Anthropogenic and biogenic sources of Ethylene and the potential for human exposure: A literature review

Sex difference in the non-linear relationship between ethylene oxide exposure and depressive symptoms: A cross-sectional study

BACKGROUND

Ethylene oxide (EO) has been recognized as an animal carcinogen and environmental EO exposure was linked to several diseases. However, the association of EO exposure with depression prevalence is still not clear.

METHODS

We included 6016 participants with complete data on HbEO concentrations, depression diagnosis, and necessary covariates using the 2013-2020 National Health and Nutrition Examination Survey. Weighted multivariable logistic model was applied to examine the association of HbEO concentrations with depression risk. Weighted restricted cubic spline model was applied to draw the dose-response curve.

RESULTS

In the total population, individuals in the second, third, and fourth quartile of HbEO respectively had an adjusted OR of 0.99 (95%CI: 0.60, 1.63), 1.13 (95%CI: 0.73, 1.75), and 2.87 (95%CI: 1.86, 4.45) (Ptrend < 0.001) for depression with a significant "J" shaped non-linear dose-response relationship (Pnon-linear < 0.001). Females, drinkers, and smokers were susceptible to the depressive effect of EO. Doubling the HbEO concentrations was respectively associated with a 1.50-fold (95%CI: 1.25, 1.79), 1.29-fold (1.15, 1.44), and 1.17-fold (1.04, 1.33) increased risk of depression for females, drinkers, and smokers.

LIMITATIONS

Cross-sectional study design and self-reported depressive symptoms.

CONCLUSIONS

Environmental EO exposure was associated with increased depression risk, especially among females, drinkers, and smokers. Further prospective studies are required to affirm these findings.

A new NMVOC speciated inventory for a reactivity-based approach to support ozone control strategies in Spain

Ozone (O₃) pollution is a persistent problem in many regions of Spain, so understanding O₃ precursor emissions and trends is essential to design effective control strategies. We estimated the impact of Non-Methane Volatile Organic Compounds (NMVOC) species upon O₃ formation potential (OFP) using the maximum incremental reactivity approach. For this, we developed a speciated NMVOC emission inventory for Spain from 2010 to 2019 combining national reported emissions with state-of-the-art speciation profiles, which resulted in a database of emissions for over 900 individual NMVOC species and 153 individual sectors. Additionally, we analysed 2030 emission projections to quantify the expected impact of planned measures on future OFP levels. Overall, the main activities contributing to OFP in Spain are paint manufacturing and applications (20 %), manure management (16 %), and domestic solvent use (6 %). These activities contribute unevenly across regions. The more urbanised areas report a larger contribution from the solvent sector (64 % in Madrid), while in rural areas, manure management and agricultural waste burning gain importance (24 % in Extremadura), indicating that local control measures should be implemented. The top 10 NMVOC species contributing to OFP are ethanol, ethene, xylenes, propene, toluene, formaldehyde, 1,3-butadiene, styrene, n-butane, and cyclopentane, which together are responsible for 54 % of the total OFP. Our trend analysis indicates a reduction of NMVOC emissions and OFP of -5 % and -10 % between 2010 and 2019, respectively. The larger decrease in OFP is driven by a bigger reduction in xylenes (-29 %) and toluene (-28 %) from paint application industries and the road transport sector. By 2030 a significant increase (+37 %) in the OFP from the public electricity sector is expected due to the planned increase in biomass use for power generation. Our results indicate that policies should focus on paint reformulation, limiting aerosol products, and implementing NMVOC control devices in future biomass power plants.

Species richness, extent and potential threats to mangroves of Sarangani Bay Protected Seascape, Philippines

Mangroves form one of the most vital tropical ecosystems that support many species and surrounding communities. The Sarangani Bay Protected Seascape (SBPS) in the south of Mindanao Islands in the Philippines is home to a large number of mangrove species, which have not been fully explored. We updated the list of true mangrove species for SBPS from 10 to 24 by integrating the results of our survey and other past mangrove assessments. A practical spatial analysis approach was used to estimate the current mangrove forest extent of SBPS at 514 ha, as compared to 479 ha and 332 ha in 1998 and 2016, respectively, from other independent reports. Mangrove cover was negatively related to built area, cropland, bare ground, rangeland and total human population, but positively related to the number of fishing boats and total tree cover. In addition, we identified other potential anthropogenic threats to mangroves and categorised them into forest clearing or deforestation, over-extraction and pollution. The benefits of mangrove cover expansion, adoption of mangrove-friendly aquaculture and revitalising degraded mangrove forests outweigh their constraints. Our work provided a locally relevant understanding of the potential causes of mangrove loss and the values of human actions in mangrove dynamics, which will contribute to reliable and informed decision-making for the conservation of mangrove species and restoration of mangrove forests in SBPS.

