investigators have exposed immature animals to EMFs and studied their impact on growth rate. Rats
exposed to an intermittent EMF at 3 GHz, 153 µW/cm2, exhibited a smaller weight gain than the
control animals (31). The difference became statistically significant after 4 months' exposure, and it
persisted during the subsequent 3 months' exposure.
Noval et al. (32), studied the effect on growth rate of rats of exposure to 0.5-100 v/m, 45 Hz, as
compared to the growth rate of control rats maintained under Farady-cage conditions. He found a
consistent depression of the body weights of the exposed animals, even for fields as low as 0.5 v/m
(Table 8.6). Low-frequency fields-electric and magnetic-also produced growth depression in 25-day-
old chicks (33).
Table 8.6. CHANGES IN AVERAGE BODY WEIGHTS OF RATS EXPOSED TO 45-HZ VERTICAL
By the mid-190's, no studies had been done to assess the possible impact on successive
generations of animals of the continuous presence of a low-frequency EMF; we therefore undertook
such a study (34). Initially, mature male and female mice were split into horizontal, vertical, and
control groups. Mice in the horizontal group were allowed to mate, gestate, deliver, and rear their
offspring in a horizontal 60-Hz electric field of 10 kv/m. At maturity, randomly selected individuals
from the first generation were similarly allowed to mate and rear their offspring while being
continuously exposed. Randomly selected individuals from the second generation were then mated to
produce the third and final generation. A parallel procedure was followed for the vertical group
wherein three generations were produced in a 60 Hz vertical electric field of 15 kv/m, and for the
control group wherein three generations were produced in the ambient !laboratory electric field. In the
first and second generations, males and females reared i both the horizontal and vertical electric field
were significantly smaller than the controls when weighed at 35 days after birth In the third generation,
the only group whose body weights were significantly affected were the males exposed to the vertical
field. In both the second and third generation, a large mortality rate in the vertical-field mice was seen
during the 8-35 day postpartum period. We repeated the multi-generation study at 3 .5 kv/m using an
improved exposure system (55) (Fig. 8.2 and 8.3). In the first generation, no consistent effect on body
weight attributable to the EMF was seen throughout a 63-day observation period. In both the vertical
and horizontal groups, however, infant mortality was increased; in the vertical-control group 48
animals (about 17%) died between birth and weaning. In the vertical-exposed group, if the electric field
wasn't a causative factor, a 17% mortality rate should also have been seen. However, that group
exhibited a 31% mortality-82 animals died and not the expected 44. Thus, 38 animals, about 16% of
ELECTROMAGNETISM & LIFE - 110