The Joint Toxicity Evaluation Of Chiral Organophosphrus Pesticides Enantiomers

In this study, we evaluate the joint toxicity of chiral organophosphorus pesticides enantiomers, such as methamidophos, fensulfothion, profenofos with electriceel acetylcholinesterase (AChE) and daphnia magna. At the same time, the zebrafish embryonic developmental toxicity was assessed. All of these aimed to give a comprehensive information on the environmental safety. The related results are as follows:The IC₅₀ value showed that the acute toxicity of (-)-enantiomer of methamidophos and profenofos was significantly higher than (+)-enantiomer. While the (+)-enantiomer of fensulfothion was more potential than (-)-enantiomer to inhibit the activity of AChE. Results concerning on joint toxicity of chiral organophosphorus pesticides enantiomer to AChE activity showed that the two enantiomers of methamidophos and profenofos acted as a simple additive effect, while antagonism effect of fensulfothion enantiomers.Secondly, data on 24h acute toxicity of methamidophos, fensulfothion, profenofos enantiomers to daphnia magna were as followed: (+)-methamidophos>(-)-methamidophos, (+)-fensulfothion>(-)-fensulfothion and (-)-profenofos >(+)-profenofos. The results of the joint toxicity show that methamidophos and fensulfothion enantiomers are additive effect on daphnia magna. While synergistic effect was observed in the joint toxicity of profenofos enantiomers.Finally, according to OECD standards, we evaluated the enantioselective development toxicity on zebrafish embryonic with methamidophos, fensulfothion, profenofos. Among several endpoints, yolk sac edema could be seemed as an typical endpoint on zebrafish embryos at 48h. The toxic effect on yolk sac edema level showed as follow:(-)-methamidophos>(+)-methamidophos>(±)-methamidophos; (±)-fensulfothion > (+)-fensulfothion (-)-fensulfothion;(±)-profenofos> (+)-profenofos >(-)-profenofos.