Applications in environmental risk assessment of biochemical analysis on the Indian fresh water fish, Labeo rohita exposed to monocrotophos pesticide.

Pesticides are widely used in modern agriculture to aid in the production of high quality food. However, some pesticides have the potential to cause serious health and environmental damage. Repeated exposure to sub-lethal doses of pesticides can cause physiological and behavioral changes in fish that reduce populations such as abandonment of nests and broods, decreased immunity to disease and increased failure to avoid predators. Monocrotophos is one of the organophosphorus pesticide used in this study. The median lethal concentration (LC50) of Monocrotophos to fish L. rohita for 96h was found to be 45.1ppm. In sublethal concentration (1/10th of LC50 96h value, 4.51ppm) fishes were exposed for 24, 48, 72, 96h and 10, 20 and 30days. Organs of fishes were sacrificed and tested for biochemical analysis. A significant decrease in protein, carbohydrate and lipids were observed throughout the study period when compared to the control. It is essential for assessing the ecological risk of these pesticides.

Cytogenotoxicity assessment of monocrotophos and butachlor at single and combined chronic exposures in the fish Catla catla (Hamilton).

Cytogenotoxic effects in the form of micronuclei and deformed nucleus, nuclear buds, binucleated cells, vacuolated nucleus, vacuolated cytoplasm, echinocytes, and enucleus induced by two compounds belonging to two different chemical classes of agrochemicals (monocrotophos and butachlor) at sublethal concentrations (0.625, 1.3, and 2.3 ppm and 0.016, 0.032, and 0.064 ppm) in single and combined chronic exposures were studied under laboratory conditions for a period of 35 days in the economically important Indian fish Catla catla. Statistically significant duration-dependent increases in the frequencies of micronucleus (MN) and other cytological anomalies were observed. Compared to single exposures, a twofold increase in micronuclei frequency was noted at combined exposures indicating the synergistic phenomenon. Binucleated and enucleated cells appeared only in fishes exposed to sublethal concentrations of butachlor. The present study is the first of its kind in exploring a significant positive correlation between micronuclei and other nuclear anomalies suggesting them as new possible biomarkers of genotoxicity after agrochemical exposures. The study highlights the sensitivity of the assay in exploring various predictive biomarkers of genotoxic and cytotoxic events and also elicits the synergistic effects of agrochemicals in apparently healthy fishes. C. catla can be considered as a suitable aquatic biomonitoring sentinel species of contaminated water bodies.

Oral exposure to the organophosphorus insecticide, Monocrotophos induces intestinal dysfunction in rats.

There is limited experimental evidence to imply the role of organophosphorus insecticides on intestinal dysfunctions. Residues of Monocrotophos (MCP), above maximum residue limits (MRL), have been reported in fruits and vegetables from various parts of India. Hence, in this study, we investigated the potential of MCP to induce intestinal dysfunction in rats. MCP was administered orally to rats at sublethal doses (0.45, 0.9 and 1.8 mg/kgb.w/d) for 30 days. MCP at the highest dose significantly increased the unit weight of the small intestine. MCP increased the activities of intestinal brush border disaccharidases, intestinal alkaline phosphatase, glycyl-glycine dipeptidase, and Na(+)/K(+)-ATPase while it decreased cholesterol: phospholipid ratio. Histology and scanning electron microscopy of small intestine of MCP treated rats revealed disruption in terms of congestion, increased length of villi, goblet cell hyperplasia, infiltration of inflammatory cells and necrotic villi tip. Further, the intestinal transit rate was found to be increased in MCP treated rats. Collectively, our findings provide evidence that repeated oral intake of MCP has the propensity to alter small intestinal structure and functions, which might lead to intestinal dysfunctions and abnormal nutrient uptake and thereby affect the human health. Although we have employed doses, which are higher than those likely to be encountered as residues, we speculate that further studies should be performed to determine whether MCP residues in foods in the long-term will interfere with the digestive capacity of the small intestine and thus exert adverse effects on the health of human.

Evaluation of micronuclei induction capacity and mutagenicity of organochlorine and organophosphate pesticides.

The genotoxic and mutagenic effects of two commonly used organochlorine pesticides, lindane (LND) and endosulfan (ENS), and two commonly used organophosphate pesticides, chlorpyrifos (CPF) and monocrotophos (MCP) were assessed using in vivo mouse bone marrow micronucleus test and in vitro Ames Salmonella/ microsome mutagenicity test. The results showed that these pesticides alone or in combination, induced significantly high frequency of micronuclei (MN) formation that increased with concentration of pesticides. All these four pesticides produced significant increase in the frequencies of micronucleated-polychromatic erythrocytes (MN-PCE) and decrease infrequencies of PCE in dose-dependent manner. The results indicate the suppression of proliferative activity of the bone marrow and increase in the extent of cell death. ENS and MCP showed mutagenic potential in Salmonella/ microsome assay. ENS induced mutagenic and nontoxic response only in TA98 tester strain of S.typhimurium at the dose of 500 µg/plate and in the absence of metabolic activation. MCP showed weak mutagenic and nontoxic effect only in TA100 tester strain at the dose of 5000 µg/plate in both assays, with or without metabolic activation when compared with negative control. MCP was toxic in TA98 tester strain at the dose of 5000 µg/plate in absence of metabolic activation while reduction in toxicity was seen on addition of S9 mixture. The study clearly showed the genotoxic potential of all these four pesticides and mutagenic response of endosulfan and monocrotophos.

Exposure to monocrotophos pesticide during sexual development causes the feminization/demasculinization of the reproductive traits and a reduction in the reproductive success of male guppies (Poecilia reticulata).

