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Toxicology and Applied Pharmacology Sep 2014Methamidophos (MET) is a highly toxic organophosphate (OP) pesticide that is widely used in developing countries. MET has male reproductive effects, including decreased...
Methamidophos (MET) is a highly toxic organophosphate (OP) pesticide that is widely used in developing countries. MET has male reproductive effects, including decreased fertility. We evaluated MET effects on sperm quality, fertilization and DNA integrity, exploring the sensitivity of different stages of spermatogenesis. Adult male mice received MET (3.75 or 5mg/kg-bw/ip/day/4 days) and were euthanized 1, 28 or 45 days post-treatment (dpt) to evaluate MET's effects on epididymal maturation, meiosis or mitosis, respectively. Spermatozoa were obtained from the cauda epididymis-vas deferens and were evaluated for sperm quality, acrosome reaction (AR; Coomassie staining), mitochondrial membrane potential (by JC-1), DNA damage (comet assay), oxidative damage (malondialdehyde (MDA) production), in vitro fertilization and protein phosphorylation (immunodetection), and erythrocyte acetylcholinesterase (AChE) activity. At 1-dpt, MET inhibited AChE (43-57%) and increased abnormal cells (6%). While at 28- and 45-dpt, sperm motility and viability were significantly reduced with an increasing MET dose, and abnormal morphology increased at 5mg/kg/day/4 days. MDA and mitochondrial activity were not affected at any dose or time. DNA damage (OTM and %DNA) was observed at 5mg/kg/day/4 days in a time-dependent manner, whereas both parameters were altered in cells from mice exposed to 3.75 mg/kg/day/4 days only at 28-dpt. Depending on the time of collection, initial-, spontaneous- and induced-AR were altered at 5mg/kg/day/4 days, and the fertilization capacity also decreased. Sperm phosphorylation (at serine and tyrosine residues) was observed at all time points. Data suggest that meiosis and mitosis are the more sensitive stages of spermatogenesis for MET reproductive toxicity compared to epididymal maturation.
Topics: Acetylcholinesterase; Acrosome Reaction; Animals; Body Weight; Comet Assay; DNA Replication; Female; Fertilization; In Vitro Techniques; Infertility, Male; Insecticides; Lipid Peroxidation; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred ICR; Oocytes; Organ Size; Organothiophosphorus Compounds; Oxidative Stress; Phosphorylation; Reproduction; Spermatogenesis; Spermatozoa
PubMed: 24998973
DOI: 10.1016/j.taap.2014.06.017 -
Mikrochimica Acta Feb 2024A reliable, rapid, and inexpensive nano-sized chemosensor is presented for methamidophos (MET) - an insecticide. Poly(lactic acid) (PLA)-stabilized gold...
A reliable, rapid, and inexpensive nano-sized chemosensor is presented for methamidophos (MET) - an insecticide. Poly(lactic acid) (PLA)-stabilized gold nanoparticles (AuNPs) were synthesized by a simple one-pot, two-phase chemical reduction method. The synthesized PLA-AuNPs were subsequently employed for selective, efficient, and quantitative detection of MET. MET is one of the highly toxic pesticides used for eradication of agricultural and urban insects. Upon the addition of MET, the wine-red color of PLA-AuNPs swiftly transformed into greyish-blue, further corroborated by a significant bathochromic and hyperchromic shift in the SPR band. The presence of other interfering insecticides, metal salts, and drugs did not have any pronounced effect on quantitative MET detection. The detection limit, the quantification limit, and linear dynamic range of MET utilizing PLA-AuNPs were 0.0027 µM, 0.005 µM, and 0.005-1000 µM, respectively. The PLA-AuNP-based assay renders an efficient, rapid, accurate, and selective quantification of MET in food, biological, and environmental samples. The proposed sensor provides an appropriate platform for fast and on-the-spot determination of MET without requiring a well-equipped lab setup.
Topics: Gold; Insecticides; Colorimetry; Metal Nanoparticles; Polyesters; Organothiophosphorus Compounds
PubMed: 38413405
DOI: 10.1007/s00604-024-06237-z -
Salud Publica de Mexico Jun 2021Objective. Evaluate compliance with the maximum permissible limits for pesticide residues in food in the state of Veracruz, as well as the risk to human health due to...
