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Food and Chemical Toxicology : An... Sep 2020Data on the bioactivation of Phosmet (Pho), a phthalimide-derived organophosphate pesticide (OPT), to the neurotoxic metabolite Phosmet-oxon (PhOx) in human are not...
Data on the bioactivation of Phosmet (Pho), a phthalimide-derived organophosphate pesticide (OPT), to the neurotoxic metabolite Phosmet-oxon (PhOx) in human are not available. The characterization of the reaction in single human recombinant CYPs evidenced that the ranking of the intrinsic clearances was: 2C18>2C19>2B6>2C9>1A1>1A2>2D6>3A4>2A6. Considering the average human hepatic content, CYP2C19 contributed for the great majority (60%) at relevant exposure concentrations, while CYP2C9 (33%) and CYP3A4 (31%) were relevant at high substrate concentration. The dose-dependent role of the active isoforms was confirmed in human liver microsomes by using selective CYP inhibitors. This prominent role of CYP2C in oxon formation was not shared by other OPTs. The pre-systemic Pho bioactivation measured in human intestinal microsomes was relevant accounting for ¼ of that measured in the liver showing two reaction phases catalysed by CYP2C and CYP3A4. Phosmet efficiently inhibited CPF bioactivation and detoxication, with Ki values (≈30 μM) relevant to pesticide concentrations achievable in the human liver, while the opposite is unlikely (Ki ≈ 160 μM) at the actual exposure levels, depending on the peculiar isoform-specific Pho bioactivation. Kinetic information in humans can support the development of quantitative in vitro/in vivo extrapolation and in silico models for risk assessment refinement for single and multiple pesticides.
Topics: Chlorpyrifos; Cytochrome P-450 Enzyme System; Drug Interactions; Gene Expression Regulation, Enzymologic; Humans; Insecticides; Isoenzymes; Liver; Molecular Structure; Phosmet; Risk Assessment
PubMed: 32590074
DOI: 10.1016/j.fct.2020.111514 -
Pest Management Science Sep 2020Preventative application of insecticides reduces marketable yield losses caused by Drosophila suzukii females that selectively lay eggs into ripe and ripening fruits....
BACKGROUND
Preventative application of insecticides reduces marketable yield losses caused by Drosophila suzukii females that selectively lay eggs into ripe and ripening fruits. However, repeated applications of insecticides increase the risk of resistance development. It is therefore critical to test field-collected flies on-site to assess the level of sensitivity of D. suzukii to insecticides to monitor resistance, before it becomes a widespread issue. This requires that insecticide-treated vials be readily available to conduct bioassays. Thus, bioassays were conducted using malathion-, methomyl-, zeta-cypermethrin-, phosmet-, spinetoram- and spinosad-treated scintillation vials at 1 to 28 days after treatment to assess how residue age affects insecticide toxicity in scintillation vials. The impact of temperature on residue longevity was also assessed.
RESULTS
Insecticide-treated vials stored for 28 days provided reliable estimates of susceptibility of D. suzukii to some of the tested insecticides. The toxicity of malathion remained consistently high throughout the experiment followed by methomyl. However, toxicities of zeta-cypermethrin, phosmet were variable whereas those of the spinosyns declined relatively quickly. Overall, storage temperature did not affect the residual toxicity of most of the tested insecticides except zeta-cypermethrin.
CONCLUSION
These findings suggest that the toxicity of insecticide residues in treated vials remains active for ≤28 d for malathion and ≤21 and 28 days in methomyl-treated vials stored at 4 °C in Georgia and Michigan, respectively. However, the toxicities of spinosad, zeta-cypermethrin and phosmet were less consistent. Hence, vials treated with these insecticides should be freshly made to be effective for screening D. suzukii field populations for resistance. © 2020 Society of Chemical Industry.
Topics: Animals; Drosophila; Female; Insect Control; Insecticide Resistance; Insecticides; Longevity; Malathion
PubMed: 32356402
DOI: 10.1002/ps.5880 -
International Journal of Hygiene and... May 2020A number of epidemiologic studies with a variety of exposure assessment approaches have implicated pesticides as risk factors for childhood cancers. Here we explore the...
BACKGROUND
A number of epidemiologic studies with a variety of exposure assessment approaches have implicated pesticides as risk factors for childhood cancers. Here we explore the association of pesticide exposure in pregnancy and early childhood with childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) utilizing land use and pesticide use data in a sophisticated GIS tool.
