Health effects of extremely low‐frequency magnetic fields: reconsidering the melatonin hypothesis in the light of current data on magnetoreception

Abstract

The so-called 'Melatonin Hypothesis' proposed that decreased nocturnal production of melatonin (MLT) might explain the increased risk of breast cancer that has been formerly attributed to extremely low-frequency (ELF) magnetic fields (MF) of weak intensity. Although the risk of ELF MF upon breast cancer was later dismissed, repeated reports were published of partial inhibition of MLT secretion in rats under long-term (≥ 4 weeks) exposure to weak ELF MF. Since 2004, however, this topic has not been experimentally studied any more. In the present study, we propose to go back to the MLT hypothesis and apply it to childhood leukemia, for which an increased risk has been robustly associated with residential exposure to ELF MF. Contrary to the original hypothesis, however, we do not consider decreased MLT levels, but disruption of circadian rhythmicity per se as the effector mechanism. Indeed, the role of the circadian timing system in the development of childhood leukemia has been well established. Motivation for going back to the MLT hypothesis comes from recent data that suggest magnetosensory disruption by ELF MF in mammals, and magnetosensitivity in humans, together with current evidence for an influence on circadian rhythmicity from disruption of non-photic sensory stimuli of various natures. We thus suggest further study on circadian rhythmicity in humans (children if possible) under long-term exposure to weak ELF MF.

Melatonin Levels and Low‐Frequency Magnetic Fields in Humans and Rats: New Insights From a Bayesian Logistic Regression

“…) and rat (Fig. ) studies, as others have reported [e.g., Selmaoui and Touitou, ; Kurokawa et al, ; Savitz, ; Jahandideh et al, ; Vanderstraeten et al, ]; human and rat studies are entirely consistent with one another, but only after matching the MF strengths to similar ranges, i.e., B ≲ 50 μT; there seems to be no dose‐dependence between any change in the MLT levels with MF strengths ranging from 0.5 to 100μT as others have reported [e.g., Kato et al, ; Reiter, ; Pfluger and Minder, ; Halgamuge, ]; and the impact of MF on the MLT levels does, however, depend on the ELF‐MF strength, in the regime where ELF‐MFs are weaker than (Fig. ).…”

The Influence of Electromagnetic Pollution on Living Organisms: Historical Trends and Forecasting Changes

“…Despite the lack of sufficient empirical data resources, several interesting hypotheses were proposed in the literature, according to which electromagnetic fields affect the pineal gland and its hormone melatonin, interfering with its physiological mechanisms leading to sleep disorders, lower mood, reduced concentration, depression, and the development of certain cancers [115–119]. These hypotheses, unsupported by sufficient scientific evidence reflect explicitly the importance of the pineal gland in investigations of related mechanisms of the harmful effects of electromagnetic fields and/or electromagnetic radiation published in journals, textbooks, and even on the Internet.…”

The effects of extremely low frequency magnetic fields on mutation induction in mice

“…Ultimately, in light of the present literature, the melatonin hypothesis stating that disruption of melatonin secretion is a main factor in the carcinogenic effects of magnetic fields is not supported by either epidemiological or experimental data (Lewczuk et al, 2014), and thus should be regarded as negatively corroborated and rebutted (Vanderstraeten et al, 2012). Furthermore, the core of the original hypothesis was conceived on the potential association between ELF-MF and breast cancer (Stevens, 1987), which has also been dismissed (Feychting, 2013).…”

“…The majority of in vivo studies have provided very little evidence to suggest ELF-MF reduces melatonin synthesis. However, whilst covering a variety of exposure parameters, these have predominantly occurred in short-term studies (< 2 weeks of exposure duration) conducted on rodents (Vanderstraeten et al, 2012). The issue with this is therefore two-fold as the majority of studies have been conducted on a nocturnally active species whose anatomical location of the pineal gland is largely different from that of humans (Touitou et al, 2006).…”