Health risk assessment of toxic VOCs species for the coal fire well drillers

Application of homemade portable gas chromatography coupled to photoionization detector for the detection of volatile organic compounds in an industrial park

Traditional offline detection of volatile organic compounds (VOCs) requires complex and time-consuming pre-treatments including gas sampling in containers, pre-concentrations, and thermal desorption, which hinders its application in rapid VOCs monitoring. Developing a cost-effective instrument is of great importance for online measurement of VOCs. Recently, photoionization detectors (PID) are received great attention due to their fast response time and high sensitivity. This study a portable gas chromatography coupled to PID (pGC-PID) was developed and optimized experimental parameters for the application in online monitoring of VOCs at an industrial site. The sampling time, oven temperature and carrier gas flow rate were optimized as 80 s, 50 °C and 60 ml·min^-1, respectively. The sampling method is direct injection. Poly tetra fluoroethylene (PTFE) filter membranes were selected to remove particulate matter from interfering with PID. The reproducibility and peak separation were good with relative standard deviations (RSD) ≤ 7%. Good linearities of 27 VOCs standard curves were achieved with R² ≥ 0.99, and the detection limits were ≤10 ppb with the lowest being 2 ppb for 1,1,2-Trichloroethane. Finally, the pGC-PID is successfully applied in online VOCs monitoring at an industrial site. A total of 17 VOCs species was detected and their diurnal variations were well obtained, indicating pGC-PID is well suited for online analysis in field campaign.

Occupational health risk assessment methods in China: A scoping review

Background

Over the decades, many assessment methods have been developed around the world and used for occupational health risk assessment (OHRA). This scoping review integrated the literature on methodological studies of OHRA in China and aimed to identifies the research hot-spots and methodological research perspectives on OHRA in China.

Methods

A scoping review of literature was undertaken to explore the research progress on OHRA methods in China. Focusing on OHRA methods, the authors systematically searched Chinese and English databases and relevant guideline websites from the date of establishment to June 30, 2022. Databases included Web of Science, PubMed, Scopus, the China National Knowledge Internet, WanFang Database. Some other websites were also searched to obtain gray literature. The extracted information included the author, year, region of first author, the target industry, risk assessment model, study type, the main results and conclusions.

Results

Finally, 145 of 9,081 studies were included in this review. There were 108 applied studies, 30 comparative studies and 7 optimization studies on OHRA in China. The OHRA methods studied included: (1) qualitative methods such as Romanian model, Australian model, International Council on Mining and Metals model, and Control of Substances Hazardous to Health Essentials; (2) quantitative methods such as the U. S. Environmental Protection Agency inhalation risk assessment model, Physiologically Based Pharmacokinetic, and Monte Carlo simulation; (3) semi-quantitative methods such as Singapore model, Fuzzy mathematical risk assessment model, Likelihood Exposure Consequence method and Occupational Hazard Risk Index assessment method; (4) comprehensive method (Chinese OHRA standard GBZ/T 298-2017). Each of the OHRA methods had its own strengths and limitations. In order to improve the applicability of OHRA methods, some of them have been optimized by researchers.

Conclusions

There is a wide range of OHRA methods studied in China, including applied, comparative, and optimization studies. Their applicability needs to be further tested through further application in different industries. Furthermore, quantitative comparative studies, optimization studies, and modeling studies are also needed.

Effect-directed analysis of toxic organics in PM2.5 exposure to the cellular bioassays in vitro: Application in Shanxi of China