Objective. Evaluate compliance with the maximum permissible limits for pesticide residues in food in the state of Veracruz, as well as the risk to human health due to its consumption. Materials and methods. The concentration of pesticide residues in plant products were measured for comparison with the values established as safety limits and the regulatory framework for the use of pesticides. The hazard quotient and its possible effect on health were calculated. Results. 14.8% of the samples exceeded the allowed concentration. We found banned pesticides (methamidophos, monochotophos, triazophos and chlorpyrifos) that exceeded the established references dose, which increase the risk of possible neurological, hepatotoxic and endocrine alterations in health. Conclusions. There is the presence of highly hazardous pesticides, which are prohibited by international environmental conventions due to their impact on health and the environment, which is why their elimination is necessary. The regulatory framework in Mexico must be updated and dynamic as the knowledge of the adverse health effects of pesticides advances.
Topics: Food Contamination; Humans; Mexico; Pesticide Residues; Pesticides; Risk Assessment
PubMed: 35077103
DOI: 10.21149/12297 -
Chemical Research in Toxicology Sep 2016There is a pressing need for new therapeutics to reactivate covalently inactivated acetylcholinesterase (AChE) due to exposure to organophosphorus (OP) compounds....
There is a pressing need for new therapeutics to reactivate covalently inactivated acetylcholinesterase (AChE) due to exposure to organophosphorus (OP) compounds. Current reactivation therapeutics (RTs) are not broad-spectrum and suffer from other liabilities, specifically the inability to cross the blood-brain-barrier. Additionally, the chemical diversity of available therapeutics is small, limiting opportunities for structure-activity relationship (SAR) studies to aid in the design of more effective compounds. In order to find new starting points for the development of oxime-containing therapeutic reactivators and to increase our base of knowledge, we have employed a combination of computational and experimental procedures to identify additional compounds with the real or potential ability to reactivate AChE while augmenting and complementing current knowledge. Computational methods were used to identify previously uninvestigated oxime-containing molecules. Experimentally, six compounds were found with reactivation capabilities comparable to, or exceeding, those of 2-pralidoxime (2-PAM) against a panel of AChE inactivated by paraoxon, diisopropylfluorophosphate (DFP), fenamiphos, and methamidophos. One compound showed enhanced reactivation ability against DFP and fenamiphos, the least tractable of these OPs to be reactivated.
Topics: Acetylcholinesterase; Computer Simulation; Databases, Chemical; Enzyme Activation; Erythrocytes; Humans; Molecular Structure; Organophosphorus Compounds; Oximes; Pralidoxime Compounds; Structure-Activity Relationship
PubMed: 27494215
DOI: 10.1021/acs.chemrestox.6b00198 -
The Science of the Total Environment Mar 2020Amounts of banned and current pesticides have been used in domestic and agricultural pest control, and their residues have accumulated along the waste stream. In this...
Amounts of banned and current pesticides have been used in domestic and agricultural pest control, and their residues have accumulated along the waste stream. In this work, pesticides were characterized in concentrated leachates (CLs) from 5 municipal landfill sites, 2 incineration plants and 1 composting plant in six provinces. A total of 31 pesticides were detected which included 8 organochlorine pesticides (OCPs, 303-2974 ng/L), 16 organophosphorus pesticides (OPPs, 1380-13,274 ng/L) and 7 synthetic pyrethroids (SPs, 319-5636 ng/L). Despite the ten years ban of hexachlorocyclohexane, methamidophos and parathion-methyl, they were still in CL at a mean value of 320 ng/L and 88 ng/L, respectively. The average ΣOCPs, ΣOPPs and ΣSPs in CL from landfill sites were approximately 2.8, 1.1 and 4.5 times higher than those from incineration plants, which might have been influenced by pH, moisture and/or HRT. Additionally, it was found that CL from incineration plants and composting plant with lower pesticide contents posed a much higher acute and chronic eco-risk. Methamidophos was the dominant pesticide in CL from incineration plants, which was much higher than any other pesticides detected. The annual emissions of ΣOCPs, ΣOPPs and ΣSPs discharged from landfill-CL were estimated to be 2370, 10,357 and 2994 g, respectively. It was evident from the study that long-term release of CL after waste disposal could cause potential risk of ecological pollution.