Monocrotophos is a highly toxic organophosphorus pesticide that has been confirmed to be an endocrine-disrupting chemical. To evaluate the influence of this pollutant on the reproductive system of male fish, we studied the sex steroid levels, reproductive traits, sex ratio, and reproductive success in male guppies (Poecilia reticulata) exposed to 40% monocrotophos pesticide at the nominal concentrations of 0.01, 0.10, and 1.00 mg/L for 90 days from birth to adulthood in a semi-static exposure system. Radioimmunoassay and western blot analyses demonstrated that the long-term exposure to monocrotophos pesticide during the sexual development of male guppies caused a significant increase in 17ß-estradiol levels and consequently induced vitellogenin synthesis, suggesting the feminization of the males. Monocrotophos pesticide also caused a significant decrease in testosterone levels, which consequently inhibited testis growth and reduced the sperm count and the area and intensity of their sexually attractive orange spots, which collectively indicated the significant demasculinization of the male sexual characteristics. Furthermore, these changes in the sexual characteristics at the cellular and organ levels translated into ecologically important effects on the reproductive success at the individual level, as measured by a decrease in offspring production and survival rate. The present study provides the first evidence that monocrotophos pesticide can cause severe reproductive abnormalities in fish due to its endocrine-disrupting action.

Cytotoxicity assessment of monocrotophos in Paramecium caudatum and Oxytricha fallax.

Experiments were conducted to evaluate the toxic effects ofmonocrotophos in ciliate models Paramecium caudatum and Oxytricha fallax. In acute toxicity studies higherconcentrations of monocrotophos caused marked increase in mobility of cells exhibiting rocking movements within two mins of exposure but were decreased after 30 mins. LC50 value by mortality curve for 3 hr acute toxicity test of Oxytricha fallax and Paramecium caudatum was found 307.744 +/- 33.27 mg l(-1) and 332.284 +/- 57.52 mg l(-1) respectively. Oxytricha fallax was found sensitive than Paramecium caudatum to monocrotophos. In acute exposure cells showed deformities such as swelling, oval shaped deformity and in higher concentrations shortening of longitudinal axis with blackening of cytoplasm occurred. The length of paramecia was reduced prominently. Similarly enlargement of contractile vacuole and stress egestion of food vacuoles was also observed. The morphological studies showed the changes in shape, size, colour and width of Paramecia and Oxytricha. Frequencies of macronuclear aberrations were significant showing deformities such as rod shaped, elongation, fragmentation, diffusion and total absence of nucleus and were concentration dependent. The data provided in the present study on interaction of pesticides with nuclear structure can be of immense value because most of these pesticides have been reported to have carcinogenic, mutagenic and teratogenic properties.

Efficacy of trimedoxime in mice poisoned with dichlorvos, heptenophos or monocrotophos.

The aim of the study was to examine antidotal potency of trimedoxime in mice poisoned with three direct dimethoxy-substituted organophosphorus inhibitors. In order to assess the protective efficacy of trimedoxime against dichlorvos, heptenophos or monocrotophos, median effective doses and efficacy half-times were calculated. Trimedoxime (24 mg/kg intravenously) was injected 5 min. before 1.3 LD50 intravenously of poisons. Activities of brain, diaphragmal and erythrocyte acetylcholinesterase, as well as of plasma carboxylesterases were determined at different time intervals (10, 40 and 60 min.) after administration of the antidotes. Protective effect of trimedoxime decreased according to the following order: monocrotophos > heptenophos > dichlorvos. Administration of the oxime produced a significant reactivation of central and peripheral acetylcholinesterase inhibited with dichlorvos and heptenophos, with the exception of erythrocyte acetylcholinesterase inhibited by heptenophos. Surprisingly, trimedoxime did not induce reactivation of monocrotophos-inhibited acetylcholinesterase in any of the tissues tested. These organophosphorus compounds produced a significant inhibition of plasma carboxylesterase activity, while administration of trimedoxime led to regeneration of the enzyme activity. The same dose of trimedoxime assured survival of experimental animals poisoned by all three organophosphorus compounds, although the biochemical findings were quite different.

Preparation and characterization of microcapsules of water-soluble pesticide monocrotophos using polyurethane as carrier material.

Microencapsulation of the water soluble pesticide monocrotophos (MCR), using polyurethane (PU) as the carrier polymer, has been developed using two types of steric stabilizers, namely PLMA macrodiol and PLMA-g-PEO graft copolymer. The microencapsulation process is carried out in non-aqueous medium and at a moderate temperature to avoid any chemical degradation of monocrotophos during the encapsulation process. Microcapsules were characterized by optical microscopy and SEM for particle size and morphology, respectively. The effects of loading of MCR, crosslinking density of PU, and nature of steric stabilizer on the release of MCR from PU microcapsules have been studied.

Detection of DNA damage in mouse peripheral blood leukocytes by the comet assay after oral administration of monocrotophos.

The objective of this study was to determine if single/double strand DNA breaks could be induced by monocrotophos (organophosphorus pesticide) in mice in vivo using the comet assay. Mice were dosed orally with 0.046, 0.093, 0.186, 0.373 and 0.746 mg/kg body weight of monocrotophos, and the assay was performed on whole blood after 24, 48 and 72 h. A significant increase in mean comet tail length indicating DNA damage was observed at 24 and 48 h post-treatment with monocrotophos when compared to controls. A decrease in the mean tail length was observed at 72 h post-treatment indicating repair of the damaged DNA. The mean tail length showed a dose-related increase and time dependent decrease. The study reveals that comet assay is a sensitive and rapid method to detect genotoxicity of monocrotophos.