To optimize the effect-directed analysis (EDA) approach to identify the fine particulate matter (PM_2.5) bound organic toxicants, Jinzhong city, in the Shanxi Province of China, was selected as the object of our study. First, PM_2.5 samples were collected and their organic extracts were separated out in 9 fractions (F1-F9) using reversed-phase high performance liquid chromatography after purification using gel permeation chromatography. Second, the toxicity effects of each fraction were measured by human bronchial epithelial cells (BEAS-2B) in vitro. And toxicity effects included antioxidant stress (ROS, LDH, and CAT) and an inflammatory response (IL-6, IL-1β, and TNF-α). The results showed that the scores of the toxicity effects on multiple lines of evidence were the highest in the F3 and F4 fractions compared with those of the control. Subsequently, the main poisons, o-cymene, p-cymene, benzene, ethylbenzene, xylene, and styrene, were identified using GC×GC-TOF/MS. Finally, to confirm the above possible candidates, (1) the levels of o-cymene, p-cymene and BTEXS in daily PM_2.5 were measured using GC-MS in November 2020, and the rates of detection of these pollutants were 100% in PM_2.5. Among them, o-cymene and p-cymene were first reported as the key toxic substances of PM_2.5, and their average concentration values were 0.16 ± 0.11 and 0.18 ± 0.15 ng‧m^-3, respectively. (2) the toxicity of p-cymene may be no less than that of other benzene derivatives according to their LC50 in Daphnia magna. (3) based on canonical correlation analysis, the exposure to p-cymene, benzene, and styrene in PM_2.5 was most likely associated with the toxicity effects (CAT, IL-6, and TNF-α), which in turn caused the observed toxicity. In conclusion, p-cymene, benzene, and styrene were found to be the key toxic organics in PM_2.5 for cells in vitro. EDA technology avoids the limitations of chemical analysis and uncertainty of the biological testing and adds new toxicants to the control list of PM_2.5, contributing to this study field. However, the application of EDA to PM_2.5 still faces challenges such as the selection of biological effects, loss of toxicity with the separation process, influence of the dosing method, and identification of the unknown effects of pollutants.

Carcinogenic and health risk assessment of respiratory exposure to Acrylonitrile, 1,3-Butadiene and Styrene (ABS) in a Petrochemical Industry Using the United States Environmental Protection Agency (EPA) Method

PURPOSE

This study aimed to carcinogenic and health risk assessment of respiratory exposure to acrylonitrile, 1,3-butadiene, and styrene in the petrochemical industry.

MATERIALS AND METHODS

This cross-sectional study was conducted in a petrochemical plant producing acrylonitrile, butadiene, and styrene (ABS) copolymers. Respiratory exposure with acrylonitrile, 1,3-butadiene and styrene was measured using methods No. 1604, 1024, and 1501 of the National Institute of Occupational Safety and Health, respectively. The US Environmental Protection Agency method was used to assess carcinogenic and health risks.

RESULTS

The average occupational exposure to acrylonitrile, 1,3-butadiene, and styrene was 560.82 μg. m^-3 for 1,3-butadiene, 122.8 μg. m^-3 for acrylonitrile and 1.92 μg. m^-3 for styrene. The average lifetime cancer risk (LCR) in the present study was 2.71 ×10^-3 for 1,3-butadiene, 2.1 ×10^-3 for acrylonitrile, and 6.6 for styrene. Also, the mean non-cancer risk (HQ) among all participants for 1,3-butadiene, acrylonitrile, and styrene was 4.04 ± 6.93, 10.82 ± 14.76, and 0.19 ± 0.11, respectively.

CONCLUSION

The values of carcinogenic and health risks in the majority of the subjects were within the unacceptable risk levels due to exposure to 1,3-butadiene, acrylonitrile, and styrene vapors. Hence, corrective actions are required to protect the workers from non-cancer and cancer risks.

External Exposure to BTEX, Internal Biomarker Response, and Health Risk Assessment of Nonoccupational Populations near a Coking Plant in Southwest China

Benzene, toluene, ethylbenzene and xylene isomers (BTEX) have raised increasing concern due to their adverse effects on human health. In this study, a coking factory and four communities nearby were selected as the research area. Atmospheric BTEX samples were collected and determined by a preconcentrator GC-MS method. Four biomarkers in the morning urine samples of 174 participants from the communities were measured by LC-MS. The health risks of BTEX exposure via inhalation were estimated. This study aimed to investigate the influence of external BTEX exposure on the internal biomarker levels and quantitatively evaluate the health risk of populations near the coking industry. The results showed that the average total BTEX concentration in residential area was 7.17 ± 7.24 μg m^-3. Trans,trans-muconic acid (T,T-MA) was the urinary biomarker with the greatest average level (127 ± 285 μg g^-1 crt). Similar spatial trends can be observed between atmospheric benzene concentration and internal biomarker levels. The mean values of the LCR for male and female residents were 2.15 × 10^-5 and 2.05 × 10^-5, respectively. The results of the risk assessment indicated that special attention was required for the non-occupational residents around the area.

