Analysis of Benzene Exposure in Gas Station Workers Using Trans,Trans-Muconic Acid

Biomarkers of occupational benzene exposure: A Systematic Review to estimate the exposure levels and individual susceptibility at low doses

Benzene is associated with diverse occupational and public health hazards. It exhibits an ability to rapidly permeate the skin and contaminate water and food sources, leading to dermal and ingestion exposures. Despite numerous studies examining the associations between benzene and various indicators of harm, the findings have yielded inconsistent results. Furthermore, relying solely on air concentration as a measure of benzene exposure is limited, as it fails to account for internal exposure dose and individual susceptibility. This study aimed to conduct a comprehensive review in order to present current knowledge on benzene biomarkers and their significance in evaluating exposure levels and associated health hazards. The search methodology adhered to the PRISMA guidelines and involved the application of specific inclusion and exclusion criteria across multiple databases including PubMed, Embase, and Web of Science. Two researchers independently extracted and evaluated the relevant data based on predetermined criteria. Following the screening process, a total of 80 articles were considered eligible out of the initially retrieved 1053 articles after undergoing screening and assessment for inclusion. As the level of exposure decreased, specific biomarkers demonstrated a gradual increase in limitations, including heightened background concentrations and vulnerability to confounding factors. The advancement of sampling and analysis techniques will yield new biomarkers. Additionally, when conducting practical work, it is crucial to employ a comprehensive utilization of diverse biomarkers while excluding individual metabolic variations and combined exposure factors.

Novel Serum Proteomes Expressed from Benzene Exposure Among Gasoline Station Attendants

Background

Research on the proteomes impact of benzene exposure in fuel station employees remains sparse, underscoring the need for detailed health impact assessments focusing on biomarker evaluation.

Objectives

This investigation aimed to analyze the differences in blood parameters and serum proteomes resulting from benzene exposure between gasoline station attendants (B-GSA) and a control group.

Design and methods

A cross-sectional analytical study was conducted with 96 participants, comprising 54 in the B-GSA group and 42 in the control group. The methodology employed included an interview questionnaire alongside urine and blood sample collections. The urine samples were analyzed for trans,trans-muconic acid (t,t-MA) levels, while the blood samples underwent complete blood count analysis and proteome profiling.

Results

Post-shift analysis indicated that the B-GSA group exhibited significantly higher levels of t,t-MA and monocytes compared to the control group (P < .05). Proteome quantification identified 1448 proteins differentially expressed between the B-GSA and control groups. Among these, 20 proteins correlated with the levels of t,t-MA in urine. Notably, 4 proteins demonstrated more than a 2-fold down-regulation in the B-GSA group: HBS1-like, non-structural maintenance of chromosomes element 1 homolog, proprotein convertase subtilisin/kexin type 4, and zinc finger protein 658. The KEGG pathway analysis revealed associations with apoptosis, cancer pathways, p53 signaling, and the TNF signaling pathway.

Conclusion

The changes in these 4 significant proteins may elucidate the molecular mechanisms underlying benzene toxicity and suggest their potential as biomarkers for benzene poisoning in future assessments.

False positives and false negatives in benzene biological monitoring

Benzene is a commonly used industrial chemical that is a significant environmental pollutant. Occupational health specialists and industrial toxicologists are concerned with determining the exact amount of exposure to chemicals in the workplace. There are two main approaches to assess chemical exposure; air monitoring and biological monitoring. Air monitoring has limitations, which biological monitoring overcomes and could be used as a supplement to it. However, there are several factors that influence biological monitoring results. It would be possible to assess exposure more accurately if these factors were taken into account. This study aimed to review published papers for recognizing and discussing parameters that could affect benzene biological monitoring. Two types of effects can be distinguished: positive and negative effects. Factors causing positive effects will increase the metabolite concentration in urine more than expected. Furthermore, the parameters that decrease the urinary metabolite level were referred to as false negatives. From the papers, sixteen influential factors were extracted that might affect benzene biological monitoring results. Identified factors were clarified in terms of their nature and mechanism of action. It is also important to note that some factors influence the quantity and quality of the influence of other factors. As a result of this study, a decision-making protocol was developed for interpreting the final results of benzene biological monitoring.

The Benzene-induced Hepatic Cytochrome P450 2E1 Expression and Activity are Reduced by Quercetin Administration in Mice

BACKGROUND

Benzene as an environmental and industrial agent induces adverse effects that are mainly metabolism-dependent.

OBJECTIVES

Effects of Quercetin (QCN) on Benzene (BNZ)-induced changes in the hepatic Cytochrome P450 2E1 expression and activity were investigated.

METHODS

Thirty-six adult male mice were divided into 6 groups (n = 6) and nominated as control, BNZ (exposed to BNZ: 30 ppm), QCN (received QCN: 50 mg/kg, orally), and the fourth, fifth and sixth groups were exposed to 30 ppm BNZ and received 10, 50 and 100 mg/kg QCN respectively, for 28 days. The microsomal subcellular fraction was isolated from the liver samples and the activity of CYP 2E1 was measured based on the hydroxylation rate of 4-nitrophenol. The hepatic activity of myeloperoxidase also was assessed. Total antioxidant capacity and nitric oxide contents of the liver were determined. Expression changes of CYP 2E1 at the mRNA level were examined by qPCR technique.

