Effect of methamidophos on the morphology and male reproductive parameters of the earthworm eisenia foetida / Efecto del metamidofos sobre la morfología y parámetros reproductivos espermáticos de la lombriz de tierra eisenia foetida

The earthworm Eisenia foetida (Annelida, Oligochaeta) is an excellent biosentinel model organism for assessing potential toxicological risks by xenobiotics in terrestrial ecosystems. Methamidophos is an organophosphorous insecticide widely used to control agricultural pests. Its main action is due to inhibition of the enzyme acetylcholinesterase. The aim of this study was to evaluate the toxicity of methamidophos on the morphology and male parameters in Eisenia foetida. After determining the LD50 for methamidophos (85.34 mg/kg soil), five groups were formed, including control subjects, and sprayed with tap water. Methamidophos treated groups were subjected to doses of 1/10, 1/6, 1/3 and 2/3 of the LD50. Each group was analyzed at day 1, 6, 14 and 30 post-treatment. The results show a significant decrease in the weight of all individuals treated with methamidophos, besides showing a coiled body in 100 percent of them. Sperm count showed a significant increase in the treated groups after 1, 6 and 14 days post exposure and a significant decrease by day 30. Using the technique of acridine orange, a significant increase in abnormal metachromatic sperm (red fluorescence) in treated animals was shown. Methamidophos alters the overall behavior in earthworms and the male reproductive parameters of Eisenia foetida possibly altering the structure and conformation of DNA.

La Lombriz de tierra, Eisenia foetida (Annelida, Oligochaeta), constituye un excelente modelo de organismo biocentinela para evaluar los riesgos tóxicos de xenobióticos, en ecosistemas terrestres. Metamidofos es un insecticida organofosforado de amplio uso para controlar plagas agrícolas. Su acción principal se debe a la inhibición de la enzima acetilcolinesterasa. El objetivo de este estudio fue evaluar la toxicidad de metamidofos sobre la morfología y parámetros espermáticos de Eisenia foetida. Una vez determinada la LD50 para metamidofos (85,34 mg/kg de tierra), se tomaron 5 grupos, entre ellos los individuos del grupo control, los cuales fueron asperjados con agua potable. Los grupos tratados con metamidofos fueron sometidos a dosis de 1/10, 1/6, 1/3 y 2/3 de la LD50. Cada grupo fue analizado al día 1, 6, 14, y 30 post tratamiento. Los resultados muestran una baja significativa en el peso de todos los individuos tratados con metamidofos, además de presentar enrrollamiento corporal, en el 100 por ciento de ellos. El recuento espermático presenta un aumento significativo en los grupos tratados a 1,6 y 14 días, para luego decaer significativamente el día 30. El uso de la técnica del naranja de acridina, mostró un aumento significativo de espermatozoides metacromáticos anormales en los animales tratados (fluorescencia de color rojo). Se concluye que Metamidofos altera el comportamiento general de la lombriz de tierra y los parámetros reproductivos espermáticos de Eisenia foetida posiblemente alterando la conformación y estructura del ADN.

Effect of hemoperfusion on dearance of organophosphorus in rabbits poisoned by methamidophos / 中华急诊医学杂志

Objective To evaluate the clearance efficacy of resin hemoperfusion(HP) on the removal of organophosphorus in the rabbits poisoned by methamidophos(MAP) and its effects on organ injury. Method Six-teen healthy Japanese white rabbits were randomly divided into HP group and non-HP group. MAP was given through gastric tube in a dosage of 20 mg/kg to rabbits of both groups. Rabbits of liP group received resin hemop-ersion plus conventional treatment including early gastric lavage, atropine and pralidoxime. Rabbits of non-HP group received only conventional treatment. The plasma concentration of MAP was determined by using gas chro-matography before and after rabbits were poisoned at different intervals. Serum choline esterase (ChE),lactic de-hydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) of rabbits of both groups were assayed 6 hours after rabbits poisoned. Pathological changes in lung, liver, kidney and muscle were investigated simutaneously. SPSS 10.0 software was used for statistical analysis. The comparison between groups was carried out by using t -test. Results ① The typical symptoms of organophospborus poisoning were occurred in rabbits within 5 - 10 minutes after ingestion of MAP. In HP group, the plasma levels of rabbits before,and 30 min,60 min,90 min and 120 min after hemoperfu-sion were (11.43±1.56),(7.82±1.54),(4.97±1.58),(5.66±1.75) ,(5.49±1.68) μg/mL, respectively (P <0.01). After hemoperfusion, the plasma MAP levels of rabbits in HP group were lower than those in non-HP groups (P < 0.01). The improveme, nt of clinical presentation of rabbits was observed shortly after HP. ② The blood choline esterase activity of rabbits were depressed in hoth groups without significant difference. In contrast, the blood levels of ALT, AST,LDH,CK and CK-MB of rabbits in non-HP group elevated significantly than in HP group (P < 0.01). ③ The more severe injury of muscle, liver, kidnet and lung of rabbits can could be seen in non-HP group. Conclusions ① HP can effectively eliminate the plasma MAP and has the potential to improve the clinical presentation of intoxication in rabbits. ② Early intervention of Hp exerts a protection from organ dam-age of organophosphorus pesticide.

