Telecommniatons Health & Safety - High-Tension Transmission-Line Exposure of Pregnant Dairy Heifers

The question of whether effects of 735 kV AC high-tension power-transmission-line exposure are associated with the electric-field (EF) or magnetic-field (MF) component remains uncertain, because the observed effects of electric fields and magnetic fields are inconsistent. The discordant results may have been confounded by differences in the age, production status, and reproduction condition of the cattle used, and the various light regimes employed in different experiments. Nevertheless, it is interesting to note that exposure to only electric fields did not cause any change in body weight or weekly weight gain. However, animals increased in body weight and weekly body-weight gain when compared to control animals in similar experiments with lactating pregnant cows exposed to magnetic fields and electromagnetic fields. The consistency between body-weight gains of cattle exposed to magnetic fields and electromagnetic fields suggests a possible causal relationship between the magnetic-field exposure and the animal´s weight gain.