-
Journal of Exposure Science &... Mar 2022Silicone personal samplers are increasingly being used to measure chemical exposures, but many of these studies do not attempt to calculate environmental concentrations.
BACKGROUND
Silicone personal samplers are increasingly being used to measure chemical exposures, but many of these studies do not attempt to calculate environmental concentrations.
OBJECTIVE
Using measurements of silicone wristband uptake of organic chemicals from atmospheric exposure, create log K and k predictive models based on empirical data to help develop air equivalency calculations for both volatile and semi-volatile organic compounds.
METHODS
An atmospheric vapor generator and a custom exposure chamber were used to measure the uptake of organic chemicals into silicone wristbands under simulated indoor conditions. Log K models were evaluated using repeated k-fold cross-validation. Air equivalency was compared between best-performing models.
RESULTS
Log K and log k estimates calculated from uptake data were used to build predictive models from boiling point (BP) and other parameters (all models: R = 0.70-0.94). The log K models were combined with published data and refined to create comprehensive and effective predictive models (R: 0.95-0.97). Final estimates of air equivalency using novel BP models correlated well over an example dataset (Spearman r = 0.984) across 5-orders of magnitude (<0.05 to >5000 ng/L).
SIGNIFICANCE
Data from silicone samplers can be translated into air equivalent concentrations that better characterize environmental concentrations associated with personal exposures and allow direct comparisons to regulatory levels.
Topics: Air Pollutants; Environmental Monitoring; Humans; Silicones; Volatile Organic Compounds
PubMed: 33953340
DOI: 10.1038/s41370-021-00332-6 -
Geobiology Sep 2022Mineral-associated organic matter is an integral part of soil carbon pool. Biological processes contribute to the formation of such organo-mineral complexes when soil...
Mineral-associated organic matter is an integral part of soil carbon pool. Biological processes contribute to the formation of such organo-mineral complexes when soil microbes, and in particular soil fungi, deposit a suite of extracellular metabolic compounds and their necromass on the mineral surfaces. While studied in bulk, micro- to nanoscale fungal-mineral interactions remain elusive. Of particular interest are the mutual effects at the interface between the fungal exometabolites and proximal mineral particles. In this work, we have grown saprotrophic and symbiotic fungi in contact with two soil minerals with contrasting properties: quartz and goethite, on top of X-ray transparent silicon nitride membrane windows and analyzed fungal hyphae by synchrotron-based scanning transmission X-ray microscopy in combination with near edge X-ray fine structure spectroscopy at C(K) and Fe(L) absorption edges. In the resultant chemical maps, we were able to visualize and differentiate organic compounds constituting the fungal cells, their extracellular metabolites, and the exometabolites adsorbing on the minerals. We found that the composition of the exometabolites differed between the fungal functional guilds, particularly, in their sugar to protein ratio and potassium concentration. In samples with quartz and goethite, we observed adsorption of the exometabolic compounds on the mineral surfaces with variations in their chemical composition around the particles. Although we did not observe clear alteration in the exometabolite chemistry upon mineral encounters, we show that fungal-mineral interaction result in reduction of Fe(III) in goethite. This process has been demonstrated for bulk systems, but, to our knowledge, this is the first observation on a single hypha scale offering insight into its underlying biological mechanisms. This demonstrates the link between processes initiated at the single-cell level to macroscale phenomena. Thus, spatially resolved chemical characterization of the microbial-mineral interfaces is crucial for an increased understanding of overall carbon cycling in soil.
