Exposure to electromagnetic fields and the risk of childhood leukaemia: a review

Enhanced Electromagnetic Interference Shielding Properties of CNT/Carbon Composites by Designing a Hierarchical Porous Structure

With the widespread use of electronic devices, electromagnetic interference (EMI) has become an increasingly severe issue, adversely affecting device performance and human health. Carbon nanotubes (CNTs) are recognized for their electrical conductivity, flexibility, and stability, making them promising candidates for EMI shielding applications. This research developed hierarchical porous-structured CNT/carbon composites for enhancing electromagnetic interference (EMI) shielding properties. Featuring a CNT film with nano-scale pores and an amorphous carbon layer with micro-scale pores, the CNT/carbon composites are strategically arranged to promote the penetration of EM waves into the composite's interior and facilitate multiple reflections, thereby improving the EMI shielding performance. An impressive EMI shielding effectiveness of 61.4 dB was achieved by the CNT/carbon composites, marking a significant improvement over the 36.5 dB measured for the pristine CNT film. Owing to the micro pores in the amorphous carbon layer, a notable reduction in the reflection shielding efficiency (SER) but, concurrently, a substantial increase in the absorption shielding efficiency (SEA) compared with the pristine CNT film was realized in the composites. This study successfully validated the effectiveness of the hierarchical porous structure in enhancing the EMI shielding performance, providing a promising new strategy for the development of lightweight, flexible, and efficient EMI shielding materials.

Robust ultrahigh electromagnetic interference shielding effectiveness based on engineered structures of carbon nanotube films

High-performance electromagnetic interference (EMI) shielding materials with ultrathin, flexible, and pliable mechanical properties are highly desired for high-end equipments, yet there remain large challenges in the manufacture of these materials. Here, carbon nanotube film (CNTF)/copper (Cu) nanoparticle (NP) composite films are fabricated via a facile electrodeposition method to achieve high electromagnetic shielding efficiency. Notably, a CNTF/Cu NP composite film with 15 μm thickness can achieve excellent EMI shielding efficiency of ∼248 dB and absolute EMI shielding effectiveness as high as 2.17 × 105 dB cm2 g-1, which are the best values for composite EMI shielding materials with similar or greater thicknesses. These engineered composite films exhibit excellent deformation tolerance, which ensures the robust reliability of EMI shielding efficiency after 20,000 cycles of repeated bending. Our results represent a critical breakthrough in the preparation of ultrathin, flexible, and pliable shielding films for applications in smart, portable and wearable electronic devices, and 5G communication.

Residential exposure to magnetic fields from transformer stations and risk of childhood leukemia

BACKGROUND

Several studies have documented an increased risk of leukemia among children exposed to magnetic fields from high-voltage power lines, with some evidence of dose-response relation. However, findings in some studies have been inconsistent, and data on the effects of different sources of exposure are lacking. In this study, we evaluated the relation of childhood leukemia risk to exposure to magnetic fields from transformer stations.

METHODS

We conducted a population-based case-control study in a pediatric population of two Northern Italian provinces of Modena and Reggio Emilia. We included 182 registry-identified childhood leukemia cases diagnosed during 1998-2019 and 726 population controls matched on sex, year of birth, and province of residence. We assessed exposure by calculating distance from childhood residence to the nearest transformer station within a geographical information system, computing disease odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression, adjusting for potential confounders. We evaluated exposure using two buffers (15 m and 25 m radius) and assessed two case groups: leukemia (all subtypes) and acute lymphoblastic leukemia (ALL).

RESULTS

Residing within 15 m of a transformer station (vs. ≥15 m) was not appreciably associated with risk of leukemia (all subtypes) or ALL. We found similar results using a less stringent exposure buffer (25 m). Among children aged ≥5 years, the adjusted ORs were 1.3 (95% CI 0.1-12.8) for leukemia and 1.3 (95% CI 0.1-12.4) for ALL using the 15 m buffer, while they were 1.7 (95% CI 0.4-7.0) for leukemia and 0.6 (95% CI 0.1-4.8) for ALL using the 25 m buffer.

CONCLUSIONS

While we found no overall association between residential proximity to transformer stations and childhood leukemia, there was some evidence for elevated risk of childhood leukemia among children aged ≥5 years. Precision was limited by the low numbers of exposed children.

Complex Electromagnetic Issues Associated with the Use of Electric Vehicles in Urban Transportation

The electromagnetic field (EMF) in electric vehicles (EVs) affects not only drivers, but also passengers (using EVs daily) and electronic devices inside. This article summarizes the measurement methods applicable in studies of complex EMF in EVs focused on the evaluation of characteristics of such exposure to EVs users and drivers, together with the results of investigations into the static magnetic field (SMF), the extremely low-frequency magnetic field (ELF) and radiofrequency (RF) EMF related to the use of the EVs in urban transportation. The investigated EMF components comply separately with limits provided by international labor law and guidelines regarding the evaluation of human short-term exposure; however other issues need attention-electromagnetic immunity of electronic devices and long-term human exposure. The strongest EMF was found in the vicinity of direct current (DC) charging installations-SMF up to 0.2 mT and ELF magnetic field up to 100 µT-and inside the EVs-up to 30 µT close to its internal electrical equipment. Exposure to RF EMF inside the EVs (up to a few V/m) was found and recognized to be emitted from outdoor radiocommunications systems, together with emissions from sources used inside vehicles, such as passenger mobile communication handsets and antennas of Wi-Fi routers.

Anti-Oxidative and Immune Regulatory Responses of THP-1 and PBMC to Pulsed EMF Are Field-Strength Dependent

Innate immune cells react to electromagnetic fields (EMF) by generating reactive oxygen species (ROS), crucial intracellular messengers. Discrepancies in applied parameters of EMF studies, e.g., flux densities, complicate direct comparison of downstream anti-oxidative responses and immune regulatory signaling. We therefore compared the impact of different EMF flux densities in human leukemic THP1 cells and peripheral blood mononuclear cells (PBMC) of healthy donors to additionally consider a potential disparate receptivity based on medical origin. ROS levels increased in THP1 cells stimulated with lipopolysaccharide (LPS) after one hour of EMF exposure. Moreover, weak EMF mitigated the depletion of the reducing agent NAD(P)H in THP1. Neither of these effects occurred in PBMC. Landscaping transcriptional responses to varied EMF revealed elevation of the anti-oxidative enzymes PRDX6 (2-fold) and DHCR24 (6-fold) in THP1, implying involvement in lipid metabolism. Furthermore, our study confirmed anti-inflammatory effects of EMF by 6-fold increased expression of IL10. Strikingly, THP1 responded to weak EMF, while PBMC were primarily affected by strong EMF, yet with severe cellular stress and enhanced rates of apoptosis, indicated by HSP70 and caspase 3 (CASP3). Taken together, our results emphasize an altered susceptibility of immune cells of different origin and associate EMF-related effects with anti-inflammatory signaling and lipid metabolism.

