Comparative toxicity, cholinergic effects, and tissue levels of S,S,S,-tri-n-butyl phosphorotrithioate (DEF) to channel catfish (ictalurus punctatus) and blue crabs (callinectes sapidus)

Abstract The acute neurotoxic effects of S , S , S -tri- n -butyl phosphorotrithioate (DEF) on juvenile channel catfish and adult blue crabs was examined using short-term exposures in aerated, static aquaria. The effects on acetylcholinesterase (AChE) activity in catfish brain and skeletal muscle, and in crab ganglia, was studied. In addition, recovery of AChE activity was followed after transferring the animals to DEF-free water. The results indicate that both species exhibit pronounced anticholinesterase effects due to DEF. Recovery of AChE activity is quite slow in nervous tissues of both animals and catfish skeletal muscle, with effects persisting for several weeks following a single acute exposure. Tissue levels of DEF, as well as its rate of disappearance, were followed in several tissues of each species. The highest levels were detected in fish liver, but high levels were also detected in fish brain. Levels in crab ganglia were an order of magnitude lower than those in fish brain, but the anticholinergic effects were similar in both species. Disappearance was biphasic from tissues in both animals, with relatively long half-lives in target tissues.