Topics: Carbon; Ferric Compounds; Minerals; Organic Chemicals; Quartz; Soil
PubMed: 35686583
DOI: 10.1111/gbi.12504 -
Molecules (Basel, Switzerland) Feb 2023Photodynamic therapy (PDT) is a promising method for the treatment of cancer, because of its advantages including a low toxicity, non-drug-resistant character, and... (Review)
Review
Photodynamic therapy (PDT) is a promising method for the treatment of cancer, because of its advantages including a low toxicity, non-drug-resistant character, and targeting capability. From a photochemical aspect, a critical property of triplet photosensitizers (PSs) used for PDT reagents is the intersystem crossing (ISC) efficiency. Conventional PDT reagents are limited to porphyrin compounds. However, these compounds are difficult to prepare, purify, and derivatize. Thus, new molecular structure paradigms are desired to develop novel, efficient, and versatile PDT reagents, especially those contain no heavy atoms, such as Pt or I, etc. Unfortunately, the ISC ability of heavy atom-free organic compounds is usually elusive, and it is difficult to predict the ISC capability of these compounds and design novel heavy atom-free PDT reagents. Herein, from a photophysical perspective, we summarize the recent developments of heavy atom-free triplet PSs, including methods based on radical-enhanced ISC (REISC, facilitated by electron spin-spin interaction), twisted π-conjugation system-induced ISC, the use of fullerene C as an electron spin converter in antenna-C dyads, energetically matched S/T states-enhanced ISC, etc. The application of these compounds in PDT is also briefly introduced. Most of the presented examples are the works of our research group.
Topics: Photosensitizing Agents; Molecular Structure; Organic Chemicals; Photochemotherapy
PubMed: 36903415
DOI: 10.3390/molecules28052170 -
Chemosphere Jan 2022The persistence of trace organic chemicals in treated effluent derived from both centralized wastewater treatment plants (WWTPs) and decentralized wastewater treatment...
The persistence of trace organic chemicals in treated effluent derived from both centralized wastewater treatment plants (WWTPs) and decentralized wastewater treatment systems (DEWATS) is of concern due to their potential impacts on human and ecosystem health. Here, we utilize non-targeted analysis (NTA) with comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry (GC × GC/TOF-MS) to conduct an evaluation of the common persistent and removed compounds found in two centralized WWTPs in the USA and South Africa and one DEWATS in South Africa. Overall, removal efficiencies of chemicals were similar between the treatment plants when they were compared according to the number of chemical features detected in the influents and effluents of each treatment plant. However, the DEWATS treatment train, which has longer solids retention and hydraulic residence times than both of the centralized WWTPs and utilizes primarily anaerobic treatment processes, was able to remove 13 additional compounds and showed a greater decrease in normalized peak areas compared to the centralized WWTPs. Of the 111 common compounds tentatively identified in all three influents, 11 compounds were persistent in all replicates, including 5 compounds not previously reported in effluents of WWTPs or water reuse systems. There were no significant differences among the physico-chemical properties of persistent and removed compounds, but significant differences were observed among some of the molecular descriptors. These results have important implications for the treatment of trace organic chemicals in centralized and decentralized WWTPs and the monitoring of new compounds in WWTP effluent.
Topics: Ecosystem; Environmental Monitoring; Humans; Organic Chemicals; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical; Water Purification
PubMed: 34325254
DOI: 10.1016/j.chemosphere.2021.131621 -
Food Research International (Ottawa,... Aug 2022This study aimed to investigate for the first time fourteen aliphatic organic acids (AOA) in honeys produced by different species of Brazilian stingless bees (Melipona...
This study aimed to investigate for the first time fourteen aliphatic organic acids (AOA) in honeys produced by different species of Brazilian stingless bees (Melipona bicolor, Scaptotrigona bipunctata, Melipona quadrifasciata, and Melipona marginata) and characterize them regarding their physicochemical properties. Thirteen AOAwere quantified in the samples, in which five of them (malonic, fumaric, glycolic, glutaric, and propionic acids) were identified for the first time instingless bee honey (SBH). Acetic, gluconic, and lactic acids were predominant in all the samples analyzed varying from 0.0067 ± 0.0001 to 1.5993 ± 0.0003 g 100 g, 0.0808 ± 0.0007 to 1.3460 ± 0.0006 g 100 g, and 0.0370 ± 0.000 to 0.5760 ± 0.0006 g 100 g, respectively. Most physicochemical properties showed significant differences (p < 0.05) among the samples. However, it was observed that the water activity (Aw) did not differ significantly between honey samples produced by the same species. Moreover, it is important to highlight the high moisture content, Aw, and free acidity that were found in the range of 29.6 to 40.1 g 100 g, 0.75 to 0.84, and 37.8 to 123 mEq kg, respectively. This information reinforces such peculiar characteristics of SBH and a need to deeply investigate the physical and chemical characteristics of honey from different species of stingless bees. In conclusion, it was observed that the honey samples of the different stingless bee species presented a great variation regarding their AOA content, highlighting acetic, gluconic, and lactic acids as the major AOA in all the samples. However, since this was an exploratory study, it was not possible to find any correlation between honey produced by the same species.
