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International Journal of Environmental... Mar 2020Methyl bromide (CHBr) is one of the largest natural sources of bromine in the stratosphere, where it leads to ozone depletion. This paper reported the photochemical...
Methyl bromide (CHBr) is one of the largest natural sources of bromine in the stratosphere, where it leads to ozone depletion. This paper reported the photochemical production of CHBr from syringic acid (SA) that has been used as an environmentally relevant model compound for terrestrially-derived dissolved organic matter. The formation of CHBr increased with the increase of bromide ion concentration ranging from 0.8 to 80 mmol L. Ferric ions (Fe(III)) enhanced CHBr production, while chloride inhibited it, with or without Fe(III). Meanwhile, methyl chloride (CHCl) was generated in the presence of chloride and was inhibited by Fe(III). The different effects of Fe(III) on the formation of CHCl and CHBr indicate their diverse formation paths. Based on the intermediates identified by liquid chromatography-mass spectrometry and the confirmation of the formation of Fe(III)-SA complexes, it was proposed that there were two formation paths of CHBr from SA in the bromide-enriched water under simulated sunlight irradiation. One path was via nucleophilic attack of Br on the excited state protonation of SA; the other was via the combination of methyl radical and bromine radical when Fe(III) was present. This work suggests that the photochemical formation of CHBr may act as a potential natural source of CHBr in the bromide-enriched environmental matrix, and helps in better understanding the formation mechanism of CHBr.
Topics: Bromides; Ferric Compounds; Gallic Acid; Hydrocarbons, Brominated; Photochemical Processes; Sunlight
PubMed: 32245114
DOI: 10.3390/ijerph17062081 -
Journal of Occupational and... Jan 2021To determine whether methyl bromide (MB) fumigation work for plants imported in Korea affects workers' health by assessing heart rate variability (HRV).
OBJECTIVE
To determine whether methyl bromide (MB) fumigation work for plants imported in Korea affects workers' health by assessing heart rate variability (HRV).
METHODS
We measured HRV indices (TP, VLF, LF, HF, HR, SDNN, pNN50 and HRV-index) and urinary bromide ion (Br-) in 62 fumigators (study group) and 34 inspectors (the control group) before and after fumigation work. In addition, the relationship between Br- concentration and HRV indices was analysed.
RESULTS
The fumigators' post-work HRV indices and Br- level were changed compared with their pre-work values (P < 0.001). Conversely, inspectors' values were not shown a difference before and after work. The HRV indices in all subjects were negatively correlated with the Br- levels (P < 0.05).
CONCLUSIONS
Fumigators with high Br- concentrations and low post-work HRV indices following MB fumigation work experienced adverse effects on their autonomic nervous systems.
Topics: Autonomic Nervous System; Heart Rate; Humans; Hydrocarbons, Brominated; Quarantine
PubMed: 33177473
DOI: 10.1097/JOM.0000000000002083 -
Applied and Environmental Microbiology Sep 2023The application of microfluidic techniques in experimental and environmental studies is a rapidly emerging field. Water-in-oil microdroplets can serve readily as...
The application of microfluidic techniques in experimental and environmental studies is a rapidly emerging field. Water-in-oil microdroplets can serve readily as controllable micro-vessels for studies that require spatial structure. In many applications, it is useful to monitor cell growth without breaking or disrupting the microdroplets. To this end, optical reporters based on color, fluorescence, or luminescence have been developed. However, optical reporters suffer from limitations when used in microdroplets such as inaccurate readings due to strong background interference or limited sensitivity during early growth stages. In addition, optical detection is typically not amenable to filamentous or biofilm-producing organisms that have significant nonlinear changes in opacity and light scattering during growth. To overcome such limitations, we show that volatile methyl halide gases produced by reporter cells expressing a methyl halide transferase (MHT) can serve as an alternative nonoptical detection approach suitable for microdroplets. In this study, an MHT-labeled reporter strain was constructed and characterized. Protocols were established for the encapsulation and incubation of in microdroplets. We observed the complete life cycle for including the vegetative expansion of mycelia, mycelial fragmentation, and late-stage sporulation. Methyl bromide (MeBr) production was detected by gas chromatography-mass spectrometry (GC-MS) from gas reporters incubated in either liquid suspension or microdroplets and used to quantitatively estimate bacterial density. Overall, using MeBr production as a means of quantifying bacterial growth provided a 100- to 1,000-fold increase in sensitivity over optical or fluorescence measurements of a comparable reporter strain expressing fluorescent proteins. IMPORTANCE Quantitative measurement of bacterial growth in microdroplets is desirable but challenging. Current optical reporter systems suffer from limitations when applied to filamentous or biofilm-producing organisms. In this study, we demonstrate that volatile methyl halide gas production can serve as a quantitative nonoptical growth assay for filamentous bacteria encapsulated in microdroplets. We constructed an gas reporter strain and observed a complete life cycle for encapsulated in microdroplets, establishing microdroplets as an alternative growth environment for spp. that can provide spatial structure. We detected MeBr production from both liquid suspension and microdroplets with a 100- to 1,000-fold increase in signal-to-noise ratio compared to optical assays. Importantly, we could reliably detect bacteria with densities down to 10 CFU/mL. The combination of quantitative gas reporting and microdroplet systems provides a valuable approach to studying fastidious organisms that require spatial structure such as those found typically in soils.
