农药混剂联合毒性评价

Assessment on acute toxicity of combined pesticides

用Harris法研究了3类杀虫剂(有机磷、拟除虫菊酯和氨基甲酸酯)的二元混剂对大鼠的急性毒性联合作用。涉及的有机磷类农药有:甲基对硫磷、氧乐果、甲胺磷、辛硫磷、敌敌畏、丙溴磷、马拉硫磷、水胺硫磷;拟除虫菊酯类农药有:高效氯氰菊酯、氰戊菊酯、甲氰菊酯、溴氰菊酯:氨基甲酸酯类农药有:灭多威、异丙威、速灭威等。有机磷+有机磷或有机磷+拟除虫菊酯混配的结果表明:敌敌畏+氧乐果、甲胺磷+丙溴磷混配时均为相加作用;辛硫磷+甲基对硫磷为拮抗作用;辛硫磷+溴氰菊酯、辛硫磷+高效氯氰菊酯、水胺硫磷+甲氰菊酯、甲基对硫磷+高效氯氰菊酯混配时毒性显著增加并呈现协同作用;辛硫磷+氰戊菊酯等虽属相加作用但毒性也有所增加;唯有溴氰菊酯+敌敌畏也属相加作用但毒性却略有降低。有机磷与氨基甲酸酯混配时马拉硫磷+异丙威呈协同作用,辛硫磷+灭多威、甲胺磷+速灭威属相加作用,但前者毒性有较大增加,后者毒性略有降低,而甲基对硫磷+灭多威呈拮抗作用。从毒代动力学、毒效动力学和所涉及的生化机制对所发生的联合作用的性质进行了讨论,认为有机磷与有机磷、有机磷与氨基甲酸酯类混配出现相加作用的较多,有机磷与拟除虫菊酯混配后则以出现协同作用或毒性增加的情况较多。

The acute oral toxicity (LD 50 ) of two pesticides combined from 3 categroies of insecticides,i.e. organophosphates(OPs),pyrethroids and carbamates,was evaluated by Harris method on equal toxicity doses.The OPs compounds studied included:methylparathion,omethoate,methamidophos,phoxim,dichlorvos,profenofos,isocarbophos and malathion;the pyrethroids:α cypermethrin,deltamethrin,fenvalerate and fenpropathrin;the carbamates:methomyl,isoprocarb and metolcarb.The mixtures of two OPs on the combination of dichlorvos plus omethoate and methamidophos plus profenofos showed additive effects,but methylparathion plus phoxim showed antagonistic effect.Most of the combinations of OPs with pyrethroids showed synergistic effects,such as the mixtures of phoxim plus deltamethrin,phoxim plus α cypermethrin,methlyparathion plus α cypermethrin and ioscoarbphos plus fenpropthrin,with the exception of two mixtures showed additive effects:phoxim plus fenvalerate resulting in 1 5 times higher toxicity than expected,while dichlorvos plus deltamethrin resulting in less toxicity than expected.The effects of the mixtures of OPs and carbamates:phoxim plus methomyl and methamidophos plus metolcarb,were all additive,but the mixtures of he methylparathion plus methomyl showed antagonistic effect and malathion plus isoprocarb were synergistic.The biochemical mechanisms of changed toxicity of pesiticides mixtures were disccussed based on their toxicokinetics and toxicodynamics.It was concluded that the combined effects of insecticide mixtures were additive for OPs plus OPs or plus carbamates in most cased,but synergistic for OPs plus pyrethroids.