Power Frequency Electromagnetic Fields Research Articles

Effects of 0.5mT power frequency electromagnetic fields on delayed rectifier potassium channels in hippocampus CA3 pyramidal neurons

Objective To study the effects of 0.5mT power frequency electromagnetic fields on hippocampus CA3 pyramidal neurons. Methods Hippocampus CA3 pyramidal neurons of rats were prepared by acute isolation and then exposed to an electromagnetic fields, with frequency of 50 Hz and the intensity of 0.5 mT,for 30 minutes. The delayed rectifier potassium channel currents were recorded by whole-cell patch-clamp technique. Results The results showed that after 30 minutes exposure to the electromagnetic fields, the delayedrectifier potassium channel current density of the rats' hippocampus CA3 area pyramidal neurons decreased, with the maximum value of control group was(171.05±1.32) pA/pF, and that of the exposure group was(139.65±2.37)pA/pE(n=12, P<0.05). The half-activation potential of control group and that of exposure group were (7.44±0.64)mV and (34.09±6.48) mV(n=12, P<0.05), respectively and the slope factor were 11.36±0.57 and 19.97 ±3.45(n=12, P<0.05), respectively. APD90 extended from (14.63±0.34) ms to (21.74±1.47) ms (n=12, P<0.05). Conclusion It can be speculated that the electromagnetic fields can reduce the currents of delayed rectifier potassium,change the process of activation and increase the half activation potential. After exposure, the activation speed decreased, while the APD increases. Key words: Delayed rectifier potassium channel; Patch-clamp technique; Electromagnetic fields; Action potential; Neurons

Combined Exposure of Peripubertal Male Rats to the Endocrine-Disrupting Compound Atrazine and Power–Frequency Electromagnetic Fields Causes Degranulation of Cutaneous Mast Cells: A New Toxic Environmental Hazard?

The effects of single and combined treatments of the endocrine-disrupting compound atrazine and the power-frequency electromagnetic fields (EMFs) were investigated on cutaneous mast cells in juvenile/peripubertal male Wistar rats. Animals were divided into six groups: (1) 4 h/day exposure to EMFs (50 Hz), (2) 20 mg/kg of body weight (bw) of atrazine, (3) 200 mg/kg bw of atrazine, (4) EMFs with 20 mg/kg bw of atrazine, (5) EMFs with 200 mg/kg bw of atrazine, and (6) control. Both the atrazine and the combined treatments, but not the single EMF exposure, increased the number of degranulated mast cells. Statistically significant differences were demonstrated between the control and both of the combined treatments (p<0.01 and p<0.001, respectively). Additionally, low and high doses of atrazine combined with the EMFs were found significantly different when compared to the EMF group alone (both at p<0.001). Considering the biological importance of mast cells in cutaneous immune reactions, future studies should reveal whether combined exposures to chemical and physical environmental agents pose a serious health risk.

Cancer and the environment: Ten topics in environmental cancer epidemiology in Canada

This Chronic Diseases in Canada supplement is a compilation of literature reviews by scientific experts. It was initiated as follow-up to the Green Plan, the federal government's environmental agenda in the 1990s. In recognizing that Canadians are concerned about the environment and its relationship to their health, this document attempts to address some of these concerns in relation to cancer by reviewing and summarizing the epidemiological literature for ten environmental exposures, and highlighting future research needs. The topics include three types of radiation exposure (ultraviolet, radon and electromagnetic (powerfrequency electromagnetic fields)), three classes of chemical exposure (organochlorines, disinfection by-products, and pesticides), two types of air pollution (environmental tobacco smoke and outdoor air pollution), and two industrial sources (pulp and paper milling, and metal mining and processing). This publication is intended to provide a base of information for researchers interested in environmental cancer epidemiology and to assist with the formulation of research priorities. The ten topics reviewed here were selected because concern about them has been expressed or because they involve known animal carcinogens. Complete elimination of exposures to carcinogens in the environment, synthetic or natural, is not technically feasible if cancer can potentially occur at any level of exposure (i.e., the linear non-threshold theory). Consequently, it is important to have an operational concept of safety which is more practical than that of zero risk. Such an approach uses the concept of acceptable or essentially negligible risk to determine the exposure levels at which carcinogens are regulated. Acceptable risk has been defined as one that is "so small, whose consequences are so slight, or whose associated benefits (perceived or real) are so great that persons or groups in society are willing to take or be subjected to that risk". The level of risk where remedial action is recommended will vary according to the "agent or process being regulated, the economic and social costs and benefits and technology factors". In accordance with the system used by the International Agency for Research on Cancer (IARC) to assess the strength of the evidence for human carcinogenicity, the ten exposures reviewed here can be grouped into three broad categories, with some exposures occupying more than one and the first category-human carcinogens-should be subdivided. Tables 1-4 refer to these categories. For many of the exposures discussed here, ongoing etiological research awaits methods development, particularly in exposure assessment.