Topics: Emulsions; Fluorescence; Gases; Transferases
PubMed: 37699129
DOI: 10.1128/aem.00764-23 -
Journal of Nematology 2020The last decade has seen a sharp increase in nematicide research in the agricultural industry. As a result, several new synthetic nematicides have become available to...
The last decade has seen a sharp increase in nematicide research in the agricultural industry. As a result, several new synthetic nematicides have become available to growers, and several more are expected in the near future. This new interest in nematicides is directly related to the growing demand for safer and more selective products, and the increasing regulatory pressure on many of the traditional nematicides. This has led to a ban of several widely used fumigant (e.g. methyl bromide) and non-fumigant (e.g. aldicarb) nematicides. The loss of traditional nematicides, combined with a lack of replacement products and awareness of the damage that nematodes can cause, has not only raised concern among growers, but has also created new opportunities for the crop protection industry. Nematicides have become a priority, and many companies are now allocating significant research dollars to discover new nematicides. The new nematicides are very different from previous products: (i) they are more selective, often only targeting nematodes, and (ii) they are less toxic, and safer to use. This review article describes these new developments by discussing the challenges that are associated with finding new nematicides, reviewing the nature, characteristics, and efficacy of new nematicides, and discussing the impact they could have on future nematode management.
PubMed: 33829179
DOI: 10.21307/jofnem-2020-091 -
Plant Disease Feb 2023Globisporangium sylvaticum (syn. Pythium sylvaticum), is an oomycete that causes root rot and damping off of field crops, ornamentals, and vegetables. Several species in...
Globisporangium sylvaticum (syn. Pythium sylvaticum), is an oomycete that causes root rot and damping off of field crops, ornamentals, and vegetables. Several species in Pythiaceae are associated with black root rot of strawberry [(Fragaria × ananassa) Duchesne] (Millner 2006). Mature, stunted 'Chandler' strawberry plants, with reduced shoot vigor and black necrotic roots, were collected from Rhea County (June 2018) and Cumberland County, TN (May 2019). Aboveground symptoms occurred in low incidence (<5% of plants) in the fields. Plant roots were rinsed with tap water, cut into 1 to 3 cm pieces, and surface-disinfested (70% ethanol, 1 min) followed by a sterile water rinse. Root segments were crushed, placed on 20% V8 juice agar, and incubated in the dark at 21°C for 3 days. White fluffy mycelia grew from a majority of roots and coenocytic hyphae with globose hyphal swellings, delimited from hyphae by septa, were observed with microscopy. Hyphae were initially branched, curled, hyaline, and aseptate; however, septations were observed in older cultures. Globose structures (terminal and intercalary) were identified as sporangia [11 to 32 (avg. 22.1) µm diameter] when zoospores were observed (Parikh et al. 2022). Oospores [9 to 21 (avg. 16) μm diameter] were globose, smooth, aplerotic, and thick-walled. Oogonia, with or without one or more inflated antheridia, were observed when isolates were paired in culture, characteristics consistent with descriptions of Campbell and Hendrix (1967), Pratt and Green (1971), van der Plaats-Niterink (1981), and Uzuhashi et al. (2010). Genomic DNA was extracted (Extract-N-Amp™; Sigma-Aldrich, MO) for PCR amplification of internal transcribed spacer (ITS) regions of rDNA with primers ITS1/ITS4 (White et al. 1990); ITS and large subunit rRNA regions with primers UN-up18S42/UN-lo28S22 (Robideau et al. 2011); and cytochrome c oxidase subunit I (COI) mitochondrial DNA with primers OomCoxI-Levup/OomCoxI-Levlo (Robideau et al. 2011). Primers ITS1/ITS4 were used to amplify isolate TN (GenBank Accession MW386310, which had 100% homology with reference isolate MK326528). Primers UN-up18S42/UN-lo28S22 amplified isolates SAP18 and OO1 (Accessions MZ881935 and MZ881936, which had 99.8% homology with HQ665236), and COI primers amplified isolate SAP18 (Accession OK020192, which had 100% homology with GU071816 and KT692835). To satisfy Koch's postulates, inoculum of G. sylvaticum grown on autoclaved wheat seeds was added (5% w/v) to planting mix (1 peat:1 sand, v/v). Young, rooted strawberry plants were planted in 1.2-L pots with infested (n = 6) and control (no pathogen, n = 6) mixes, which was saturated with deionized water. Pots were covered with clear plastic for 48 h to maintain high humidity. Plants were grown in a greenhouse (24°C avg.) for 8 weeks. The disease assay was repeated. All plants in infested mix died, with black, necrotic roots. Plants in the control mix were healthy and well-established. The pathogen was reisolated from roots of all inoculated plants and confirmed to be G. sylvaticum based on morphology and molecular analyses. Root disease of strawberry caused by G. sylvaticum has been reported in the USA (Campbell and Hendrix 1967; Nemec and Sanders 1970; Pratt and Green 1971). This is the first report of G. sylvaticum causing root rot of strawberry in Tennessee. With the loss of methyl bromide, sustainable disease control strategies are needed to provide effective management options for strawberry black root rot.
PubMed: 36825322
DOI: 10.1094/PDIS-01-23-0007-PDN -
Foods (Basel, Switzerland) Aug 2022The new scenario for global food production and supply is decidedly complex given the current forecast of an increase in food fragility due to international tensions. In...
The new scenario for global food production and supply is decidedly complex given the current forecast of an increase in food fragility due to international tensions. In this period, exports from other parts of the world require different routes and treatments to preserve the food quality and integrity. Fumigation is a procedure used for the killing, removal, or rendering infertile of pests, with serious dangers to human health. The most-used fumigants are methyl bromide and ethylene dibromide. It is important to bear in mind that the soil may contain bromide ions naturally or from anthropogenic source (fertilizers and pesticides that contain bromide or previous fumigations). Different methods (titrimetric, spectrophotometric, and fluorometric approaches) are available to rapidly determine the amount of bromide ion on site in the containers, but these are non-specific and with high limits of quantification. The increasing interest in healthy food, without xenobiotic residues, requires the use of more sensitive, specific, and accurate analytical methods. In order to help give an overview of the bromide ion scenario, a new, fast method was developed and validated according to SANTE 11312/2021. It involves the determination of bromide ion in cereals and legumes through ion chromatography-Q-Orbitrap. The extraction was performed by the QuPPe method, but some modifications were applied based on the matrix. The method described here was validated at four different levels. Recoveries were satisfactory and the mean values ranged between 99 and 106%, with a relative standard deviation lower than 3%. The linearity in the matrix was evaluated to be between 0.010 and 2.5 mg kg, with a coefficient of determination (R) of 0.9962. Finally, the proposed method was applied to different cereals and legumes (rice, wheat, beans, lentils pearled barley, and spelt) and tested with satisfactory results in EUPT-SMR16 organized by EURL.
