Residential Magnetic Fields Research Articles

Residential extremely low frequency magnetic fields and skin cancer

ObjectivePhotoinduced radical reactions have a fundamental role in skin cancer induced by ultraviolet radiation, and changes in radical reactions have also been proposed as a mechanism for the putative carcinogenic...

Residential exposure to electromagnetic fields and risk of amyotrophic lateral sclerosis: a dose\u2013response meta-analysis

Amyotrophic lateral sclerosis (ALS) is neurodegenerative disease characterized by a fatal prognosis and still unknown etiology. Some environmental risk factors have been suggested, including exposure to magnetic fields. Studies have suggested positive associations in occupationally-exposed populations, but the link with residential exposure is still debated as is the shape of such relation. Due to recent availability of advanced biostatistical tools for dose–response meta-analysis, we carried out a systematic review in order to assess the dose–response association between ALS and residential exposure to magnetic fields. We performed an online literature searching through April 30, 2021. Studies were included if they assessed residential exposure to electromagnetic fields, based either on distance from overhead power lines or on magnetic field modelling techniques, and if they reported risk estimates for ALS. We identified six eligible studies, four using distance-based and one modelling-based exposure assessment, and one both methods. Both distance-based and particularly modelling-based exposure estimates appeared to be associated with a decreased ALS risk in the highest exposure category, although estimates were very imprecise (summary RRs 0.87, 95% CI 0.63–1.20, and 0.27, 95% CI 0.05–1.36). Dose–response meta-analysis also showed little association between distance from power lines and ALS, with no evidence of any threshold. Overall, we found scant evidence of a positive association between residential magnetic fields exposure and ALS, although the available data were too limited to conduct a dose–response analysis for the modelled magnetic field estimates or to perform stratified analyses.

Exposure to Magnetic Fields and Childhood Leukemia: An Overview of Meta-Analysis

Background: Leukemia is the most common cancer in children. We aimed to evaluate the association between exposure to magnetic fields and childhood leukemia. Materials and Methods: In this overview,the relevant articles evaluating the association between exposure to magnetic fields and childhood leukemia are screened on the electronic databases of Scopus, EMBASE, Cochrane, Web of Science, and Medline until February 10, 2019. Results: The first meta-analysis showed a statistical association between the magnetic field intensity of ≥0.4 μT and ≥0.2 μT and childhood leukemia. The second meta-analysis based on wiring configuration codes resulted in a pooled relative risk estimate of 1.46 (95% CI=1.05-2.04 μT, P=0.024) and 1.59 (95% CI=1.14-2.22 μT, P=0.006) for exposure to 24-h measurements of magnetic fields, indicating a potential effect of residential magnetic field exposure on childhood leukemia. In the third meta-analysis, the odds ratios of exposure categories of 0.1-0.2 μT, 0.2-0.3 μT, and ≥0.3 μT over Conclusion: Three meta-analyses showed a statistical association between magnetic field intensity and childhood leukemia (ranged 0.1-2.36 μT). The results of one study also showed that there was no relationship between exposure to ≥ 0.1 μT and childhood leukemia.

Measurement and analysis of power-frequency magnetic fields in residences: Results from a pilot study

AimExtremely low-frequency magnetic fields (ELF-MFs) are emitted by electrical household appliances, wiring, meter boxes, conductive plumbing, power lines and transformers. Some of the studies investigating the link between ELF-MFs and health problems have not adequately characterized the magnetic field exposure of subjects, as they did not always measure residential magnetic fields or measure in locations where residents are most exposed. Considering this, there is a need for good quality assessments of residential ELF-MFs in different geographical regions to collect general public exposure data and to identify high sources of magnetic fields. Such studies have the potential to add significant scientific knowledge about residential exposure and appropriate precautions to reduce exposure, improve the quality of life and substantially reduce health care costs. Subject and methodsIn this work, we analyzed the ELF-MFs from 3163 datasets collected from 100 houses in Australia. Measurements were carried out in different geographical locations and were assessed for compliance with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) Guidelines. Then we compared our measurements with another twenty-three peer-reviewed studies, published 1987–2015, reporting magnetic field measurements in residences. ResultsThe observed average (geometric mean) magnetic field values were; bed 0.85, bedroom 1.39 mG, baby cot 0.39 mG, children’s play area 0.47 mG, and family room 0.30 mG. Our results show considerable variation in the fields to which residents are typically exposed, particularly in beds (21.83%) and bedrooms (33.33%) where the percentage of measurements greater than 4 mG was considerable. Some emissions exceeded the general public exposure levels of the ICNIRP Guidelines, with the potential for residents to be exposed above these levels. However, away from electrical appliances, the average field in all rooms was 0.30–1.39 mG. We show that simple precautions can be applied to reduce exposure to ELF-MFs in residences and thereby minimize potential risks to health and wellbeing. ConclusionOur investigation provides a new data collection model for future surveys, which could be conducted with larger samples to verify our observations. Additionally, this data could be useful as a reference for researchers and those members of the general public who do not have access to the necessary measuring equipment.

