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Scientific Reports Dec 2019Methyl bromide (MB), a dominant ozone-depleting substance, is scheduled to be completely phased out for soil fumigation by December 30th 2018, in China. The combined...
Methyl bromide (MB), a dominant ozone-depleting substance, is scheduled to be completely phased out for soil fumigation by December 30th 2018, in China. The combined effects of dimethyl disulfide (DMDS) plus metham sodium (MNa) were assessed in controlling soilborne pests for soil fumigation. A study was designed in laboratory for the evaluation of the efficacy of DMDS + MNa to control major soilborne pests. At the same time, two trials were conducted in cucumber field located in Tongzhou (in 2012) and Shunyi (in 2013), respectively, in order to assess the potential of DMDS + MNa in controlling soilborne pests. Laboratory studies disclosed positive synergistic effects of almost all four used combinations on Meloidogyne spp., Fusarium spp., Phytophthora spp., Abutilon theophrasti and Digitaria sanguinalis. Field trials found that DMDS + MNa (30 + 21 g a. i. m), both at a 50% reduced dose, effectively suppressed Meloidogyne spp. with a low root galling index (2.1% and 11.7%), significantly reduced the levels of Phytophthora and Fusarium spp. with a low root disease index (7.5% and 15.8%), gave very high cucumber yields (6.75 kg m and 10.03 kg m), and increased income for cucumber growers with the highest economic benefits (20.91 ¥ m and 23.58 ¥ m). The combination treatment provided similar results as MB standard dose treatment (40 g a. i. m) or DMDS standard dose treatment (60 g a. i. m) in pest control and yield, but was more effective than MNa standard dose treatment (42 g a. i. m). Usage of all chemical treatments gave better significant results than the untreated group of control. Considering the economic benefits, the DMDS plus MNa combination (30 + 21 g a. i. m) could be used for soil fumigation in cucumber production in China.
Topics: Animals; Cucumis sativus; Disulfides; Fumigation; Fusarium; Hydrocarbons, Brominated; Nematoda; Permeability; Pest Control; Phytophthora; Plant Diseases; Plant Roots; Soil Microbiology; Thiocarbamates; Tylenchoidea
PubMed: 31875039
DOI: 10.1038/s41598-019-56450-7 -
PloS One 2019Root-knot nematode is an important soil pest in horticulture crops and constrains the protected cultivation development after methyl bromide (MB) was phased out in...
Root-knot nematode is an important soil pest in horticulture crops and constrains the protected cultivation development after methyl bromide (MB) was phased out in China. Dimethyl disulfide (DMDS) exhibits excellent efficacy against nematodes. Laboratory experiments and field trials were set up to clarify DMDS dose, efficacy, and yield. A dose-response experiment using three methods showed that DMDS presented high efficacy against the nematode Meloidogyne incongnita. The LC50 values of direct fumigation activity in the dessicator method were 0.086 and 0.070 mg L-1 for DMDS and 1,3-D, 29.865 and 18.851 mg L-1 for DMDS and 1,3-D of direct contact activity in the small tube method, 6.438 and 3.061 mg L-1 for DMDS and 1,3-D of soil fumigation activity in the soil fumigation method, respectively. The field trials indicated that DMDS showed an excellent efficacy of 80%-94% on root-knot nematode applied at 10-100 g m-2 on tomato in Tongzhou, Beijing. The crop yields showed no significant difference after applying 10-80 g m-2 DMDS. Results indicate that DMDS applied at 10 g m-2 for controlling root-knot nematode in Beijing is cost effective. In conclusion, DMDS is an excellent soil fumigant that can be used for controlling root-knot nematode and can be an potential novel alternative to MB in China.
Topics: Animals; Antinematodal Agents; China; Disulfides; Dose-Response Relationship, Drug; Feasibility Studies; Fumigation; Soil; Tylenchoidea
PubMed: 31658285
DOI: 10.1371/journal.pone.0224456 -
Insects Sep 2019This study was conducted to evaluate the insecticidal effects of ethyl formate (EF), methyl bromide (MB), and phosphine (PH) fumigants against PH-susceptible and...
This study was conducted to evaluate the insecticidal effects of ethyl formate (EF), methyl bromide (MB), and phosphine (PH) fumigants against PH-susceptible and -resistant strains of the rice weevil (), a major rice pest. The highest lethal concentration time 50 (LCt) values of the PH-susceptible strains were 255.797, 21.104, and 6.171 mg h L for EF, MB, and PH, respectively, at pupal stage. The highest LCt values of the PH-resistant strains were 149.028 and 48.170 mg h L for EF and PH, respectively, at late larval stage, and 43.520 mg h L for MB at pupal stage. In comparison to the susceptible strains, the PH-resistant strain collected in South Korea had a resistance level 4 to 56 times higher. Use of the major quarantine fumigants EF, MB, and PH indicated the existence of PH-resistant rice weevils in South Korea for the first time.