Visible Human Utilization to Render Induced Electric Field and Current Density Images Inside the Human

The external and internal exposure to power frequency electromagnetic field, generated by high-voltage power transmission lines, raises serious safety concerns. Since we cannot measure the induced electric fields and current densities inside the human body, we used the Visible Human (VH) to investigate the induced electric fields and currents in human body tissues and organs of a worker standing 2 m away from conductor phase C of a double-circuit 132 kV transmission line. The double circuit 132 kV 60 Hz transmission line has a power rating of 293 MVA and a maximum recorded peak load current of 603 A. Charge simulation method and the Biot-Savart law have been used for computation of external electric and magnetic fields. Finite-difference time-domain technique was used to calculate the organs' internal induced electric field and circulating current densities in more than 40 different tissues of the VH with 3 mm voxel size. The simulation indicates that, at 2 m away from a 132 kV transmission line, the computed external electric field is 6.485 kV/m and the external magnetic field is 66.4 muT, which are below the limits set by the IEEE standards for external exposure for live-line workers. The maximum induced electric fields in the brain and heart are 23 and 14 mV/m, respectively. These values are below the IEEE standard recommended limits of 53 mV/m for the brain and 943 mV/m for the heart. The VH data allowed us to obtain two- and three-dimensional images of the induced electric field and current density distribution in different organs, tissues, and cross-sections of the human body.

Reproducibility and desensitization of the power frequency magnetic field effect on movement of the common cutworm Spodoptera litura

AbstractAll creatures on Earth, including human beings, can be influenced by the power frequency electromagnetic field (EMF), even though the consequence and degree of the effect may vary due to regional context, species, etc. Most of the outstanding scientific achievements about the EMF effect on life have come from behavioral studies. In such studies, in contrast to the geomagnetic field or static magnetic field (MF), the oscillating MF has attracted far less attention so far. Following a previous report, to attain deep basic knowledge about the effect of an extremely low frequency (ELF) MF on animal behavior, we characterized the 60‐Hz MF‐responsive movement activity of common cutworm larvae using sophisticated experimental schemes. The MF‐exposed third instar larvae showed significantly reduced locomotive activity compared to the matching sham‐exposed larvae. Moreover, repeated MF exposure to the same larvae up to three times also showed similar behavioral responsiveness even though the extent of movement decrease was attenuated by the repetition time. These results suggest that sinusoidal power frequency MF could disrupt the normal locomotory activity of insect larvae, and the insects may show adaptive desensitization to the same MF.