Residential magnetic fields exposure and childhood leukemia: a population-based case-control study in California.

Studies have reported an increased risk of childhood leukemia associated with exposure to magnetic fields. We conducted a large records-based case-control study of childhood leukemia risk and exposure to magnetic fields from power lines in California. The study included 5,788 childhood leukemia cases (born in and diagnosed in California 1986-2008) matched to population-based controls on age and sex. We calculated magnetic fields at birth addresses using geographic information systems, aerial imagery, historical information on load and phasing, and site visits. Based on unconditional logistic regression controlling for age, sex, race/ethnicity, and socioeconomic status using subjects geocoded to a basic standard of accuracy, we report a slight risk deficit in two intermediate exposure groups and a small excess risk in the highest exposure group (odds ratio of 1.50 (95% confidence interval [0.70, 3.23])). Subgroup and sensitivity analyses as well as matched analyses gave similar results. All estimates had wide confidence intervals. Our large, statewide, record-based case-control study of childhood leukemia in California does not in itself provide clear evidence of risk associated with greater exposure to magnetic fields from power lines, but could be viewed as consistent with previous findings of increased risk.

Survey of residential power-frequency magnetic fields in Melbourne, Australia.

Pooled analyses of epidemiological studies have reported an association between prolonged residential exposure to power-frequency magnetic fields of >0.4 μT and an increased risk in childhood leukaemia. In order to compare residential magnetic fields in Australia with those in other countries, a survey was conducted in 296 randomly selected homes in Melbourne. Magnetic fields were assessed by performing spot measurements throughout the house and 24-h measurements in rooms where children spend large amounts of time. Children's exposure in Australia was generally comparable with that in other countries with average fields of 0.05-0.06 μT (95 % CI 0.05-0.06 μT). Prolonged exposure of >0.4 μT was shown in ∼2 % of the homes (95 % CI 0.2-3.6 %) mainly being due to close proximity of the house to transmission lines. Based on the results of this survey, the public health impact of a causal association between residential magnetic fields and childhood leukaemia is expected to be small.

Assessment of bias in a survey of residential magnetic fields in Melbourne, Australia.

An important consideration in surveys of residential magnetic fields is whether the sample of homes measured is representative of the population. This study assessed the potential bias in a survey of magnetic fields conducted in 296 homes randomly selected from the telephone directory in Melbourne. The choice of the telephone directory as the sampling frame introduced some bias when compared with census information. There was also evident self-selection bias with residents twice as likely to participate if they lived in the vicinity of visible electrical infrastructure such as transmission lines. However, when corrected for bias the corrected magnetic fields were only slightly lower than the measurements with a percentage difference in the range of 2.8-6.0 %. These results provide confidence that the measurements in the survey were good estimates of the distribution of residential magnetic fields in Melbourne.

