Development of chicken embryos in a pulsed magnetic field

Abstract

Six independent experiments of common design were performed in laboratories in Canada, Spain, Sweden, and the United States of America. Fertilized eggs of domestic chickens were incubated as controls or in a pulsed magnetic field (PMF); embryos were then examined for developmental anomalies. Identical equipment in each laboratory consisted of two incubators, each containing a Helmholtz coil and electronic devices to develop, control, and monitor the pulsed field and to monitor temperature, relative humidity, and vibrations. A unipolar, pulsed, magnetic field (500-microseconds pulse duration, 100 pulses per s, 1-microT peak density, and 2-microseconds rise and fall time) was applied to experimental eggs during 48 h of incubation. In each laboratory, ten eggs were simultaneously sham exposed in a control incubator (pulse generator not activated) while the PMF was applied to ten eggs in the other incubator. The procedure was repeated ten times in each laboratory, and incubators were alternately used as a control device or as an active source of the PMF. After a 48-h exposure, the eggs were evaluated for fertility. All embryos were then assayed in the blind for development, morphology, and stage of maturity. In five of six laboratories, more exposed embryos exhibited structural anomalies than did controls, although putatively significant differences were observed in only two laboratories (two-tailed Ps of .03 and less than .001), and the significance of the difference in a third laboratory was only marginal (two-tailed P = .08). When the data from all six laboratories are pooled, the difference in incidence of abnormalities in PMF-exposed embryos (approximately 25 percent) and that of controls (approximately 19 percent), although small, is highly significant, as is the interaction between incidence of abnormalities and laboratory site (both Ps less than .001). The factor or factors responsible for the marked variability of inter-laboratory differences are unknown.

Chromosome aberrations in lymphocytes of high-voltage laboratory cable splicers exposed to electromagnetic fields.

“…As for alcohol con sumption, use of prescribed medicine, infections durin g the last three month s, off-work chemica l expo sure, chroni c diseases, and diagnostic radiography, there were only minor differences between the exposed subjects and the matched referents. The mean expo sure time in cable testing was I I (range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] years; the test splicers had a mean emplo yment time of 12 years, and the corresponding value for the engineers was 9 years. Blood samples were collected by venipuncture.…”

“…The high est risk was observed for power statio n operators (proportionate mortality rat io 195). It has also been sug gested that pulsed magnetic fields produce teratogeni c effects in chicken em bryo s (4,5) In a hig h-voltage laboratory in Oslo, the management and workers were concerned abo ut several cases of cance r (although at variou s sites) among the em ployees . How ever , the number of workers ever employe d in the laborato ry was not sufficient for a ca ncer incidence study.…”

The Effect of Electromagnetic Fields with the Mg<sup>2+</sup> Cyclotron Frequency on Mouse Reproductive Performance

“…Alternatively, there is a wide body of evidence that electromagnetic field exposure induces noteworthy effects in vitro [29], including specific outcomes on processes that are related to embryogenesis [30]. With respect to in vivo studies, there are many reports on high frequency field exposure; however, fewer data are available regarding exposure to low frequency fields even though many positive reports are available [7].…”

Effects of low-frequency magnetic fields on embryonic development and pregnancy.

“…A larg e well-design ed intern ational study aimed at repli cat ing Delgad o ' s (10) results has been carried ou t in six separate lab oratories (26). Identical equipme nt and sta ndardized experiment al procedures were used.…”