Extremely Low-Frequency Magnetic Fields Exposure Measurement during Lessons in Elementary Schools

Schools are an important place for children's exposure to electromagnetic fields, which may cause adverse health effects. To better understand environmental extremely low-frequency magnetic fields (ELF-MFs) exposure among elementary school students, we measured numeric values of ELF-MFs in five classrooms at four schools during digital learning class hours. The measurement of ELF-MFs was taken with an EMDEX II field analyzer. Specifically, we examined the level of exposure to ELF-MFs for each student's seating position in the classroom. The results showed that ELF-MFs exposure levels were lower than those in the International Commission on Non-Ionizing Radiation Protection guidelines; however, there were significant differences in the level of magnetic field exposure at each school and at each student's seat. The exposure to ELF-MFs at students' seat positions was mostly caused by electrical appliances, electronic wiring, and distribution boxes, but the exposure level decreased as the distance increased. Therefore, it is important to design safe and appropriate environments for digital learning in schools, such as proper seating arrangements, to avoid ELF-MFs exposure to students as much as possible. Future studies should measure ELF-MFs levels in other areas and investigate the effects of exposure to ELF-MFs during school hours on children's health.

Exposure levels of ELF magnetic fields in the residential areas of Mangaung Metropolitan Municipality

The aim of this study was to evaluate the exposure levels of ELF magnetic fields in the residential areas of Mangaung metropolitan municipality. Fifteen residential sites were randomly selected in Bloemfontein, nine in Botshabelo and six in Thaba Nchu areas of Mangaung. Measurements were collected at the distances of 3 m, 6 m and 9 m outside electrical substations, near every corner, using a Trifield meter model XE 100. Measurements were also collected from four different corners inside substations, near barrier screening and were referred to as a distance of 0 m (reference point). The results indicated a non-significant difference among 15 residential areas; BRE1 to BRE15 and six areas; TNRE1 to TRNE6. The exposure levels were significantly high in one residential area BORE1 (0.55 μT) as compared to other residential sites in Botshabelo (p < 0.001). The results obtained from the measurements also show a significant difference between the residential areas BORE4 and BORE8 (p < 0.01) as well as BORE4 and BORE9 (p < 0.006). The four distance interims also demonstrated a highly significant difference (p < 0.0001) when compared to one another. The t test showed a statistically significant difference for exposure levels recorded at 3 m, 6 m and 9 m in comparison to 0 m (p < 0.01). The exposure levels recorded at 3 m were also significantly different to those recorded at 6 m (p < 0.05) and 9 m (p < 0.01). The exposure levels measured at all distances are below the ICNIRP guidelines and the fields decrease rapidly with an increased distance from the source.

Biological effects of non-ionizing electromagnetic fields: Two sides of a coin

Controversial, sensational and often contradictory scientific reports have triggered active debates over the biological effects of electromagnetic fields (EMFs) in literature and mass media the last few decades. This could lead to confusion and distraction, subsequently hampering the development of a univocal conclusion on the real hazards caused by EMFs on humans. For example, there are lots of publications indicating that EMF can induce apoptosis and DNA strand-breaks in cells. On the other hand, these effects could rather be beneficial, in that they could be effectively harnessed for treatment of various disorders, including cancer. This review discusses and analyzes the results of various in vitro, in vivo and epidemiological studies on the effects of non-ionizing EMFs on cells and organs, including the consequences of exposure to the low and high frequencies EM spectrum. Emphasis is laid on the analysis of recent data on the role of EMF in the induction of oxidative stress and DNA damage. Additionally, the impact of EMF on the reproductive system has been discussed, as well as the relationship between EM radiation and blood cancer. Apart from adverse effects, the therapeutic potential of EMFs for clinical use in different pathologies is also highlighted.

Extremely Low-Frequency Electromagnetic Fields Affect Myogenic Processes in C2C12 Myoblasts: Role of Gap-Junction-Mediated Intercellular Communication

Extremely low-frequency electromagnetic fields (ELF-EMFs) can interact with biological systems. Although they are successfully used as therapeutic agents in physiatrics and rehabilitative practice, they might represent environmental pollutants and pose a risk to human health. Due to the lack of evidence of their mechanism of action, the effects of ELF-EMFs on differentiation processes in skeletal muscle were investigated. C2C12 myoblasts were exposed to ELF-EMFs generated by a solenoid. The effects of ELF-EMFs on cell viability and on growth and differentiation rates were studied using colorimetric and vital dye assays, cytomorphology, and molecular analysis of MyoD and myogenin expression, respectively. The establishment of functional gap junctions was investigated analyzing connexin 43 expression levels and measuring cell permeability, using microinjection/dye-transfer assays. The ELF-EMFs did not affect C2C12 myoblast viability or proliferation rate. Conversely, at ELF-EMF intensity in the mT range, the myogenic process was accelerated, through increased expression of MyoD, myogenin, and connexin 43. The increase in gap-junction function suggests promoting cell fusion and myotube differentiation. These data provide the first evidence of the mechanism through which ELF-EMFs may provide therapeutic benefits and can resolve, at least in part, some conditions of muscle dysfunction.

Analysis of personal and bedroom exposure to ELF-MFs in children in Italy and Switzerland

Little is known about the real everyday exposure of children in Europe to extremely low-frequency magnetic fields (ELF-MFs). The aims of this study are to (i) assess personal ELF-MF exposure in children; (ii) to identify factors determining personal and bedroom ELF-MF exposure measurements in children; (iii) to evaluate the reproducibility of exposure summary measures; and (iv) to compare personal with bedroom measurements. In Switzerland and Italy, 172 children aged between 5 and 13 years were equipped with ELF-MF measurement devices (EMDEX II, measuring 40-800 Hz) during 24-72 h twice, in the warm and the cold season. In addition, 24-h measurements were taken in the bedroom of children. In our study, sample geometric mean ELF-MF exposure was 0.04 μT for personal and 0.05 μT for bedroom measurements. Living within 100 m of a highest voltage power line increased geometric mean personal exposure by a factor of 3.3, and bedroom measurements by a factor 6.8 compared to a control group. Repeated measurements within the same subject showed high reproducibility for the geometric mean (Spearman's correlation 0.78 for personal and 0.86 for bedroom measurements) but less for the 95th and 99th percentile of the personal measurements (≤0.42). Spearman's correlation between bedroom and personal exposure was 0.86 for the geometric mean but considerably lower for the 95th and 99th percentiles (≤0.60). Most previous studies on ELF-MF childhood leukaemia used mean bedroom exposure. Our study demonstrates that geometric mean bedroom measurements is well correlated with personal geometric mean exposure, and has high temporal reproducibility.

