The association between extremely low-frequency electromagnetic fields and childhood leukaemia in epidemiology: enough is enough?

Computational analysis of electromagnetic field exposure in passengers near high- current contact wire environments

The electromagnetic environment of a railway station is composed of electrical, magnetic, and electromagnetic fields, which are generated by various sources such as traction current, voltage, pantograph-catenary arc, locomotive braking, wheel-rail rolling arc, and communication systems. However, there is public growing concern among the public about the potential negative human health effects of this electromagnetic environment. To analyze the distribution of electromagnetic fields in human tissues, electromagnetic simulation software is used to create a model that includes six track contact wires and four waiting passengers on three platforms. This model is used to analyze the magnetic field environment created by high currents in the contact wires of a multi-track high-speed railway station. By varying the loads on different contact wires, the distribution of electric field and magnetic flux density within human tissues of waiting passengers on different platforms is studied using this model. When the track is unoccupied, the calculation results show that the maximum values of the electric field and magnetic flux density of the passenger's human body tissue at the blind way on the platform and 1 m of the blind way are 17.6 mV m-1 and 52.7 μT, respectively. These values increase by 9.28 mV m-1 and 16.4 μT compared to when the track is occupied. When more contact wires are loaded with currents, the electric field mode and magnetic flux density mode of human tissues increase at the same position on the platform. Specifically, when the contact wires of six tracks are loaded with current at the same time, the maximum values of the electric field mode and magnetic flux density mode of the waiting passengers' human tissues at the blind way on different platforms are 29.6 mV m-1 and 88.1 μT, respectively. These maximum values are lower than the public electromagnetic exposure limits that are designated by the International Commission on Non-Ionizing Radiation Protection guidelines. The research results demonstrate that the magnetic field environment generated by the current in the contact wires of a railway station with six tracks does not pose a health risk to human tissues of passengers waiting at the blind way and 1 m of the blind way on the platform. These findings can provide valuable data reference for the formulation of relevant standards for the design of electrified rail transit, as well as the suppression of electromagnetic interference and protection of human bioelectromagnetism.

Nasal mucociliary clearance after extremely low frequency by scintigraphic and histopathologic evaluation

OBJECTIVE

To investigate the effect of exposure to extremely low-frequency magnetic fields (ELF-MFs) on nasal mucociliary clearance (MCC) by rhinosintigrapic and histopathological evaluation.

MATERIALS AND METHODS

The rats were separated into three groups according to ELF-MFs intensity and control group. The exposure groups were standardized for the ELF-MFs of 1, 1.5, and 2 mT emitted by 3 Helmholtz coils for 4 h/day for 30 days. Rhinoscintigraphy was performed to measure nasal MCC. The nasal tissues were examined for edema, inflammation, hyperemia, necrosis, ciliary loss, goblet cell density, and fibroblast proliferation. The data were evaluated statistically (p < 0.05).

RESULTS

Nasal mucociliary clearance rates (NMCR) were calculated as 33.13 ± 5.91% in control, 27.78 ± 4.7% in 1 mT, 22.67 ± 5.43% in 1.5 mT, and 18.11 ± 6.33% in 2 mT. NMCR were decreased with increasing ELF-MFs, in 1.5 and 2 mT groups (p < 0.05) compared to control. Nasal mucociliary transport rate (NMTR) values were found to be 2.17 ± 0.33 mm/min in control, 1.82 ± 0.32 mm/min in 1 mT, 1.46 ± 0.34 mm/min in 1.5 mT and 1.24 ± 0.29 mm/min in 2 mT. NMTR was decreased in the groups exposed to 1.5 and 2 mT (p < 0.05) compared to control. The edema, hyperemia, inflammation, ciliary loss, and goblet cell density were statistically significant differences between control and groups exposed to 1.5 and 2 mT (p < 0.05).

CONCLUSION

Our rat model has shown nasal mucosa damage and decreased NMCR and NMTR by rhinoscintigraphy as ELF-MFs intensity increases. It may be detrimental to nasal mucosa mucociliary function depending on the ELF-MFs intensity.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:2081-2089, 2023.

Germline De Novo Mutations as a Cause of Childhood Cancer

Germline de novo mutations (DNMs) represent one of the important topics that need extensive attention from epidemiologists, geneticists, and other relevant stakeholders. Advances in next-generation sequencing technologies allowed examination of parent-offspring trios to ascertain the frequency of germline DNMs. Many epidemiological risk factors for childhood cancer are indicative of DNMs as a mechanism. The aim of this review was to give an overview of germline DNMs, their causes in general, and to discuss their relation to childhood cancer risk. In addition, we highlighted existing gaps in knowledge in many topics of germline DNMs in childhood cancer that need exploration and collaborative efforts.

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.

Resveratrol may reverse the effects of long-term occupational exposure to electromagnetic fields on workers of a power plant

High-voltage electricity lines are known to generate extremely low-frequency electromagnetic fields (ELF-EMFs). With the process of urbanization, increasing concerns has been focused on the potentially hazardous impacts of ELF-EMF on human health, and the conclusions are controversial. Little is known about the method of prevention against ELF-EMF induced healthy problems. A total of 186 male workers with occupational exposure to high-voltage electricity lines, and 154 male subjects with insignificant exposure as reference control were enrolled in this study. Resveratrol or placebo was given as dietary supplements (500 mg twice daily), and several inflammatory biomarkers and biomarkers of oxidative stress were assessed. Workers who had long-term exposure to high-voltage electricity lines exhibited elevated urinary levels of 8-hydroxy-2-deoxy-guanosine (8-OHdG) and F2-isoprostane, compared to the reference group. Lower plasma nuclear factor kappa B (NF-κB) and interleukin (IL)-6 were observed in exposed workers compared to the reference group. Resveratrol significantly reversed the adverse impacts of ELF-EMF. Stimulated cytokine production by resveratrol was found in exposed workers but not in the reference group. This study supported that occupational and long-term exposure to high-voltage electricity lines has an adverse effect on homeostasis of human body, and resveratrol supplement could be an effective protection strategy against the adverse effects induced by ELF-EMFs.

