Effects of low-frequency electromagnetic fields
When an organism is exposed to low-frequency fields, such as those at 50 or 60 Hz, the electromagnetic waves can penetrate the body, causing electric currents to flow within the organism. This can result in significant alterations to normal biological functions, as these induced currents overlap with the endogenous currents generated by the body itself during normal functioning. Consequently, low-frequency fields can cause both acute and chronic effects in humans.
Acute effects occur when individuals are exposed to high-intensity magnetic fields above 100 µT, leading to the stimulation of nerves and muscles and variations in the excitation of central nervous system cells. Acute effects have been observed on the visual system, central nervous system, and can manifest as cardiac disturbances such as extrasystole and ventricular fibrillation. Symptoms such as headaches, insomnia, and fatigue have also been reported in the presence of electromagnetic fields, both low and high frequency, even below the recommended legal limits for protection against acute effects. This condition is commonly referred to as "electromagnetic hypersensitivity" (EHS) or electrosensitivity.
Concerning chronic or long-term effects, the focus has been on the possibility that exposure to non-ionizing radiation may increase the risk of developing tumors, based on results from various epidemiological investigations. Numerous studies have indicated an increased risk of leukemia starting from a certain magnetic field value (0.3-0.4 μT), although other studies have not confirmed this association.
In 2002, the International Agency for Research on Cancer (IARC) classified low-frequency electromagnetic fields as "possible human carcinogens" (group 2B). However, the agency acknowledged that while the epidemiological evidence for a cause-effect relationship between exposure and disease is credible, other explanations for the observed association cannot be excluded with certainty due to the absence of supporting laboratory studies at that time.
Over the years, both epidemiological and experimental research has advanced. Experimental studies, conducted more frequently than epidemiological studies, involve specific model organisms (cells or animals) and have yielded interesting results. Laboratory studies conducted over the past two decades have shown that electric and magnetic fields at the mains frequency do not have mutagenic effects, meaning they do not cause cancer on their own.
However, some in vitro cell and in vivo animal studies suggest that low-frequency magnetic fields (50 or 60 Hz) may act as promoters or co-promoters of cancer in cells that have already initiated the cancer process. The suspected mechanism for this effect involves the reduction of melatonin levels in the blood, a hormone that has an anti-cancer function. Low-frequency magnetic fields may alter the level of melatonin and potentially act as co-promoters of cancer.
For instance, a study conducted by the Ramazzini Institute in 2016 found that lifelong exposure of rats to a high-intensity 50 Hz magnetic field (1000 μT) and a low acute dose of gamma radiation (0.1 Gy, similar to a CT scan) induced carcinogenic effects such as breast cancer, leukemia, and malignant schwannoma of the heart. The study's authors concluded that the findings warrant a reassessment of the safety of low-frequency electromagnetic radiation, especially considering the increasing use of electric mobility as a shift from conventional fuel-based transportation.