Environmental Exposure and Risk of Childhood Leukemia: An Overview

Childhood leukemia is the most common cancer diagnosed in children worldwide. However, only a few causes have been established so far, mainly some genetic syndromes and high doses of ionizing radiation. Major efforts have been undertaken to study the relationship between environmental factors and the risk of childhood leukemia, inspired by geographical variation in incidence rates. Some evidence has emerged for parental occupational exposures to pesticides, whereas there is less evidence for an association with postnatal pesticide exposure. Diagnostic radiation and radon exposure have been suggested but there remains a lack of convincing studies. Extremely low-frequency magnetic fields consistently showed a small increase in risk in numerous studies, but bias and confounding cannot be ruled out as possible explanations. From among factors other than environmental and radiation-related, the most promising candidate is abnormal patterns to common infections, but which children are most at risk and the pathways are not fully understood. In conclusion, although childhood leukemia shows some distinct incidence patterns by sex, age, and geography suggesting a role of the environment in its etiology, no major environmental risk factors including radiation have been established as major contributors to the global childhood leukemia burden. Due to the young age at diagnosis and evidence of chromosomal damage before birth in many of the affected children, parental exposures remain of high interest. Although cure rates of childhood leukemia are high in economically developed countries, because of the adverse late effects of the disease and its treatment, identification of modifiable risk factors for implementing primary prevention remains the ultimate goal.

The effect of electromagnetic radiation emitted by display screens on cell oxygen metabolism - in vitro studies

INTRODUCTION

Research studies carried out for decades have not solved the problem of the effect of electromagnetic radiation of various frequency and strength on the human organism. Due to this fact, we decided to investigate the changes taking place in human blood platelets under the effect of electromagnetic radiation (EMR) emitted by LCD monitors.

MATERIAL AND METHODS

The changes of selected parameters of oxygen metabolism were measured, i.e. reactive oxygen species concentration, enzymatic activity of antioxidant defence proteins - superoxide dismutase (SOD-1) and catalase (CAT) - and malondialdehyde concentration (MDA). A suspension of human blood platelets was exposed to electromagnetic radiation of 1 kHz frequency and 150 V/m and 220 V/m intensity for 30 and 60 min. The level of changes of the selected parameters of oxidative stress was determined after the exposure and compared to the control samples (not exposed).

RESULTS

The measurements revealed an increase of the concentration of reactive oxygen species. The largest increase of ROS concentration vs. the control sample was observed after exposure to EMF of 220 V/m intensity for 60 min (from x = 54.64 to x = 72.92). The measurement of MDA concentration demonstrated a statistically significant increase after 30-min exposure to an EMF of 220 V/m intensity in relation to the initial values (from x = 3.18 to x = 4.41). The enzymatic activity of SOD-1 decreased after exposure (the most prominent change was observed after 60-min and 220 V/m intensity from x = 3556.41 to x = 1084.83). The most significant change in activity of catalase was observed after 60 min and 220 v/m exposure (from x = 6.28 to x = 4.15).

CONCLUSIONS

The findings indicate that exposure to electromagnetic radiation of 1 kHz frequency and 150 V/m and 220 V/m intensity may cause adverse effects within blood platelets' oxygen metabolism and thus may lead to physiological dysfunction of the organism.

European Code against Cancer 4th Edition: Ionising and non-ionising radiation and cancer

Ionising radiation can transfer sufficient energy to ionise molecules, and this can lead to chemical changes, including DNA damage in cells. Key evidence for the carcinogenicity of ionising radiation comes from: follow-up studies of the survivors of the atomic bombings in Japan; other epidemiological studies of groups that have been exposed to radiation from medical, occupational or environmental sources; experimental animal studies; and studies of cellular responses to radiation. Considering exposure to environmental ionising radiation, inhalation of naturally occurring radon is the major source of radiation in the population - in doses orders of magnitude higher than those from nuclear power production or nuclear fallout. Indoor exposure to radon and its decay products is an important cause of lung cancer; radon may cause approximately one in ten lung cancers in Europe. Exposures to radon in buildings can be reduced via a three-step process of identifying those with potentially elevated radon levels, measuring radon levels, and reducing exposure by installation of remediation systems. In the 4th Edition of the European Code against Cancer it is therefore recommended to: "Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels". Non-ionising types of radiation (those with insufficient energy to ionise molecules) - including extremely low-frequency electric and magnetic fields as well as radiofrequency electromagnetic fields - are not an established cause of cancer and are therefore not addressed in the recommendations to reduce cancer risk.

Residential exposure to extremely low-frequency magnetic fields and risk of childhood leukaemia, CNS tumour and lymphoma in Denmark

BACKGROUND

We previously reported that children exposed to elevated extremely low-frequency magnetic fields (ELF-MF) had a five to six times higher risk of leukaemia, central nervous system (CNS) tumour and malignant lymphoma. Here we extend the study from 1968 to 1986 through 2003.

METHODS

We included 3277 children with leukaemia, CNS tumour or malignant lymphoma during 1968-2003 recorded in the Danish Cancer Registry and 9129 controls randomly selected from the Danish childhood population. ELF-MF from 50 to 400 kV facilities were calculated at the residences.

RESULTS

For recently diagnosed cases (1987-2003), the relative risk (RR) was 0.88 (95% confidence interval (CI): 0.32-2.42), while for the total period (1968-2003) it was 1.63 (95% CI: 0.77-3.46) for leukaemia, CNS tumour and malignant lymphoma combined for exposures ⩾0.4 μT compared with <0.1 μT. These results were based on five cases (recent period) and 11 cases (total period) in the highest exposure group.

CONCLUSIONS

We did not confirm the previous finding of a five- to six-fold higher risk for leukaemia, CNS tumour and malignant lymphoma when including data from the more recent time period. For the total time period, the results for childhood leukaemia were in line with large pooled analyses showing RRs between 1.5 and 2.