PubMed: 31923666
DOI: 10.1016/j.scitotenv.2019.136287 -
Food and Chemical Toxicology : An... Oct 2016A major pathway for exposure to many pesticides is through diet. The objectives were to rank pesticides by comparing their calculated daily dietary exposure as...
A major pathway for exposure to many pesticides is through diet. The objectives were to rank pesticides by comparing their calculated daily dietary exposure as determined by EPA's Stochastic Human Exposure and Dose Simulation (SHEDS) to single pesticides for different age groups to acceptable daily intakes (ADI), characterize pesticide trends in exposures over different time periods, and determine commodities contributing to pesticide exposures. SHEDS was applied, using Pesticide Data Program (PDP) (1991-2011) and pesticide usage data on crops from USDA combined with NHANES dietary consumption data, to generate exposure estimates by age group. ADI data collected from EPA, WHO, and other sources were used to rank pesticides based on relativeness of the dietary exposure potential to ADI by age groups. Sensitivity analysis provided trends in pesticide exposures. Within SHEDS, commodities contributing the majority of pesticides with greatest exposure potential were determined. The results indicated that the highest ranking pesticides were methamidophos and diazinon which exceeded 100% of the ADI. Sensitivity analysis indicated that exposure to methamidophos, diazinon, malathion, ethion and formetanate hydrochloride had a marked decrease from 1991-1999 to 2000-2011. Contributions analysis indicated that apples, mushroom, carrots, and lettuce contributed to diazinon exposure. Beans and pepper contributed to methamidophos exposure.
Topics: Adolescent; Adult; Age Factors; Child; Child, Preschool; Environmental Exposure; Feeding Behavior; Food Contamination; Humans; Infant; Infant, Newborn; Middle Aged; Models, Statistical; Pesticides; Stochastic Processes; Young Adult
PubMed: 27497764
DOI: 10.1016/j.fct.2016.07.025 -
Toxicology Apr 2016Organophosphorus (OP) and N-methylcarbamate pesticides inhibit acetylcholinesterase (AChE), but differences in metabolism and detoxication can influence potency of these... (Comparative Study)
Comparative Study
Organophosphorus (OP) and N-methylcarbamate pesticides inhibit acetylcholinesterase (AChE), but differences in metabolism and detoxication can influence potency of these pesticides across and within species. Carboxylesterase (CaE) and A-esterase (paraoxonase, PON1) are considered factors underlying age-related sensitivity differences. We used an in vitro system to measure detoxication of AChE-inhibiting pesticides mediated via these esterases. Recombinant human AChE was used as a bioassay of inhibitor concentration following incubation with detoxifying tissue: liver plus Ca(+2) (to stimulate PON1s, measuring activity of both esterases) or EGTA (to inhibit PON1s, thereby measuring CaE activity). AChE inhibitory concentrations of aldicarb, chlorpyrifos oxon, malaoxon, methamidophos, oxamyl, paraoxon, and methylparaoxon were incubated with liver homogenates from adult male rat or one of 20 commercially provided human (11-83 years of age) liver samples. Detoxication was defined as the difference in inhibition produced by the pesticide alone and inhibition measured in combination with liver plus Ca(+2) or liver plus EGTA. Generally, rat liver produced more detoxication than did the human samples. There were large detoxication differences across human samples for some pesticides (especially malaoxon, chlorpyrifos oxon) but not for others (e.g., aldicarb, methamidophos); for the most part these differences did not correlate with age or sex. Chlorpyrifos oxon was fully detoxified only in the presence of Ca(+2) in both rat and human livers. Detoxication of paraoxon and methylparaoxon in rat liver was greater with Ca(+2), but humans showed less differentiation than rats between Ca(+2) and EGTA conditions. This suggests the importance of PON1 detoxication for these three OPs in the rat, but mostly only for chlorpyrifos oxon in human samples. Malaoxon was detoxified similarly with Ca(+2) or EGTA, and the differences across humans correlated with metabolism of p-nitrophenyl acetate, a substrate for CaEs. This suggests the importance of CaEs in malaoxon detoxication. Understanding these individual differences in detoxication can inform human variability in pesticide sensitivity.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Aryldialkylphosphatase; Calcium; Calcium Chelating Agents; Carboxylesterase; Child; Cholinesterase Inhibitors; Egtazic Acid; Female; Humans; Insecticides; Liver; Male; Middle Aged; Nitrophenols; Rats; Rats, Long-Evans; Species Specificity; Young Adult
PubMed: 27132127
DOI: 10.1016/j.tox.2016.04.006 -
Toxicology Letters Feb 2016There is an ongoing debate about the benefit of fresh frozen plasma (FFP) infusion in organophosphorus (OP) pesticide-poisoned patients. This prompted us to investigate...
