Mutagenesis
Rats were exposed for 7 hours/day to 50 and 500 µW/cm2, 2.4 GHz (total exposure of 1 and 10
days at the higher and lower intensities respectively) (41). At 50 µW/cm2, the number of chromosomal
abnormalities increased by 55 % compared to the controls when assayed 18 hours after the end of the
exposure period; 2 weeks after exposure the increase was 150% . Eighteen hours following exposure at
500 µW/cm2, the number of chromosomal abnormalities was more than 5 times that of the controls,
and it remained elevated (340%) even after z weeks. In a comparable study (42) (3 GHz, 3 500
µW/cm2, 3 hr./day for 3 mo.) mitotic disorders were seen in guinea-pig and rabbit Iymphocytes.
We studied the mutagenetic effect of 60 Hz electric fields on the cells of a free-floating
peritoneal-cavity tumor implanted in mature female mice (43, 44). The tumor was propagated in
control mice by injecting the host intraperitoneally with tumor-containing fluid that had been freshly
removed from an unexposed animal. After 14 days, a few drops of tumor were removed and the tumor
cells were processed for chromosomal analysis. Tumor propagation in the 2-week exposed groups was
identical except that the mice were exposed to DC electric fields of 8-16 kv/m. The tumor cells were
ordinarily lethal to the host about 3 weeks after injection. To propagate the tumor for longer periods it
was therefore necessary to transplant it to a new host every 7-14 days. Consequently, tumor cells
exposed for 4-15 weeks required serial inoculations into 2-9 continuously exposed mice. On the day the
chromosomal analysis was to be performed, the host was injected with colcemid to arrest cell division
in metaphase and allow direct visualization of the chromosomes. Cells exposed to horizontal EMFs for
2 weeks exhibited almost a threefold increase in the percentage of abnormal chromosomes when
compared to control cells (Table 8.9); cells exposed to vertical EMFs for the same period, however,
had a percentage of abnormal chromosomes comparable to that of the control cells. Extended exposure
to both EMFs appeared to produce opposite results. The percentage of cells with abnormal
chromosomes tended to decrease systematically in the horizontal EMF but increase systematically in
the vertical EMF. The number of mice analyzed prohibited a precise determination of the dependence
on exposure time, and in both cases, when the results were averaged over the entire extended exposure
period (4-15 weeks for the horizontal EMFs, and 6-15 weeks for the vertical EMFs), no statistically
significant results were seen (Table 8.9).
Table 8 .9. EFFECT OF DC ELECTRIC FIELDS IN THE RANGE 8-1 6 kv/m ON THE INCIDENCE
OF CHROMOSOMAL ABERRATIONS IN EHRLICH ASCITES TUMOR CELLS EXPOSED IN VIVO
ELECTROMAGNETISM & LIFE - 114