Vollrath L, Spessert R, Kratzsch T, Keiner M, et al. (1997)
In this study both rats and hamsters were used. The animals were exposed to 900 MHz electromagnetic fields. Both continuous and pulsed (217 Hz) waves were used. The SARs were approximately 0.06 to 0.36 W/kg in rats and 0.04 W/kg in hamsters. Different periods of exposure, from 15 minutes to 6 hours, were employed. Pineal gland activity was measured in 3 ways - by serum melatonin levels, by pineal gland N-Acetyltransferase (NAT) level, and by pineal synaptic ribbon profile (SRP) numbers. NAT is an enzyme that controls the rate of synthesis of melatonin in the pineal gland. SRPs are structural bodies found in several locations including the pineal gland, and like melatonin they decrease in numbers after light exposure at night.
No significant changes were seen in pineal gland activity as a result of the EMF exposure.