Chronic toxicity of a synthetic tri-aryl phosphate oil to fish.

Rainbow trout (Salmo gairdneri) were exposed to IMOL S-140, a synthetic high-temperature lubricating oil composed of tri-aryl phosphates and, although no sign of acute toxicity was evident, the fish slowly developed symptoms of chronic posioning. Thus, floating food pellets were refused, the activities of glutamic oxalacetic transaminase and lactate dehydrogenase in serum were greatly elevated, and internal fatty tissues became discoloured. Neither serum nor brain cholinesterase activities were inhibited.