Socioeconomic Status and Childhood Leukemia Incidence in Switzerland

Socioeconomic status (SES) discrepancies exist for child and adult cancer morbidity and are a major public health concern. In this Swiss population-based matched case–control study on the etiology of childhood leukemia, we selected the cases from the Swiss Childhood Cancer Registry diagnosed since 1991 and the controls randomly from census. We assigned eight controls per case from the 1990 and 2000 census and matched them by the year of birth and gender. SES information for both cases and controls was obtained from census records by probabilistic record linkage. We investigated the association of SES with childhood leukemia in Switzerland, and explored whether it varied with different definitions of socioeconomic status (parental education, living condition, area-based SES), time period, and age. In conditional logistic regression analyses of 565 leukemia cases and 4433 controls, we found no consistent evidence for an association between SES and childhood leukemia. The odds ratio comparing the highest with the lowest SES category ranged from 0.95 (95% CI: 0.71–1.26; P_trend = 0.73) for paternal education to 1.37 (1.00–1.89; P_trend = 0.064) for maternal education. No effect modification was found for time period and age at diagnosis. Based on this population-based study, which avoided participation and reporting bias, we assume the potential association of socioeconomic status and childhood leukemia if existing to be small. This study did not find evidence that socioeconomic status, of Switzerland or comparable countries, is a relevant risk factor or strong confounder in etiological investigations on childhood leukemia.

Childhood cancer incidence patterns by race, sex and age for 2000-2006: a report from the South African National Cancer Registry

Higher childhood cancer incidence rates are generally reported for high income countries although high quality information on descriptive patterns of childhood cancer incidence for low or middle income countries is limited, particularly in Sub-Saharan Africa. There is a need to quantify global differences by cancer types, and to investigate whether they reflect true incidence differences or can be attributed to under-diagnosis or under-reporting. For the first time, we describe childhood cancer data reported to the pathology report-based National Cancer Registry of South Africa in 2000-2006 and compare our results to incidence data from Germany, a high income country. The overall age-standardized incidence rate (ASR) for South Africa in 2000-2006 was 45.7 per million children. We observed substantial differences by cancer types within South Africa by racial group; ASRs tended to be 3-4-fold higher in South African Whites compared to Blacks. ASRs among both Black and White South Africans were generally lower than those from Germany with the greatest differences observed between the Black population in South Africa and Germany, although there was marked variation between cancer types. Age-specific rates were particularly low comparing South African Whites and Blacks with German infants. Overall, patterns across South African population groups and in comparison to Germans were similar for boys and girls. Genetic and environmental reasons may probably explain rather a small proportion of the observed differences. More research is needed to understand the extent to which under-ascertainment and under-diagnosis of childhood cancers drives differences in observed rates.

Influence of extremely low frequency electromagnetic fields on growth performance, innate immune response, biochemical parameters and disease resistance in rainbow trout, Oncorhynchus mykiss

The effects of extremely low frequency electromagnetic fields on rainbow trout growth performance, innate immunity and biochemical parameters were studied. Rainbow trout (17-18 g) were exposed to electromagnetic fields (15 Hz) at 0.01, 0.1, 0.5, 5 and 50 µT, for 1 h daily over period of 60 days. Growth performance of fish improved in different treatment groups, especially at 0.1, 0.5, 5 and 50 µT. Immunological parameters, specifically hemagglutinating titer, total antiprotease and α1-antiprotease levels in treatment groups, were also enhanced. Total protein and globulin contents in the serum of fish exposed to 0.1, 0.5, 5 and 50 µT were significantly higher than those in the control group. No significant differences were found in serum enzyme activities, namely aspartate aminotransferase and alanine aminotransferase of fish in all treatment groups. Conversely, alkaline phosphatase level decreased in fish exposed to 0.01 and 50 µT electromagnetic fields. Meanwhile, electromagnetic induction at 0.1, 0.5, 5 and 50 µT enhanced fish protection against Yersinia ruckeri. These results indicated that these specific electromagnetic fields had possible effects on growth performance, nonspecific immunity and disease resistance of rainbow trout.

Occupational exposure to electromagnetic fields of uninterruptible power supply industry workers

There is an increasing concern that exposure to extremely low-frequency (ELF) electromagnetic fields (EMFs) may cause or contribute to adverse health effects. To assess exposure to ELF EMFs, electric and magnetic field spot measurements were performed extensively at the workplace of a worldwide uninterruptible power supply (UPS) factory. The measurements were carried out in order to get the electric and magnetic field exposure results in real working situations in test areas, production lines and power substations. The electric and magnetic fields reached up to 992.0 V m(-1) and 215.6 μT in the test areas, respectively. The fields existed up to 26.7 V m(-1) and 7.6 μT in the production lines. The field levels in the vicinity of the power substations did not exceed 165.5 V m(-1) and 65 μT. The data presented are useful in determining the occupational exposure levels of UPS industry workers. The measurements are below the reference levels recommended by the guideline published in 2010 by the International Commission on Non-Ionizing Radiation Protection and action levels of the directive adopted in 2013 by European Parliament and Council.

Variability in electromagnetic field levels over time, and Monte-Carlo simulation of exposure parameters

This article analyses the electric field levels around medium-wave transmitters, delimiting the temporal variability of the levels received at a pre-established reception point. One extensively used dosimetric criterion is to consider historical levels of the field recorded over a certain period of time so as to provide an overall perspective of radio-frequency electric field exposure in a particular environment. This aspect is the focus of the present study, in which the measurements will be synthesised in the form of exposure coefficients. Two measurement campaigns were conducted: one short term (10 days) and the other long term (1 y). The short-term data were used to study which probability density functions best approximate the measured levels. The long-term data were used to compute the principal statistics that characterise the field values over a year. The data that form the focus of the study are the peak traces, since these are the most representative from the standpoint of exposure. The deviations found were around 6 % for short periods and 12 % for long periods. The information from the two campaigns was used to develop and implement a computer application based on the Monte Carlo method to simulate values of the field, allowing one to carry out robust statistics.

