Teratogenic effects of exposure to radiofrequency radiation (27.12 MHz) from a shortwave diathermy unit.

The aim of this study was to determine whether the teratogenic effects of radiofrequency (RF) radiation are due to induced hyperthermia at 27.12 MHz. This was achieved by controlling the degree of temperature change and the duration of the elevation at this RF frequency. Pregnant Sprague-Dawley rats, at 9 days gestation were either sham-irradiated or irradiated with continuous shortwave radiation at 27.12 MHz. Rectal temperature, monitored by a thermistor probe was elevated by 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0°C for various durations.Sham-irradiation was associated with few resorptions, no malformations and a mean fetal weight of 3.7±0.60 g. Radiofrequency radiation induced fetal malformations (microphthalmia, encephalocele, facial clefting and maxillary hypoplasia) and embryolethality, the incidence increasing with the temperature elevation, while fetal weight decreased (+5.0°C = 2.5 ± 0.41 g). An elevation of 5.0°C for a few seconds was teratogenic, 4.5°C was teratogenic within 2 min ; 4.0°C-3 min, 3.5°C-15 min, 3.0°C-20 min and 2.5°C-60 min. These data are similar to those obtained by heating Sprague-Dawley rats on the same day of gestation in a water-bath1) indicating that the teratogenicity of RF radiation is primarily related to hyperthermia.