METHODS
We identified cancer cases less than 6 years of age from the California Cancer Registry and cancer-free controls from birth certificates. Analyses were restricted to those living in rural areas and born 1998-2011, resulting in 162 cases of childhood leukemia and 9,805 controls. Possible carcinogens were selected from the Environmental Protection Agency's classifications and pesticide use was collected from the California Department of Pesticide Regulation's (CDPR) Pesticide Use Reporting (PUR) system and linked to land-use surveys. Exposures for subjects were assessed using a 4000m buffer around the geocoded residential addresses at birth. Unconditional logistic and hierarchical regression models were used to assess individual pesticide and pesticide class associations.
RESULTS
We observed elevated risks for ALL with exposure to any carcinogenic pesticide (adjusted Odds Ratio (aOR): 2.83, 95% CI: 1.67-4.82), diuron (Single-pesticide model, adjusted (OR): 2.38, 95% CI: 1.57-3.60), phosmet (OR: 2.10, 95% CI: 1.46-3.02), kresoxim-methyl (OR: 1.77, 95% CI: 1.14-2.75), and propanil (OR: 2.58, 95% CI: 1.44-4.63). Analyses based on chemical classes showed elevated risks for the group of 2,6-dinitroanilines (OR: 2.50, 95% CI: 1.56-3.99), anilides (OR: 2.16, 95% CI: 1.38-3.36), and ureas (OR: 2.18, 95% CI: 1.42-3.34).
CONCLUSION
Our findings suggest that in rural areas of California exposure to certain pesticides or pesticide classes during pregnancy due to residential proximity to agricultural applications may increase the risk of childhood ALL and AML. Future studies into the mechanisms of carcinogenicity of these pesticides may be beneficial.
Topics: Adult; California; Case-Control Studies; Child, Preschool; Female; Humans; Infant; Infant, Newborn; Leukemia, Myeloid, Acute; Male; Maternal Exposure; Maternal-Fetal Exchange; Pesticides; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Pregnancy; Prenatal Exposure Delayed Effects; Young Adult
PubMed: 32087503
DOI: 10.1016/j.ijheh.2020.113486 -
Aquatic Toxicology (Amsterdam,... Apr 2020For decades, organophosphate (OP) insecticides have been used as chemical control agents in watersheds that support at-risk populations of Pacific salmon throughout...
For decades, organophosphate (OP) insecticides have been used as chemical control agents in watersheds that support at-risk populations of Pacific salmon throughout western North America. Spray drift, runoff, and other processes transport OPs to critical surface water habitats for migratory salmonids. While most OPs share a common mechanism of action (i.e., inhibition of neuronal acetylcholinesterase, or AChE), they typically vary in toxic potency. Moreover, dose-response relationships for exposure and sublethal neurotoxicity (e.g., brain AChE inhibition) in salmonids have not been defined for many OPs. Here we exposed juvenile coho salmon (Oncorhynchus kisutch) to five common anticholinesterase insecticides (dimethoate, ethoprop, naled, phorate and phosmet) that are widely used on agricultural, commercial, residential, and public lands. Each of the five pesticides produced a concentration-dependent inhibition of AChE enzyme activity. The effective concentration for 50 % AChE inhibition (96-hr EC) indicated the highest toxicity for phorate (EC = 0.57 μg/L) followed by phosmet (3.3 μg/L), naled (7.8 μg/L), ethoprop (90.6 μg/L) and dimethoate (273 μg/L). These findings can inform 1) relative hazard analyses for OP use near sensitive aquatic habitats, 2) predictions of sublethal OP mixture toxicity, and 3) ecological risk assessments for threatened or endangered species of Pacific salmon.
Topics: Acetylcholinesterase; Animals; Brain; Cholinesterase Inhibitors; Fisheries; Insecticides; Oncorhynchus kisutch; Organophosphorus Compounds; Washington; Water Pollutants, Chemical
PubMed: 32058876
DOI: 10.1016/j.aquatox.2020.105424 -
Analytica Chimica Acta Mar 2020A facile strategy was developed for the fabrication of a magnetic covalent organic framework (COF) via grafting of the monomers, 2,5-dihydroxyterephthalaldehyde (Dt) and...
A facile strategy was developed for the fabrication of a magnetic covalent organic framework (COF) via grafting of the monomers, 2,5-dihydroxyterephthalaldehyde (Dt) and 1,3,5-tris(4-aminophenyl) benzene (Tb) onto surface-modified FeO nanoparticles. The magnetic COF, named as magnetic COF-DtTb, was readily fabricated without high temperature or harsh reaction conditions. The synthesized magnetic COF-DtTb nanoparticles were fully characterized, presenting a regular core-shell spherical structure, large specific surface area, superparamagnetism, and good thermal stability. Their potential as an enrichment adsorbent was investigated to establish an efficient magnetic solid-phase extraction method for the determination of organophosphorus pesticide residues in fruits. Systematic method validation revealed good linearity in the concentration range of 1-200 μg L (correlation coefficient >0.9957). The method limits of detection were in the range of 0.002-0.063 μg kg, the method limit of quantification was 1.00 μg kg and recoveries ranged from 72.8% to 111% with RSDs lower than 12.3%. The results indicated that magnetic COF-DtTb possesses superior trace enrichment properties for organophosphorus pesticides in fruits.
