Enduring learning deficits and cerebral synaptic malformation from exposure to 10 parts of halothane per million.

Chronic exposure of rats to 10 parts of halothane per million during early life produced later deficits in learning a shock-motivated light-dark discrimination and a food-motivated maze pattern, correlated with enduring synaptic nembrane malformation in cerebral cortex. Adult exposure had no effect. Halothane may provide a useful analytical tool for study of brain. The behavioral-ultrastructural techniques also suggest a standard for assessing the safety of trace toxicants with central nervous system effects.