1,3-Butadiene: a ubiquitous environmental mutagen and its associations with diseases

1,3-Butadiene (BD) is a petrochemical manufactured in high volumes. It is a human carcinogen and can induce lymphohematopoietic cancers, particularly leukemia, in occupationally-exposed workers. BD is an air pollutant with the major environmental sources being automobile exhaust and tobacco smoke. It is one of the major constituents and is considered the most carcinogenic compound in cigarette smoke. The BD concentrations in urban areas usually vary between 0.01 and 3.3 μg/m³ but can be significantly higher in some microenvironments. For BD exposure of the general population, microenvironments, particularly indoor microenvironments, are the primary determinant and environmental tobacco smoke is the main contributor. BD has high cancer risk and has been ranked the second or the third in the environmental pollutants monitored in most urban areas, with the cancer risks exceeding 10^-5. Mutagenicity/carcinogenicity of BD is mediated by its genotoxic metabolites but the specific metabolite(s) responsible for the effects in humans have not been determined. BD can be bioactivated to yield three mutagenic epoxide metabolites by cytochrome P450 enzymes, or potentially be biotransformed into a mutagenic chlorohydrin by myeloperoxidase, a peroxidase almost specifically present in neutrophils and monocytes. Several urinary BD biomarkers have been developed, among which N-acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine is the most sensitive and is suitable for biomonitoring BD exposure in the general population. Exposure to BD has been associated with leukemia, cardiovascular disease, and possibly reproductive effects, and may be associated with several cancers, autism, and asthma in children. Collectively, BD is a ubiquitous pollutant that has been associated with a range of adverse health effects and diseases with children being a subpopulation with potentially greater susceptibility. Its adverse effects on human health may have been underestimated and more studies are needed.

The role of airborne particles and environmental considerations in the transmission of SARS-CoV-2

Corona Virus Disease 2019 (COVID-19) caused by the novel coronavirus, results in an acute respiratory condition coronavirus 2 (SARS-CoV-2) and is highly infectious. The recent spread of this virus has caused a global pandemic. Currently, the transmission routes of SARS-CoV-2 are being established, especially the role of environmental transmission. Here we review the environmental transmission routes and persistence of SARS-CoV-2. Recent studies have established that the transmission of this virus may occur, amongst others, in the air, water, soil, cold-chain, biota, and surface contact. It has also been found that the survival potential of the SARS-CoV-2 virus is dependent on different environmental conditions and pollution. Potentially important pathways include aerosol and fecal matter. Particulate matter may also be a carrier for SARS-CoV-2. Since microscopic particles can be easily absorbed by humans, more attention must be focused on the dissemination of these particles. These considerations are required to evolve a theoretical platform for epidemic control and to minimize the global threat from future epidemics.

Effects of air pollution control devices on volatile organic compounds reduction in coal-fired power plants

Air pollution control devices (APCDs) have been fitted to many coal-fired power plants to decrease the impacts of pollutants generated during coal combustion. APCDs remove conventional pollutants but also decrease volatile organic compound (VOC) emissions. In this study, flue gas samples were collected from different points in seven typical coal-fired power and two industrial boilers, and the VOC concentrations in the flue gas samples were determined by gas chromatography-mass spectrometry (GC-MS). Selective catalytic reduction (SCR) systems and electrostatic precipitators (ESP) can synergistically remove VOCs, the mean removal rate of VOCs by ESP was 42% ± 9%. This was caused by the catalyst in SCR systems and the condensation process in the ESP. Wet flue gas desulfurization (WFGD) affected different VOCs in different ways, increasing the halogenated hydrocarbons and aromatic hydrocarbons concentrations but decreasing the oxygenated VOCs concentrations by 12%. Wet electrostatic precipitators (WESP) increased VOC emissions. By calculating Ozone formation potential (OFP), aromatic hydrocarbons are important contributors to ozone production. The emission factor of the power plant was 0.69 g/GJ, and the Chinese annual emission was about 1.2 × 10⁴ t. VOCs emissions in different regions were affected by factors such as the economy and population. VOC emissions can be decreased by using the most appropriate unit load and improving the VOC removal efficiencies of the APCDs.

