CORTISOL SECRETION AND GROWTH IN EWE LAMBS CHRONICALLY EXPOSED TO ELECTRIC AND MAGNETIC-FIELDS OF A 60-HERTZ 500-KILOVOLT AC TRANSMISSION-LINE

A study was conducted to determine whether chronic exposure of ewe lam bs to the electric and magnetic fields (EMF) of a high-voltage ac tran smission line affected cortisol secretion and growth. Twenty Suffolk e we lambs were assigned randomly in equal numbers to a control and trea tment group. Treatment from 2 to 10 mo of age consisted of continuous exposure within the electrical environment of a 60-Hz, 500-kV transmis sion line (mean electric field 6 kV/m, mean magnetic field 40 mG). Tre ated lambs were confined directly beneath the transmission line; contr ol lambs were maintained in a pen of similar construction 229 m from t he line where the EMF were at ambient levels (mean electric field < 10 V/m, mean magnetic field < .3 mG). Cortisol was analyzed by RIA in se rum of blood samples collected at .5- to 3-h intervals over eight 48-h periods. All ewe lambs were weighed weekly and side-patch wool growth was measured biweekly. Cortisol secretion occurred in a circadian rhy thm; daytime serum concentrations were greater (P < .05) than nighttim e concentrations for both groups. Concentrations of cortisol did not d iffer between the control and exposed ewe lambs. Weight gain and wool fiber length and diameter also were not affected by treatment. These d ata suggest that chronic exposure of developing ewe lambs to 60-Hz env ironmental EMF does not affect concentrations of-cortisol secretion, b ody weight gain, and wool growth.