Effects of Diazinon and Diazinon-HC1 Reaction Mixture On Acetylcholinesterase Activity In the Brain and Blood Plasma Of Rainbow Trout (Salmo gairdneri)

Abstract

Rainbow trout (Salmo gairdneri) were exposed to various concentrations of diazinon and diazinon-HC1 reaction mixture over a 64 hour period during which time the brain and blood plasma of the fish were analyzed for acetylcholinesterase (AChE) activity. The fish were placed into glass jars containing 14 liters of well water and were sampled at 4, 8, 16, 32, and 64 hours time periods; there were five treatments per time period and three replicates per treatment. The treatments consisted of a positive control, a negative control and three concentrations of diazinon or diazinon-HC1 reaction mixture. Test concentrations for diazinon were 0.1, 0.56, and 1.0 ppm., and 0.01, 0.032, and 0.056 70 volume for the diazinon-HC1 reaction mixture. The data collected indicated that the rate of absorption of diazinon and diazinon-HC1 reaction mixture increased rapidly during the first 16 hours and for the most part, remained at or near this level throughout the duration of the remaining test periods. However, the trout were more sensitive to the residual toxicity (due to an AChE inhibitor) in the diazinon-HC1 reaction mixture than to the diazinon. This was indicated by a 504 kill in the test population over a 64 hour period in the reaction mixture as opposed to 1870 mortality over the same period with diazinon.