau of the Census; EMF, electromagnetic field; MND, motor neuron disease; MOR, mortality odds ratio; NDD, neurodegenerative disease; PD, Parkinson’s disease; PMR, proportionate mortal- ity ratios; PSD, presenile dementia. Education and Information Division, National Institute for Occupational Safety and Health, Cincinnati, Ohio Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio Division of Surveillance, Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health, Cincinnati, Ohio Department of Community & Environmental Medicine, University of California, Irvine, California Published 2005 Wiley-Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America. Department of Environmental Health, University of Washington, Seattle,Washington Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland *Correspondence to: Robert M. Park, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Education and Information Division, MS C-15, 4676 Columbia Parkway, Cincinnati, OH 45226. E-mail: rhp9@cdc.gov Accepted 27 March 2005 DOI 10.1002/ajim.20178. Published online in Wiley InterScience (www.interscience.wiley.com)

The MultiWave System III (MW III), a recently developed personal monitor for extremely low frequency (ELF) magnetic fields, was compared with the standard EMDEX Lite (Electric and Magnetic Field Digital Exposure System), the type of monitor widely used in epidemiology and other exposure assessments. The MW III captures three-axis magnetic field waveforms for the calculation of many exposure metrics, while the EMDEX monitors measure only the root-mean-squared (RMS) vector magnitude (or resultant). Thirty-eight partial period personal samples were monitored in six different job classifications. The sampling time for each personal sample ranged from 90 to 133 min, with a mean sample time of 110 min. The EMDEX Lite and MW III were evaluated by comparing the maximum and partial period time-weighted average (TWA) of the ELF magnitude. TWA exposures measured for the 38 partial period samples by the EMDEX Lite ranged from 1.2 to 65.3 mG, with a mean of 18.1 mG, while corresponding values for the MW III ranged from 1.1 to 65.8 mG, with a mean of 17.7 mG. The maximum magnetic field exposures measured for the 38 partial period personal samples by the EMDEX Lite ranged from 27.0 to 420.2 mG, with a mean of 216.3 mG, while corresponding values for the MW III ranged from 40.2 to 1311.8 mG, with a mean of 368.4 mG. The maximum and TWA ELF magnetic field exposures measured by the EMDEX Lite and MW III were compared using a two-tailed, paired t-test. Analyses indicate that there was no significant difference in the TWA magnetic field magnitude measured by the EMDEX Lite and MW III. On the other hand, the EMDEX Lite reported significantly lower (P=0.002) maximum magnetic field measurements compared to the MW III. From a detailed analysis of the time traces, the EMDEX Lite appears to measure the ELF magnitude inaccurately when the field changes rapidly over a 4-s sampling interval. The results of this comparison suggest that the standard EMDEX Lite and MW III provide similar measure of the TWA magnetic field in a variety of occupational settings and ELF magnetic field magnitudes. However, the EMDEX Lite underestimates maximum exposures when compared to the MW III.

Background: Occupational exposure to extremely low-frequency magnetic fields (ELF) is a suspected risk factor for brain tumors, however the literature is inconsistent. Few studies have assessed whether ELF in different time windows of exposure may be associated with specific histologic types of brain tumors. This study examines the association between ELF and brain tumors in the large-scale INTEROCC study. Methods: Cases of adult primary glioma and meningioma were recruited in seven countries (Australia, Canada, France, Germany, Israel, New Zealand, and the United Kingdom) between 2000 and 2004. Estimates of mean workday ELF exposure based on a job exposure matrix were assigned. Estimates of cumulative exposure, average exposure, maximum exposure, and exposure duration were calculated for the lifetime, and 1 to 4, 5 to 9, and 10+ years before the diagnosis/reference date. Results: There were 3,761 included brain tumor cases (1,939 glioma and 1,822 meningioma) and 5,404 population controls. There was no association between lifetime cumulative ELF exposure and glioma or meningioma risk. However, there were positive associations between cumulative ELF 1 to 4 years before the diagnosis/reference date and glioma [odds ratio (OR) ≥ 90th percentile vs. < 25th percentile, 1.67; 95% confidence interval (CI), 1.36–2.07; PLinear trend < 0.0001], and, somewhat weaker associations with meningioma (OR ≥ 90th percentile vs. < 25th percentile, 1.23; 95% CI, 0.97–1.57; PLinear trend = 0.02). Conclusions: Results showed positive associations between ELF in the recent past and glioma. Impact: Occupational ELF exposure may play a role in the later stages (promotion and progression) of brain tumorigenesis. Cancer Epidemiol Biomarkers Prev; 23(9); 1863–72. ©2014 AACR.