Cytogenetic and genotoxic effects of the insecticides, imidacloprid and methamidophos

We examined the cytogenetic and genotoxic effects of the neonicotinoid insecticide imidacloprid and the organophosphate insecticide methamidophos, when administered alone or in combination. These insecticides were tested with the bone marrow chromosome aberration assay and micronucleus test in rats and by the bacterial mutation assay (Salmonella/microsome mutagenicity assay). Wistar albino rats were orally fed daily with laboratory chow treated with various concentrations of insecticides, 50 and 100 mg/kg imidacloprid, 2.5 and 5 mg/kg methamidophos, and 2.5 and 5 mg/kg imidacloprid plus methamidophos, respectively, for 90 days. Numerical and structural chromosomal aberrations were evaluated. Significant differences were detected between all the insecticide-administered groups versus the control group and between the two concentrations of the pesticide-treated groups. Both concentrations of the insecticides induced a dose-related increase in the micronucleus frequency (P < 0.05). Dose-related increases in the number of revertants were observed with the two Salmonella strains (TA98 and TA100). All tested doses of the insecticides demonstrated mutagenic activity in the presence of S9 mix. These results lead us to the conclusion that the synergistic effect of methamidophos and imidacloprid causes an increase in potential damage to non-target organisms.

The in vitro effects of methamidophos on oxygen uptake, carbonic production

(MAP) on O2 uptake, CO2 production and rate of methemoglobin of human erythrocytes. The in vitro effects of methamidophos (MAP) on O2 uptake, CO2 production and rate of methemoglolin of human erythrocytes were studied: (1) after exposure of human erythrocytes to MAP at the concentrations from 1 to 10mM, only at concentration higher than 100mM of MAP in 37oC for 3 hours, the hemolysis was significantly induced. (2) at MAP concentrations between 1 and 10 mM, the significant increase of oxygen uptake and carbonic productions in human erythrocytes was seen. (3) At MAP concentrations between 1 and 10 mM, rate of methemoglobin in erythrocytes was increased significantly. These findings suggest that MAP act as oxidative chemical

Comparative Research on Removing Organophosphorus Pesticide Residues From Cucumber With Different Soak Water / 环境与健康杂志

Objective To evaluate the efficiency of different wash methods for removing organophosphorus pesticide residues from cucumber. Methods The cucumber samples were soaked with tap water, washed rice water, salt solution and detergent solution respectively for 2 to 15 minutes then organophosphorus pesticide residues in the soak water samples were determined with ultrasonic extraction and gas chromatography. Results Soaked in tap water for 2 to 5 minutes was the most effective and convenient way to remove methamidophos and dimethoate with the highest removing rate (about 70%). Conclusion Soaked with tap water for 2 to 5 minutes is more efficient for removing organophosphorus pesticide residues from vegetable.

Determination of Methamidophos in Human Serum by Gas Chromatography With Flame Photometric Detector / 环境与健康杂志

Objective To establish a simple and quick method to determine methamidophos in human serum samples. Methods The samples were extracted by acetone and were separated with centrifuge then were determined by gas chromatography (GC-FPD). Results The determine limit for methamidophos in human serum was 0.05 ng. The minimum determine concentration was 0.40 ?g/ml. Rate of recovery of methamidophos added in human serum were 90.5%-105.6%. The relative standard deviations (RSD) were 4.52%-6.63%. Conclusion This method is sensitive, accurate and reliable for the determination of methamidophos in human serum samples.