Status quo of international power frequency electromagnetic field exposure limit

近几年,电磁场及其健康影响问题的环保投诉和纠纷是输变电工程,尤其是500 kV输变电工程的环境纠纷的首要问题.造成这种状况的主要原因是,截至目前,有关工频电场、磁场的暴露问题仍然没有国家标准的限制.经过近5年的分歧和争论后,2006年国家标准化管理委员会下达了 的制定计划,于2007年10月提交了标准的征求意见稿,但由于多种原因,导致此标准目前仍未发布。

EMFs and Childhood Leukemia

In their otherwise informative and concise review of the current state of evidence concerning risk factors for acute childhood leukemia, Belson et al. (2007) did not correctly address nonionizing radiation and, in particular, power frequency magnetic fields as a possible risk factor for childhood leukemia. This failure may be due to a widespread misconception about the evidence concerning nonionizing electromagnetic fields (EMFs) as a health hazard. It is also apparent in the Churchill County leukemia cluster study published in the same issue, in which Rubin et al. (2007) investigated a multitude of factors, many with sparse or ambiguous previous evidence of an association with childhood leukemia. Although power frequency magnetic fields have been classified as a possible human carcinogen (group 2B) by the International Agency for Research on Cancer (IARC 2002) and by a National Institute of Environmental Health Sciences (NIEHS) working group (NIEHS 1998), based on the evidence of an association with childhood leukemia, these were apparently not considered by Rubin et al. (2007). In their review of nonionizing radiation, Belson et al. (2007) inappropriately mixed original research and pooled analyses, further contributing to the prevailing confusion. Both Ahlbom et al. (2000) and Greenland et al. (2000) presented pooled analyses that included the important study of Linet et al. (1997). Hence, it is inappropriate to present results of the latter as an independent source. Almost all epidemiologic studies of residential exposure to power frequency magnetic fields published before 1999 are included in either the pooled analyses of Ahlbom et al. (2000) or Greenland et al. (2000). Only the study of Myers et al. (1990) was not included because authors refused to provide requested data. Although the study of Linet et al. (1997) is often cited as failing to support the hypothesis of an association between residential exposure to magnetic fields and childhood leukemia [it was also cited by Belson et al. (2007)], it actually was one of the most important supporters of an association in the pooled analyses and contributed the greatest number of highly exposed children. Two large and well-conducted studies published after the pooled analyses (Kabuto et al. 2006; Schuz et al. 2001) lend further support to the results of the pooled analyses of an increased risk from high average levels of magnetic field exposure. It is also incorrect to characterize the evidence as “some have found a small association … while others have not ….” First of all, the association is not small, but is comparable or larger than that for all other factors considered by Belson et al. (2007). Second, the evidence is consistent across different continents, study types, measurement methods, and other factors. Of course, there are potential sources of bias, in particular selection bias. However, thorough investigations of these potential biases have rendered it unlikely that they can completely explain the association. Up to now, there is no other risk factor of childhood leukemia that has been as comprehensively studied concerning possible biases and confounding factors. It is high time that exposure to power frequency EMFs is recognized as a potential risk factor for childhood leukemia and is properly included in the protocols of cluster studies and in epidemiologic studies of other risk factors as a potential confounder.

EMF effects on microcirculatory system

Authors review the importance of studying the effects of electromagnetic fields (EMF) on microcirculatory system, especially in respect of possibility that vasculature may have direct and indirect role in interaction of static magnetic fields (SMF). We outline the physiological importance of microcirculation and relatively new methods of evaluation technique in vivo and explain in details the local and/or whole body exposure effects of SMF with␣range of 0.3–180 mT, power frequency EMF with range of 0.1–30 mT and microwaves at 1.5 GHz with range 0.08–8 W/kg brain average specific absorption rate (SAR) on microcirculatory systems in different tissues in experimental animals.

Light and electron microscopic study of the thyroid gland in rats exposed to power-frequency electromagnetic fields

The effect of 50 Hz electromagnetic field (EMF) on thyroid gland was studied using light and transmission electron microscopes. Two-month-old male rats were exposed to an EMF (100-300 microT, 54-160 V m(-1)) for 4 h a day, 5 days a week for 1 month. A predominance of microfollicles with less colloid content and dilated blood capillaries was found in the EMF group. Stereological counting showed a statistically significant increase of the volume density of follicular epithelium, interfollicular tissue and blood capillaries as well as the thyroid activation index, as compared to the controls. The volume density of colloid significantly decreased. Ultrastructural analysis of thyroid follicular cells in the EMF group revealed the frequent finding of several colloid droplets within the same thyrocyte with the occasional presence of large-diameter droplets. Alterations in lysosomes, granular endoplasmic reticulum and cell nuclei compared to the control group were also observed. Taken together, the results of this study show the stimulative effect of power-frequency EMF on thyroid gland at both the light microscope and the ultrastructural level.