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

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

Adult Cancers Near High-voltage Overhead Power Lines

Extremely low-frequency magnetic fields are designated as possibly carcinogenic in humans, based on an epidemiologic association with childhood leukemia. Evidence for associations with adult cancers is weaker and inconsistent. We conducted a case-control study to investigate risks of adult cancers in relation to distance and extremely low-frequency magnetic fields from high-voltage overhead power lines using National Cancer Registry Data in England and Wales, 1974-2008. The study included 7823 leukemia, 6781 brain/central nervous system cancers, 9153 malignant melanoma, 29,202 female breast cancer cases, and 79,507 controls frequency-matched on year and region (three controls per case except for female breast cancer, one control per case) 15-74 years of age living within 1000 m of a high-voltage overhead power line. There were no clear patterns of excess risk with distance from power lines. After adjustment for confounders (age, sex [except breast cancer], deprivation, rurality), for distances closest to the power lines (0-49 m) compared with distances 600-1000 m, odds ratios (ORs) ranged from 0.82 (95% confidence interval = 0.61-1.11; 66 cases) for malignant melanoma to 1.22 (0.88-1.69) for brain/central nervous system cancer. We observed no meaningful excess risks and no trends of risk with magnetic field strength for the four cancers examined. In adjusted analyses at the highest estimated field strength, ≥1000 nanotesla (nT), compared with <100 nT, ORs ranged from 0.68 (0.39-1.17) for malignant melanoma to 1.08 (0.77-1.51) for female breast cancer. Our results do not support an epidemiologic association of adult cancers with residential magnetic fields in proximity to high-voltage overhead power lines.

The Relationship between Residential Magnetic Fields and Contact Voltage: A Pooled Analysis

It has been suggested that residential exposure to contact currents may be more directly associated with the potential for an increased risk of leukemia in childhood than magnetic fields. Contact current exposure occurs when a child contacts a bathtub's water fixtures, which are usually contiguous with a residence's electrical ground, and when the drainpipe is conductive. The Northern California Childhood Leukemia Study (NCCLS) is the only epidemiological study known to address whether contact current may confound the reported association between residential magnetic fields and childhood leukemia. The study contributed contact voltage and magnetic-field data for over 500 residences of leukemia cases and control children. We combined these data with the results of previous measurement studies of contact voltage in other communities to conduct an analysis of the relationship of magnetic fields with contact voltage for a total sample of 702 residences. The Spearman correlation of magnetic field with contact voltage was 0.29 (Spearman, P < 0.0001). Magnetic-field and contact voltage data were both divided into tertiles, with an upper magnetic-field cutpoint of 0.3 μT suggested by values used in epidemiological results and an upper contact voltage cutpoint of 60 mV based on dosimetric considerations. Expressed as an exposure odds ratios (EOR), we report an association of contact voltage with magnetic fields of 15.1 (95% CI 3.6-61) as well as a statistically significant positive trend across magnetic-field strata (EOR of 4.2 per stratum with 95% CI 2.4-7.4). The associations appear to be large enough to support the possibility that contact current could be responsible for the association of childhood leukemia with magnetic fields.

Pooled analysis of recent studies on magnetic fields and childhood leukaemia

Background:Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.Methods:Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences.Results:In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1–0.2 μT, 0.2–0.3 μT and ⩾0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81–1.41), 1.16 (0.69–1.93) and 1.44 (0.88–2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.Conclusions:Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.

Evaluation of Continuous Exposure to Magnetic Field From AC Overhead Transmission Lines Via Historical Load Databases: Common Procedures and Innovative Heuristic Formulas

Public concern about electromagnetic fields from power systems calls for a proper evaluation of continuous exposure of the population to power frequency magnetic fields, especially those from overhead transmission lines, felt as impacting human activities and the environment. Sophisticated measuring and computing tools now available for continuous exposure evaluation may be ineffective without a sound knowledge of power system theory and of typical line loads. In this perspective, the paper firstly recalls the fundamentals of power line magnetic field calculation and shows that a proper use of historical load databases is essential for associating residential magnetic fields with load diagrams of the lines. Then, innovative heuristic formulas for ac double-circuit overhead transmission lines with independent circuits are proposed, so that line databases can be used accounting for phase-shift effects between line currents in an easier and faster way. Such formulas provide a good approximation, via one single fixed-load calculation, of the median/mean magnetic field over a reference operational period of the line (e.g., one year) and are successfully applied to an existing line, resorting to a historical load database of the line recorded from 1994 to 2001.

