Shielding Effects in Small Animal Exposure Systems

The shielding effects of cages used in biological studies of the effects of exposure to 60 Hz electric fields on small animals can reduce the apparent dosage to which the animals are subjected. This paper describes an experiment performed to determine the degree of cage shielding resulting from the combined effects of soiling of the cage walls by excretions from the animals occupying them and the relative humidity in which the system is operated. Data obtained indicates the level of cage shielding can become significant after a short period of animal occupation unless either the relative humidity is kept below 40% or the cages are frequently cleaned.