Prenatal exposure to an extremely low frequency‐low intensity rotating magnetic field and increases in thyroid and testicle weight in rats

Extremely low frequency (ELF) electromagnetic fields and waves (.1–40 Hz) Which occur daily in the environment, are associated with lightning discharges, atmospheric lability, solar eruptions, and geomagnetic micropulsations. In 3 experiments, adult rats that had been exposed to a .5–3 or 3–15 gauss ELF (.5 Hz) rotating magnetic field (RMF) during various periods of gestation, had significantly heavier thyroid and testicle weights than controls. The difference in these measures was a function of the field intensity and duration of exposure. Rats exposed prenatally to a sham‐RMF (no magnets) did not differ from controls in the above measures. No significant differences were found between the thymus weights, adrenal weights, blood sugar, or circulating blood eosinophil levels of RMF‐exposed and control rats. The implications of the thyroid and testicle changes are discussed in terms of the physiological and physicochemical effects of ELF electromagnetic phenomena.