Acute Exposure to Circularly Polarized 50-Hz Magnetic Fields of 200–300 μT Does Not Affect the Pattern of Melatonin Secretion in Young Men

Abstract

Environmental exposure to time-varying (alternating current) magnetic fields (MFs) produced by electrical current flow is a perceived public health risk. Several epidemiological studies report correlations between MF exposure and carcinogenesis. It has been hypothesized that MF-induced suppression of melatonin could provide the mechanism by which this effect is mediated. Here, we describe results from a controlled laboratory-based study designed to detect changes in human melatonin secretion after a 2-h exposure to 200-300 microTesla, 50 Hz circularly polarized MF. Exposure was timed to occur before or during the nightly melatonin rise, and levels administered were some 4-6 times higher than the commonly encountered maximum levels. Results from 19 male subjects aged between 18 and 35 yr indicate that acute exposure to 50 Hz MFs of this nature does not result in significant suppression, alteration of peak levels, or a change in timing of the nighttime melatonin rise. We conclude that acute exposure to 50 Hz MFs does not have a significant effect on the normal nighttime production of melatonin in young men.

Do magnetic fields cause increased risk of childhood leukemia via melatonin disruption?

“…Another issue is the control fields to which volunteers were exposed. For example, Warman et al [2003b] employed acute exposes up to 300 mT and found no real evidence of melatonin disruption. However, their control level is given as <0.2 mT, which could be seen as the region where chronic exposure still results in nocturnal melatonin suppression.…”

Solar and geomagnetic activity, extremely low frequency magnetic and electric fields and human health at the Earth’s surface

“…They added that, unlike light exposure, the potential neuroanatomical pathways for melatonin suppression due to magnetic field exposure remain obscure. Warman et al (2003a) reported that their study into the effects of 200-300 lT magnetic fields (50 Hz) showed no effect on melatonin suppression or circadian rhythm phase-shift.…”

“…Experimental manipulation of Earth-strength magnetic fields as well as exposure to magnetic fields (MFs) associated with the 50/60 Hz electric power distribution system have been shown to suppress melatonin production in some, but not all, studies (Warman et al 2003a;Phillips and Deutschlander 1997;Reiter 1994). Light exposure may be critical for MF-induced melatonin suppression and it also modifies the ability of certain species to derive compass information from the Earth's magnetic field (Phillips and Deutschlander 1997).…”

“…This split in the population between those who respond to 50/60 Hz magnetic fields and those who do not is reminiscent of the findings of Chernouss et al (2001) discussed earlier, who revealed that it is a subset of the population which is sensitive to auroral disturbances. Warman et al (2003a) investigated the effect of exposure to circularly polarised high magnitude, power frequency magnetic fields on 19 male subjects aged 18-35 years. The authors stated that, although melatonin suppression and circadian rhythm phase-shift due to light exposure at night is accepted and well understood, data supporting the effect of magnetic fields on melatonin level are very limited and often poorly controlled.…”

“…Commenting on the earlier study, Warman et al (2003a) suggested that the work of Wood et al (1998) provides some of the most controlled data concerning the potential effect of 50 Hz magnetic fields on the human melatonin profile to date. However, they attribute the disparity between their results and those of Wood et al (1998) to the fact that the latter did not provide controls for postural or lighting effects, and different subjects appear to have received exposures of different lengths (1.5-4 h).…”