Distance to high-voltage power lines and risk of childhood leukemia--an analysis of confounding by and interaction with other potential risk factors

We investigated whether there is an interaction between distance from residence at birth to nearest power line and domestic radon and traffic-related air pollution, respectively, in relation to childhood leukemia risk. Further, we investigated whether adjusting for potential confounders alters the association between distance to nearest power line and childhood leukemia. We included 1024 cases aged <15, diagnosed with leukemia during 1968-1991, from the Danish Cancer Registry and 2048 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132-400 kV overhead power line. Concentrations of domestic radon and traffic-related air pollution (NOx at the front door) were estimated using validated models. We found a statistically significant interaction between distance to nearest power line and domestic radon regarding risk of childhood leukemia (p = 0.01) when using the median radon level as cut-off point but not when using the 75th percentile (p = 0.90). We found no evidence of an interaction between distance to nearest power line and traffic-related air pollution (p = 0.73). We found almost no change in the estimated association between distance to power line and risk of childhood leukemia when adjusting for socioeconomic status of the municipality, urbanization, maternal age, birth order, domestic radon and traffic-related air pollution. The statistically significant interaction between distance to nearest power line and domestic radon was based on few exposed cases and controls and sensitive to the choice of exposure categorization and might, therefore, be due to chance.

Exposure to radio-frequency electromagnetic fields from broadcast transmitters and risk of childhood cancer: a census-based cohort study

We investigated the association between exposure to radio-frequency electromagnetic fields (RF-EMFs) from broadcast transmitters and childhood cancer. First, we conducted a time-to-event analysis including children under age 16 years living in Switzerland on December 5, 2000. Follow-up lasted until December 31, 2008. Second, all children living in Switzerland for some time between 1985 and 2008 were included in an incidence density cohort. RF-EMF exposure from broadcast transmitters was modeled. Based on 997 cancer cases, adjusted hazard ratios in the time-to-event analysis for the highest exposure category (>0.2 V/m) as compared with the reference category (<0.05 V/m) were 1.03 (95% confidence interval (CI): 0.74, 1.43) for all cancers, 0.55 (95% CI: 0.26, 1.19) for childhood leukemia, and 1.68 (95% CI: 0.98, 2.91) for childhood central nervous system (CNS) tumors. Results of the incidence density analysis, based on 4,246 cancer cases, were similar for all types of cancer and leukemia but did not indicate a CNS tumor risk (incidence rate ratio = 1.03, 95% CI: 0.73, 1.46). This large census-based cohort study did not suggest an association between predicted RF-EMF exposure from broadcasting and childhood leukemia. Results for CNS tumors were less consistent, but the most comprehensive analysis did not suggest an association.

Potential health impacts of residential exposures to extremely low frequency magnetic fields in Europe

Over the last two decades residential exposure to extremely low frequency magnetic fields (ELF MF) has been associated with childhood leukaemia relatively consistently in epidemiological studies, though causality is still under investigation. We aimed to estimate the cases of childhood leukaemia that might be attributable to exposure to ELF MF in the European Union (EU27), if the associations seen in epidemiological studies were causal. We estimated distributions of ELF MF exposure using studies identified in the existing literature. Individual distributions of exposure were integrated using a probabilistic mixture distribution approach. Exposure-response functions were estimated from the most recently published pooled analysis of epidemiological data. Probabilistic simulation was used to estimate population attributable fractions (AFP) and attributable cases of childhood leukaemia in the EU27. By assigning the literature review-based exposure distribution to all EU27 countries, we estimated the total annual number of cases of leukaemia attributable to ELF MF at between ~50 (95% CIs: -14, 132) and ~60 (95% CIs: -9, 610), depending on whether exposure-response was modelled categorically or continuously, respectively, for a non-threshold effect. This corresponds to between ~1.5% and ~2.0% of all incident cases of childhood leukaemia occurring annually in the EU27. Considerable uncertainties are due to scarce data on exposure and the choice of exposure-response model, demonstrating the importance of further research into better understanding mechanisms of the potential association between ELF MF exposure and childhood leukaemia and the need for improved monitoring of residential exposures to ELF MF in Europe.

Distance from residence to power line and risk of childhood leukemia: a population-based case-control study in Denmark

PURPOSE

Epidemiological studies have found an association between exposure to extremely low-frequency magnetic fields (ELF-MF) and childhood leukemia. In 2005, a large British study showed an association between proximity of residence to high-voltage power lines and the risk of childhood leukemia. The association extended beyond distances at which the 'power line'-induced magnetic fields exceed background levels, suggesting that the association was not explained by the magnetic field, but might be due to chance, bias, or other risk factors associated with proximity to power lines. Our aim was to conduct a comparable study in an independent setting (Denmark).

METHODS

We included 1,698 cases aged <15, diagnosed with leukemia during 1968-2006, from the Danish Cancer Registry and 3,396 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132-400 kV overhead power line.

RESULTS

Odds ratios (ORs) were 0.76 [95 % confidence interval (CI) 0.40-1.45] for children who lived 0-199 m from the nearest power line and 0.92 (95 % CI 0.67-1.25) for those who lived 200-599 m away when compared with children who lived ≥600 m away. When restricting the analysis to 220 and 400 kV overhead power lines, the OR for children who lived 200-599 m from a power line was 1.76 (95 % CI 0.82-3.77) compared to children who lived ≥600 m away. However, chance is a likely explanation for this finding as the result was not significant, numbers were small, and there were no indications of an higher risk closer to the lines since no cases were observed within 200 m of these.

CONCLUSIONS

We found no higher risk of leukemia for children living 0-199 m or for children living 200-599 m of a 132-400 kV overhead power line. A slightly elevated OR for children living between 200 and 599 m of a 220-400 kV overhead power line is likely to be a chance finding.

Effects of 60 Hz magnetic fields on teenagers and adults

BACKGROUND

As use of electrical devices has increased, social concerns about the possible effects of 60 Hz electromagnetic fields on human health have increased. Accordingly, the number of people who complain of various symptoms such as headache and insomnia has risen. Many previous studies of the effects of extremely low frequency (ELF) magnetic field exposure on children have focused on the occurrence of childhood leukaemia and central nervous system cancers. However, very few provocation studies have examined the health effects of ELF magnetic fields on teenagers.

METHODS

In this double-blind study, we simultaneously investigated physiological changes (heart rate, respiration rate, and heart rate variability), subjective symptoms, and magnetic field perception to determine the reliable effects of 60 Hz 12.5 μT magnetic fields on teenagers. Two volunteer groups of 30 adults and 30 teenagers were tested with exposure to sham and real magnetic fields for 32 min.

RESULTS

ELF magnetic field exposure did not have any effects on the physiological parameters or eight subjective symptoms in either group. Neither group correctly perceived the magnetic fields.

CONCLUSIONS

Physiological data were analysed, subjective symptoms surveyed, and the percentages of those who believed they were being exposed were measured. No effects were observed in adults or teenagers resulting from 32 min of 60 Hz 12.5 μT magnetic field exposure.

