BENER Abstract No. 15078. ACUTE EXPOSURE TO 50 HZ MAGNETIC FIELD DOES NOT AFFECT HEMATOLOGIC OR IMMUNOLOGIC FUNCTIONS IN HEALTHY YOUNG MEN: A CIRCADIAN STUDY.
(Eng.) Selmaoui, B.; Bogdan, A.; Auzeby, A.; Lambrozo, J.; Touitou, Y. [Faculte de Medecine Pitie-Salpetriere, Service de Biochimie, Paris, France (B.S., A.B., A.A., Y.T.); Electricite de France -- Service des Etudes Medicales, Paris, France (J.L.); Faculte de Medicine Pitie-Salpetriere, Service de Biochimie, 91 Blvd. de l'Hopital, 75634 Paris Cedex 13, France (RR/Y.T.)] Bioelectromagnetics 17(5):364-372; 1996 (21 Refs).
The authors examined the effects of acute exposure to a 50-Hz magnetic field on circadian rhythmicity in human hematological and immune functions in 32 healthy males, mean age 24.7 yr. The participants had regular sleeping habits, no chronic disease or disability, had not had a recent acute illness, did not work nights, and had not traveled to another time zone within the last 2 mo. The subjects were divided into 2 groups of 16. One group was exposed to a continuous 50-Hz, 10-uT (100-mG) magnetic field from 23:00 to 08:00 hr during one night and to an intermittent 50-Hz, 10-uT linearly-polarized field during the same period on a second night. The schedule for the intermittent magnetic field was 1 hr "off" and 1 hr "on" during which the field was switched "on" and "off" every 15 sec. The other 16 subjects were sham-exposed. The experiment took place in a specially-designed laboratory consisting of 3 independent rooms and a shared bathroom. The exposed subjects slept in one room and the sham-exposed subjects slept in the second room. None of the subjects knew whether he was in the exposure or sham-exposure group. The experiment was conducted during 2 mo (mid-February to mid-April) to avoid possible seasonal variations. The experimental protocol studied 4 subjects per day, and each subject participated in two 24-hr sessions starting at 09:30 hr. The subjects slept in 90 x 200 cm wooden beds that were oriented along the north-south axis of the geomagnetic field. The geomagnetic field magnitude in the experimental area was 46 uT. The level of the background magnetic field was less than 40 nT (0.4 mG). The magnetic fields were generated by a system of 3 rectangular 120 x 140 cm Helmholtz-type coils spaced 80 cm apart and enclosed in wood. The coils were placed around each bed at the level of the head, crotch, and ankles with their horizontal axes parallel to that of the bed. The coils were energized by a Tollner generator and amplified by a Kepco amplifier that were controlled by a computerized system. The intermittent field was produced using the technique described by Graham et al. (Electric Power Res. Inst. Report No. TR-104278, 1994). The "on" and "off" switching operations were synchronized with passages at zero of the sine wave current to avoid any transient electric field. The 10 uT flux density was chosen to be representative of the average exposure that would be expected in occupational settings. Blood samples were collected from an indwelling antecubital vein catheter at 3-hr intervals between 11:00 and 20:00 hr and at hourly intervals from 22:00 to 08:00 hr. From midnight to 08:00 hr, the samples were obtained under dim light without waking the subjects who slept with eye masks. The samples were analyzed for: changes in hemoglobin; hematocrits; differential red blood cell, platelet, total leukocyte, monocyte, lymphocyte, eosinophil, and neutrophil counts; and, changes in lymphocyte subpopulation counts, such as CD3, CD4, CD8, natural killer, and B-cells. The data were tested statistically using analysis of variance for repeated measures. Neither the continuous nor the intermittent magnetic field significantly altered the hematological variables or the lymphocyte subpopulation cell counts. The profiles of the variables (plots of the value vs. time) for the exposed and sham-exposed subjects were nearly identical when superimposed. For example, the values of the erythrocyte parameters (red blood cell counts, hematocrit, and hemoglobin) peaked around 11:00 hr and those of the platelets peaked around 16:00 hr in both exposed and sham-exposed groups. The authors concluded that acute exposure to a continuous or intermittent 10-uT 50-Hz magnetic field does not alter the circadian profiles of hematological and immunologic functions in healthy young males, at least under these experimental conditions.
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