Studies On The Jointaction And Poisoning Mechanism Of The Organophosphorus And Pyrethroid Pesticides

1. Mixed insecticides, with the significant effect on enhancing insecticidal effect, postponing resistance development, decreasing mammalian toxicity and increasing economy benefit, have been an important formulation and broken into the pesticide market. It becomes a main stream in the pesticide industry in this country. There are four kinds of the mixed insecticides, of which the most common is the binary mixture derived from pyrethroid and organophosphorus insecticides. As the mixed pesticides are widely produced and used, the cases of acute poisoning have been increasing which has become an important occupational hazard to peasants and a problem of public health in this country, so scientists in the medical and environmental sciences are of great concern to the grand project. According to the research progress at home and abroad, this project was studied deeply and systematically in the joint action, toxicokinetics and poisoning mechanism of the organophosphorus and pyrethroid pesticides so as to provide scientific data for the control of the mixed pesticide-poisoning. 2. The common toxicity coefficients(C.T.C) on the mixtures of phoxim and fenvalerate,phoxim and cyhalothrin,cypermethrin and profenofos to the Larva with instars of cotton bollworm were 340,797 and 172,respectively,which exhibited significant insecticidal effects. The jointactions of the mixtures were assessed using Comparative Method of Expected and Experimental LD50 (E/O value) and Logistic Regression Method The increased insecticidal effects or synergistic effects were testified according to the fact that the E/O values were 2.67,1.71 and 1.91, l3values>0, and CTC of the mixtures to SD rat were 285,165 and 180, respectively 3. The toxicokinetics of fenvalerate and the mixture derived from fenvalerate and phoxim with gas chromatography showed that 1. concentration-time profiles were fitted to one-compartment open model with first order absorption, the main toxicokinetic parameters were respectively Ka=0.47h? Ke=0.19 W1, t1,(Ka)1.60h, t112(Ke)3.74h and Ke=0.04 h? t1(Ke)=21.70h (no lag time); 2. the elimination rate of fenvalerate was decreased, the metabolizability and exclusion of fenvalerate in rat body was retarded. So the acute toxicity of fenvalerate to mammal is increased after expoure to the mixture. The toxicokinetics of phoxim and the mixture of phoxim and fenvalerate with HIPLC showed that 1. concentration-time profiles were also fitted to one-compartment open model with first order absorption, the main toxicokinetic parameters were separately Ka1 .87h? Ke=0.47 h? t1^Ka=0.37h, t1^Ke=l 47h and Ka=4.33 h? Ke=0.07 h? t112(Ka)=0.lSh, t1,2(Ke)10.63h (with lag time); 2. as compared with expoure to single phoxim, the toxicokinetic findings after exposure to the mixture exhibited that absorption rate of phoxiin was significantly increased and half-life time of elimination phase was delayed and metabolic degeneration of phoxim was slowed because of fenvalerate involvement. These results could be used to explain a part of the jointaction mechanism of the increased insecticidal effects and toxicities resulted from the mixture. 4. By immunohistochemical method, the changes in glutamate(Glu) and gama- aminobutyric acid(GABA) immunoreactive cells were observed in the central nervous system of rats which were orally treated with fenvalerate(2omglkg), phoxim( 1 60mg/kg), and fenvalerate(2Omg/kg) plu...