Long-term effects of 60-Hz electric vs. magnetic fields on IL-1 and IL-2 activity in sheep

This study was designed to assess the effect of exposure to long-term extre mely low-frequency electric and magnetic fields (ELF-EMF) from a 500 kV tra nsmission line on IL-1 and IL-2 activity in sheep. The primary hypothesis w as that the reduction in IL-1 activity observed in our two previous short-t erm studies (10 months) was due to EMF exposure from this transmission line . To repeat and expand these studies and to characterize the components of EMF responsible for the previously observed reduction in IL-1 activity, the current experiment examined not only the effect of exposure to electric an d magnetic fields, but also the magnetic field component alone. In the curr ent study, IL-2 was examined to characterize the effects of EMF exposure an an indicator of T cell responses. 45 Suffolk ewe lambs were randomized int o three groups of 15 animals each. One group of animals was placed in the E MF pen, located directly beneath the transmission line. A second group was placed in the shielded MF (magnetic held only) pen, also directly beneath t he transmission line. The third group of animals was placed in the control pen located several hundred meters away from the transmission line. During the 27 month exposure period, blood samples were taken from all animals mon thly. When the data were analyzed collectively over time, no significant di fferences between the groups were found for IL-1 or IL-2 activity. In previ ous studies ewe lambs of 8-10 weeks of age were used as the study animals a nd significant differences in IL-1 activity were observed after exposure of these animals to EMF at mean magnetic fields of 3.5-3.8 muT (35-38 mG) and mean electric fields of 5.2-5.8 kV/m. At the start of the current study EM F levels were reduced as compared to previous studies. One interpretation o f the current data is that magnetic held strength and age of the animals ma y be important variables in determining whether EMF exposure will affect IL -1 activity. (C) 2001 Wiley-Liss, Inc.