A walkthrough survey method was developed for measuring ambient magnetic fields (MFs) in industrial facilities as the first stage in hazard surveillance. This survey was designed to measure the mean and peak MF magnitudes at extremely low frequencies (ELFs), so that factories could be ranked by MF levels and prioritized for subsequent personal exposure monitoring. Sixty-two facilities from 13 Standard Industrial Classifications (SICs) with the highest monthly electric power usage were surveyed. To measure ambient MFs, a structured walkthrough survey with a special emphasis on workstations was conducted with an EMDEX-II meter in continuous operation, while MF sources were noted. The broadband MF data (40‐800 Hz) for each facility were summarized with the geometric mean (GM) and the average of the five highest readings (Hi-5). The range of the GM magnetic field magnitude was 0.04‐1.61 mT, where the maximum was measured at a steel mill operating large electric furnaces. Maximum values for specific sources were highly variable across and within facilities (Hi-5 range: 1.0‐530 mT). Chemical and Allied Products (SIC 28) and Primary Metal Products (SIC 33) had facilities with GM and Hi-5 magnetic fields greater than any of the other industrial categories. However, the SIC categories were found to be poor predictors of the ambient MF in this sample of factories. A weak relationship was found between the facility-specific monthly electric power consumption and the GM magnetic field magnitude, but confidence limits were too broad to make meaningful exposure predictions from electric power data. Overall, 89% of the GMs were at or below 0.4 mT, consistent with most other studies that collected industrial MF exposure data. The walkthrough survey is a practical way of measuring ambient MFs in a large number of workplaces, and should be evaluated with personal measurements as a screening method for hazard surveillance. Published by Elsevier Science Ltd on behalf of British Occupational Hygiene Society.

Magnetic field characteristics have been surveyed systematically in six factories with the Multiwave® II waveform capture instrument. These six facilities manufactured plastics, pharmaceuticals, cement, liquid air products, aluminum parts, and aluminum-framed filters. The study goals were to survey the physical characteristics of magnetic fields that may be related to biological effects under various interaction mechanisms and to relate those characteristics to the field's sources. From 59 waveform measurements at worker locations near sources, we calculated the extremely low frequency (ELF) and static field magnitudes, their frequency characteristics, and spatial characteristics of the 60 Hz component. The RMS vector magnitude of the ELF magnetic field (the usual exposure metric in most studies) had medians ranging from 0.53 to 12.83 μT in the six factories. The static magnetic field magnitudes had medians of 24.2–46.2 μT, which is well below the geomagnetic reference field of 55.0 μT because of shielding from steel structures. The maximum static field was 128.6 μT near a DC motor. The frequency spectra of the most common fields is dominated by 60 Hz, and has a median total harmonic distortion equal to 14.8%. The most common higher frequencies are the third, fifth, and second harmonics of 60 Hz. However, magnetic fields in these workplaces had many other 60 Hz harmonics and non-harmonic frequencies due particularly to electric motors and computer monitors. The 60 Hz component magnetic fields have elliptical polarization with median axial ratio of 25.4%. The average proportion of the 60 Hz component parallel to the static field vector was 51.5±3.0%, which indicates a significant trend towards perpendicular orientation between these two field components. In this survey of only six factories, the Multiwave® II measurements documented a wide diversity of complex magnetic field characteristics and non-sinusoidal waveforms. Although these characteristics are important to the various mechanisms postulated to explain biological effects, they are overlooked by the popular exposure assessment methods which only measure the ELF magnitude. Therefore, spot measurements with the Multiwave® II or similar waveform capture instruments are necessary for a complete magnetic field exposure assessment.

Case-control data on childhood leukemia in Los Angeles County were reanalyzed with residential magnetic fields predicted from the wiring configurations of nearby transmission and distribution lines. As described in a companion paper, the 24-h means of the magnetic field's magnitude in subjects' homes were predicted by a physically based regression model that had been fitted to 24-h measurements and wiring data. In addition, magnetic field exposures were adjusted for the most likely form of exposure assessment errors: classic errors for the 24-h measurements and Berkson errors for the predictions from wire configurations. Although the measured fields had no association with childhood leukemia (P for trend=.88), the risks were significant for predicted magnetic fields above 1.25 mG (odds ratio=2.00, 95% confidence interval=1.03-3.89), and a significant dose-response was seen (P for trend=.02). When exposures were determined by a combination of predictions and measurements that corrects for errors, the odds ratio (odd ratio=2.19, 95% confidence interval=1.12-4.31) and the trend (p =.007) showed somewhat greater significance. These findings support the hypothesis that magnetic fields from electrical lines are causally related to childhood leukemia but that this association has been inconsistent among epidemiologic studies due to different types of exposure assessment error. In these data, the leukemia risks from a child's residential magnetic field exposure appears to be better assessed by wire configurations than by 24-h area measurements. However, the predicted fields only partially account for the effect of the Wertheimer-Leeper wire code in a multivariate analysis and do not completely explain why these wire codes have been so often associated with childhood leukemia. The most plausible explanation for our findings is that the causal factor is another magnetic field exposure metric correlated to both wire code and the field's time-averaged magnitude.