PubMed: 36010386
DOI: 10.3390/foods11162385 -
Environmental Monitoring and Assessment Aug 2021
PubMed: 34387752
DOI: 10.1007/s10661-021-09246-0 -
Research in Microbiology 2024This review summarizes the literature on efficacy of techniques to sterilize soil. Soil may need to be sterilized if contaminated with pathogens such as Bacillus... (Review)
Review
This review summarizes the literature on efficacy of techniques to sterilize soil. Soil may need to be sterilized if contaminated with pathogens such as Bacillus anthracis. Sterilizing soil in-situ minimizes spread of the bio-contaminant. Soil is difficult to sterilize, with efficacy generally diminishing with depth. Methyl bromide, formaldehyde, and glutaraldehyde are the only soil treatment options that have been demonstrated at full-scale to effectively inactivate Bacillus spores. Soil sterilization modalities with high efficacy at bench-scale include wet and dry heat, metam sodium, chlorine dioxide gas, and activated sodium persulfate. Simple oxidants such as chlorine bleach are ineffective in sterilizing soil.
Topics: Bacillus anthracis; Spores, Bacterial; Soil Microbiology; Sterilization; Disinfectants
PubMed: 38141796
DOI: 10.1016/j.resmic.2023.104175 -
Sangyo Eiseigaku Zasshi = Journal of... Mar 2024A new system for the regulation of chemical substances was introduced in Japan in April 2023. Unlike delineated rules, the new system does not specify any specific...
OBJECTIVE
A new system for the regulation of chemical substances was introduced in Japan in April 2023. Unlike delineated rules, the new system does not specify any specific measures for individual substances, but is rather based on the management of health through the voluntary implementation of measures in order to reduce exposure to all dangerous/hazardous chemical substances. Regarding specific methods, exposures will be mainly elucidated through the measurement of a work environment. However, the necessity of biological monitoring should also be considered. This study aimed to identify the importance of biological monitoring by reviewing changes made over time in biological monitoring methods used for occupational poisoning.
METHOD
The study presents occupational poisoning by several compounds (methyl bromide, polycyclic aromatic hydrocarbons, and MOCA) and the corresponding biological monitoring methods utilized, as researched by the author. Changes in biological monitoring based on the history of the Study Group on Occupational Poisoning and Biological Monitoring of the Japan Society for Occupational Health are also introduced.
RESULTS
The areas of occupational poisoning at different times and cases of occupational cancer caused by exposure to chemical substances were presented in lectures held by the Study Group on Occupational Poisoning and Biological Monitoring. These lectures showed that although biological monitoring was previously implemented primarily by measuring the urinary metabolites of the exposed substance, the monitoring methods used have changed as the nature of exposure has changed, leading to the development of new tools that detect trace, low concentration, and mixed exposures.
CONCLUSION
The health management of workers handling chemical substances at occupational sites will be shifted to autonomous management. However, it should be noted that only biological monitoring can detect and prove true exposure. Particularly, risk assessment by biological monitoring is necessary for substances that are suspected to be absorbed through the skin, and the measurement methods used should continue to be developed and refined. The significance of biological monitoring will continue to increase.
Topics: Humans; Occupational Exposure; Biological Monitoring; Hazardous Substances; Occupational Health; Polycyclic Aromatic Hydrocarbons; Environmental Monitoring
PubMed: 37766566
DOI: 10.1539/sangyoeisei.2023-026-A -
Heliyon Nov 2022The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were...
The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were investigated using density functional theory (DFT) with the B97XD and M06-2x functionals, as well as the benchmark CBS-QB3 composite method. Transition state theory (TST) and RRKM theory calculations of rate constants under atmospheric pressure and in the fall-off regime were used to supplement the measured energy profiles. The results show that the formation of propene and bromoacetic acid is the most dominant pathway at the CBS-QB3 composite method, both kinetically and thermodynamically. There was a good agreement with experimental results. Pressures greater than 0.01 bar, corresponding to larger barrier heights are insufficient to ensure saturation of the measured rate coefficient when compared to the RRKM kinetic rates. Natural bond orbitals (NBO) charges, bond orders, bond indices, and synchronicity parameters all point to the considered pathways taking place via a homogenous, first-order concerted, as well as an asynchronous mechanism involving a non-planar cyclic six-membered transition state. The calculated data exhibit that the elongation of the C-O bond length and subsequent polarization of the C …O bond is the rate-determining step of the considered reactions in the cyclic transition state, which appears to be involved in this type of reaction.
PubMed: 36339763
DOI: 10.1016/j.heliyon.2022.e11274