United States
Environmental Protection
Agency
Health Effects
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S1-88/004 Nov. 1988
Project Summary
Cerebellar Histogenesis in Rats
Exposed to 2450 MHz
Microwave Radiation
Ernest N. Albert
Pregnant rats were either exposed
or sham exposed to 2450 MHz
linearly polarized microwaves at 10
mW/cm2. A third matching group
served as cage control. Pregnant
animals were exposed from day 13 of
gestation until birth. Subsequently,
the pups were kept with their
mothers for 21 days without any
treatment
The brains of the new born rats
were fixed by perfusion at age 20 or
21 with 10% buffered formalin and
cerebella prepared for histological
analysis. The results showed that
there was a statistically significant
difference in the cerebellar area
among the three exposure groups.
When data from the sexes were
analyzed separately, statistical
significance was seen among the
groups only in the females and not in
the males. Purkinje cell density was
not significantly different (P>0.05)
among the three exposure groups.
However, Purkinje cell density in the
females was highest in the
microwave exposed rats and lowest
in the cage controls.
It appears that the significant
differences in the cerebellar area
among the three exposure groups,
may not be attributed to microwave
exposure. Instead the positive results
may be from some other factor in
experimental design which could not
be identified but which differentiated
the cage controls from both
exposure groups.
This report was submitted In
fulfillment of contract number 68-
02-4149 under sponsorship of the
U.S. Environmental Protection
Agency. This report covers a period
from September 29, 1985 to
September 30,1988.
This Project Summary was
developed by EPA's Health Effects
Research Laboratory, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
Controversial evidence exists
regarding possible deleterious effects of
non-ionizing radiation on the
development of the brain. This
investigation was designed to examine
whether microwave radiation during
pregnancy would affect development of
the rat cerebellum. Particular emphasis
was placed on the density of cerebellar
Purkinje cells and cerebellar area.
Experimental Procedures
Three groups of pregnant rats formed
the basis of this study. Group A was
exposed to 2450 MHz microwave
radiation at 10 mW/cm2 for 21 hours
daily starting on day thirteen of
pregnancy and terminating at delivery.
Group B was sham exposed. Group C
served as cage controls and therefore
was not handled daily as groups A and B.
After delivery the rat pups were kept with
their mothers for 20 or 21 days. At this
point brains of one male and one female
pup from each litter were prepared for
microscopic examination. Purkinje cells
from 5 sections of each brain were
counted. The cerebellar cortical area was
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also measured in the five sections from
each brain. Purkinje cell density was
expressed as cells per mm2 for each
animal. Analysis of variance (ANOVA)
was performed for the three groups.
ANOVA was also performed among
males and females within each group.
Results and Discussion
Tables 1 through 3 show the
cerebellar data on rat Purkinje cells from
the experimental group (Group A), sham
exposed group (Group B) and the cage
control group (Group C). The number of
rat pups in group A,B,and C were twelve,
ten and eight, respectively. There were
equal numbers of males and females in
each group. The differences in group
size were due to failure of two dams in
each exposure group to deliver and
damage of brains during technical
histological procedures.
The results of ANOVA are shown in
Table 4. It is apparent from Table 4 that
there is a significant difference in
cerebellar area among the three
experimental groups. When the sexes
were analyzed separately for cerebellar
area, only females demonstrated
significant differences. Cerebellar area in
males was not significantly different
among the three groups. The Purkinje
cell density was not statistically different
among the three groups. However,
Purkinje cell density showed a trend of
being highest in the microwave exposed
female rats and lowest in the cage
control female rats.
From the above results it appears that
the significant results recorded are
probably due to factors other than
exposure to microwaves. The nature of
extraneous experimental artifacts that
may be responsible for the cerebellar
area differences are not clear at present.
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Table 1. Rat Cerebellar Purkinje Cell Data for
Microwave Exposed Rats
Sex
Males Females
Both
Purkinje cell
Density/mm2
Cerebellar area
(mm2)
44.37
±2.03
6.34
±0.59
50.67
±2.66
5.95
±1.31
47.52
±1.77
6.15
±.95
Table 4. ANOVA - F Values and Significance, P
i. Area, all animals
for degrees of freedom of 2 and 26:
F = 3.41
*P < 0.05
2. Cell density. aU animals
for degrees of freedom of 2 and 26: F - 2.00
P > 0.05
3. Area, males
for degrees of freedom of 2 and 12: F =• .29
P > 0.05
Area, females
for degrees of freedom of 2 and 11:
F - 5.44
*P < 0.05
Table 2. Cerebellar Purkinje Cell Data for Sham
Exposed Rats
Sex
Males Females
Purkinje cell 49.53
Density/mm2 ± .84
Cerebellar area
(mm2)
6.85
±.63
44.60
±1.90
6.93
±.40
Both
47.30
±.90
6.89
±.27
Table 3. Rat Cerebellar Purkinje Cell Data for
Cage Control Rats
Cell density, males
for degrees of freedom of 2 and 12: F - 2.20
P > 0.05
Cell density, females
for degrees of freedom of 2 and 11: F =* 3.84
P > 0.05
Significant at P< 0.05.
Sex
Males Females
Both
Purkinje cell
Density/mm2
Cerebellar area
(mm2)
45.30
±2.22
6.65
±1.38
39.45
±1.80
8.35
±1.26
42.38
±1.84
7.50
±1.07
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Ernes/ N. Albert is with Cheung Laboratories, Inc. Lanham-Seabrook, MD
20706-2217.
Michael Gage is the EPA Project Officer (see below).
The complete report, entitled "Cerebellar Histogenesis in Rats Exposed to 2450
MHz Microwave Radiation," (Order No. PB 88-243 878IAS; Cost: $12.95,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S1 -88/004
0000329 PS
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