Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

In Men Chronically Exposed To Magnetic Fields, No Disruptions Of Melatonin Exists

30.07.2003


A new study offers direction for those examining the illnesses of those working or living near large electrical facilities.



Exposure to light has been proven to inhibit the normal secretion of melatonin from the light-sensitive pineal gland. But light is only one part of the electromagnetic spectrum, occupying a wavelength between 730 and 400 nm. Because light is the only visible portion of the electromagnetic spectrum, other wavelengths may also inhibit melatonin secretion, including the omnipresent magnetic fields generated by the production, transport, and distribution of electricity (50 Hz in Europe, 60 Hz in North America). These fields are encountered in most activities of daily life, from lighting to heating and other routine household applications of electricity.

Past experimental studies of rats exposed to electric or magnetic fields have found a diminution in melatonin secretion. The importance of the length of magnetic field exposure in this inhibitory effect suggests that the effect of these fields on pineal function may be cumulative, at least in rats. In fact, much of the evidence for the melatonin hypothesis is based on data for rodents. But humans and rodents differ with respect to melatonin secretion in two important ways: (1) rodents are nocturnally active, and they show differences in the anatomical location of the pineal gland; and (2) the geometry of the skull may cause stronger eddy currents in field-exposed animals.


Results about the effects of magnetic fields in higher mammals – lambs, monkeys and humans -- have heretofore been either negative or provide controversial results. Most work published thus far has involved the acute exposure of healthy volunteers to magnetic fields and has not found it to affect melatonin secretion. Nevertheless, it is possible that chronic human exposure to magnetic fields might affect melatonin secretion, its circadian rhythm, or both. Because of the obvious technical difficulties in exposing healthy volunteers to magnetic fields for a long period, at a high intensity, or both, the only feasible experimental approach toward the study of such chronic exposure involves the study of subjects exposed continually either on the job or at home -- occupationally or residentially.

A New Study

The possible effects of magnetic fields on human melatonin secretion is important from a public health perspective, because alterations in the secretion of this hormone (for example, phase shifting or reduced amplitude) are likely to lead to clinical disorders involving fatigue, sleep and mood disturbances, altered performance, and depression, all signs that can be related to desynchronization of circadian rhythms. Now, an innovative study addresses this issue. The methodology entails the examination of workers exposed to magnetic fields daily for 1 one to 20 years, both in the workplace and at home.

The authors of “Magnetic Fields and The Melatonin Hypothesis: A Study of Workers Chronically Exposed to 50-Hz Magnetic Fields” are Yvan Touitou, Françoise Camus, and Henriette Charbuy, from the Department of Biochemistry and Molecular Biology, Faculty of Medicine Pitié-Salpêtrière, and Jacques Lambrozo, Service des Etudes Médicales, Electricité de France/Gaz de France, all in Paris, France. Their findings appear in the June 2003 edition of the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology.

Methodology

Thirty male volunteers (15 exposed and 15 controls) participated in the autumn study, when the light-dark cycle was 10 hours light-14 hours dark. All subjects had similar schedules, with daytime activity from 0700 to 2300 and nocturnal rest, and were similar in age and in physical activity. Subjects were required to have no acute or chronic diseases, have regular sleep habits, do no night work, have taken no trans-meridian airplane flights during the preceding two months, and take no drugs. All were nonsmokers who used alcohol and coffee in moderate quantities. The exposed workers had not been on call in the 48 hours preceding the experiment. They were asked not to use electric razors or hair dryers during the study or in the 24 hours before the blood samples were taken. Women were not included in this study because the interaction of their ovarian hormone cycle with melatonin secretion might have made the study results difficult to interpret.

The 15 test subjects all worked in extra high voltage (EHV) substations in the Paris metropolitan region, operating and maintaining the EHV electricity transmission network (225 and 400 KV). Their work essentially involved installing couplings between EHV lines as well as voltage transformers. The exposed subjects were also housed near the substations, which means that they were exposed to magnetic fields both while working and during their daily life in their lodgings. Ten of the 15 subjects were exposed from seven to 20 years, and five subjects were exposed from one to four years. The 15 control subjects did not work in a technical job that could have resulted in occupational exposure to magnetic fields. They were subjected only to the normal electromagnetic fields of our daily environment.

Dosimeters measured the exposure continuously for seven days, during the daytime and at night. Measurements were taken and recorded every 30 seconds all day long. Both exposed and control subjects wore the magnetic field recording device throughout the workday. At home, they placed it in a "public" room. The weekly geometric mean of individual exposures ranged from 0.1 to 2.6 µT. The results are compared with those for 15 unexposed men who served as controls. Blood samples were taken hourly from 2000 to 0800. Nighttime urine was also collected and analyzed.

Results

The weekly geometric mean of individual exposures ranged from 0.1 to 2.6 µT. The arithmetic mean of the 15 exposure values was 0.72 µT. The arithmetic mean of daytime (workday) exposure of the 15 exposed subjects was 0.64 µT and nighttime (residential) exposure 0.82 µT. A subset of three subjects had a substantially higher exposure with an arithmetic mean of 2.10 µT. Their arithmetic mean workday exposure was 1.50 µT and nighttime residential exposure 2.71 µT. For the control subjects the weekly geometric mean of individual exposures ranged from 0.004 to 0.092 µT. The arithmetic mean of the 15 exposure values was 0.04 µT. The arithmetic mean of both the workday and nighttime exposure for the 15 controls was 0.04 µT.

A comparison between groups found that that melatonin secretion did not differ for the exposed and control groups.

Conclusions

This study of workers exposed daily to magnetic fields for a period of one to 20 years in their workplace and at home shows that this exposure does not lead to alterations in their melatonin secretion. The clinical signs (depression, mood and sleep disorders, malignant diseases, etc.) reported in some studies of people living or working near electric lines or substations thus do not appear to be associated with a disturbance in their melatonin levels.

It is possible that the difference in the effects observed in animals and humans is the result of both the anatomical configuration of the pineal gland and the principally nocturnal rhythm of rodent activity. A different sensitivity to magnetic fields between species could also be part of the explanation, as it is known that some species detect and perceive magnetic fields differently. It is also possible that some subjects are more sensitive to magnetic fields than others; this is very difficult to demonstrate in a case-control study because of the enormous interindividual variability of melatonin secretion and plasma melatonin concentrations in humans.

To the researchers’ knowledge, this study is the first to examine both plasma melatonin circadian rhythm and urinary 6-sulfatoxymelatonin concentration in subjects who have been exposed chronically and for a long period to magnetic fields at home and at work. Therefore, it is the first research to show that chronic magnetic field exposure appears to have no cumulative effect in humans on serum melatonin secretion and circadian rhythm or urinary excretion of 6-sulfatoxymelatonin, at least among men in their forties.

Donna Krupa | American Physiological Society
Further information:
http://www.faseb.org/aps

More articles from Studies and Analyses:

nachricht Amputees can learn to control a robotic arm with their minds
28.11.2017 | University of Chicago Medical Center

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>