Ethylene industrial emitters seen from space

Volatile organic compounds are emitted abundantly from a variety of natural and anthropogenic sources. However, in excess, they can severely degrade air quality. Their fluxes are currently poorly represented in inventories due to a lack of constraints from global measurements. Here, we track from space over 300 worldwide hotspots of ethylene, the most abundant industrially produced organic compound. We identify specific emitters associated with petrochemical clusters, steel plants, coal-related industries, and megacities. Satellite-derived fluxes reveal that the ethylene emissions of the industrial sources are underestimated or missing in the state-of-the-art Emission Database for Global Atmospheric Research (EDGAR) inventory. This work exposes global emission point-sources of a short-lived carbonated gas, complementing the ongoing large-scale efforts on the monitoring of inorganic pollutants.

Monitored and Modeled Ambient Air Concentrations of Ethylene Oxide: Contextualizing Health Risk for Potentially Exposed Populations in Georgia

Recent studies have monitored and modeled long-term ambient air concentrations of ethylene oxide (EO) around emitting facilities in Georgia with the intent of informing risk management of potentially exposed nearby residential populations. Providing health context for these data is challenging because the U.S. Environmental Protection Agency’s risk-specific concentrations lack practical utility in distinguishing a health significant increase in exposure. This study analyzes EO data for eight emitting facilities, using a previously published alternative exposure metric, the total equivalent concentration, which is based on U.S. Centers for Disease Control biomarker data for the non-smoking U.S. population. Mean concentrations for monitoring sites were compared to mean background concentrations to assess whether emissions contribute significantly to environmental concentrations. To assess the health significance of potential exposure at nearby residential locations, the 50th percentile concentration was added to the 50th percentile endogenous equivalent concentration and compared to the total equivalent concentration distribution for the non-smoking U.S. population. The findings demonstrate that impacts from nearby emission sources are small compared to mean background concentrations at nearby locations, and the total equivalent concentrations for exposed populations are generally indistinguishable from that of the 50th percentile for the non-smoking U.S. population.

Lack of ethylene does not affect reproductive success and synergid cell death in Arabidopsis

The signaling pathway of the gaseous hormone ethylene is involved in plant reproduction, growth, development, and stress responses. During reproduction, the two synergid cells of the angiosperm female gametophyte both undergo programmed cell death (PCD)/degeneration but in a different manner: PCD/degeneration of one synergid facilitates pollen tube rupture and thereby the release of sperm cells, while PCD/degeneration of the other synergid blocks supernumerary pollen tubes. Ethylene signaling was postulated to participate in some of the synergid cell functions, such as pollen tube attraction and the induction of PCD/degeneration. However, ethylene-mediated induction of synergid PCD/degeneration and the role of ethylene itself have not been firmly established. Here, we employed the CRISPR/Cas9 technology to knock out the five ethylene-biosynthesis 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes and created Arabidopsis mutants free of ethylene production. The ethylene-free mutant plants showed normal triple responses when treated with ethylene rather than 1-aminocyclopropane-1-carboxylic acid, but had increased lateral root density and enlarged petal sizes, which are typical phenotypes of mutants defective in ethylene signaling. Using these ethylene-free plants, we further demonstrated that production of ethylene is not necessarily required to trigger PCD/degeneration of the two synergid cells, but certain components of ethylene signaling including transcription factors ETHYLENE-INSENSITIVE 3 (EIN3) and EIN3-LIKE 1 (EIL1) are necessary for the death of the persistent synergid cell.

Ethylene oxide review: characterization of total exposure via endogenous and exogenous pathways and their implications to risk assessment and risk management

This review is intended to provide risk assessors and risk managers with a better understanding of issues associated with total exposures of human populations to ethylene oxide from endogenous and exogenous pathways. Biomonitoring of human populations and lab animals exposed to ethylene oxide has relied upon the detection of hemoglobin adducts such as 2-hydroxyethylvaline (HEV), which provides a useful measure of total exposure to ethylene oxide from all pathways. Recent biomonitoring data from CDC provide an excellent characterization of total exposure to ethylene oxide to the general U.S. population by demographic factors such as age, gender, and race as well as smoking habit, which might be comparable to previous measurements reported for humans and lab animals. The biochemical pathways including gastrointestinal (production by bacteria) and systemic (enzymatic production) pathways by which endogenous ethylene is generated and converted to ethylene oxide are described. The relative importance of endogenous pathways and exogenous pathways via ambient air or tobacco smoke was quantified based upon available data to characterize their relative importance to total exposure. Considerable variation was noted for HEV measurements in human populations, and important sources of variation for all pathways are discussed. Issues related to risk assessment and risk management of human populations exposed to ethylene oxide are provided within the context of characterizing total exposure, and data needs for supporting future risk assessment identified.