Electromagnetic Fields and Female Breast Cancer

The possibility that long term exposure to relatively weak power frequency electromagnetic fields (EMF) could increase the risk of breast cancer has been investigated during the past decade. The hypothesis is based on the assumption that magnetic field exposures suppress melatonin production and that melatonin is protective against breast cancer. Most epidemiological studies have indicated little or no overall effect of EMF exposure, but some early studies suggested effects among premenopausal women, particularly for estrogen receptor positive breast tumors. The early studies were often limited by small numbers, crude exposure information and lack of information on confounding factors. In more recent occupational studies, again no overall risk increases were reported, but some studies found increased risks in certain subgroups, although with no consistent pattern across studies. A recent very large occupational study with improved exposure assessment and enough statistical power also for subgroup analyses found no indications of increased risks in any subgroups. Most of the recent well-designed residential studies report no increased risks, and similar findings are reported in the majority of studies of bed heating devices. Overall, the weight of the evidence available today does not suggest an increased risk of breast cancer related to EMF exposure.

Effects of Power Frequency Electromagnetic Fields on Growth of Germinating Vicia faba L., the Broad Bean

Experimental investigations were carried out to evaluate the effect of continuous and delayed exposure of power frequency electromagnetic fields at 5, 50 and 100 μT on germinating Vicia faba seedlings as a model system. These studies included physical parameters (length and girth of primary roots, number as well as length of lateral roots and imbibition), major biochemical constituents (total sugar, protein, and fat) and activities of important housekeeping enzymes (amylases, proteases, and lipase) at 2, 4, and 8 days of growth. Also, mitotic index and rate of DNA synthesis were studied at day 8 of growth. There was no significant change in physical parameters and major biochemical constituents between control and experimental groups. Also, the comparison between the control and experimental group of seeds showed that α-amylase activity significantly decreased at 5, 50 and 100 μT on day 2 and 4 of growth. β-amylase and protease (37○C & 50○C) showed a significant decrease in activity on day 2 and 4 of growth at 100 μT, whereas activity of lipase significantly decreased only on day 2 of growth at 100 μT. At day 8 of growth, all enzyme activities reverted back to the same as control. Also, there was a significant increase in mitotic index as well as 3H-thymidine uptake at 100 μT delayed exposure on day 8. The present study suggests that exposure to power frequency electromagnetic fields up to 100 μT on germinating seedlings does not cause any permanent damage since the initial alteration under the magnetic fields in some important housekeeping enzymes involved in the onset of seed germination were returened to control values on day 8 of growth. Also, the growth of the germinated seedlings was found to be enhanced by the application of power frequency magnetic fields (100 μT) as evidenced by mitotic index and 3H-thymidine uptake.

Histological characteristics of cutaneous and thyroid mast cell populations in male rats exposed to power-frequency electromagnetic fields

Purpose:The objective of this study was to determine whether mast cells (MC) in skin and thyroid gland, cutaneous nerve fibers and eosinophils are sensitive to the influence of electromagnetic fields (EMF).Materials and methods:The experiment was performed on two-month-old Wistar male rats, exposed to 50 Hz EMF (100 – 300 μT, 54 – 160 V/m) for 4 h a day, seven days a week during one month. After sacrifice, samples of skin and thyroid were processed for toluidine blue staining or indirect immunohistochemistry. The M42 grid placed in the ocular of a light microscope and a special microscopic frame placed in the ocular of a fluorescence microscope were used for stereological analysis.Results:The numerical and volume density of intact type A MC in the thyroid of the exposed group was significantly higher compared to the control. A number of MC and immunoreactive nerve fibers were observed in the skin and of histamine-immunoreactive MC in the thyroid of exposed animals. The differences in stereological data were not statistically significant by the Mann-Whitney test.Conclusions:The results indicate certain alterations of cutaneous and thyroid MC in rats exposed to EMF. However, the possible outcome of changes in the MC population under EMF influence on morphophysiological properties of other structures in skin and thyroid requires further investigation.

