OVERVIEW
In electric and hybrid vehicles, high electric currents are generated by the power unit and delivered throughout the vehicle. These currents generate low frequency (LF) magnetic fields that the passengers are being exposed to, in a similar way humans are exposed to magnetic fields from power grid and high-power electrical appliances. The international bodies that are responsible for standards and guidelines for human exposure recognized the stimulation of the nervous system as the established adverse health effects of these fields. IARC (International Agency for Research on Cancer) has classified the magnetic fields as “possibly carcinogenic to humans” (2B category). The WHO (World Health Organization) recommends application of reasonable precautionary measures to further reduce human exposure to these fields, particularly to new facilities and equipment. Several countries have adopted the precautionary principle according to measures suggested by the WHO, by adopting low target exposure levels, or by administrative steps, for electrical grid exposures.
Low Frequency (LF) magnetic fields which exist in electric and hybrid vehicles and around the power grid and electrical appliances, can penetrate into the human body and interact with tissues. Very high magnetic fields that may exist in occupational exposures (e.g. welding), can stimulates the nervous system and cause perceptions and muscle stimulation. These acute effects are recognized by the international bodies that are responsible for standards and guidelines for human exposure to Non-Ionizing Radiation protection (ICNIRP and IEEE) as the established adverse health effects, and are the basis of their limitations to avoid them.
Chronic daily exposures to lower intensity magnetic fields from typical sources are encountered in some of the population (such as those living in a very close proximity to power lines) , and it is this exposure regime that raises questions regarding possible chronic health effects. Several clinical endpoints have been examined, particularly childhood leukemia. These studies mostly predate electrified cars, but the conclusions can be directly applied since the frequency range and the levels of the fields are very similar.
Studies that suggest an elevated risk of leukemia among children in the vicinity of power lines, as well as other studies, are the basis of the IARC classification of the magnetic fields as “possibly carcinogenic to humans (2B category).
Other possible human health effects related to low-level chronic exposure were and still are being examined by various studies. Examined health effects and clinical endpoints are related to (according to WHO, ICNIRP and IEEE): Neurobehavior (e.g., brain activity, cognition, hypersensitivity); Neuroendocrine system (e.g., melatonin and other hormones); Neurodegenerative disorders (Parkinson’s disease, Multiple Sclerosis, Alzheimer’s, ALS, etc.); Cardiovascular disorders (changes of EKG, pulse rate and HRV, blood pressure, and cardiovascular diseases); Immunology and Hematology; Reproduction and development (fertility; pregnancy – early term birth, miscarriages, and low birth weight); Cancer (cancers in both children and adults; blood cancers, brain and nerve system cancers, breast cancer and more). Other effects that are being examined are exposure influences upon pacemakers and other implanted/ carried medical equipment.
INTERNATIONAL BODIES PUBLICATIONS
- WHO, Environmental Health Criteria 238, extremely low frequency fields, 2007.
World Health Organization critical review on the effect on human health regarding exposure to ELF electric and magnetic fields.
- ICNIRP guidelines, guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz), 2010.
International Commission on Non-Ionizing Radiation Protection guidelines for protecting human exposure, to low frequency electric and magnetic fields.
- IEEE, Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz, IEEE Std C95.1™-2019, 2019.
Institute of Electrical and Electronics Engineers international standard for protecting human exposure, to Electric, Magnetic, and Electromagnetic Fields.
- WHO, IARC, IARC monographs on the evaluation of carcinogenic risks to humans, Volume 80, non-ionizing radiation, part 1: static and extremely low-frequency (ELF) electric and magnetic fields, 2002.
International Agency for Research on Cancer publication regarding classification of ELF magnetic fields as “possibly carcinogenic to humans” (2B group).
CHILDHOOD LEUKEMIA SELECTED BASIC STUDIES PRIOR TO IARC 2002 CLASSIFICATION
- Electrical wiring configurations and childhood cancer, Wertheimer N & Leeper E, American Journal of Epidemiology, 1979; 109(3):273-84.
An excess of electrical wiring configurations suggestive of high current-flow was noted in Colorado in 1976-1977 near the homes of children who developed cancer, as compared to the homes of control children. The finding was strongest for children who had spent their entire lives at the same address, and it appeared to be dose-related. It did not seem to be an artifact of neighborhood, street congestion, social class, or family structure. The reason for the correlation is uncertain; possible effects of current in the water pipes or of AC magnetic fields are suggested.
