Electroencephalography (E.E.G.) studies were performed on a group of R
attus norvegicus after exposing them to a chronic exposure of 50 ppm c
ommercial HCH. On day 9 of exposure, LV patterns of E.E.G. were obtain
ed in frontal, parietal and occipital regions of brain. E.E.G. normali
zed after 3 days of end of chronic exposure.