Electric and magnetic fields at power frequencies

Exposures to electric and magnetic fields are among the most ubiquitous exposures that the Canadian population experiences. Sources of electric and magnetic field exposures may be occupational or residential and include proximity to certain types of electrical equipment, transmission and distribution power lines as well as appliance use. The early studies of children tended toward a consistent association between risks for leukemia and brain cancer and residential proximity to power lines having high wire configuration. More recent studies-and studies which have attempted to improve upon the measurement of exposure by using calculated fields, point-in-time or personal monitoring-have been inconsistent, with some suggesting increased risk and others not. Occupational exposures have suggested an increase in risk for leukemia, and to a lesser extent brain cancer and Non-Hodgkin lymphoma. However, studies of residential exposures and cancer in adults generally have suggested no effect. Laboratory work has been unable to demonstrate a biological mechanism which might explain the epidemiological findings. In spite of extensive efforts over the past 20 years and many expert reviews, it has been difficult to reach consensus regarding the carcinogenic effects of electric and magnetic fields. Exposure assessment has proven to be complex, and agreement on the relevant exposure metric has not yet been obtained. There is justification to question whether point-in-time measures in homes are appropriate indices of the relevant etiological exposure, as they fail to account for changes over time, peak exposures or time-varying fields. Nevertheless, it is probably desirable to err on the side of caution in not placing too much weight on the inconsistencies. The IARC has classified EMF as a "possible carcinogen" which refers to the circumstances where there is limited evidence of carcinogenicity in humans and inadequate evidence in experimental animals. The IARC review indicated limited evidence for the carcinogenicity of extremely low-frequency magnetic fields in relation to childhood leukemia at high level exposure in the residential environment (average residential magnetic field strength >0.4 μT). Even higher levels of exposure in the occupational environment may increase the risk of leukemia in adults.

Residential Magnetic Fields and Measures of Neutral-to-Earth Voltage: Variability Within and Between Residences

The objectives of this study were to characterize temporal patterns of magnetic fields (Bavg) and two measures of neutral-to-earth voltage: the voltage between the water line and earth (VW-E), and the voltage between bathtub plumbing fixtures and the drain (Vbath). The latter is a source of exposure to contact current in bathing children that has been proposed to explain the reported association between power-frequency magnetic fields and childhood leukemia. These quantities were measured each minute in a sample of 15 single-detached residences in San Jose, CA. Generally, Bavg, VW-E, and Vbath were positively correlated with each other within residences, and displayed similar diurnal patterns. Weekday and weekend patterns displayed qualitative differences that reflect the more scheduled workday for weekdays, and a less structured pattern for weekends. When pooled with two prior measurement studies, positive associations across residences between Bavg and both VW-E and Vbath were observed. Home designs over the past 30-40 years have lead to a decreasing prevalence of Vbath as conductive drains have been swapped out for non-conductive materials. Nonetheless, the observed relationships within and across residences indicate that contact current has the characteristics of a factor that could explain the association of magnetic fields with childhood leukemia.

Morbidity Experience in Populations Residentially Exposed to 50 Hz Magnetic Fields: Methodology and Preliminary Findings of a Cohort Study

A morbidity study of the population of a district of Rome built in part under a 60 kV electric distribution line, included 345 subjects resident in the study area in any period between 1954 and 2003, excluding those deceased before 1998. Residential magnetic field levels were estimated based on current load, line characteristics, and distance of the dwellings from the power line, and the study area was divided into sub-areas with differing magnetic field levels. Standardized morbidity ratios were computed from hospital discharge records dated 1998-2003. Non statistically significant increases were observed for all and primary cancers; primary cancers were significantly increased among subjects with > 30 years' residence and latency. A significant increase for all, primary, and secondary cancers, and a two-fold increase for ischaemic diseases, was observed in subjects in the sub-area with the highest exposure. No increase was seen in neoplastic haematological diseases.

Morbidity Experience in Populations Residentially Exposed to 50 Hz Magnetic Fields: Methodology and Preliminary Findings of a Cohort Study

A morbidity study of the population of a district of Rome built in part under a 60 kV electric distribution line, included 345 subjects resident in the study area in any period between 1954 and 2003, excluding those deceased before 1998. Residential magnetic field levels were estimated based on current load, line characteristics, and distance of the dwellings from the power line, and the study area was divided into sub-areas with differing magnetic field levels. Standardized morbidity ratios were computed from hospital discharge records dated 1998–2003. Non statistically significant increases were observed for all and primary cancers; primary cancers were significantly increased among subjects with >30 years' residence and latency. A significant increase for all, primary, and secondary cancers, and a two-fold increase for ischaemic diseases, was observed in subjects in the sub-area with the highest exposure. No increase was seen in neoplastic haematological diseases.