Effect of 50 Hz electromagnetic fields on the induction of heat-shock protein gene expression in human leukocytes.

Although evidence is controversial, exposure to environmental power-frequency magnetic fields is of public concern. Cells respond to some abnormal physiological conditions by producing cytoprotective heat-shock (or stress) proteins. In this study, we determined whether exposure to power-frequency magnetic fields in the range 0-100 microT rms either alone or concomitant with mild heating induced heat-shock protein gene expression in human leukocytes, and we compared this response to that induced by heat alone. Samples of human peripheral blood were simultaneously exposed to a range of magnetic-field amplitudes using a regimen that was designed to allow field effects to be distinguished from possible artifacts due to the position of the samples in the exposure system. Power-frequency magnetic-field exposure for 4 h at 37 degrees C had no detectable effect on expression of the genes encoding HSP27, HSP70A or HSP70B, as determined using reverse transcriptase-PCR, whereas 2 h at 42 degrees C elicited 10-, 5- and 12-fold increases, respectively, in the expression of these genes. Gene expression in cells exposed to power-frequency magnetic fields at 40 degrees C was not increased compared to cells incubated at 40 degrees C without field exposure. These findings and the extant literature suggest that power-frequency electromagnetic fields are not a universal stressor, in contrast to physical agents such as heat.

Biological effects of power frequency magnetic fields: Neurochemical and toxicological changes in developing chick embryos

BackgroundThere are several reports that indicate a linkage between exposure to power frequency (50 – 60 Hz) magnetic fields with abnormalities in the early embryonic development of the chicken. The present study was designed to understand whether power frequency electromagnetic fields could act as an environmental insult and invoke any neurochemical or toxicological changes in developing chick embryo model.MethodsFertilized chicken eggs were subjected to continuous exposure to magnetic fields (50 Hz) of varying intensities (5, 50 or 100 μT) for a period of up to 15 days. The embryos were taken out of the eggs on day 5, day 10 and day 15. Neurochemical (norepinephrine and 5-hydroxytryptamine) and amino acid (tyrosine, glutamine and tryptophan) contents were measured, along with an assay of the enzyme glutamine synthetase in the brain. Preliminary toxicological investigations were carried out based on aminotransferases (AST and ALT) and lactate dehydrogenase activities in the whole embryo as well as in the liver.ResultsThe study revealed that there was a significant increase (p < 0.01 and p < 0.001) in the level of norepinephrine accompanied by a significant decrease (p < 0.01 and p < 0.001) in the tyrosine content in the brain on day 15 following exposure to 5, 50 and 100 μT magnetic fields. There was a significant increase (p < 0.001) in glutamine synthetase activity resulting in the significantly enhanced (p < 0.001) level of glutamine in the brain on day 15 (for 100 μT only). The possible mechanisms for these alterations are discussed. Further, magnetic fields had no effect on the levels of tryptophan and 5-hydroxytryptamine in the brain. Similarly, there was no effect on the activity of either aminotransferases or lactate dehydrogenase in the whole embryo or liver due to magnetic field exposure.ConclusionsBased on these studies we conclude that magnetic field-induced changes in norepinephrine levels might help explain alterations in the circadian rhythm, observed during magnetic field stress. Also, the enhanced level of glutamine can act as a contributing factor for developmental abnormalities.

Association between occupational exposure to power frequency electromagnetic fields and amyotrophic lateral sclerosis: a review.

