The c-wave of the electroretinogram and the standing potential of the eye as highly sensitive measures of effects of low doses of trichloroethylene, methylchloroform, and halothane.

Low and moderate intravenous doses of trichloroethylene, methylchloroform, and halothane dissolved in a lipid emulsion (Intralipid) were given to cynomolgus monkeys. The DC electroretinogram (ERG) and the standing potential of the eye (SP) were recorded directly with corneal contact lenses, very stable calomel electrodes, and under very constant general anesthesia. Even low doses of the substances (close to the hygienic threshold limit values in Sweden) clearly provoked slow variations with time in the amplitude of the c-wave of the ERG and in the SP level. Both potentials are generated mainly in the pigment epithelium. It is suggested that the effects reflect a direct influence of the chemicals upon the metabolism of the pigment epithelium or on the cell membrane. Thus the method used is a highly sensitive measure of effects of certain halogenated hydrocarbons on structures belonging to the central nervous system.