Power frequency magnetic fields and risk of childhood leukaemia: Misclassification of exposure from the use of the ‘distance from power line’ exposure surrogate

A recent study examining the relationship between distance to nearby power lines and childhood cancer risk re-opened the debate about which exposure metrics are appropriate for power frequency magnetic field investigations. Using data from two large population-based UK and German studies we demonstrate that distance to power lines is a comparatively poor predictor of measured residential magnetic fields. Even at proximities of 50 m or less, the positive predictive value of having a household measurement over 0.2 microT was only 19.4%. Clearly using distance from power lines, without taking account of other variables such as load, results in a poor proxy of residential magnetic field exposure. We conclude that such high levels of exposure misclassification render the findings from studies that rely on distance alone uninterpretable.

Residence Near Power Lines and Mortality From Neurodegenerative Diseases: Longitudinal Study of the Swiss Population

The relation between residential magnetic field exposure from power lines and mortality from neurodegenerative conditions was analyzed among 4.7 million persons of the Swiss National Cohort (linking mortality and census data), covering the period 2000-2005. Cox proportional hazard models were used to analyze the relation of living in the proximity of 220-380 kV power lines and the risk of death from neurodegenerative diseases, with adjustment for a range of potential confounders. Overall, the adjusted hazard ratio for Alzheimer's disease in persons living within 50 m of a 220-380 kV power line was 1.24 (95% confidence interval (CI): 0.80, 1.92) compared with persons who lived at a distance of 600 m or more. There was a dose-response relation with respect to years of residence in the immediate vicinity of power lines and Alzheimer's disease: Persons living at least 5 years within 50 m had an adjusted hazard ratio of 1.51 (95% CI: 0.91, 2.51), increasing to 1.78 (95% CI: 1.07, 2.96) with at least 10 years and to 2.00 (95% CI: 1.21, 3.33) with at least 15 years. The pattern was similar for senile dementia. There was little evidence for an increased risk of amyotrophic lateral sclerosis, Parkinson's disease, or multiple sclerosis.

Designs and analyses for exploring the relationship of magnetic fields to childhood leukaemia: A pilot project for the Danish National Birth Cohort

Pooled analyses have consistently displayed an association of childhood leukaemia with residential magnetic fields, even after attempting to account for study problems. In light of the serious possibility that the link is indeed causal, a study of possible joint effects (interactions) of magnetic fields and genetic cofactors on childhood leukaemia may be justifiable. Such a study would face serious obstacles of limited numbers for subgroup analysis. To address these obstacles, we describe a design and analysis strategy that combines multiphase (multistage) sampling, measurement error modelling, and Bayesian methods for subgroup analysis that incorporate information from earlier pooled analyses. Special attention is given to prior specification, which would be the potentially controversial element. The approach could be pilot tested on data from the Danish National Birth Cohort, but an informative study would require augmenting these data with case-control sampling. We conclude that the approach outlined may be of value not only for this topic but also in other studies of effects of rare exposures and genetic factors on rare outcomes.

Residential Magnetic Field Exposure and Childhood Brain Cancer

We conducted a meta-analysis of studies on magnetic field exposure and childhood brain tumors to evaluate homogeneity in the results, to examine reasons for heterogeneity, and to derive a summary effect estimate. Comparison of results from studies of childhood brain cancer and childhood leukemia may also help to assess the potential for selection bias in childhood leukemia studies. We included results from 13 studies. Using an inverse variance-weighted method, summary effect estimates were calculated separately for distance, wire codes, and measured and calculated magnetic fields. Sensitivity analyses were conducted to assess the influence of individual studies, the potential for selection bias, and the possibility of publication bias. With the exception of wire-code studies, results were compatible with homogeneity across studies. The summary odds ratios (95% confidence intervals) were 0.88 (0.57-1.37) for distance <50 m and 1.14 (0.78-1.67) for calculated or measured magnetic fields above 0.2 microT. For measured or calculated exposures above 0.3 or 0.4 microT, the summary odds ratio was 1.68 (0.83-3.43), with no differences by method of exposure assessment. No single study had a substantial effect on the summary estimates. There was no indication of publication bias. With the exception of high cut-point analyses (0.3/0.4 microT), where the possibility of a moderate risk increase cannot be excluded, no increase in childhood brain cancer risk was evident for any of the exposure metrics.