Underground coal fire emission of spontaneous combustion, Sandaoba coalfield in Xinjiang, China: Investigation and analysis

Long-term spontaneous combustion of coal has caused serious ecological and environmental problems. Only in recent years has it received growing popularity to undertake relevant researches. In order to study the impact of combustion by-products on atmosphere in the Sandaoba fire field, Xinjiang, a region-scale field survey was firstly conducted to investigate the gaseous-solid emissions in separated fire sections. The evaluation method and model have been proposed to describe the underground combustion and the related air pollution. Every year, the total estimates of the gaseous emission are approximately 4030 t of CO₂, 113.6 t of SO₂ and 57.3 t of CO. The emission pollution varies considerably from regions, and is substantially attenuated with the advancement of fire control. Principal component analysis (PCA) refines the thermophysical parameters into three attributions: the intrinsic thermophysical property, atmospheric dynamics, and combustion degree. PCA score distribution shows that thermophysical parameter is dominated by the combustion condition at severely polluted areas. Factor Analysis is used to extract four contaminant indicators, which suggests the local air suffers sulfur oxides pollution the most. The air quality index of the eight study sections calculated are all below 60, ranging from 24 to 58. It indicates that coal fire air pollution is in the medium-to-severe stage. By Canonical Correlation Analysis, it is noted that thermophysical indicator performs outstanding explanatory for contaminant variates. On the whole, the higher the level of thermophysical properties in the fire area, the greater the intensity of pollutant emission. Underground coalfield fire is dominated by smoldering, and the overall combustion efficiency is lower than 0.8 which generally declines as the excess air coefficient increasing.

Specification of complex-PAHs in coal fire sponges (CFS) by high-resolution mass spectrometry with electrospray ionization

Underground coal fires are considered an ecological disaster. While underground coal fires are prevalent in coal-producing areas throughout the world, they are most problematic in northern China. Previous studies have shown that underground coal fires stimulate the formation of cracks or gas outlets on the surface, as well as coal fire sponges (CFS) on the soil layer surface, which collect coal-fired pollutants. Herein, ultra-high-performance liquid chromatography (UHPLC) was used in conjunction with electrospray ionization (ESI) high-resolution mass spectrometry to analyze CFS samples collected from the No. 8 fire zone, located in Wuda coalfield, Inner Mongolia, China. The results show that CFS contain 233 oxy-substituted polycyclic aromatic hydrocarbons (O-PAHs), e.g., naphthaldehyde; 40 oxapolycyclic aromatic hydrocarbons (OPAHs), e.g., dibenzofuran; 40 alkyl-substituted polycyclic aromatic hydrocarbons (R-PAHs); and 11 parent polycyclic aromatic hydrocarbons (PPAHs). Thus, CFS are primarily composed of O-PAHs, which are 25 times and 5 times more prevalent than PPAHs and R-PAHs, respectively. As such, a high relative abundance of varied O-PAHs are discharged from underground coal fires, which is significantly different from what is released during industrial coal burning. Owing to their water solubility and condensability, the new facts disclosed in this paper may provide a new perspective for understanding complex organic pollutants from underground coal fires and their environmental impacts.

Cancer and non-cancer health risk assessment of occupational exposure to 1,3-butadiene in a petrochemical plant in Iran

1,3-Butadiene is classified as carcinogenic to humans by inhalation. This study aimed to assess cancer and non-cancer risk following occupational exposure to 1,3-butadiene. This cross-sectional study was conducted in a petrochemical plant producing acrylonitrile butadiene styrene copolymer in Iran. Occupational exposure to 1,3-butadiene was measured according to the National Institute for Occupational Safety and Health 1024 method. Cancer and non-cancer risk assessment were performed according to the United States Environmental Protection Agency method. The average occupational exposure to 1,3-butadiene during work shifts among all participants was 560.82 ± 811.36 µg m^-3. The average lifetime cancer risk (LCR) in the present study was 2.71 × 10^-3; 82.2% of all exposed workers were within the definite carcinogenic risk level. Also, the mean non-cancer risk (hazard quotient (HQ)) among all participants was 10.82 ± 14.76. The highest LCR and HQ were observed in the safety and fire-fighting station workers with values of 7.75 × 10^-3 and 36.57, respectively. The findings revealed that values of carcinogenic and noncarcinogenic risk in the majority of participants were within the definitive and unacceptable risk levels. Therefore, corrective measures are necessary to protect these workers from non-cancer and cancer risks from 1,3-butadiene exposure.