A physically based model for residential magnetic fields from electric transmission and distribution wiring was developed to reanalyze the Los Angeles study of childhood leukemia by London et al. For this exposure model, magnetic field measurements were fitted to a function of wire configuration attributes that was derived from a multipole expansion of the Law of Biot and Savart. The model parameters were determined by nonlinear regression techniques, using wiring data, distances, and the geometric mean of the ELF magnetic field magnitude from 24-h bedroom measurements taken at 288 homes during the epidemiologic study. The best fit to the measurement data was obtained with separate models for the two major utilities serving Los Angeles County. This model's predictions produced a correlation of 0.40 with the measured fields, an improvement on the 0.27 correlation obtained with the Wertheimer-Leeper (WL) wire code. For the leukemia risk analysis in a companion paper, the regression model predicts exposures to the 24-h geometric mean of the ELF magnetic fields in Los Angeles homes where only wiring data and distances have been obtained. Since these input parameters for the exposure model usually do not change for many years, the predicted magnetic fields will be stable over long time periods, just like the WL code. If the geometric mean is not the exposure metric associated with cancer, this regression technique could be used to estimate long-term exposures to temporal variability metrics and other characteristics of the ELF magnetic field which may be cancer risk factors. Bioelectromagnetics 20:399–413, 1999. © 1999 Wiley-Liss, Inc.

In an hypothesis-generating case-control study of amyotrophic lateral sclerosis, lifetime occupational histories were obtained. The patients (n = 28) were clinic based. The occupational exposure of interest in this report is electromagnetic fields (EMFs). This is the first and so far the only exposure analyzed in this study. Occupational exposure up to 2 years prior to estimated disease symptom onset was used for construction of exposure indices for cases. Controls (n = 32) were blood and nonblood relatives of cases. Occupational exposure for controls was through the same age as exposure for the corresponding cases. Twenty (71%) cases and 28 (88%) controls had at least 20 years of work experience covering the exposure period. The occupational history and task data were used to classify blindly each occupation for each subject as having high, medium/high, medium, medium/low, or low EMF exposure, based primarily on data from an earlier and unrelated study designed to obtain occupational EMF exposure information on workers in ``electrical`` and ``nonelectrical`` jobs. By using the length of time each subject spent in each occupation through the exposure period, two indices of exposure were constructed: total occupational exposure (E{sub 1}) and average occupational exposure (E{sub 2}). For cases andmore » controls with at least 20 years of work experience, the odds ratio (OR) for exposure at the 75th percentile of the E{sub 1} case exposure data relative to minimum exposure was 7.5 (P < 0.02; 95% CI, 1.4--38.1) and the corresponding OR for E{sub 2} was 5.5 (P < 0.02; 95% CI, 1.3--22.5). For all cases and controls, the ORs were 2.5 (P < 0.1; 95% CI, 0.9--8.1) for E{sub 1} and 2.3 (P = 0.12; 95% CI, 0.8--6.6) for E{sub 2}. This study should be considered an hypothesis-generating study. Larger studies, using incident cases and improved exposure assessment, should be undertaken.« less