Childhood leukaemia close to high-voltage power lines--the Geocap study, 2002-2007

Background:

High-voltage overhead power lines (HVOLs) are a source of extremely low-frequency magnetic fields (ELF-MFs), which are classified as possible risk factors for childhood acute leukaemia (AL). The study was carried out to test the hypothesis of an increased AL incidence in children living close to HVOL of 225–400 kV (VHV-HVOL) and 63–150 kV (HV-HVOL).

Methods:

The nationwide Geocap study included all the 2779 cases of childhood AL diagnosed in France over 2002–2007 and 30 000 contemporaneous population controls. The addresses at the time of inclusion were geocoded and precisely located around the whole HVOL network.

Results:

Increased odds ratios (ORs) were observed for AL occurrence and living within 50 m of a VHV-HVOL (OR=1.7 (0.9–3.6)). In contrast, there was no association with living beyond that distance from a VHV-HVOL or within 50 m of a HV-HVOL.

Conclusion:

The present study, free from any participation bias, supports the previous international findings of an increase in AL incidence close to VHV-HVOL. In order to investigate for a potential role of ELF-MF in the results, ELF-MF at the residences close to HVOL are to be estimated, using models based on the annual current loads and local characteristics of the lines.

Investigation of transcriptional responses of juvenile mouse bone marrow to power frequency magnetic fields

To seek alterations in gene transcription in bone marrow cells following in vivo exposure of juvenile mice to power frequency magnetic fields, young (21-24-day old) C57BL/6 mice were exposed to a 100μT 50Hz magnetic field for 2h. Transcription was analysed by three methods, High Coverage Expression Profiling (HiCEP), Illumina microarrays and quantitative real-time polymerase chain reaction (QRT-PCR). A pilot HiCEP experiment with 6 exposed (E) and 6 non-exposed (NE) mice identified four candidate responsive transcripts (two unknown transcripts (AK152075 and F10-NED), phosphatidylinositol binding clathrin assembly protein (Picalm) and exportin 7 (Xpo7)). A larger experiment compared 19 E and 15 NE mice using two independent QRT-PCR assays and repeated microarray assays. No significant field-dependent changes were seen, although Picalm showed a trend to significance in one QRT-PCR assay (E/NE=0.91; P=0.06). However, the study was underpowered to detect an effect of this magnitude (52% power at P=0.05). These data indicate the current experimental constraints in detecting small changes in transcription that may occur in response to magnetic fields. These constraints result from technical limitations in the accuracy of assays and biological variation, which together were sufficient to account statistically for the number of differentially expressed transcripts identified in the pilot experiment.

Extremely low-frequency magnetic fields and survival from childhood acute lymphoblastic leukemia: an international follow-up study

A previous US study reported poorer survival in children with acute lymphoblastic leukemia (ALL) exposed to extremely low-frequency magnetic fields (ELF-MF) above 0.3 μT, but based on small numbers. Data from 3073 cases of childhood ALL were pooled from prospective studies conducted in Canada, Denmark, Germany, Japan, UK and US to determine death or relapse up to 10 years from diagnosis. Adjusting for known prognostic factors, we calculated hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival and event-free survival for ELF-MF exposure categories and by 0.1 μT increases. The HRs by 0.1 μT increases were 1.00 (CI, 0.93-1.07) for event-free survival analysis and 1.04 (CI, 0.97-1.11) for overall survival. ALL cases exposed to >0.3 μT did not have a poorer event-free survival (HR=0.76; CI, 0.44-1.33) or overall survival (HR=0.96; CI, 0.49-1.89). HRs varied little by subtype of ALL. In conclusion, ELF-MF exposure has no impact on the survival probability or risk of relapse in children with ALL.

Measurement procedure to assess exposure to extremely low-frequency fields: a primary school case study

How to correctly measure the exposure of general public to extremely low-frequency (ELF) radiation is a key issue for ELF epidemiological studies. This paper proposes a measurement procedure to accurately assess the exposure of people to electric and magnetic field in the frequency band from 5 Hz to 100 kHz in buildings and their premises. As ELF radiation could be particularly harmful to children, the measurement procedure is focused on exposure to ELF in schools. Thus, the students' exposure to ELF fields can be assessed by correlating the ELF measurements to the hours of school activity. In this paper, the measurement protocol was applied to study the ELF exposure on students from García Quintana primary school in Valladolid, Spain. The campaign of measurements for ELF exposure assessment in this primary school was of great interest for the Regional Council of Public Health because of the social alarm generated by the presence of a significant number cancer cases in children.

THE BIOMECHANICS OF DRUG-TREATED LEUKEMIA CELLS INVESTIGATED USING OPTICAL TWEEZERS

Leukemia is a very common cancer worldwide, and different drugs have been applied to treat the disease. However, the influence of the drugs on the biomechanical properties of leukemia cells, which are related to the risk of leukostasis, is still unknown. Moreover, accurate measurement of biomechanical properties of leukemia cells is still a challenging task because of their non-adherent nature and high sensitivity to the surrounding physiological conditions. In this study, a protocol to measure the biomechanical properties of leukemia cells by performing indentation tests using optical tweezers is proposed. The biomechanical properties of normal leukemia cells and cells treated with various cancer drugs, including phorbol 12-myristate 13-acetate (PMA), all-trans retinoic acid (ATRa), Cytoxan (CTX), and Dexamethasone (DEX), were measured. The adhesion between the cells and certain proteins existing in the extracellular matrix, i.e., fibronetin and collagen I, was also characterized with the help of a static adhesion assay. It was found that after treatment by ATRa, CTX, and DEX, the cells became softer, and the adhesion between the cells and the proteins became weaker. PMA treatment caused no change in the stiffness of the HL60 cells, but increased the stiffness of the K562 cells, and increased the cell–protein adhesion of both K562 cells and HL60 cells.

The monitoring results of electromagnetic radiation of 110-kV high-voltage lines in one urban location in Chongqing P.R. China

To understand electromagnetic radiation field strength and its influencing factors of certain 110-kV high-voltage lines in one urban area of Chongqing by measuring 110-kV high-voltage line's electromagnetic radiation level. According to the methodology as determined by the National Hygienic Standards, we selected certain adjacent residential buildings, high-voltage lines along a specific street and selected different distances around its vertical projection point as monitoring points. The levels of electromagnetic radiations were measured respectively. In this investigation within the frequency of 5-1,000 Hz both the electric field strength and magnetic field strength of each monitoring sites were lower than the public exposure standards as determined by the International Commission on Non-Ionizing Radiation Protection. However, the electrical field strength on the roof adjacent to the high-voltage lines was significantly higher than that as measured on the other floors in the same buildings (p < 0.05). The electromagnetic radiation measurements of different monitoring points, under the same high-voltage lines, showed the location which is nearer the high-voltage line maintain a consistently higher level of radiation than the more distant locations (p < 0.05). Electromagnetic radiation generated by high-voltage lines decreases proportionally to the distance from the lines. The buildings can to some extent shield (or absorb) the electric fields generated by high-voltage lines nearby. The electromagnetic radiation intensity near high-voltage lines may be mitigated or intensified by the manner in which the high-voltage lines are set up, and it merits attention for the potential impact on human health.