There is an ongoing debate about the benefit of fresh frozen plasma (FFP) infusion in organophosphorus (OP) pesticide-poisoned patients. This prompted us to investigate the kinetics of OP pesticide degradation by FFP with an enzymatic assay in vitro. Degradation was rapid with shortest half-lives of 19.5s for chlorpyrifos-oxon, 6.3min for paraoxon-ethyl and 17.9min for dichlorvos. Heptenophos (78.0min), mevinphos (101.8min), profenofos (162.3min) and malaoxon (179.7min) showed half-lives of up to 3h. Substantial longer degradation half-lives of 69.7-80.8h were determined with chlorfenvinphos and bromfenvinphos. Methamidophos and omethoate showed no degradation by FFP indicated by half-lives similar to spontaneous hydrolysis. In conclusion, degradation by FFP depends on the particular OP pesticide and the used FFP batch.
Topics: Aryldialkylphosphatase; Carboxylic Ester Hydrolases; Half-Life; Humans; Hydrolysis; Kinetics; Pesticides; Plasma
PubMed: 26220518
DOI: 10.1016/j.toxlet.2015.07.014 -
Journal of Insect Science (Online) 2015Arthropods are an important group of macroorganisms that work to maintain ecosystem health. Despite the agricultural benefits of chemical control against arthropod...
Arthropods are an important group of macroorganisms that work to maintain ecosystem health. Despite the agricultural benefits of chemical control against arthropod pests, insecticides can cause environmental damage. We examined the effects of one and two applications of the insecticides chlorfenapyr (0.18 liters a.i. ha-1) and methamidophos (0.45 liters a.i. ha-1), both independently and in combination, on arthropods in plots of common bean. The experiment was repeated for two growing seasons. Principal response curve, richness estimator, and Shannon-Wiener diversity index analyses were performed. The insecticides generally affected the frequency, richness, diversity, and relative abundance of the arthropods. In addition, the arthropods did not experience recovery after the insecticide applications. The results suggest that the insecticide impacts were sufficiently drastic to eliminate many taxa from the studied common bean plots.
Topics: Agriculture; Animals; Arthropods; Biodiversity; Brazil; Ecosystem; Fabaceae; Insecticides; Organothiophosphorus Compounds; Pyrethrins
PubMed: 25700537
DOI: 10.1093/jisesa/ieu172 -
Journal of Veterinary Emergency and... 2023To discuss the clinical presentation and successful treatment of a suspected case of intermediate syndrome due to organophosphate (OP) poisoning in a dog.
OBJECTIVE
To discuss the clinical presentation and successful treatment of a suspected case of intermediate syndrome due to organophosphate (OP) poisoning in a dog.
CASE SUMMARY
Two dogs presented with acute cholinergic signs after ingesting an OP insecticide containing 50% acephate. Clinical signs consistent with acute cholinergic crisis resolved in both dogs within 24 hours postingestion. One dog developed an onset of neurological signs consistent with intermediate syndrome approximately 24 hours postingestion. This patient's clinical signs resolved with the use of pralidoxime chloride.
NEW OR UNIQUE INFORMATION PROVIDED
OP poisoning most commonly presents as an acute cholinergic crisis, with rare instances of animals developing intermediate syndrome. Few reports of successful treatment and recovery from intermediate syndrome exist in the veterinary literature, particularly with instances in which 2 dogs within the same exposure setting were treated for acute cholinergic signs and only 1 progressed to an intermediate syndrome. This report also highlights the importance of early intervention with pralidoxime chloride prior to the onset of aging.
Topics: Dogs; Animals; Organophosphate Poisoning; Pralidoxime Compounds; Insecticides; Cholinergic Agents; Poisoning; Dog Diseases
PubMed: 37943072
DOI: 10.1111/vec.13342