A measurement study of residential magnetic fields and brain tumors in children that was added onto an ongoing case-control interview study in Los Angeles County, California, include 298 children under age 20 years with a primary brain tumor diagnosed from 1984 to 1991 and 298 control children identified by random digit dialing. Magnetic fields were determined for all Los Angeles homes where these 596 children lived from conception to diagnosis (1,131 homes) by mapping and coding the wiring configurations outside the home and by taking a series of exterior spot and profile measurements. In addition, for a subset of subjects (35%; 211 homes) 24-hour measurements were taken in the child's room and one other room. Although measured fields are consistently highest in the highest of the five wire code categories, fields in homes in this category are much lower in Los Angeles than in Denver, where the code originated. Brain tumor risk appears not to relate to measured fields inside (p for trend for child's room = 0.98) or outside (p for trend for front wall = 0.82) the home. An apparent increase in risk among children living at diagnosis in homes with underground wiring appears to be an artifact introduced by using current controls for historical cases because this apparent excess risk disappeared in an analysis restricted to the later years of the study when cases and controls were accrued concurrently. Our study does not show an overall association of pediatric brain tumors with measured fields, with "very high" wiring configurations, or with any of several other potential sources of exposure, such as use of various electrical appliances, but the prevalence of high fields (> 2 mG) and very high fields (> 3 mG) in Los Angeles homes was too low to detect a moderate effect of the magnitude reported in other studies.

The authors present analyses of data from three independent clinical series and controls indicating an association between working in occupations with probable medium to high exposure to extremely low frequency (300 Hz) electromagnetic fields and sporadic Alzheimer's disease. Case-control analyses were carried out using data from patients examined at the following locations: the Department of Neurology, University of Helsinki, Helsinki, Finland, 1982-1985; the Koskela Hospital in Helsinki, 1977-1978; and the University of Southern California site of the Alzheimer's Disease Research Center of Los Angeles and Orange Counties, 1984-1993. The predominant occupations among medium (2-10 mG or10 mG intermittently) to high (10 mG or100 mG intermittently) exposed cases were seamstress, dressmaker, and tailor. The results appear to be independent of education, and the sex-combined odds ratios for the three series are quite homogeneous: 2.9, 3.1, and 3.0. The odds ratio for the three series analyzed together is 3.0 (p0.001), with a 95% confidence interval of 1.6-5.4. The odds ratio for women is 3.8 (p0.001), with a 95% confidence interval of 1.7-8.6. The most obvious, possibly etiologically relevant exposure is that of electromagnetic fields, which may have biologic plausibility because they may adversely influence calcium homeostasis and/or inappropriately activate immune system cells such as microglial cells, initiating events that result in neuronal degeneration.

Standards setting committees in the United States and Great Britain have adopted exposure limits for magnetic fields with a single frequency in the sub-radio frequency (sub-RF) range (1 Hz to 30 kHz). Since sub-RF magnetic fields in most occupational and residential settings have multiple frequencies, a more practical exposure assessment approach is derived in this article. To avoid adverse health effects, the present exposure limits control the currents induced in the body by the magnetic field. In this article, limits on induced current are shown to be equivalent to placing limits on the magnetic field's derivative dB/dt, both of which are applicable to the multifrequency fields found in the environment. The existing exposure limits are therefore used to derive bounds on dB/dt. Commercially available gaussmeters can be used to measure sub-RF magnetic fields for comparison with these limits on dB/dt exposures. To measure dB/dt, the gaussmeter needs a linear frequency response, and a correction f...

We present a hypothesis that the risk of childhood leukemia is related to exposure to specific combinations of static and extremely-low-frequency (ELF) magnetic fields. Laboratory data from calcium efflux and diatom mobility experiments were used with the gyromagnetic equation to predict combinations of 60 Hz and static magnetic fields hypothesized to enhance leukemia risk. The laboratory data predicted 19 bands of the static field magnitude with a bandwidth of 9.1 microT that, together with 60 Hz magnetic fields, are expected to have biological activity. We then assessed the association between this exposure metric and childhood leukemia using data from a case-control study in Los Angeles County. ELF and static magnetic fields were measured in the bedrooms of 124 cases determined from a tumor registry and 99 controls drawn from friends and random digit dialing. Among these subjects, 26 cases and 20 controls were exposed to static magnetic fields lying in the predicted bands of biological activity centered at 38.0 microT and 50.6 microT. Although no association was found for childhood leukemia in relation to measured ELF or static magnetic fields alone, an increasing trend of leukemia risk with measured ELF fields was found for subjects within these static field bands (P for trend = 0.041). The odds ratio (OR) was 3.3 [95% confidence interval (CI) = 0.4-30.5] for subjects exposed to static fields within the derived bands and to ELF magnetic field above 0.30 microT (compared to subjects exposed to static fields outside the bands and ELF magnetic fields below 0.07 microT). When the 60 Hz magnetic fields were assessed according to the Wertheimer-Leeper code for wiring configurations, leukemia risks were again greater with the hypothesized exposure conditions (OR = 9.2 for very high current configurations within the static field bands; 95% CI = 1.3-64.6). Although the risk estimates are based on limited magnetic field measurements for a small number of subjects, these findings suggest that the risk of childhood leukemia may be related to the combined effects of the static and ELF magnetic fields. Further tests of the hypothesis are proposed.