Extremely low-frequency magnetic fields and risk of childhood leukemia: A risk assessment by the ARIMMORA consortium

Exposure to extremely low-frequency magnetic fields (ELF-MF) was evaluated in an International Agency for Research on Cancer (IARC) Monographs as "possibly carcinogenic to humans" in 2001, based on increased childhood leukemia risk observed in epidemiological studies. We conducted a hazard assessment using available scientific evidence published before March 2015, with inclusion of new research findings from the Advanced Research on Interaction Mechanisms of electroMagnetic exposures with Organisms for Risk Assessment (ARIMMORA) project. The IARC Monograph evaluation scheme was applied to hazard identification. In ARIMMORA for the first time, a transgenic mouse model was used to mimic the most common childhood leukemia: new pathogenic mechanisms were indicated, but more data are needed to draw definitive conclusions. Although experiments in different animal strains showed exposure-related decreases of CD8+ T-cells, a role in carcinogenesis must be further established. No direct damage of DNA by exposure was observed. Overall in the literature, there is limited evidence of carcinogenicity in humans and inadequate evidence of carcinogenicity in experimental animals, with only weak supporting evidence from mechanistic studies. New exposure data from ARIMMORA confirmed that if the association is nevertheless causal, up to 2% of childhood leukemias in Europe, as previously estimated, may be attributable to ELF-MF. In summary, ARIMMORA concludes that the relationship between ELF-MF and childhood leukemia remains consistent with possible carcinogenicity in humans. While this scientific uncertainty is dissatisfactory for science and public health, new mechanistic insight from ARIMMORA experiments points to future research that could provide a step-change in future assessments. Bioelectromagnetics. 37:183-189, 2016. © 2016 Wiley Periodicals, Inc.

Childhood leukemia and 50 Hz magnetic fields: findings from the Italian SETIL case-control study

We report on an Italian case-control study on childhood leukemia and exposure to extremely low frequency magnetic fields (ELF-MF). Eligible for inclusion were 745 leukemia cases, aged 0–10 years at diagnosis in 1998–2001, and 1475 sex- and age-matched population controls. Parents of 683 cases and 1044 controls (92% vs. 71%) were interviewed. ELF-MF measurements (24–48 h), in the child’s bedroom of the dwelling inhabited one year before diagnosis, were available for 412 cases and 587 controls included in the main conditional regression analyses. The magnetic field induction was 0.04 μT on average (geometric mean), with 0.6% of cases and 1.6% of controls exposed to >0.3 μT. The impact of changes in the statistical model, exposure metric, and data-set restriction criteria was explored via sensitivity analyses. No exposure-disease association was observed in analyses based on continuous exposure, while analyses based on categorical variables were characterized by incoherent exposure-outcome relationships. In conclusion, our results may be affected by several sources of bias and they are noninformative at exposure levels >0.3 μT. Nonetheless, the study may contribute to future meta- or pooled analyses. Furthermore, exposure levels among population controls are useful to estimate attributable risk.

Invited commentary: extremely low-frequency magnetic fields and breast cancer--now it is enough!

Research on an association between extremely low frequency (ELF) magnetic fields and breast cancer has been conducted since the 1980s, based on the hypothesis that ELF fields suppress melatonin production and melatonin protects against breast cancer development. In this issue of the Journal, Li et al. (Am J Epidemiol. 2013;178(7):1038-1045) present a well-designed study on occupational exposure to ELF fields and breast cancer that adds to the already large pool of data that has not supported the hypothesis. Over time, the quality and statistical power of studies within this research area have increased considerably, and advances in exposure assessment have reduced exposure misclassification. The evidence is consistently negative. A World Health Organization health risk assessment concluded in 2005 that the evidence from experimental and epidemiologic studies is sufficient to give confidence that ELF magnetic fields do not cause breast cancer. The new study adds even more confidence to this conclusion. We should now focus our time and research resources on more promising hypotheses, the results of which could make a difference for public health and advance science. Further epidemiologic studies on ELF fields and breast cancer are likely to have little new knowledge to add.

Powerline bioactivity - more than magnetism

BACKGROUND

Previous work on the possible public health impact of electricity utilization has mostly considered low frequency electromagnetic fields, particularly those associated with high voltage overhead powerlines, but no generally accepted biological mechanism has been proposed. The present study seeks to expand the area of debate to include airborne electroactivity.

FINDINGS

From a literature survey it is concluded that there is statistically significant published evidence consistent with the involvement of airborne electroactive agents in the powerline proximity modulation of some cytokine activity. Attention is drawn to overhead line fault associated corona discharge action as a source of potentially bioactive agents deserving careful study in view of the widespread close residential proximity to overhead power distribution lines in many countries. Particular attention is given to the role of electricity access associated faults as a possible explanation for the high childhood leukaemia rates in certain districts of Mexico City.

CONCLUSIONS

Despite more than 30 years research worldwide there is no generally accepted biological mechanism to explain the adverse health impact of overhead powerline residential proximity. Expanding the area of consideration to include airborne electroactivity may provide the basis for a plausible outline model of such a mechanism. More attention should be given to this research area.

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.