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

The use of experimental studies to reveal suspected neurotoxic chemicals as occupational hazards: acute and chronic exposures to organic solvents

The nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects. However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposure. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.

The effect of acute trichloroethylene exposure on electroretinogram components

The effects of acute exposure to trichloroethylene (TCE) on the electroretinogram (ERG) and oscillatory potentials (OPs) were studied on adult New Zealand rabbits anesthetized with urethane. The ERG and OPs were recorded under photopic conditions with a speculum electrode, with pupils fully dilated and the cornea anesthetized. Emulsified (Intralipid) TCE was given intravenously in three consecutive injections of equal volume for a total dose varying between 24 and 85 mg/kg. Averaged ERG and OPs (50 sweeps) were taken up to 250 minutes after the last TCE injection. Our results indicated that, irrespective of the dose used, there was a significant (p less than 0.001) reduction (average: 50%) in the amplitude of the b-wave of the ERG following TCE injection. In contrast, the OPs showed a differential effect. At low doses, OP4 showed a significant (p less than 0.001) reduction resulting in some cases to its complete extinction, while at higher dose there is a marked increase in amplitude. Our results would suggest that the OPs are a better retinal potential to assess the level of TCE toxicity than is the b-wave of the ERG.