PubMed: 31575082
DOI: 10.3390/insects10100327 -
Frontiers in Immunology 2019Farming and pesticide use have been associated with systemic autoimmune diseases, and while certain organochlorine insecticides and other pesticides are suspected to...
Farming and pesticide use have been associated with systemic autoimmune diseases, and while certain organochlorine insecticides and other pesticides are suspected to influence risk, the role of specific pesticides in the development of systemic autoimmunity is not known. We measured serum antinuclear autoantibodies (ANA) by immunofluorescence on Hep-2 cells in 668 male farmers in the study of Biomarkers of Exposure and Effect in Agriculture (BEEA; 2010-2013), an Agricultural Health Study (AHS) subcohort. We examined ANA in relation to lifetime use of 46 pesticides first reported at AHS enrollment (1993-1997) and updated at intervals through BEEA enrollment. Odds ratios (OR) and 95% confidence intervals (CI) were estimated after adjusting for age, state, education, season of blood draw, current pesticide use, and correlated pesticides. Having ANA antibodies (3 or 4+ intensity at a 1:80 dilution, 21% of study participants) was associated with a reported history of seeking medical care due to exposure to pesticides (OR 2.15; 95%CI 1.17, 3.95), use of the fumigant methyl bromide (OR 3.16; 95%CI 1.05, 9.5), and use of petroleum oil/distillates (OR 1.50; 95%CI 1.00, 2.25). Using a higher threshold (3 or 4+ at a 1:160 dilution, 9%) ANA positivity was associated with the carbamate insecticide aldicarb (OR 4.82; 95%CI 1.33, 17.5) and greater combined use of four cyclodiene organochlorine insecticides (top tertile of intensity-weighted lifetime days vs. no use; OR 3.20; 95%CI 1.10, 9.27). By contrast, greater use of non-cyclodiene organochlorine insecticides was inversely associated with ANA (1:80 dilution 3 or 4+, OR 0.24; 95%CI 0.08, 0.72). Specific autoantibodies (to extractable nuclear antigens and anti-dsDNA), measured on those with ANA detected at the 1:80 dilution 3 or 4+, were seen in 15 individuals (2%), and were associated with use of two or more cyclodiene organochlorine insecticides and several other pesticides (e.g., carbofuran, ethylene dibromide). These findings suggest that specific pesticide exposures may have long-term effects on ANA prevalence and support the hypothesis that certain organochlorine insecticides may increase the risk of developing systemic autoimmunity.
Topics: Aged; Agriculture; Antibodies, Antinuclear; Autoimmunity; Farmers; Humans; Hydrocarbons, Chlorinated; Longitudinal Studies; Male; Middle Aged; Occupational Exposure; Pesticides; Prevalence; Risk Factors; Surveys and Questionnaires
PubMed: 31354699
DOI: 10.3389/fimmu.2019.01476 -
Nature Communications Jul 2019Attosecond probing of core-level electronic transitions provides a sensitive tool for studying valence molecular dynamics with atomic, state, and charge specificity. In...
Attosecond probing of core-level electronic transitions provides a sensitive tool for studying valence molecular dynamics with atomic, state, and charge specificity. In this report, we employ attosecond transient absorption spectroscopy to follow the valence dynamics of strong-field initiated processes in methyl bromide. By probing the 3d core-to-valence transition, we resolve the strong field excitation and ensuing fragmentation of the neutral σ* excited states of methyl bromide. The results provide a clear signature of the non-adiabatic passage of the excited state wavepacket through a conical intersection. We additionally observe competing, strong field initiated processes arising in both the ground state and ionized molecule corresponding to vibrational and spin-orbit motion, respectively. The demonstrated ability to resolve simultaneous dynamics with few-femtosecond resolution presents a clear path forward in the implementation of attosecond XUV spectroscopy as a general tool for probing competing and complex molecular phenomena with unmatched temporal resolution.
PubMed: 31311933
DOI: 10.1038/s41467-019-10789-7 -
Methods and Protocols Dec 2018Compared to previously tested fumigants such as methyl bromide, sulfuryl fluoride and phosphine; ethanedinitrile (EDN) is a new fumigant which is being trialled around...