- Magnetic field exposure from electric appliances and childhood cancer, Savitz DA, John EM, Kleckner EC, American Journal of Epidemiology, 1990; 131(5):763-73.
The effect on childhood cancer of prolonged exposure to 60-H magnetic fields from electric appliances was examined using interview data from a recently completed case-control study. After adjustment for income, prenatal electric blanket exposure was associated with a small increase in the incidence of childhood cancers. Postnatal exposure to electric blankets was also weakly associated with childhood cancer.
- A pooled analysis of magnetic fields and childhood leukemia, Ahlbom, Day N, Feychting M, Roman E, Skinner J, Dockerty J, Linet M, McBride M, Michaelis J, Olsen J, Tynes T, Verkasalo PK, British Journal of Cancer, 2000; 83(5):692-8
The pooled analysis found that children exposed to higher levels of magnetic fields (specifically above 0.4 microteslas) had a twofold increased risk of developing leukemia compared to those exposed to lower levels. This suggests a potential link between high magnetic field exposure and an elevated risk of childhood leukemia.
- A pooled analysis of magnetic fields, wire codes, and childhood leukemia, Greenland S, Sheppard AR, Kaune WT, Poole C, Kelsh MA, Epidemiology, 2000; 11(6):624-34.
The analysis found a modestly increased risk of childhood leukemia associated with higher levels of magnetic field exposure, particularly above 0.3 to 0.4 µT (3-4 milliGauss). This suggests a possible association between higher magnetic field exposure and the incidence of childhood leukemia.
CHILDHOOD LEUKEMIA SELECTED STUDIES LATER TO IARC 2002 CLASSIFICATION
- Residential magnetic fields exposure and childhood leukemia: a population-based case-control study in California, Kheifets L, Crespi CM, Hooper C, Cockburn M, Amoon AT, Vergara XP, Cancer Causes & Control, 2017; 28 (10): 1117-1123.
The study found a modest association between higher residential magnetic field exposure (particularly above 0.3 microteslas) and an increased risk of childhood leukemia. This suggests that children living in environments with higher magnetic field exposure may have a slightly elevated risk of developing leukemia compared to those with lower exposure.
- Childhood leukaemia and distance from power lines in California: a population-based case-control study, Crespi CM, Vergara XP, Hooper C, Oksuzyan S, Wu S, Cockburn M, Kheifets L, British Journal of Cancer, 2016; 115 (1): 122-128.
We conducted a large records-based case-control study of childhood leukaemia risk in the population living near power lines in California. For leukaemia, there was a slight excess of cases within 50 m of a transmission line over 200 kV. There was no evidence of increased risk for distances beyond 50 m, for lower-voltage lines, or for CNS cancers. Our findings did not clearly support an increased childhood leukaemia risk associated with close proximity (<50 m) to higher voltage lines, but could be consistent with a small increased risk. Reports of increased risk for distances beyond 50 m were not replicated.
- Residential distance at birth from overhead high-voltage powerlines: childhood cancer risk in Britain 1962-2008, Bunch KJ, Keegan TJ, Swanson J, Vincent TJ, Murphy MF, British Journal of Cancer, 2014; 110 (5): 1402-1408.
The study found that children born within 200 meters of high-voltage power lines had a slightly higher risk of developing childhood leukemia compared to those born further away.
- Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study, Draper G, Vincent T, Kroll ME, Swanson J, British Medical Journal, 2005; 330 (7503): 1290-1292.
The study found that children living within 200 meters of high voltage power lines had a slightly higher risk of developing leukemia compared to those living farther away. The risk was also slightly elevated for children living between 200 and 600 meters from power lines, although the association was weaker.
NEURODEGENERATION AND NEUROBEHAVIOR
- A meta-analysis on residential exposure to magnetic fields and the risk of amyotrophic lateral sclerosis, Röösli M, Jalilian H, 2018; Rev Environ Health; 33 (3): 295-299.
The analysis noted variability in the results of the included studies, with some suggesting a possible risk and others finding no association. This heterogeneity highlights the challenges in drawing definitive conclusions about the relationship between magnetic field exposure and ALS.
- Residence near power lines and mortality from neurodegenerative diseases: longitudinal study of the Swiss population, Huss A, Spoerri A, Egger M, Röösli M, 2009; Am J Epidemiol 169 (2): 167-175.