Topics: Adsorption; Chromatography, Liquid; Coumaphos; Fruit; Limit of Detection; Magnetite Nanoparticles; Metal-Organic Frameworks; Organothiophosphorus Compounds; Pesticide Residues; Phosmet; Solid Phase Extraction; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry
PubMed: 32029120
DOI: 10.1016/j.aca.2019.12.012 -
Nanotechnology Apr 2020Self-assembled polymersomes encapsulate, protect, and deliver hydrophobic and hydrophilic drugs. Though spherical polymersomes are effective, early studies suggest that...
Self-assembled polymersomes encapsulate, protect, and deliver hydrophobic and hydrophilic drugs. Though spherical polymersomes are effective, early studies suggest that non-spherical structures may enhance specificity of delivery and uptake due to similarity to endogenous uptake targets. Here we describe a method to obtain persistent non-spherical shapes, prolates, via osmotic pressure and the effect of prolates on uptake behavior. Polyethylene glycol-b-poly(lactic acid) polymersomes change in diameter from 145 ± 6 nm to 191 ± 1 nm and increase in polydispersity from 0.05 ± 0.02 to 0.12 ± 0.01 nm after addition of 50 mM salt. Transmission and scanning electron microscopy confirm changes from spheres to prolates. Prolate-like polymersomes maintain their shape in 50 mM NaCl for seven days. Nile Red and bovine serum albumin-Fluorescein dyes are taken up in greater amounts by SH-SY5Y neural cells when encapsulated in polymersomes. Prolate polymersomes may be taken up more efficiently in neural cells than spherical polymersomes.
Topics: Cell Line; Drug Carriers; Humans; Hydrophobic and Hydrophilic Interactions; Insecticides; Microscopy, Electron, Scanning; Nanoparticles; Particle Size; Phosmet
PubMed: 31940601
DOI: 10.1088/1361-6528/ab6bf1 -
Food Chemistry May 2020There have been increasing concerns among consumers about pesticide residues in Oolong tea. This study aimed to establish surface-enhanced Raman scattering (SERS) method...
There have been increasing concerns among consumers about pesticide residues in Oolong tea. This study aimed to establish surface-enhanced Raman scattering (SERS) method for rapid measurement of chemical contaminants in Oolong tea. Synthesis of SERS substrate was achieved by synthesizing silver nanoparticles (AgNPs) via a reduction method. AgNPs were spherical and highly monodispersed, which created remarkable electromagnetic fields during SERS activities to measure phosmet in the methanol-water solution and Oolong tea. Partial least squares regression models were established to predict the concentrations of phosmet in the methanol-water solution (r = 0.934; slope = 0.880; RMSEP = 1.001 mg/L) and Oolong tea samples (r = 0.927; slope = 0.938; RMSEP = 1.157 mg/kg) with the detection limit of 0.1 mg/kg. The results indicate that SERS coupled with silver nanoparticles is a fast, sensitive, and reliable method for detection and characterization of pesticide contaminants in Oolong tea products.
Topics: Color; Least-Squares Analysis; Limit of Detection; Metal Nanoparticles; Pesticide Residues; Phosmet; Silver; Spectrum Analysis, Raman; Tea
PubMed: 31896459
DOI: 10.1016/j.foodchem.2019.126016 -
Ecotoxicology (London, England) Jan 2020Use of pesticides in agroecosystems is considered a major cause of bees diversity losses in the Neotropics, where Plebeia emerina (Friese) and Tetragonisca fiebrigi...