For the past two decades, there has been concern over electromagnetic exposure and human health. While most research has focused on cancer and reproductive outcomes, there is interest in the relationship between electromagnetic fields (EMF) and neurodegenerative diseases. We review epidemiological findings and evidence regarding the association between occupational exposure to power frequency EMFs and amyotrophic lateral sclerosis (ALS). Medline was searched for citations related to occupational hazards and ALS, literature reviews and epidemiological evaluations. Nine out of the ten epidemiological studies that have been conducted on the risk of ALS in relation to occupational exposure to EMF show moderate to strong relative risk estimates that supported a link between them. Although data from these studies was consistent, the causal inference to a link between EMF exposure and ALS is restricted mainly due to the lack of direct information on EMF exposure and incomplete consideration of the other potential risk factors for ALS at workplaces. For instance, electric shock, in particular, is more common in electrical occupations than in any other occupations. This review concludes that further studies should consider investigating the separate effect of EMF exposure and electrical shocks to make more specific interpretations. On-site measurements of EMF should be conducted to include information on EMF exposure from residences as well as workplaces to improve exposure assessment.

Epidemiology of primary brain tumors: Current concepts and review of the literature

The purpose of this review is to provide a sufficiently detailed perspective on epidemiologic studies of primary brain tumors to encourage multidisciplinary etiologic and prognostic studies among surgeons, neuro-oncologists, epidemiologists, and molecular scientists. Molecular tumor markers that predict survival and treatment response are being identified with hope of even greater gains in this area from emerging array technologies. Regarding risk factors, studies of inherited susceptibility and constitutive polymorphisms in genes pertinent to carcinogenesis (for example, DNA repair and detoxification genes and mutagen sensitivity) have revealed provocative findings. Inverse associations of the history of allergies with glioma risk observed in 3 large studies and reports of inverse associations of glioma with common infections suggest a possible role of immune factors in glioma genesis or progression. Studies continue to suggest that brain tumors might result from workplace, dietary, and other personal and residential exposures, but studies of cell phone use and power frequency electromagnetic fields have found little to support a causal connection with brain tumors; caveats remain. The only proven causes of brain tumors (that is, rare hereditary syndromes, therapeutic radiation, and immune suppression giving rise to brain lymphomas) account for a small proportion of cases. Progress in understanding primary brain tumors might result from studies of well-defined histologic and molecular tumor types incorporating assessment of potentially relevant information on subject susceptibility and environmental and noninherited endogenous factors (viruses, radiation, and carcinogenic or protective chemical exposures through diet, workplace, oxidative metabolism, or other sources). Such studies will require the cooperation of researchers from many disciplines.

Aneuploidy in Workers Occupationally Exposed to Electromagnetic Field Detected by FISH.

Summary Exposure to power frequency electromagnetic fields (EMF) may cause adverse health effects in humans. Some epidemiological studies support an association between exposure to EMF and the incidence of different types of cancer, which may be associated with the presence of chromo-somal aneuploidy. In this study, fluorescence in situ hybridization (FISH) was used to detect numeri-cal chromosomal aberrations induced by occupational exposure to EMF. The labeled probes used in this study were repetitive a-satellite probes for chromosomes 7, 12, 17 and heterochromatic region of the Y chromosome. This study was conducted using 23 male individuals, 18 of which are occupa-tionally exposed to EMF whereas the other 5 individuals are used as controls. Our study shows monosomy of chromosomes 7 and 17 in 4 and 3 exposed individuals, respectively. The mean per-centages of nuclei with monosomy of chromosomes 7 and 17 in these affected individuals are 18.3% and 16.1%, respectively. The loss of Y chromosome was detected in 6 exposed individuals and the mean percentage of nuclei showing this aberration is 15.8%. In control individuals, the mean per-centages of nuclei with monosomy of chromosomes 7, 17 and loss of the Y chromosome were 3.2%, 3.7% and 4.5%, respectively. The increase in monosomy of chromosomes 7 and 17 and the loss of Y chromosome compared to the control is statistically significant (P<0.001). No significant increase in numerical aberrations of chromosome 12 was observed in exposed individuals. Key words EMF exposure, Aneuploidy, FISH.

Nonlinear response of the immune system to power-frequency magnetic fields.

