Cognitive and neuro-endocrine effects of MF (1999-2005)

M. Crasson & J.J. Legros

The role of laboratory experiments is to evaluate the effects of short term exposure. From published psychophysiological and cognitive laboratory studies we cannot exclude the possibility of 50-60-Hz weak magnetic field exposure influence on human cognitive processes. The observed effects, however, are small. Reaction time changes or accuracy differences are generally about 10 %. These changes were all well within the normal ranges obtained using these measurements. Effects are inconsistent, subtle, transitory and specific for some aspects of cognitive functioning, without clear dose-response relationship and difficult to reproduce. It is difficult to state whether the observed effects are simply chance effects. They occur for the majority of the subjects tested and when a high number of subjects participate in the study.Also the observed effects are not due to stress induced by perception of the fields by the volunteers because they are not susceptible to independent field perception. Finally, study reports indicate that weak 50-60 Hz EF and/or MF exposure might affect some aspects of attention, memory or time perception processes without affecting the total capacity of information processing or the global arousal level.

One consistent phenomenon of laboratory studies is related to the absence of power-frequency EF and/or MF exposure effect on self-reported moods, often measured by mean of subjective scales.

Within the 2001-2005 BBEMG project, we performed the following tasks related to cognitive studies :

• Publication of a study realised within the previous BBEMG research agreement: Absence of daytime 50 Hz, 100 µT magnetic field or bright light (5.000 lux) exposure effect on human performance and psychophysiological parameters. (Crasson, M., Legros, J.J. (2005). Bioelectromagnetics 26:225-233).
• Realisation and publication of a study related to cognitive effects and pineal function effects of 50 Hz 400 µT magnetic field exposures. The aim of this study was to investigate cognitive effects of a vertical extremely low frequency (50 Hz) magnetic field (MF) exposure of 20 and 400 µT in healthy young men during cognitive performance tests. Thirty-two volunteers (20-30 years old) participated in this double blind study. The test protocol consisted of a set of tests: divided attention, flexibility, memory updating, digit span, digit span with articulary suppression, and time perception. The total duration of the exposure was 65 min. Participants were randomly assigned to one of four sessions: three conditions inside the helmet (sham exposure, 20 and 400 µT) and one condition outside the helmet (to control the expectancy effect). No effect of MF exposure was observed on performance or on the melatonin urinary metabolite excretion (aMT6s) during the night following each exposure condition.

  This study was also presented as a poster at the 6th International Congress of the European Bioelectromagnetics Association, 13-15 November 2003, Budapest, Hungary. (Delhez, M., Legros, J.J., Crasson, M. (2004). Bioelectromagnetics, 25 (8):592-598).
  

• Review of the literature on human psychophysiological and cognitive studies, published in Radiation Protection Dosimetry (Crasson, 2003): 50-60 Hz electric and magnetic field effects on cognitive function in humans : a review. (Crasson, M. (2003). Radiation Protection Dosimetry, 106 (4):333-340).

M. Crasson, P. Pirotte, F. Rogé, MT. Hagelstein, J.J. Legros

One of the premises of the “melatonin hypothesis” is that chronic exposure to 50-60 Hz magnetic fields suppresses the normal nocturnal synthesis of melatonin in the pineal gland. However, to date, no study has been published that addresses residential exposure to MF and pineal function. Moreover, the melatonin hypothesis has been extended to other pathological situations related to magnetic field exposure like psychological depression. In 1997, Beale and colleagues found significant linear dose-response relationships between residential exposure and some psychological and mental health variables. The goal of our study was to evaluate psychological well-being in relation to residential magnetic field exposure and to conjointly evaluate pineal function through measurements of urinary 6-sulfatoxymelatonin (aMT6s), the principal metabolite of pineal melatonin. Urinary excretion of aMT6s was measured for three periods of urine samples (19-23h, 23-07h, 07-11h). To investigate psychological well-being, we used the French version of the General Health Questionnaire (GHQ-28) (Goldberg and Williams, 1988). A life habits (including electrical apparatus use) and health status questionnaire was also developed specifically for this study.

The MF measurements were taken at three places in each room occupied for at least one hour per day to provide an estimate of total-time-integrated exposure and average exposure, in accordance with the Beale et al. (1997) methodology. Electrical consumption and measurements taken near some electrical appliances and near the energy meter were also recorded. 111 persons were initially included in this study. Completed data were obtained for 77 persons, which represent 50 households (mean age: 38 ± 13 years (from 19 to 70), 36 females, 41 males). Multiple regression analyses, including confounding factors like age, gender, and weight, did not indicate a significant correlation between the neuro-hormonal variable (aMT6s) or the GHQ-28 scores and MF parameters. However, one GHQ28 factor, social dysfunction, was positively associated with electrical consumption (kWh) (p=0.01). Using gender, age, and height as possible confounding variables, weight was correlated with many MF measurements (p> 0.0005), indicating that weight increases with MF exposure.

Conclusions : This preliminary study failed to demonstrate consistent alteration of pineal function and psychological well-being in humans exposed to different degrees and different sources of ELF magnetic fields at home. An unexpected result is the significant correlation between weight and MF.