Use of pesticides in agroecosystems is considered a major cause of bees diversity losses in the Neotropics, where Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) (Hymenoptera: Apidae: Meliponini) are wild pollinators of native and crop plants. The aim of this study was to know the acute lethal toxicity of acetamiprid, malathion, phosmet and spinosad insecticides on P. emerina and T. fiebrigi. We obtained the mean concentration and mean lethal dose (LC and LD) and the mean survival of workers after oral and topical exposure to insecticides, respectively. The LC values (ng a.i./μl of diet) and the decreasing order of toxicity for P. emerina was spinosad (4.96) > malathion (18.75) > phosmet (97.33) > acetamiprid (4204.06), and for T. fiebrigi also was spinosad (5.65) > malathion (8.39) > phosmet (53.91) > acetamiprid (9841.32), when orally exposed. The LD values (ng a.i./bee) and the decreasing order of toxicity for P. emerina was spinosad (1.90) > malathion (10.90) > phosmet (19.54) > acetamiprid (6216.55) and for T. fiebrigi was malathion (29.29) ≥ spinosad (29.79) > phosmet (41.95) > acetamiprid (1421.23), when topically exposed. The mean survival (hours) of contaminated bees by malathion, phosmet, and spinosad, was 11.81, 7.20, and 12.32 for P. emerina and 8.55, 7.20, and 13.34 for T. fiebrigi when orally exposed; and was 4.87, 9.87 and 11.17 for P. emerina, and 4.87, 4.76, and 19.05 for T. fiebrigi when topically exposed. Malathion, phosmet, and spinosad were highly toxic, while acetamiprid was moderately toxic. Our results indicated that the insecticides tested, mainly malathion, phosmet, and spinosad may be harmful to P. emerina and T. fiebrigi, making it essential to propose measures to minimize their impact on wild pollinators.
Topics: Animals; Bees; Drug Combinations; Hymenoptera; Insecticides; Lethal Dose 50; Macrolides; Malathion; Neonicotinoids; Pollination
PubMed: 31863232
DOI: 10.1007/s10646-019-02150-x -
Nanomaterials (Basel, Switzerland) Dec 2019Nanostructures with spikes (NSPs) have been a subject of several surface-enhanced Raman scattering (SERS) applications owing to their significant Raman signal...
Nanostructures with spikes (NSPs) have been a subject of several surface-enhanced Raman scattering (SERS) applications owing to their significant Raman signal enhancement brought about by the combined effects of interspike coupling and the accumulated induction on the tips of spikes. Thus, NSPs offer great potential as a SERS-active substrate for relevant applications that require a high density of enhanced "hot spots". In this study, Ag NSPs were synthesized in varying degrees of agglomeration and were thereafter deposited onto a transparent adhesive tape as a flexible substrate for SERS applications, specifically, in the detection of trace amounts of pesticides. These flexible substrates were referred to as Ag NSPs/tape and optimized with an enhancement factor (EF) of ca. 1.7 × 10. A strong resulting signal enhancement could be attributed to an optimal degree of agglomeration and, consequently, the distances among/between spikes. Long spikes on the synthesized core of Ag NSPs tend to be loosely spaced, which are suitable in detecting relatively large molecules that could access the spaces among the spikes where "hot spots" are generally formed. Since one side of the transparent tape is adhesive, the paste-and-peel off method was successful in obtaining phosmet and carbaryl residues from apple peels as reflected in the acquired SERS spectra. In situ trace detection of the pesticides at low concentrations down to 10 M could be demonstrated. In situ trace detection of mixed pesticides was possible as the characteristic peaks of both pesticides were observed in equimolar mixtures of the analytes at 10 to 10 M. This study is, thus, premised upon applying for in situ trace detection on e.g., fruit skin.
PubMed: 31835301
DOI: 10.3390/nano9121750 -
Pest Management Science Apr 2020Insecticide applications in blueberry production systems play a crucial role in the control of Drosophila suzukii populations. Here, quantitative spray deposition...
BACKGROUND
Insecticide applications in blueberry production systems play a crucial role in the control of Drosophila suzukii populations. Here, quantitative spray deposition patterns were obtained under replicated field experiments in blueberry during two field seasons with three sprayers, i.e. cannon, electrostatic, and air-blast. Seven insecticides were tested (at 6 hours using a Potter spray tower) to determine the mortality data for adult D. suzukii. Spray deposition and mortality data for adult D. suzukii were used to create model simulations for insect populations. Model simulations included field deposition rates of sprayers and insecticide mortality as factors. Simulations were applied in different combinations with five applications over a 6-week period.
RESULTS
Relative deposition rates for the cannon sprayer were elevated in the upper zones of the canopy, whereas for the air-blast sprayer, deposition was greater in the bottom zones. Electrostatic spray deposition was relatively uniform within the six canopy zones. Clear trends in D. suzukii laboratory mortality were found with lowest to highest mortality recorded for phosmet, spinetoram, spinosad, malathion, cyantraniliprole, zeta-cypermethrin, and methomyl respectively. Maximum D. suzukii population impacts, as shown by model outputs, were observed with air-blast sprayers together with zeta-cypermethrin.
CONCLUSION
The electrostatic sprayer had the least variable canopy deposition among the three types of spray equipment, and the air-blast sprayer had the highest overall deposition rates. This study provides new hypotheses that can be used for field verification with these spray technologies and insecticides as key factors. © 2019 Society of Chemical Industry.
Topics: Animals; Blueberry Plants; Drosophila; Insect Control; Insecticides; Malathion
PubMed: 31692223
DOI: 10.1002/ps.5672