To address the hypotheses that electrical workers are exposed to higher magnetic fields and are at higher risk of leukemia than nonelectrical workers, we performed a registry-based case-control study among men aged 20-64 years with known occupation who were diagnosed with cancer in Los Angeles County between 1972 and 1990. Controls were men with cancers other than those of the central nervous system or leukemia. Magnetic field measurements on workers in each electrical occupation and in a random sample of occupations presumed to be nonelectrical were used to estimate magnetic field exposures for each occupation. Among men in electrical occupations, 121 leukemias were diagnosed. With the exception of electrical engineers, magnetic field exposures were higher among workers in electrical occupations than in nonelectrical occupations. A weakly positive trend in leukemia risk across average occupational magnetic field exposure was observed (odds ratio [OR] per 10 milligauss increase in average magnetic field = 1.2, 95% confidence interval [CI] 1.0-1.5). A slightly stronger association was observed for chronic myloid leukemia, although only 28 cases occurred among electrical workers (OR 10 milligauss increase = 1.6, 95% CI = 1.2-2.0). The results were not materially altered by adjustment for exposure to several agents known or suspected to cause leukemia. Although not conclusive, these results are consistent with findings from studies based on job title alone that electrical workers may be at slightly increased risk of leukemia.

Over the past several decades, there has been continuing concern over whether exposure to extremely-low-frequency magnetic fields can adversely affect health. A recent review of the epidemiologic literature concluded that although occupational magnetic fields may increase the risk for some health outcomes, the evidence is not strong or consistent enough to draw firm conclusions.1 Nevertheless, continued research of the impact of magnetic field exposure on amyotrophic lateral sclerosis (ALS), which comprises more than 90% of all motor neuron disease (MND),2 was recommended on the basis of consistent evidence linking electrical occupations to an increased risk of ALS but weaker evidence based on measured magnetic field.1,3 The etiology for ALS is still largely unknown,4 but primarily animal studies have pointed toward oxidative damage, protein aggregation, mitochondrial dysfunction, and caspase-mediated apoptosis as possible causative mechanisms in the disease.5-8 Therefore, it is important to pursue leads regarding potential risk factors, including magnetic field exposure. It has been suggested that magnetic field exposure can result in neurological damage through increasing oxidative stress and inducing DNA breaks. The association between magnetic fields and oxidative DNA stress has been demonstrated in some studies9,10 but not others.11 A study by Falone and colleagues12 showed an interaction between rat age and magnetic fields in the decreasing activity levels of antioxidant enzymes, suggesting a susceptibility to oxidative stress from magnetic fields as the rats mature. As oxidative damage is thought to be involved in toxicity targeting motor neurons,13 it is possible that magnetic field exposure may result in motor neuron degeneration through this pathway. Nevertheless, the biological mechanism responsible for an association between magnetic fields and ALS, or the broader group of MND, remains unclear. We evaluated the association between quantitative levels of occupational magnetic field exposure and MND mortality in a population-based cohort representative of the general US population.

International audience; OBJECTIVES: The objective of this study was to examine the associations of brain tumours with radio frequency (RF) fields from mobile phones. METHODS: Patients with brain tumour from the Australian, Canadian, French, Israeli and New Zealand components of the Interphone Study, whose tumours were localised by neuroradiologists, were analysed. Controls were matched on age, sex and region and allocated the 'tumour location' of their matched case. Analyses included 553 glioma and 676 meningioma cases and 1762 and 1911 controls, respectively. RF dose was estimated as total cumulative specific energy (TCSE; J/kg) absorbed at the tumour's estimated centre taking into account multiple RF exposure determinants. RESULTS: ORs with ever having been a regular mobile phone user were 0.93 (95% CI 0.73 to 1.18) for glioma and 0.80 (95% CI 0.66 to 0.96) for meningioma. ORs for glioma were below 1 in the first four quintiles of TCSE but above 1 in the highest quintile, 1.35 (95% CI 0.96 to 1.90). The OR increased with increasing TCSE 7+ years before diagnosis (p-trend 0.01; OR 1.91, 95% CI 1.05 to 3.47 in the highest quintile). A complementary analysis in which 44 glioma and 135 meningioma cases in the most exposed area of the brain were compared with gliomas and meningiomas located elsewhere in the brain showed increased ORs for tumours in the most exposed part of the brain in those with 10+ years of mobile phone use (OR 2.80, 95% CI 1.13 to 6.94 for glioma). Patterns for meningioma were similar, but ORs were lower, many below 1.0. CONCLUSIONS: There were suggestions of an increased risk of glioma in long-term mobile phone users with high RF exposure and of similar, but apparently much smaller, increases in meningioma risk. The uncertainty of these results requires that they be replicated before a causal interpretation can be made.