RESULTS

QCN lowered significantly (p < 0.05) the BNZ-increased hepatic nitric oxide levels and restored the BNZ-reduced antioxidant capacity. The BNZ-elevated activity of myeloperoxidase was declined in QCN-received mice. QCN downregulated the expression and activity of hepatic CYP 2E1 in BNZ-exposed animals.

CONCLUSION

Our results suggest that QCN could be a novel hepatoprotective compound for BNZ-induced hepatotoxicities, which is attributed to its capability in the down-regulation of CYP 2E1 expression and activity.

Reducing the negative impact of accidents associated with the release of dangerous substances to environment

Background

The article is concerned with an evaluation of the current state of emergency readiness of industrial companies in the event of dangerous substance leakage and with a presentation of textile sorbents used for the purposes of capturing an escaped substance.

Methods

A part of the article is concerned with the experimental designation of sorption capacity of hydrophobic, chemical, and universal sorption mats for chosen polar (water and alcohol) and non-polar (oil and gasoline) liquids. Experiments were realized according to Standard Test Method for Sorbent Performance of Adsorbents for use on Crude Oil and Related Spills, American Society for Testing and Materials (ASTM F726-17), type I. and Test methods for non-woven fabrics, European Union International Organization for Standardization (EN ISO 9073-6:2004). The aim of the article is an experimental designation of sorption capacity of textile sorption mats using two different methods, a comparison of the acquired results and a comparison of the acquired data with the data given by the manufacturer.

Results

Textile sorbents, which can, owing to their sorption ability, allow the elimination or mitigation of a negative impact of a possible accident in the company connected with an escape of a liquid dangerous substance were tested and compared with the established values. Based on the obtained results it is possible to state that sorption capacities of the chemical and universal mat for the substrate water are equal and consistent with the data given by the manufacturer. Textile sorption mats also have a comparable sorption capacity. The sorption capacity on the substrate gasoline is the same in all textile sorbents. The adsorption capacity per unit mass all type's sorbents was similar for non-polar liquids (gasoline was values from 6.41 to 6.57 and oil was values from 9.54 to 10.24).

Conclusion

The acquired results confirmed the universality of textile sorption mats for gasoline. Sorption capacities of the chemical and universal mat for the substrate water are equal and match the data given by the manufacturer. Textile sorption mats have a maximum sorption output up to 60 s, afterwards the sorption capacity values remain unchanged.

Comparison of acetylcholinesterase among employees based on job positions and personal protective equipment in fuel station

The purpose of this study was to compare the levels of acetylcholinesterase (AChE) among employees based on job positions and the wearing of personal protective equipment (PPE) in fuel station areas. The sample group consisted of 200 people sorted into various groups, including (i) Inside fuel dispenser area (I-FDA) group consisting of 100 employees for refueling, cashier, and loading fuel into storage tanks, and (ii) Outside fuel dispenser area (O-FDA) group, consisting of 100 employees working in convenience stores, food stores, coffee shops, and offices, as well as general staff and car washers. Data were collected using interview questionnaires and blood samples were analyzed for AChE activity. The results showed that the I-FDA group had a significantly lower mean of serum AChE (7.38±1.73 U/ml) than the O-FDA group (7.85±1.49 U/ml) (p<0.05). The I-FDA group had a 2.43 times higher risk of abnormal serum AChE than the O-FDA group (OR=2.43, 95%CI=1.05-5.60). When considering the risk factors for job positions, it was found that refueling and cashier positions had lower AChE activity levels than those who did not (p<0.05). In the part, employees for food sales in a closed building and those wearing PPE masks had significantly higher AChE activity levels than those who did not or who wore them (p<0.05). Based on the aforementioned, employers at fuel stations should strictly determine the appropriate measures for wearing a PPE mask. Further, employees should be provided accommodation away from oil supply or enclosed buildings during breaks to reduce the effects on the neurotransmitter.