Direct Trace Fitting of Experimental Data Using the Master Equation: Testing Theory and Experiments on the OH + C2H4 Reaction

Laser flash photolysis coupled with laser-induced fluorescence observation of OH has been used to observe the equilibration of OH + C₂H₄ ↔ HOC₂H₄ over the temperature range 563-723 K and pressures of bath gas (N₂) from 58 to 250 Torr. The time-resolved OH traces have been directly and globally fitted with a master equation in order to extract Δ_RH₀⁰, the binding energy of the HOC₂H₄ adduct, with respect to reagents. The global approach allows the role that OH abstraction plays at higher temperatures to be identified. The resultant value ofΔ_RH₀⁰, 111.8 kJ mol^-1, is determined to be better than 2 kJ mol^-1 and is in agreement with our ab initio calculations (carried out at the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level), 111.4 kJ mol^-1, and other state of the art calculations. Parameters for the abstraction channel are also in good agreement with previous experimental studies. To effect this analysis, the MESMER master equation code was extended to directly incorporate secondary chemistry: diffusional loss from the observation region and reaction with the photolytic precursor. These extensions, which, among other things, resolve issues related to the merging of chemically significant and internal energy relaxation eigenvalues, are presented.

Simultaneous and interference-free measurements of temperature and C2H4 concentration using a single tunable diode laser at 1.62 µm

In the tunable diode laser absorption spectroscopy-based diagnostics, the absorption of the measured target species may be influenced by the interference absorption from other vapor-phase species and the extinction from particles and liquid droplets, especially at high temperatures and pressures. Here, we report the first application (to our knowledge) of a differential absorption diagnostic for interference-free, simultaneous measurement of temperature and ethylene concentration using a single distributed-feedback diode laser near 1.62 μm. According to the detailed study of the C₂H₄ spectra in this region, two wavelength pairs are chosen to measure the temperature based on six selection criteria. C₂H₄ concentration is measured by one of the selected wavelength pairs with higher differential absorption. To validate the developed system, experiments are performed in a well-controlled heated static cell at a range of temperatures (300-900 K) and pressures (1-6 atm). The measurement accuracies for temperature and ethylene concentration are 1.83% and 1.65%, respectively, over the considered ranges. The precision, stability, and detection limit are also analyzed to validate the system's performance. This system can potentially be applied in a variety of combustion applications.

High-throughput, simultaneous quantitation of hemoglobin adducts of acrylamide, glycidamide, and ethylene oxide using UHPLC-MS/MS

Ethylene oxide (EO), acrylamide (AA) and glycidamide (GA) exposures are associated with mammary tumors in animals. Currently available information about human exposure to these chemicals is limited creating the need for analytical methods to assess their exposure. We developed a sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to simultaneously quantitate hemoglobin (Hb) N-terminal valine adducts of AA (HbAA), GA (HbGA), and EO (HbEO) using modified Edman reaction. The limits of detection of this method were 3.9, 4.9 and 12.9 in pmol/g Hb for HbAA, HbGA and HbEO, respectively. The among-day and within-day precision for all analytes determined with three levels of quality control pools ranged from 2.2-13.0% in percent coefficient of variation (%CV). The accuracy determined by standard addition was between 94 and 111% among all analytes. The median HbAA, HbGA and HbEO values in 34 self-reported non-smokers were 64.9, 45.3 and 113.6 pmol/g Hb and in 70 self-reported smokers were 127.8, 69.6 and 237.1 pmol/g Hb, respectively. HbAA, HbGA, and HbEO were detectable in all samples suggesting that the described method is suitable for measuring hemoglobin adducts of AA, GA and EO in the general population. This high throughput method can process 148 samples in 8 h. The HbEO/HbGA ratio appears independent of the HbAA levels in non-smokers and decreases with increasing HbAA concentration in smokers. This new method is suitable for measuring human exposure to AA, GA and EO and can provide further insight into the metabolism of these chemicals in humans.