The relation between exposure to electric and magnetic fields in the home, as assessed by measurements, wiring configuration, and self-reported appliance use, and risk of leukemia was investigated in a case-control study among children from birth to age 10 years in Los Angeles County, California. Cases were ascertained through a population-based tumor registry from 1980 to 1987. Controls were drawn from friends and by random digit dialing. Interviews were obtained from 232 cases and 232 controls. Available for analysis were measurements of the magnetic field in the child's bedroom over 24 hours or longer (164 cases and 144 controls), spot measurements of magnetic and electric fields (140 cases and 109 controls), and wiring configuration (219 cases and 207 controls). No clear associations between leukemia risk and measured magnetic or electric fields were seen. An association between the Denver Wertheimer-Leeper wiring configuration and childhood leukemia risk was observed (odds ratio for very high relative to very low current and underground configuration combined = 2.15, 95% confidence interval 1.08-4.28; p for trend = 0.008) and was not substantially altered by adjustment for potential confounding factors. Cases were more likely than controls to report use of several appliances that produce high electric and magnetic fields. Our results support an association between childhood leukemia risk and wiring configuration, but not direct measurements of electric and magnetic fields.

A population-based job exposure matrix (JEM) was developed to assess personal exposures to power-frequency magnetic fields (MF) for epidemiologic studies. The JEM compiled 2,317 MF measurements taken on or near workers by 10 studies in the United States, Sweden, New Zealand, Finland, and Italy. A database was assembled from the original data for six studies plus summary statistics grouped by occupation from four other published studies. The job descriptions were coded into the 1980 Standard Occupational Classification system (SOC) and then translated to the 1980 job categories of the U.S. Bureau of the Census (BOC). For each job category, the JEM database calculated the arithmetic mean, standard deviation, geometric mean, and geometric standard deviation of the workday-average MF magnitude from the combined data. Analysis of variance demonstrated that the combining of MF data from the different sources was justified, and that the homogeneity of MF exposures in the SOC occupations was comparable to JEMs for solvents and particulates. BOC occupation accounted for 30% of the MF variance (p10(-6)), and the contrast (ratio of the between-job variance to the total of within- and between-job variances) was 88%. Jobs lacking data had their exposures inferred from measurements on similar occupations. The JEM provided MF exposures for 97% of the person-months in a population-based case-control study and 95% of the jobs on death certificates in a registry study covering 22 states. Therefore, we expect this JEM to be useful in other population-based epidemiologic studies.

A magnetic field transduction mechanism based on an ion oscillator model is derived from an explicit quantum mechanical description. The governing equation prescribes how the electric dipole moment of an ion oscillating in a symmetric potential well evolves under the influence of an arbitrary magnetic field. The resulting equation is an analog of the Bloch equation, a well-studied model for magnetic resonances in atomic and molecular spectroscopy. The differential equation for this ion oscillator model is solved numerically for a few illustrative magnetic field exposures, showing when those resonances occur with single frequency, linearly polarized fields. Our formulation makes explicit the conditions that must be present for magnetic fields to produce observable biological effects under the ion oscillator model. The ion's potential well must have symmetry sufficient to produce a degenerate excited state, e.g., octahedral or trigonal bipyramid potentials. The impulse that excites the ion must be spatially correlated with the orientation of the detector that reads off the final state of the oscillator. The orientation between the static and oscillating magnetic fields that produces resonance is a complicated function of the field magnitudes and frequency. We suggest several classes of experiments that could critically test the validity of the model presented here.