Occupational exposure to respirable dust from the coal-fired power generation process: sources, concentration, and health risk assessment

To investigate the contamination levels of respirable dust released in the work environment and the induced workers' health risk at a coal-fired power plant, we collected 405 dust samples from different dusty workstations by personal sampling during the coal-fired power generation process. Then, an inhalation risk assessment model from the USEPA was combined with the Monte Carlo simulation method to quantitatively evaluate the health risk caused by dust inhalation. Of 10 workstations researched, the dust concentration in the most workstations exceeded the prescribed occupational exposure limit. Workers engaged in ash removal suffered the highest health risk at 4.08 × 10^-6 ± 2.85 × 10^-6 (95% CI), closely followed by those involved in other job categories. The results can contribute to the formulation of targeted dust prevention measures and implementation of risk management for the coal-fired power sector.

A review on the mechanism, risk evaluation, and prevention of coal spontaneous combustion in China

In recent years, the ecology, security, and sustainable development of modern mines have become the theme of coal mine development worldwide. However, spontaneous combustion of coal under conditions of oxygen supply and automatic exothermic heating during coal mining lead to coalfield fires. Coal spontaneous combustion (CSC) causes huge economic losses and casualties, with the toxic and harmful gases produced during coal combustion not only polluting the working environment, but also causing great damage to the ecological environment. China is the world's largest coal producer and consumer; however, coal production in Chinese mines is seriously threatened by the CSC risk. Because deep underground mining methods are commonly adopted in Chinese coal mines, coupling disasters are frequent in these mines with the coalfield fires becoming increasingly serious. Therefore, in this study, we analyzed the development mechanism of CSC. The CSC risk assessment was performed from the aspects of prediction, detection, and determination of the "dangerous area" in a coal mine (i.e., the area most susceptible to fire hazards). A new geophysical method for CSC determination is proposed and analyzed. Furthermore, the main methods for CSC fire prevention and control and their advantages and disadvantages are analyzed. To eventually construct CSC prevention and control integration system, future developmental direction of CSC was given from five aspects. Our results can present a reference for the development of CSC fire prevention and control technology and promote the protection of ecological environment in China.

Quantification and risk assessment of organic products resulting from non-thermal plasma removal of toluene in nitrogen

RATIONALE

Non-thermal plasma (NTP) has proven to be an effective approach for the removal of volatile organic compounds (VOCs). However, harmful organic by-products, produced during NTP-mediated removal of VOCs, hinder practical applications of this technology. It is necessary to characterize the organic by-products to assess their health risks.

METHODS

A method is proposed for analyzing and evaluating organic by-products for NTP-mediated removal of VOCs in this work. NTP generated by a coaxial dielectric barrier discharge (DBD) reactor was used for the removal of a model VOC, toluene, in nitrogen. Organic products were characterized using a real-time proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) apparatus.

RESULTS

The PTR-TOF-MS apparatus has been shown to be effective for real-time high-sensitivity detection of trace VOCs. The main observed organic compounds, with concentrations on the order of ppb/ppm, were hydrogen cyanide, acetonitrile, propanenitrile, benzene, benzonitrile, and benzyl nitrile, etc.

CONCLUSIONS

A health-related index (HRI) was introduced to assess the health risks associated with these organic products. The HRI was not correlated with the removal efficiency (η), with higher η possibly yielding higher HRI, associated with higher health risks. Specific input energy (SIE) was a key factor affecting the formation of the observed organic products and their HRI values. We conclude that in practical applications, SIE, HRI, and η must be balanced.