Exposure to electromagnetic fields from laptop use of "laptop" computers

Portable computers are often used at tight contact with the body and therefore are called "laptop." The authors measured electromagnetic fields (EMFs) laptop computers produce and estimated the induced currents in the body, to assess the safety of laptop computers. The authors evaluated 5 commonly used laptop of different brands. They measured EMF exposure produced and, using validated computerized models, the authors exploited the data of one of the laptop computers (LTCs) to estimate the magnetic flux exposure of the user and of the fetus in the womb, when the laptop is used at close contact with the woman's womb. In the LTCs analyzed, EMF values (range 1.8-6 μT) are within International Commission on Non-Ionizing Radiation (NIR) Protection (ICNIRP) guidelines, but are considerably higher than the values recommended by 2 recent guidelines for computer monitors magnetic field emissions, MPR II (Swedish Board for Technical Accreditation) and TCO (Swedish Confederation of Professional Employees), and those considered risky for tumor development. When close to the body, the laptop induces currents that are within 34.2% to 49.8% ICNIRP recommendations, but not negligible, to the adult's body and to the fetus (in pregnant women). On the contrary, the power supply induces strong intracorporal electric current densities in the fetus and in the adult subject, which are respectively 182-263% and 71-483% higher than ICNIRP 98 basic restriction recommended to prevent adverse health effects. Laptop is paradoxically an improper site for the use of a LTC, which consequently should be renamed to not induce customers towards an improper use.

Comparative health risk assessment of electromagnetic fields

Comparative health risk assessment of electromagnetic fields (EMFs) has been performed in their entire frequency range from static fields until ionizing radiation. Due to considerable change of physical and biologic interaction and the nature of potential adverse health effects comparison was based on the carcinogenic potential of environmental EMF exposure levels. There was a need for sophisticated discrimination of levels of evidence as well as the available database. Conclusions were based on a synoptic view to results of different scientific approaches such as theoretical and biologic interaction modeling, evidence for accumulative effects, in vitro and in vivo investigations and epidemiologic studies. The comparative assessment revealed significant differences of objective results and public risk perception, and puts EMF risks into perspective. It highlights the necessity for individual's responsible behavior in terms of prudent avoidance. The comparison indicates where risk awareness might merit priority. This is not restricted to the UV range but includes also other exposures such as to nocturnal light or within infrared cabins.

Acute lymphoblastic leukemia and developmental biology: a crucial interrelationship

The latest scientific findings in the field of cancer research are redefining our understanding of the molecular and cellular basis of the disease, moving the emphasis toward the study of the mechanisms underlying the alteration of the normal processes of cellular differentiation. The concepts best exemplifying this new vision are those of cancer stem cells and tumoral reprogramming. The study of the biology of acute lymphoblastic leukemias (ALLs) has provided seminal experimental evidence supporting these new points of view. Furthermore, in the case of B cells, it has been shown that all the stages of their normal development show a tremendous degree of plasticity, allowing them to be reprogrammed to other cellular types, either normal or leukemic. Here we revise the most recent discoveries in the fields of B-cell developmental plasticity and B-ALL research and discuss their interrelationships and their implications for our understanding of the biology of the disease.

Childhood cancer and nuclear power plants in Switzerland: a census-based cohort study

BACKGROUND

Previous studies on childhood cancer and nuclear power plants (NPPs) produced conflicting results. We used a cohort approach to examine whether residence near NPPs was associated with leukaemia or any childhood cancer in Switzerland.

METHODS

We computed person-years at risk for children aged 0-15 years born in Switzerland from 1985 to 2009, based on the Swiss censuses 1990 and 2000 and identified cancer cases from the Swiss Childhood Cancer Registry. We geo-coded place of residence at birth and calculated incidence rate ratios (IRRs) with 95% confidence intervals (CIs) comparing the risk of cancer in children born <5 km, 5-10 km and 10-15 km from the nearest NPP with children born >15 km away, using Poisson regression models.

RESULTS

We included 2925 children diagnosed with cancer during 21 117 524 person-years of follow-up; 953 (32.6%) had leukaemia. Eight and 12 children diagnosed with leukaemia at ages 0-4 and 0-15 years, and 18 and 31 children diagnosed with any cancer were born <5 km from a NPP. Compared with children born >15 km away, the IRRs (95% CI) for leukaemia in 0-4 and 0-15 year olds were 1.20 (0.60-2.41) and 1.05 (0.60-1.86), respectively. For any cancer, corresponding IRRs were 0.97 (0.61-1.54) and 0.89 (0.63-1.27). There was no evidence of a dose-response relationship with distance (P > 0.30). Results were similar for residence at diagnosis and at birth, and when adjusted for potential confounders. Results from sensitivity analyses were consistent with main results.

CONCLUSIONS

This nationwide cohort study found little evidence of an association between residence near NPPs and the risk of leukaemia or any childhood cancer.

Exposure to extremely low-frequency magnetic fields and the risk of childhood cancer: update of the epidemiological evidence

There is an ongoing scientific controversy whether the observed association between exposure to residential extremely low-frequency magnetic fields (ELF-MF) and the risk of childhood leukaemia observed in epidemiological studies is causal or due to methodological shortcomings of those studies. Recent pooled analysis confirm results from previous studies, namely an approximately two-fold risk increase at ELF-MF exposures ≥0.4 μT, and demonstrate consistency of studies across countries, with different design, different methods of exposure assessment, and different systems of power transmission and distribution. On the other hand, recent pooled analyses for childhood brain tumour show little evidence for an association with ELF-MF, also at exposures ≥0.4 μT. Overall, the assessment that ELF-MF are a possible carcinogen and may cause childhood leukaemia remains valid. Ongoing research activities, mainly experimental and few new epidemiological studies, hopefully provide additional insight to bring clarity to a research area that has remained inconclusive.