Objectives Exposure to electromagnetic fields (EMF) has become ubiquitous in modern life and concern has increased regarding possible associated health effects. To date, assessment of occupational exposure has relied on job-exposure matrices, with exposure estimates for very broad occupational categories. To move EMF research forward, a new approach was necessary. A source-based strategy, incorporating detailed information on tasks, equipment used and work organisation could allow a more individualised exposure assessment. Method Information on occupational histories and sources of EMF was collected as part of the INTERPHONE-INTEROCC study, providing an opportunity to assess occupational EMF exposure by assigning exposure to each source used. A source-exposure matrix (SEM) was developed based on measurements identified in the literature and estimates obtained through experts’ elicitation, for sources without available measurements. This paper focuses on the SEM development methodology to ensure the quality and representativeness of the estimates. Results Estimates of exposure for 138 EMF sources were obtained from measurements (1424 aggregated records) extracted from 71 papers and hygiene reports (1974–2013). For each source, exposure was calculated by frequency band and dosimetry type, as the arithmetic and geometric means of all measurements identified. Standard deviations were included in order to characterise the variability of the estimates. Conclusions A source-exposure matrix has been constructed for the most common sources of EMF in the workplace, based on the responses to the INTERPHONE-INTEROCC study questionnaire. This database currently represents the most comprehensive source of information on occupational EMF exposure and is available on request to researchers.

Siemiatycki et al. (2004) published a list of occupational carcinogens based largely on the evaluations published by the International Agency for Research on Cancer (IARC), augmented with additional information on the extent of workplace exposure. They considered 28 agents as definite human occupational carcinogens (IARC group 1), 27 agents as probable occupational carcinogens (group 2A), and 113 agents as possible occupational carcinogens (group 2B). However, missing from their list of occupational carcinogens is magnetic fields (MFs) at extremely low frequencies (ELF; 3–3000-Hz), which were classified as group 2B by IARC (2002).

The relation between the intake of certain food items thought to be precursors or inhibitors of N-nitroso compounds (NOC) and risk of leukemia was investigated in a case-control study among children from birth to age 10 years in Los Angeles County, California (United States). Cases were ascertained through a population-based tumor registry from 1980 to 1987. Controls were drawn from friends and by random-digit dialing. Interviews were obtained from 232 cases and 232 controls. Food items of principal interest were: breakfast meats (bacon, sausage, ham); luncheon meats (salami, pastrami, lunch meat, corned beef, bologna); hot dogs; oranges and orange juice; and grapefruit and grapefruit juice. We also asked about intake of apples and apple juice, regular and charcoal broiled meats, milk, coffee, and coke or cola drinks. Usual consumption frequencies were determined for both parents and the child. When the risks were adjusted for each other and other risk factors, the only persistent significant associations were for children's intake of hot dogs (odds ratio [OR] = 9.5, 95 percent confidence interval [CI] = 1.6-57.6 for 12 or more hot dogs per month, trend P = 0.01), and fathers' intake of hot dogs (OR = 11.0, CI = 1.2-98.7 for highest intake category, trend P = 0.01). There was no evidence that fruit intake provided protection. While these results are compatible with the experimental animal literature and the hypothesis that human NOC intake is associated with leukemia risk, given potential biases in the data, further study of this hypothesis with more focused and comprehensive epidemiologic studies is warranted.

Dr. Poole has made a number of useful points about the interpretation of studies of the association of childhood cancers with extremely low frequency magnetic fields (1). We wish to comment on only two of his points. First, Dr. Poole takes issue with the appliance-specific relative risks that were reported in the two papers in this issue (2, 3) and several earlier ones, including another Los Angeles study (4). We agree with his desire for an exposure assessment that consolidates appliances with other sources of magnetic fields, including power lines. However, numerous difficulties preclude doing so at this time. Too little is known about the fields generated by each appliance at the target organs, variations between brands, duration and frequency of use, and other modifying influences needed for a sensible summary index. More important is the uncertainty over the appropriate "exposure metric," a single number that represents a subject's magnetic field environment, including its frequency spectrum, time variation, polarization, spatial orientation, and high-frequency transients. Since fields from appliances and power lines differ in many of these qualities, weighting exposures from various electromagnetic field sources requires an exposure metric that is hypothetically carcinogenic. "Combining apples and oranges" makes sense in dietary epidemiology only because fructose has been identified as an etiologically relevant nutrient! Although summary electromagnetic field exposure indices would be useful, their development clearly poses formidable challenges to epidemiologists, exposure assessors, and biologists. During the present state of ignorance, however, we feel that appliance-specific risk estimates may provide potential clues about etiologically important components of magnetic fields (if any) and may provide some preliminary guidance to individuals and officials in making decisions about their safety. Second, we agree that the best use of household magnetic field measurements is not as a direct cancer risk factor, but in building exposure models from wiring configuration data. Where Dr. Poole uses the measured fields simply to combine categories of the Wertheimer-Leeper wire code (5), we feel that a more powerful application is predicting long-term residential exposures to a variety of magnetic field metrics. For example, we recently developed a regression model for predicting the mean magnetic field from measurements, wire configurations, and physical principles (6). When applied to the data from the Los Angeles childhood leukemia study (3), this model predicted household magnetic fields far better than did the Wertheimer-Leeper code and was significantly associated with leukemia risk, providing new evidence for magnetic field carcinogenicity. However, the predicted fields did not improve upon the Wertheimer-Leeper code in a multivariate risk model, suggesting that the mean magnetic field may not be the appropriate exposure metric (6). Such wire configuration models could be used to evaluate other plausible exposure metrics. Metrics correlated with the Wertheimer-Leeper categories would more likely be associated with cancer. We have identified two such candidates: the field's autocorrelation over time (7) and frequency components that create ionic resonances with the earth's magnetic field (8). We are looking forward to the postpublication phase of the peer-review process that Dr. Poole describes. We hope Dr. Poole's commentary (1) and the responses by Gurney et al. (9) and ourselves to this debate will stimulate further thinking about some of these methodological issues, as well as our substantive conclusions.