Topics: Acids; Animals; Antioxidants; Bees; Brazil; Fatty Acids; Honey; Organic Chemicals
PubMed: 35840224
DOI: 10.1016/j.foodres.2022.111516 -
International Journal of Environmental... Mar 2022A 2019 retrospective study analyzed wristband personal samplers from fourteen different communities across three different continents for over 1530 organic chemicals....
A 2019 retrospective study analyzed wristband personal samplers from fourteen different communities across three different continents for over 1530 organic chemicals. Investigators identified fourteen chemicals (G14) detected in over 50% of personal samplers. The G14 represent a group of chemicals that individuals are commonly exposed to, and are mainly associated with consumer products including plasticizers, fragrances, flame retardants, and pesticides. The high frequency of exposure to these chemicals raises questions of their potential adverse human health effects. Additionally, the possibility of exposure to mixtures of these chemicals is likely due to their co-occurrence; thus, the potential for mixtures to induce differential bioactivity warrants further investigation. This study describes a novel approach to broadly evaluate the hazards of personal chemical exposures by coupling data from personal sampling devices with high-throughput bioactivity screenings using in vitro and non-mammalian in vivo models. To account for species and sensitivity differences, screening was conducted using primary normal human bronchial epithelial (NHBE) cells and early life-stage zebrafish. Mixtures of the G14 and most potent G14 chemicals were created to assess potential mixture effects. Chemical bioactivity was dependent on the model system, with five and eleven chemicals deemed bioactive in NHBE and zebrafish, respectively, supporting the use of a multi-system approach for bioactivity testing and highlighting sensitivity differences between the models. In both NHBE and zebrafish, mixture effects were observed when screening mixtures of the most potent chemicals. Observations of BMC-based mixtures in NHBE (NHBE BMC Mix) and zebrafish (ZF BMC Mix) suggested antagonistic effects. In this study, consumer product-related chemicals were prioritized for bioactivity screening using personal exposure data. High-throughput high-content screening was utilized to assess the chemical bioactivity and mixture effects of the most potent chemicals.
Topics: Animals; Flame Retardants; Organic Chemicals; Pesticides; Retrospective Studies; Zebrafish
PubMed: 35409514
DOI: 10.3390/ijerph19073829 -
The Lancet. Planetary Health May 2023Global production and emission of chemicals exceeds societal capacities for assessment and monitoring. This situation calls for improved chemical regulatory policy... (Review)
Review
Global production and emission of chemicals exceeds societal capacities for assessment and monitoring. This situation calls for improved chemical regulatory policy frameworks and increased support for expedited decision making within existing frameworks. The polar regions of the Earth represent unique sentinel areas for the study of global chemical behaviour, and data arising from these areas can strengthen existing policy frameworks. However, chemical pollution research and monitoring in the Antarctic is underdeveloped, with geopolitical complexities and the absence of legal recognition of international chemical policy serving to neutralise progress made in other global regions. This Personal View represents a horizon scan by the action group Input Pathways of Persistent Organic Pollutants to Antarctica, of the Scientific Committee for Antarctic Research. Four priority research and research facilitation gaps are outlined, with recommendations for Antarctica Treaty parties for strategic action against these priorities.