Compared to previously tested fumigants such as methyl bromide, sulfuryl fluoride and phosphine; ethanedinitrile (EDN) is a new fumigant which is being trialled around the world as a pre-plant soil treatment and as a quarantine and pre-shipment (QPS) treatment of commodities. To collect the data necessary to assess the effectiveness of this fumigant, an accurate analytical method is needed across a wide concentration range. We reviewed the methods of detection for EDN described in recently published fumigation studies and have developed and validated a method to quantify EDN in air using a gas chromatograph equipped with a flame ionization detector (GC-FID). Our tested method has a linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ) of R 0.9988, 1.36%, 98.8%, 0.750 ppm and 1.073 ppm, respectively. These values were determined using internationally recognised guidelines for the validation of non-standard analytical methods, which means that our method can be applied to the different validation requirements of regulatory agencies and countries. Our method can be used for experimental conditions that require detection at low and high concentrations simultaneously because it is accurate, fast (0.6 min) and repeatable across a concentration range of 1 to 40,000 ppm. This method will help to standardise the quantification of EDN by research groups and facilitate acceptance of data by regulatory organisations around the world.
PubMed: 31164586
DOI: 10.3390/mps2010001 -
Chimia Apr 2019Development of catalytic technologies enabling the direct functionalization of light alkanes, main components of abundant natural gas, into value-added chemicals and...
Development of catalytic technologies enabling the direct functionalization of light alkanes, main components of abundant natural gas, into value-added chemicals and liquid fuels is quite possibly the key strategy to transit from the oil to the renewables era. A cornerstone to meet this great challenge comprises the in-depth understanding of complex reaction mechanisms over dynamic surfaces, allowing to elucidate catalyst design criteria for selective alkane functionalization processes. Prominent examples are the oxybromination of methane into bromomethanes (CH₃Br+CH₂Br₂) and the oxychlorination of ethane into ethylene, which are the two highly selective routes (selectivity ≤98.5%) that have been proposed to involve gas-phase pathways or purely surface-driven reactions, respectively. Herein, we review our recent efforts to uncover these complex reaction schemes that combine kinetic analysis with advanced operando characterization techniques, including prompt-gamma activation analysis and photoelectron photoion coincidence spectroscopy, ultimately rationalized by density functional theory calculations. In particular, alkane activation to methyl bromide in oxybromination was found to occur in the gas-phase with evolved bromine and bromine radical species, thus enabling to decouple the formation of highly reactive methane-derived intermediates from the catalyst surface that are prone towards combustion. In contrast, the selectivity control in ethane oxychlorination is achieved via a purely surface-driven functionalization of ethane into ethyl chloride, which is further dehydrochlorinated to ethylene over chlorine modified active centers.
PubMed: 30975258
DOI: 10.2533/chimia.2019.288 -
Physiological Research Jun 2019The objectives of this study were to investigate the role of endogenous opioids in the mediation of stress-induced cardiomyopathy (SIC), and to evaluate which opioid...
The objectives of this study were to investigate the role of endogenous opioids in the mediation of stress-induced cardiomyopathy (SIC), and to evaluate which opioid receptors regulate heart resistance to immobilization stress. Wistar rats were subjected to 24 h immobilization stress. Stress-induced heart injury was assessed by 99mTc-pyrophosphate accumulation in the heart. The opioid receptor (OR) antagonists (naltrexone, NxMB - naltrexone methyl bromide, MR 2266, ICI 174.864) and agonists (DALDA, DAMGO, DSLET, U-50,488) were administered intraperitoneally prior to immobilization and 12 h after the start of stress. In addition, the selective micro OR agonists PL017 and DAMGO were administered intracerebroventricularly prior to stress. Finally pretreatment with guanethidine was used. Naltrexone did not alter the cardiac 99mTc-PP accumulation in stressed rats. NxMB aggravated stress-induced cardiomyopathy (P=0.005) (SIC). The selective micro OR agonist DALDA, which does not cross the blood-brain barrier, completely prevented (P=0.006) SIC. The micro OR agonist DAMGO exhibited weaker effect than DALDA. The selective delta ligand (DSLET) and kappa OR ligand (U-50,488) did not alter stress-induced 99mTc-pyrophosphate accumulation in the heart. Intracerebroventricular administration of the micro OR agonists aggravated SIC. Pretreatment with guanethidine abolished this effect (P=0.01). Guanethidine alone exhibited cardioprotective properties. A stimulation of central micro OR promotes an appearance of SIC. In contrast, stimulation of peripheral micro OR contributes to an increase in cardiac tolerance to stress.
