Magnetic fields and the melatonin hypothesis: a study of workers chronically exposed to 50-Hz magnetic fields

Abstract

Because epidemiological studies report clinical disorders (mainly neurobehavioral alterations and/or cancer) that may be related to diminished melatonin secretion or to changes in its circadian rhythm in subjects living or working in environments exposed to magnetic fields, research on the effects of these fields in humans is particularly important. In this study, we examine the circadian rhythm of melatonin in 15 men exposed chronically and daily for a period of 1-20 yr, in the workplace and at home, to a 50-Hz magnetic field in search of any cumulative effect from those chronic conditions of exposure. The weekly geometric mean of individual exposures ranged from 0.1 to 2.6 microT. The results are compared with those for 15 unexposed men who served as controls (individual exposures ranged from 0.004 to 0.092 microT). Blood samples were taken hourly from 2000 to 0800. Nighttime urine was also collected and analyzed. This work shows that subjects exposed over a long period (up to 20 yr) and on a daily basis to magnetic fields experienced no changes in their plasma melatonin level, their urinary 6-sulfatoxymelatonin level, or the circadian rhythm of melatonin. Our data strongly suggest that magnetic fields do not have cumulative effects on melatonin secretion in humans and thus clearly rebut the "melatonin hypothesis" that a decrease in plasma melatonin concentration (or a disruption in its secretion) explains the occurrence of clinical disorders or cancers possibly related to magnetic fields.

No association between occupational exposure to ELF magnetic field and urinary 6‐sulfatoximelatonin in workers

“…In the study of Juutilainen et al [2000], the comparison of Monday versus Friday values of 6-OHMS suggests an irreversible effect of ELF on melatonin, at variance with the results of Pfluger and Minder [1996]. Another study measuring both environmental and occupational ELF-MF exposure monitored with personal dosimeters for 7 days found no effect on plasma melatonin or 6-OHMS [Touitou et al, 2003].…”

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

“…In contrast to the volunteer studies with short term exposure, there is now a body of studies involving either longer term or chronic magnetic field exposures which taken together show evidence of nocturnal melatonin disruption. These are listed in Table 1, numbered 1-14: [Wilson et al, 1990;Pfluger and Minder, 1996;Burch et al, 1998Burch et al, , 1999aBurch et al, ,b, 2000Burch et al, , 2002Wood et al, 1998;Graham et al, 2000;Juutilainen et al, 2000;Davis et al, 2001;Levallois et al, 2001;Weydahl et al, 2001;Touitou et al, 2003]. The two latter Studies, 13 and 14, looked at the effects of geomagnetic disturbances.…”

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

“…On the other hand, the effect of chronic exposure in humans has been less comprehensively considered, although those that have been conducted seemingly confirm a lack of effect. This was illustrated in a study of workers exposed to both daily residential and occupational 50 Hz fields over a period of 1-20 years, whereby no change was detected in either the circadian synthesis of melatonin or their plasma melatonin concentration (Touitou et al, 2003). An issue with this study is that melatonin synthesis predominantly occurs during sleep therefore only nocturnal residential exposure principally applies.…”