Topics: Antarctic Regions; Environmental Monitoring; Environmental Pollution; Organic Chemicals; Public Policy
PubMed: 37164519
DOI: 10.1016/S2542-5196(23)00076-1 -
Molecules (Basel, Switzerland) Jun 2023Water environment pollution is becoming an increasingly serious issue due to industrial pollutants with the rapid development of modern industry. Among many pollutants,... (Review)
Review
Water environment pollution is becoming an increasingly serious issue due to industrial pollutants with the rapid development of modern industry. Among many pollutants, the toxic and explosive nitroaromatics are used extensively in the chemical industry, resulting in environmental pollution of soil and groundwater. Therefore, the detection of nitroaromatics is of great significance to environmental monitoring, citizen life and homeland security. Lanthanide-organic complexes with controllable structural features and excellent optical performance have been rationally designed and successfully prepared and used as lanthanide-based sensors for the detection of nitroaromatics. This review will focus on crystalline luminescent lanthanide-organic sensing materials with different dimensional structures, including the 0D discrete structure, 1D and 2D coordination polymers and the 3D framework. Large numbers of studies have shown that several nitroaromatics could be detected by crystalline lanthanide-organic-complex-based sensors, for instance, nitrobenzene (NB), nitrophenol (4-NP or 2-NP), trinitrophenol (TNP) and so on. The various fluorescence detection mechanisms were summarized and sorted out in the review, which might help researchers or readers to comprehensively understand the mechanism of the fluorescence detection of nitroaromatics and provide a theoretical basis for the rational design of new crystalline lanthanide-organic complex-based sensors.
Topics: Lanthanoid Series Elements; Luminescence; Explosive Agents; Fluorescence; Organic Chemicals; Environmental Pollutants
PubMed: 37298958
DOI: 10.3390/molecules28114481 -
Inorganic Chemistry Oct 2019The indispensable requirement for metals in life processes has led to the evolution of sophisticated mechanisms that allow organisms to maintain dynamic equilibria of... (Review)
Review
The indispensable requirement for metals in life processes has led to the evolution of sophisticated mechanisms that allow organisms to maintain dynamic equilibria of these ions. This dynamic control of the level, speciation, and availability of a variety of metal ions allows organisms to sustain biological processes while avoiding toxicity. When functioning properly, these mechanisms allow cells to return to their metal homeostatic set points following shifts in the metal availability or other stressors. These periods of transition, when cells are in a state of flux in which they work to regain homeostasis, present windows of opportunity to pharmacologically manipulate targets associated with metal-trafficking pathways in ways that could either facilitate a return to homeostasis and the recovery of cellular function or further push cells outside of homeostasis and into cellular distress. The purpose of this Viewpoint is to highlight emerging opportunities for chemists and chemical biologists to develop compounds to manipulate metal-trafficking processes for therapeutic benefit.
Topics: Homeostasis; Humans; Metabolic Diseases; Metals; Neoplasms; Organic Chemicals
PubMed: 31247859
DOI: 10.1021/acs.inorgchem.9b01029 -
Environmental Science & Technology Jan 2021A critical review of the current state of knowledge of chemical emissions from indoor sources, partitioning among indoor compartments, and the ensuing indoor exposure... (Review)
Review
A critical review of the current state of knowledge of chemical emissions from indoor sources, partitioning among indoor compartments, and the ensuing indoor exposure leads to a proposal for a modular mechanistic framework for predicting human exposure to semivolatile organic compounds (SVOCs). Mechanistically consistent source emission categories include solid, soft, frequent contact, applied, sprayed, and high temperature sources. Environmental compartments are the gas phase, airborne particles, settled dust, indoor surfaces, and clothing. Identified research needs are the development of dynamic emission models for several of the source emission categories and of estimation strategies for critical model parameters. The modular structure of the framework facilitates subsequent inclusion of new knowledge, other chemical classes of indoor pollutants, and additional mechanistic processes relevant to human exposure indoors. The framework may serve as the foundation for developing an open-source community model to better support collaborative research and improve access for application by stakeholders. Combining exposure estimates derived using this framework with toxicity data for different end points and toxicokinetic mechanisms will accelerate chemical risk prioritization, advance effective chemical management decisions, and protect public health.
Topics: Air Pollutants; Air Pollution, Indoor; Dust; Humans; Organic Chemicals; Volatile Organic Compounds
PubMed: 33319994
DOI: 10.1021/acs.est.0c02329