Topics: Analgesics, Opioid; Animals; Cardiotonic Agents; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Heart Diseases; Immobilization; Male; Myocardium; Naltrexone; Narcotic Antagonists; Rats; Rats, Wistar; Receptors, Opioid, mu; Stress, Psychological
PubMed: 30904005
DOI: 10.33549/physiolres.933946 -
BMJ (Clinical Research Ed.) Mar 2019To examine associations between early developmental exposure to ambient pesticides and autism spectrum disorder.
OBJECTIVE
To examine associations between early developmental exposure to ambient pesticides and autism spectrum disorder.
DESIGN
Population based case-control study.
SETTING
California's main agricultural region, Central Valley, using 1998-2010 birth data from the Office of Vital Statistics.
POPULATION
2961 individuals with a diagnosis of autism spectrum disorder based on the , fourth edition, revised (up to 31 December 2013), including 445 with intellectual disability comorbidity, were identified through records maintained at the California Department of Developmental Services and linked to their birth records. Controls derived from birth records were matched to cases 10:1 by sex and birth year.
EXPOSURE
Data from California state mandated Pesticide Use Reporting were integrated into a geographic information system tool to estimate prenatal and infant exposures to pesticides (measured as pounds of pesticides applied per acre/month within 2000 m from the maternal residence). 11 high use pesticides were selected for examination a priori according to previous evidence of neurodevelopmental toxicity in vivo or in vitro (exposure defined as ever never for each pesticide during specific developmental periods).
MAIN OUTCOME MEASURE
Odds ratios and 95% confidence intervals using multivariable logistic regression were used to assess associations between pesticide exposure and autism spectrum disorder (with or without intellectual disabilities) in offspring, adjusting for confounders.
RESULTS
Risk of autism spectrum disorder was associated with prenatal exposure to glyphosate (odds ratio 1.16, 95% confidence interval 1.06 to 1.27), chlorpyrifos (1.13, 1.05 to 1.23), diazinon (1.11, 1.01 to 1.21), malathion (1.11, 1.01 to 1.22), avermectin (1.12, 1.04 to 1.22), and permethrin (1.10, 1.01 to 1.20). For autism spectrum disorder with intellectual disability, estimated odds ratios were higher (by about 30%) for prenatal exposure to glyphosate (1.33, 1.05 to 1.69), chlorpyrifos (1.27, 1.04 to 1.56), diazinon (1.41, 1.15 to 1.73), permethrin (1.46, 1.20 to 1.78), methyl bromide (1.33, 1.07 to 1.64), and myclobutanil (1.32, 1.09 to 1.60); exposure in the first year of life increased the odds for the disorder with comorbid intellectual disability by up to 50% for some pesticide substances.
CONCLUSION
Findings suggest that an offspring's risk of autism spectrum disorder increases following prenatal exposure to ambient pesticides within 2000 m of their mother's residence during pregnancy, compared with offspring of women from the same agricultural region without such exposure. Infant exposure could further increase risks for autism spectrum disorder with comorbid intellectual disability.
Topics: Adolescent; Adult; Agriculture; Autism Spectrum Disorder; California; Case-Control Studies; Environmental Exposure; Female; Humans; Infant; Infant, Newborn; Intellectual Disability; Male; Maternal Exposure; Pesticides; Pregnancy; Prenatal Exposure Delayed Effects; Risk Factors; Sex Distribution; Young Adult
PubMed: 30894343
DOI: 10.1136/bmj.l962 -
Journal of Environmental Management Feb 2019The effect of sporicidal fumigation with methyl bromide or methyl iodide on the functionality of valuable electronic equipment was evaluated using desktop computers as...
The effect of sporicidal fumigation with methyl bromide or methyl iodide on the functionality of valuable electronic equipment was evaluated using desktop computers as surrogates under target conditions of 200-250 mg/L fumigant for 48 h at 24-30 °C and 75-85% RH. Methyl iodide fumigation damaged light-emitting diodes and optical films in computer displays that were powered-on during fumigation. After five months of post-fumigation operation, five out of six methyl-bromide-fumigated and all six methyl-iodide-fumigated DVD ± RW optical drives failed. Deterioration of rubber spacers critical to maintaining correct disc geometry caused the failure. Metal coupons, included to measure corrosion, showed no significant differences in weight gain between control and fumigation conditions. Relative humidity sensors exhibited a substantial and sometimes irreversible reduction in sensitivity during and after methyl iodide fumigation. Methyl bromide and methyl iodide can cause damage to electronic equipment, but damage seems to be limited to organic materials rather than corrosion of metal surfaces.
Topics: Fumigation; Hydrocarbons, Brominated; Hydrocarbons, Iodinated
PubMed: 30602226
DOI: 10.1016/j.jenvman.2018.10.118