With the increase of system complexity, organizations are having to respond to these new demands by utilizing employee involvement methods. This paper attempts to review and examine representative studies of employee participation with particular focus on health, safety and ergonomic issues. Four topics are presented in this paper (1) the different organizational forms of participatory approaches (2) goals of the employee participation programs (3) evaluations criteria of the program and (4) conclusions. It appears that worker participatory programs are successful in addressing health, safety and ergonomie issues. However, in order to insure the success implementing a participatory decision-making program, a macroergonomics perspective should be taken.

In a case-control study of adult acute and chronic myelogenous leukemia in Los Angeles County, we tested the hypothesis that excess exposure to electromagnetic fields from electric blankets was associated with risk of leukemia. We did this by studying 116 cases of acute myelogenous leukemia (AML) and 108 cases of chronic myelogenous leukemia (CML) along with matched neighborhood controls. The cases and controls were queried as to electric blanket use and the risks computed. For AML the risk was 0.9 (95% CI 0.5-1.6) and for CML the risk was 0.8 (95% CI 0.4-1.6). Cases did not differ from controls by duration of use, year of first regular use, year since last use, or socioeconomic status. Our best estimates of exposure indicate that electric blanket use increases overall exposure to electric fields by less than 50% and magnetic fields by less than 100%. We conclude that there is no major leukemogenic risk associated with electric blanket use in Los Angeles County.

Research has been carried out to characterize personal sampling pump pulsations and their effect on the performance of the 10 mm nylon cyclone. The fluctuation about mean flows equal to 1.2 L/min and 2.0 L/min of four each of three commercially available pumps has been determined. Measurements were made both near the sampling head as well as at the sampling pump without load, since resonance of the air column between pump and sampler was found to alter the fluctuations significantly. The cyclone itself was characterized by measuring the aerodynamic diameter dependent penetration under purely harmonic flow conditions in terms of frequency and amplitude. This information is combined with Fourier analysed pump data in determining the expected effect of given pump characteristics on cyclone sampling of dust of specific size distribution.

The extended Hartree–Fock (double configuration self‐consistent field–DCSCF) energies and orbitals for the ground state (1Σg+) of H2 and the Hartree–Fock energy and orbitals for the first excited state (3Σu+) of H2 are calculated for separations ranging from the united atom to 10a0. The Σg orbital obtained from the 1Σg+ is almost the same as that from the 3Σu+ for all separations. However, when R

The very rapid worldwide increase in mobile phone use in the last decade has generated considerable interest in the possible health effects of exposure to radio frequency (RF) fields. A multinational case-control study, INTERPHONE, was set-up to investigate whether mobile phone use increases the risk of cancer and, more specifically, whether the RF fields emitted by mobile phones are carcinogenic. The study focused on tumours arising in the tissues most exposed to RF fields from mobile phones: glioma, meningioma, acoustic neurinoma and parotid gland tumours. In addition to a detailed history of mobile phone use, information was collected on a number of known and potential risk factors for these tumours. The study was conducted in 13 countries. Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the UK using a common core protocol. This paper describes the study design and methods and the main characteristics of the study population. INTERPHONE is the largest case-control study to date investigating risks related to mobile phone use and to other potential risk factors for the tumours of interest and includes 2,765 glioma, 2,425 meningioma, 1,121 acoustic neurinoma, 109 malignant parotid gland tumour cases and 7,658 controls. Particular attention was paid to estimating the amount and direction of potential recall and participation biases and their impact on the study results.