Risk of childhood acute lymphoblastic leukaemia following parental occupational exposure to extremely low frequency electromagnetic fields

Background:

Earlier studies have reported moderate increases in the risk of acute lymphoblastic leukaemia (ALL) among children whose mothers have been occupationally exposed to extremely low frequency (ELF) electromagnetic fields. Other studies examining parental occupational exposure to ELF and ALL have reported mixed results.

Methods:

In an Australian case–control study of ALL in children aged <15 years, parents were asked about tasks they undertook in each job. Exposure variables were created for any occupational exposure before the birth of the child, in jobs 2 years before birth, in jobs 1 year before birth and up to 1 year after birth.

Results:

In all, 379 case and 854 control mothers and 328 case and 748 control fathers completed an occupational history. Exposure to ELF in all time periods was similar in case and control mothers. There was no difference in exposure between case and control fathers. There was no association between maternal (odds ratio (OR)=0.96; 95% CI=0.74–1.25) or paternal (OR=0.78; 95% CI=0.56–1.09) exposure to ELF any time before the birth and risk of childhood ALL.

Conclusion:

We did not find an increased risk of ALL in offspring of parents with occupational exposure to ELF.

Indoor environment and children's health: recent developments in chemical, biological, physical and social aspects

Much research is being carried out into indoor exposure to harmful agents. This review focused on the impact on children's health, taking a broad approach to the indoor environment and including chemical, microbial, physical and social aspects. Papers published from 2006 onwards were reviewed, with regards to scientific context. Most of publications dealt with chemical exposure. Apart from the ongoing issue of combustion by-products, most of these papers concerned semi volatile organic compounds (such as phthalates). These may be associated with neurotoxic, reprotoxic or respiratory effects and may, therefore, be of particular interest so far as children are concerned. In a lesser extent, volatile organic compounds (such as aldehydes) that have mainly respiratory effects are still studied. Assessing exposure to metals is still of concern, with increasing interest in bioaccessibility. Most of the papers on microbial exposure focused on respiratory tract infections, especially asthma linked to allergens and bio-aerosols. Physical exposure includes noise and electromagnetic fields, and articles dealt with the auditory and non auditory effects of noise. Articles on radiofrequency electromagnetic fields mainly concerned questions about non-thermal effects and papers on extremely low-frequency magnetic fields focused on the characterization of exposure. The impact of the indoor environment on children's health cannot be assessed merely by considering the effect of these different types of exposure: this review highlights new findings and also discusses the interactions between agents in indoor environments and also with social aspects.

Residential pesticides and childhood leukemia: a systematic review and meta-analysis

It is a systematic review and meta-analysis of previous observational epidemiologic studies examining the relationship between residential pesticide exposures during critical exposure time windows (preconception, pregnancy, and childhood) and childhood leukemia. Searches of Medline and other electronic databases were performed (1950-2009). Study selection, data abstraction, and quality assessment were performed by two independent reviewers. Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (Cis). Of the 17 identified studies, 15 were included in the meta-analysis. Exposures during pregnancy to unspecified residential pesticides insecticides, and herbicides were positively associated with childhood leukemia. Exposures during childhood to unspecified residential pesticides and insecticides were also positively associated with childhood leukemia, but there was no association with herbicides. Positive associations were observed between childhood leukemia and residential pesticide exposures. Further work is needed to confirm previous findings based on self-report, to examine potential exposure-response relationships, and to assess specific pesticides and toxicologically related subgroups of pesticides in more detail.

A precautionary public health protection strategy for the possible risk of childhood leukaemia from exposure to power frequency magnetic fields

Background

Epidemiological evidence showing a consistent association between the risk of childhood leukaemia and exposure to power frequency magnetic fields has been accumulating. This debate considers the additional precautionary intervention needed to manage this risk, when it exceeds the protection afforded by the exposure guidelines as recommended by the International Commission on Non-Ionizing Radiation Protection.

Methods

The Bradford-Hill Criteria are guidelines for evaluating the scientific evidence that low frequency magnetic fields cause childhood leukaemia. The criteria are used for assessing the strength of scientific evidence and here have been applied to considering the strength of evidence that exposures to extremely low frequency magnetic fields may increase the risk of childhood leukaemia. The applicability of precaution is considered using the risk management framework outlined in a European Commission (EC) communication on the Precautionary Principle. That communication advises that measures should be proportionate, non-discriminatory, consistent with similar measures already taken, based on an examination of the benefits and costs of action and inaction, and subject to review in the light of new scientific findings.

Results

The main evidence for a risk is an epidemiological association observed in several studies and meta-analyses; however, the number of highly exposed children is small and the association could be due to a combination of selection bias, confounding and chance. Corroborating experimental evidence is limited insofar as there is no clear indication of harm at the field levels implicated; however, the aetiology of childhood leukaemia is poorly understood. Taking a precautionary approach suggests that low-cost intervention to reduce exposure is appropriate. This assumes that if the risk is real, its impact is likely to be small. It also recognises the consequential cost of any major intervention. The recommendation is controversial in that other interpretations of the data are possible, and low-cost intervention may not fully alleviate the risk.

Conclusions

The debate shows how the EC risk management framework can be used to apply the Precautionary Principle to small and uncertain public health risks. However, despite the need for evidence-based policy making, many of the decisions remain value driven and therefore subjective.

A pooled analysis of extremely low-frequency magnetic fields and childhood brain tumors

Pooled analyses may provide etiologic insight about associations between exposure and disease. In contrast to childhood leukemia, no pooled analyses of childhood brain tumors and exposure to extremely low-frequency magnetic fields (ELF-MFs) have been conducted. The authors carried out a pooled analysis based on primary data (1960-2001) from 10 studies of ELF-MF exposure and childhood brain tumors to assess whether the combined results, adjusted for potential confounding, indicated an association. The odds ratios for childhood brain tumors in ELF-MF exposure categories of 0.1-<0.2 μT, 0.2-<0.4 μT, and ≥0.4 μT were 0.95 (95% confidence interval: 0.65, 1.41), 0.70 (95% CI: 0.40, 1.22), and 1.14 (95% CI: 0.61, 2.13), respectively, in comparison with exposure of <0.1 μT. Other analyses employing alternate cutpoints, further adjustment for confounders, exclusion of particular studies, stratification by type of measurement or type of residence, and a nonparametric estimate of the exposure-response relation did not reveal consistent evidence of increased childhood brain tumor risk associated with ELF-MF exposure. These results provide little evidence for an association between ELF-MF exposure and childhood brain tumors.