Indoor transformer stations and ELF magnetic field exposure: use of transformer structural characteristics to improve exposure assessment

International study of childhood leukemia in residences near electrical transformer rooms

OBJECTIVES

New epidemiologic approaches are needed to reduce the scientific uncertainty surrounding the association between extremely low frequency magnetic fields (ELF-MF) and childhood leukemia. While most previous studies focused on power lines, the Transformer Exposure study sought to assess this association using a multi-country study of children who had lived in buildings with built-in electrical transformers. ELF-MF in apartments above built-in transformers can be 5 times higher than in other apartments in the same building. This novel study design aimed to maximize the inclusion of highly exposed children while minimising the potential for selection bias.

METHODS

We assessed associations between residential proximity to transformers and risk of childhood leukemia using registry based matched case-control data collected in five countries. Exposure was based on the location of the subject's apartment relative to the transformer, coded as high (above or adjacent to transformer), intermediate (same floor as apartments in high category), or unexposed (other apartments). Relative risk (RR) for childhood leukemia was estimated using conditional logistic and mixed logistic regression with a random effect for case-control set.

RESULTS

Data pooling across countries yielded 16 intermediate and 3 highly exposed cases. RRs were 1.0 (95% CI: 0.5, 1.9) for intermediate and 1.1 (95% CI: 0.3, 3.8) for high exposure in the conditional logistic model. In the mixed logistic model, RRs were 1.4 (95% CI: 0.8, 2.5) for intermediate and 1.3 (95% CI: 0.4, 4.4) for high. Data of the most influential country showed RRs of 1.1 (95% CI: 0.5, 2.4) and 1.7 (95% CI: 0.4, 7.2) for intermediate (8 cases) and high (2 cases) exposure.

DISCUSSION

Overall, evidence for an elevated risk was weak. However, small numbers and wide confidence intervals preclude strong conclusions and a risk of the magnitude observed in power line studies cannot be excluded.

Multidisciplinary and Nonpharmacological Management of Pain in Temporomandibular Disorders (TMDs)

Temporomandibular joint dysfunction (TMD) is not a single diagnosis, but a term covering a group of conditions that involve pain and dysfunction of the masticatory muscles within the temporomandibular joint (TMJ) and associated structures. It is a set of disease entities comprising various ailments and clinical symptoms. One of the most distressing symptoms for TMD patients is pain. Pain is subjective and always unpleasant. The VAS (visual analogue scale) was used in this research. The aim of this study was to assess the influence of physical stimuli, namely extremely low frequency magnetic field (ELF-MF) and LED light, on the experience of pain caused by increased tension in the masticatory muscles in adults. Out of 150 people examined, 104 were enrolled in the study after meeting the eligibility criteria. The study group was divided into 4 subgroups. Each subgroup received physical therapy treatment using a different physical stimulus. The effects of four therapeutic modalities were compared. In terms of VAS scores, pain attenuation was observed in all subgroups. The study confirmed the analgesic effect of the selected physical therapy methods. The authors focused on the analysis of the results obtained for each subgroup, comparing the effects of individual modalities on pain intensity (according to VAS scores). After the treatment, pain relief was observed in each of the studied subgroups. Treatment using ELF-MF and ELF-MF in combination with LED light in the course of TMD brings about a significant improvement in the subjective pain experience expressed in VAS pain scores. The use of selected physical stimuli and their beneficial effect on pain symptoms during mandibular movements has important implications for patients' daily life and work. Incorporation of therapeutic methods can help enhance patient satisfaction and comfort during manual TMJ therapy and lengthy dental procedures.

Effect of an Extremely Low-Frequency Electromagnetic Field on the Concentration of Salivary Immunoglobulin A

Extremely Low-Frequency Electromagnetic Field (ELF MF) therapy is effective in the treatment of injury, inflammation and postoperative complications. Its clinical applications relate to bone unification, pain reduction, soft tissue oedema and the decrease of electric potentials in the oral cavity. It enhances regeneration of periapical bone lesions. It is obvious that cells (leukocytes, platelets, keratinocytes, osteoblasts) and proteins (fibrin, collagen, elastin and growth factors) exhibit alterations when exposed to an Extremely Low-Frequency Electromagnetic Field. The aim of the study was to evaluate the effect of an Extremely Low-Frequency Electromagnetic Field (ELF MF) on the parotid gland on the concentration of salivary immunoglobulin A. The study group consisted of 24 patients, aged 14–16, who underwent ELF MF on the parotid gland region. The control group comprised 25 matching persons. The IgA concentration in saliva samples was established using radial immunodiffusion. Following ELF MF, a statistically significant increase in the concentration of secretory immunoglobulin A was found in the study group, whereas in the control group, no statistically significant differences were noted. It can be concluded that an Extremely Low-Frequency Electromagnetic Field increases the activity of the immune system of the parotid gland.

