An evaluation of the teratogenic potential of protracted exposure of pregnant rats to 2450-MHz microwave radiation. II. Postnatal psychophysiologic analysis.

The objective of this study was to determine whether protracted prenatal exposure of rats to 2450-MHz microwave radiation at a power density level of 20 mW/cm2 would significantly alter postnatal growth and psychophysiologic development. Of 75 pregnant rats, 12 were exposed to microwave radiation, 4 sham-irradiated, and 59 served as environmental control animals. Forty-five females were allowed to deliver their offspring. The neonates were examined and weighed on d 3 and weekly thereafter until 87 d of age. Neonatal reflex tests were initiated as early as d 3 (surface righting, air righting, auditory startle, visual placing). One physiologic parameter, eye opening, was also observed. Mothers were rebred 10 d after weaning and a morphologic evaluation was completed on the second litter. Behavioral tests were begun at 60 d of age and included water T-maze, conditioned avoidance response, open field, activity wheel, forelimb hanging, and swimming. At 90 d of age offspring were bred within and across groups, and a morphologic teratologic analyses was completed on the offspring. Representative tissue samples were collected and organ weights recorded for the brain, liver, kidneys, and gonads of all animals. Analyses of the data indicated that there were no significant malformations or significant alterations in the neonatal physiologic or reflex test results, body/organ weight ratios, or breeding results in the adult offspring. There were no significant alterations in five of the six adult behavioral tests. There were significant differences in activity among the irradiated and control offspring between the sexes, the irradiated offspring being more active. These results are indicative of possible radiation-induced behavioral alterations. Further studies are needed to explore the possibility of microwave radiation-related alterations in animal behavior.