Studies of the effects of power-frequency electromagnetic fields (EMFs) on the immune and other body systems produced positive and negative results, and this pattern was usually interpreted to indicate the absence of real effects. However, if the biological effects of EMFs were governed by nonlinear laws, deterministic responses to fields could occur that were both real and inconsistent, thereby leading to both types of results. The hypothesis of real inconsistent effects due to EMFs was tested by exposing mice to 1 G, 60 Hz for 1-105 days and observing the effect on 20 immune parameters, using flow cytometry and functional assays. The data were evaluated by means of a novel statistical procedure that avoided averaging away oppositely directed changes in different animals, which we perceived to be the problem in some of the earlier EMF studies. The reliability of the procedure was shown using appropriate controls. In three independent experiments involving exposure for 21 or more days, the field altered lymphoid phenotype even though the changes in individual immune parameters were inconsistent. When the data were evaluated using traditional linear statistical methods, no significant difference in any immune parameter was found. We were able to mimic the results by sampling from known chaotic systems, suggesting that deterministic chaos could explain the effect of fields on the immune system. We conclude that exposure to power-frequency fields produced changes in the immune system that were both real and inconsistent.

Power-frequency electromagnetic fields and the capacitative calcium entry system in SV40-transformed Swiss 3T3 cells.

The present study was designed to test the hypothesis that a 60 Hz electromagnetic field could affect the influx of calcium ions across the plasma membrane through the so-called capacitative calcium entry system. Recordings of cytosolic calcium-ion concentrations in SV40-transformed Swiss 3T3 cells were obtained in real time during exposure to magnetic fields ranging from 0.3-50 mT or to sham conditions using the calcium-sensitive photoprotein aequorin. This was done for cell populations whose capacitative entry system was activated by either bradykinin or thapsigargin under a variety of experimental conditions. No effects of the magnetic field were observed on bradykinin-induced calcium transients and, with the exception of a small but statistically significant increase observed in experiments performed at 50 mT, no effects of the fields were observed on baseline calcium levels prior to or after such transients. The magnetic fields also had no effects on the size or kinetics of any of the thapsigargin-induced calcium transients. Overall, the data fail to support the hypothesis tested in this work.

Exposure to power-frequency magnetic fields and the risk of childhood cancer

<h2>Summary</h2><h3>Background</h3> Previous studies have suggested an association between exposure to power-frequency electromagnetic fields (EMF) and the development of childhood malignant disease, especially leukaemia and tumours of the central nervous system. We investigated the relation between all childhood cancer and exposure to power-frequency magnetic fields. <h3>Methods</h3> The UK Childhood Cancer Study was a population case-control study covering the whole of England, Wales, and Scotland. All children with a confirmed malignant disorder were potentially eligible. For each case, we matched two controls on date of birth and sex, randomly chosen from the list of the Family Health Services Authority in England and Wales or Health Board in Scotland. In the main study, 3838 cases and 7629 controls were interviewed. The EMF part of the study included only one control per case, and household EMF measurements and school measurements where relevant were taken on 2226 matched pairs. These measurements, adjusted for historical line load and appliance fields, were used to estimate average exposure in the year before the date of diagnosis, or an equivalent date for controls. Analyses were by conditional logistic regression, incorporating a census-derived deprivation index used as a measure of socioeconomic status. <h3>Findings</h3> For children with mean exposures of more than 0·2 μT compared with children with mean exposures of less than 0·1 μT, the adjusted odds ratios were 0·92 (95% CI 0·47–1·79) for acute lymphoblastic leukaemia, 0·90 (0·49–1·63) for all leukaemia, 0·46 (0·11–1·86) for central-nervous-system tumours, 0·97 (0·46–2·05) for other malignant disease, and 0·87 (0·56–1·35) for all malignant disease combined. Higher exposures (>0·4 μT) were recorded for only 17 (<0·4%) individuals (eight cases, nine controls). <h3>Interpretation</h3> This study provides no evidence that exposure to magnetic fields associated with the electricity supply in the UK increases risks for childhood leukaemia, cancers of the central nervous system, or any other childhood cancer.