Magnetic Fields of Devices during Electric Vehicle Charging: A Slovak Case Study

The aim of this contribution is to identify and quantify the magnetic field parameter (MP) devices for charging electric vehicles (EVs). An EV is a mobile device. The EV remains a mobile device even when it is charging in a fixed charging stand. ICNIRP and SBM standards apply to stable devices. A magnetic field (MF) creates local gradient fields that change cyclically over time near the charging stations. The rotating vector MF is a specific parameter. An MF is evaluated by its strength and spatial changes. The triaxial fluxgate magnetometer VEMA-041 was used for the measurements. The MF was observed in the frequency range of 0–250 Hz, and the magnetic induction density was from T 2 × 10−9 T to 2 × 10−5 T, with a sensitivity of 1.7 nT. The MF analysis was performed within the time and frequency range. The rotating vector MF was identified at the measurement points. Measurements were realized for the charge under the following parameters: cables, 600 A; transformer, 250 kVA (22 kV/400 V); a cab-fixed charging stand, and an AC/DC charger in the EV. EV charging was performed with 6.6 kW of power and 43-kW fast charging. The measured results were satisfactory, according to the ICNIRP and SBM 2015 standard. The values measured at a distance of 1 m from the wall of the transformer were BRMS < 2 µT. BRMS values < 3 µT were measured in the space of the cable’s entry into the distribution box. EV values should not be assessed under this regulation. However, an EV is a mobile device. In the selected EV sample (a first-generation Nissan Leaf), a frequency of 10 Hz and its multiples were detected during charging. The frequencies were generated in an AC/DC charger in the EV. These frequencies reached BRMS < 0.2 µT in the driver’s footwell. The maximum value of the MF rotating vector was Btotal < 0.3 µT and was directed to the crew area of the EV. The AC/DC charger generated BRMS = 0.95 µTin the driver’s footwell. It is necessary to look for new tools for evaluating MFs for EVs, such as the standards used for stable sources today. These standards should be based on dosimetric principles.

Residential extremely low frequency magnetic fields and skin cancer

OBJECTIVE

Photoinduced 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 effects of extremely low frequency (ELF) magnetic fields (MFs). We assessed the association of melanoma and squamous cell carcinoma with residential MF exposure.

METHODS

All cohort members had lived in buildings with indoor transformer stations (TSs) during the period from 1971 to 2016. MF exposure was assessed based on apartment location. Out of the 225 492 individuals, 8617 (149 291 person-years of follow-up) living in apartments next to TSs were considered as exposed, while individuals living on higher floors of the same buildings were considered as referents. Associations between MF exposure and skin cancers were examined using Cox proportional hazard models.

RESULTS

The HR for MF exposure ≥6 month was 1.05 (95% CI 0.72 to 1.53) for melanoma and 0.94 (95% CI 0.55 to 1.61) for squamous cell carcinoma. Analysis of the age at the start of residence showed an elevated HR (2.55, 95% CI 1.15 to 5.69) for melanoma among those who lived in the apartments when they were less than 15 years old. This finding was based on seven exposed cases.

CONCLUSIONS

The results of this study suggested an association between childhood ELF MF exposure and adult melanoma. This is in agreement with previous findings suggesting that the carcinogenic effects of ELF MFs may be associated particularly with childhood exposure.

A cohort study on adult hematological malignancies and brain tumors in relation to magnetic fields from indoor transformer stations

Extremely low frequency (ELF) magnetic fields (MF) have been classified as possibly carcinogenic. This classification was mainly based on studies indicating increased risk of leukemia in children living near power lines. Increased risks of adult hematological malignancies and brain tumors have also been reported, but the results are mixed. We assessed incidence of adult hematological malignancies and brain tumors associated with residential MF exposure. All cohort members had lived in buildings with indoor transformer stations (TS). MF exposure was assessed based on apartment location. Out of the 256,372 individuals, 9,636 (165,000 person-years of follow-up) living in apartments next to TSs were considered as exposed. Associations between MF exposure and neoplasms were examined using Cox proportional hazard models. The hazard ratio (HR) for MF exposure ≥ 1 month was below one for most hematological neoplasms (HR for any hematological neoplasm: 0.75; 95% CI: 0.54-1.03), and decreased with increasing duration of exposure (HR for exposure ≥ 10 years: 0.47; 95% CI: 0.22-0.99). However, the HR for acute lymphocytic leukemia (ALL) was 2.86 (95% CI: 1.00-8.15), based on 4 exposed cases; the risk increased with duration of exposure (HR for exposure ≥3 years: 3.61; 95% CI: 1.05-12.4) and was particularly associated with childhood exposure (2 exposed cases, HR for exposure during the first two years of life: 11.5; 95% CI: 1.92-68.9). The HR for meningioma was 0.46 (95% CI: 0.19-1.11), with no evidence of exposure-response gradient with increasing duration of exposure. The HR for glioma was 1.47 (95% CI: 0.84-2.57). The hypothesis of a positive association between ELF MFs and adult hematological malignancies was supported only for ALL. The results suggested decreased rather than increased risk of most hematological neoplasms.

Exposure to 50 Hz Magnetic Fields in Homes and Areas Surrounding Urban Transformer Stations in Silla (Spain): Environmental Impact Assessment

Exposure to extremely low frequency electromagnetic fields (ELFs) is almost inevitable almost anywhere in the world. An ELF magnetic field (ELF-MF) of around 1 mG = 0.1 μT is typically measured in any home of the world with a certain degree of development and well-being. There is fear and concern about exposure to electromagnetic fields from high- and medium-voltage wiring and transformer stations, especially internal transformer stations (TSs), which in Spain are commonly located inside residential buildings on the ground floor. It is common for neighbors living near these stations to ask for stations to be moved away from their homes, and to ask for information about exposure levels and their effects. Municipality is the closest administration to the citizens that must solve this situation, mediating between the citizens, the utility companies and the national administration. In this case, the municipality of Silla (València, Spain) wanted to know the levels of exposure in the dwellings annexed to the TSs, to compare them with Spanish legislation and the recommendations coming from epidemiological studies. This article presents the first systematic campaign of ELF-MF measurements from TSs carried out in a Spanish city. Many measurements were carried out in the rooms of the apartments doing spatial averages of spatial grid measurements. Measurements are made in the bed and bedrooms and a weighted average and an environmental impact indicator were obtained for each location. We found that old TSs usually provide the highest peak exposure levels. A notable result of this work is that approximately one quarter of the population living above or next to a TS would be exposed to a weighted MF level greater than 0.3 μT, and that about a 10% of this population would not be able to relocate their bedroom or living room to minimize the level of exposure.