The study found a statistically significant association between long-term residential exposure to high-voltage power lines and an increased risk of mortality from Alzheimer’s disease. The findings suggest a potential public health concern regarding long-term residential exposure to magnetic fields from power lines, particularly in relation to Alzheimer’s disease.
- Future needs of occupational epidemiology of extremely low frequency electric and magnetic fields: review and recommendations, Kheifets L, Bowman JD, Checkoway H, Feychting M, Harrington M, Kavet R, Marsh G, Mezei G, Renew DC, van ijngaarden E, 2009; Occup Environ Med 66:72–80.
This article provides a critical assessment of the current state of occupational epidemiology related to ELF-EMFs and offers detailed recommendations for improving future research. The authors stress the need for better exposure assessment, targeted studies on high-risk populations, and interdisciplinary research to address the uncertainties surrounding the health effects of ELF-EMF exposure.
- Exposure to ELF magnetic and ELF-modulated radiofrequency fields: the time-course of physiological and cognitive effects observed in recent studies (2001–2005), Cook CM, Saucier DM, Thomas AW, Prato FS, 2006; Bioelectromagnetics 27:613– 627.
The review summarizes findings showing that exposure to ELF magnetic fields and ELF-modulated RF fields can produce subtle physiological changes. These effects include alterations in heart rate variability, electroencephalogram (EEG) patterns, and changes in melatonin levels, which could influence sleep and other biological processes..
PREGNANCY AND REPRODUCTIVE DISORDERS
- Maternal cumulative exposure to extremely low frequency electromagnetic fields, prematurity and small for gestational age: a pooled analysis of two birth cohorts, Migault L, Garlantézec R, Piel C, Marchand-Martin L, Orazio S, Cheminat M, Zaros C, Carles C, Cardis E, Ancel PY, Charles MA, de Seze R, Baldi I, Bouvier G, 2020; Occup Environ Med 77 (1): 22-31. .
To study the relation between maternal cumulative exposure to ELF-EMF during pregnancy and the risk of prematurity or small for gestational age (SGA) in a pooled analysis of two French birth cohorts. Some heterogeneous associations between ELF-EMF exposure and prematurity and SGA were observed. However, due to heterogeneity (ie, their independence regarding the level of exposure), associations cannot be definitely explained by ELF-EMF exposure.
- A population-based prospective cohort study of personal exposure to magnetic fields during pregnancy and the risk of miscarriage, Li DK, Odouli R, Wi S, Janevic T, Golditch I, Bracken TD, Senior R, Rankin R, Iriye R. 2002; Epidemiology 13 (1): 9-20.
The study found a significant association between higher personal exposure to magnetic fields during pregnancy and an increased risk of miscarriage. Specifically, women who were exposed to magnetic fields greater than 16 milligauss (mG) had a substantially higher risk of miscarriage compared to those exposed to lower levels.
OTHER TYPES OF CANCER
- Meta-analysis of extremely low frequency electromagnetic fields and cancer risk: a pooled analysis of epidemiologic studies, Zhang Y, Lai J, Ruan G, Chen C, Wang DW, 2016; Environ Int 88: 36-43.
In this comprehensive analysis, authors conducted a search for case-control surveys regarding the associations of ELF-EMF and cancer susceptibility in electronic databases. A total of 42 studies involving 13,259 cases and 100,882 controls were retrieved. Overall, increased susceptibility to cancer was identified in the ELF-EMF exposed population. Our meta-analysis suggests that ELF-EMFs are associated with cancer risk, mainly in the United States and in residential exposed populations.
- Relationship between exposure to extremely low-frequency electromagnetic fields and breast cancer risk: a meta-analysis, Zhao G, Lin X, Zhou M, Zhao J, 2014; Eur J Gynaecol Oncol 35 (3): 264-269.
Comprehensively analyzing of the relationship between human exposure to extremely low frequency electromagnetic fields (ELF-EMFs) and breast cancer and discussing the potential risk of ELF-EMFs to human breast cancer. Sixteen research reports of case-control studies which were published from 2000 to 2007 were collected. The authors found that ELF-EMFs may increase the risk of human breast cancer. The women’s exposure to ELF-EMFs may a risk factor of breast cancer when they are non-menopausal.