Hematological Changes in Gas Station Workers

(1) Background: Benzene, toluene, and xylene isomers (BTX) are present in gasoline. Exposure to benzene may lead to the appearance of a series of signs, symptoms, and complications, which are characterized by benzene poisoning, which is an occupational disease. This study evaluated the presence of signs and symptoms related to occupational exposure and whether occupational exposure to BTX is associated with the development of hematological changes. (2) Material and Methods: This cross-sectional epidemiological study included 542 participants, in which 324 were gas station workers (GSWs) and 218 were office workers (OWs) with no occupational exposure to benzene. To characterize the type of exposure (exposed and not exposed), trans,trans-Muconic acid (tt-MA), Hippuric acid (HA), and Methylhippuric acid (MHA) were used as exposure biomarkers. The tt-MA analysis revealed that the GSWs had 0.29 mg/g of urinary creatinine and the OWs had 0.13 mg/g of urinary creatinine. For HA, the GSWs presented 0.49 g/g of creatinine while the OWs presented 0.07. MHA analysis revealed that the GSWs had 1.57 g/g creatinine and the OWs had 0.01 g/g creatinine. Occupation habits and clinical symptoms were collected by questionnaire and blood samples were analyzed for hematological parameters. The persistence of hematological changes was evaluated with three serial blood collections every 15 days followed by laboratory hematological analysis. A descriptive analysis by the Chi-square test method was performed to evaluate the association between occupational exposure to fuels and the occurrence of changes in hematological parameters. (3) Results: In the GSWs, the most described signs and symptoms were somnolence (45.1%), headache (38.3%), dizziness (27.5%), tingling (25.4%), and involuntary movement (25%). Twenty GSWs that presented hematological alterations performed serial collections fifteen days apart. In addition, these workers presented total leukocyte counts above the upper limit and lymphocyte counts close to the lower limit. Leukocytosis and lymphopenia are hematological alterations present in chronic benzene poisoning. (4) Conclusions: The results found an initial change in different hematological parameters routinely used in clinics to evaluate health conditions. These findings reveal the importance of valuing clinical changes, even in the absence of disease, during the health monitoring of gas station workers and other groups that share the same space.

Iron-dependent ferroptosis participated in benzene-induced anemia of inflammation through IRP1-DHODH-ALOX12 axis

Benzene, a widely existing environmental pollutant, gives huge harm to the hematopoietic system. Iron is one of the raw materials for the creation of blood cells, but the role of iron in the blood toxicity of benzene is still unknown. Here, we examined the role of iron homeostasis in benzene-induced toxicity both in vivo and in vitro. In this study, mice exposed to benzene at 50 ppm for 8 weeks demonstrated the anemia of inflammation, mainly manifested as the decreased serum Fe²⁺, increased serum ferritin and inflammation factors (TNF-α, IL6, IL1β) in the plasma of mice. Furthermore, we found that iron maldistribution in the spleen and bone marrow is accompanied by inflammation reaction and ferroptosis. In the vitro study, benzene metabolite 1,4-BQ stimulated the obvious ROS production and ferroptosis activation in the normal B lymphocytes cells. Meanwhile, from the molecular perspective, the combined proteomics and transcriptome enriched the ferroptosis pathway, and we further confirmed the increased expression of iron regulator IRP1, ferroptosis-regulator DHODH, and fatty acids metabolism enzyme ALOX12 were the crucial participators in regulating benzene-mediated iron metabolism imbalance and ferroptosis. Particularly, the targeted and un-targeted metabolomics in the vivo and vitro study further emphasized the importance of DHODH in benzene-induced ferroptosis. In conclusion, this study revealed that iron-dependent ferroptosis participated in benzene-induced anemia of inflammation and provided a constructive perspective on targeting ferroptosis for the prevention and control of benzene toxicity.

Usage of sorbents for diminishing the negative impact of substances leaking into the environment in car accidents

Background

Car accidents are often accompanied by dangerous substances leaking into the environment. A proper reaction to the leaking substances, utilizing appropriate sorbents, is necessary for diminishing the negative impact of such events. Sorbents as substances of initial intervention in car accidents (as well as industrial and ecological accidents) are a crucial tool for solving crises connected with dangerous substances escaping into the environment. The risk resulting from the given realities is described in detail in the introduction of the article.

The goal

The goal is describing elements of crisis management in dangerous substance leakage and an analysis of sorption resources for quick and efficient interception of leaking substances, water, ethanol, oil, and gasoline in particular, as a reaction to such events.

Methods

The quality of a sorption resource is determined by a parameter called the sorption capacity, which has been established according to the ASTM F716-18 standard. Loose nature-based sorbents (peat) and synthetic silicate-based SiO₂, Al₂O₃, Fe₂O₃, and polypropylene-based ones were observed. The research has been realized on a water, oil, gasoline, and ethanol sorbate. Each experiment was repeated three times.

The results

The results attest to the diversity of sorption capacity in comparing nature-based, silicate-based, and polypropylene-based sorption materials. The highest sorption capacity values were reached with the Sorb 4 sample, which is based on 66% of silica and 18% of alumina. The stated ratio is important, because the Sorb 3 sample contains 85% of silica and 6% of alumina and its absorption capacity values are significantly lower.

Firefighters' urinary concentrations of VOC metabolites after controlled-residential and training fire responses

INTRODUCTION

Firefighters are exposed to volatile organic compounds (VOCs) during structural fire responses and training fires, several of which (e.g., benzene, acrolein, styrene) are known or probable carcinogens. Exposure studies have found that firefighters can absorb chemicals like benzene even when self-contained breathing apparatus (SCBA) are worn, suggesting that dermal absorption contributes to potentially harmful exposures. However, few studies have characterized VOC metabolites in urine from firefighters.

OBJECTIVES

We quantified VOC metabolites in firefighters' urine following live firefighting activity across two field studies.

METHODS

In two separate controlled field studies, spot urine was collected before and 3 h after firefighters and firefighter students responded to simulated residential and training fires. Urine was also collected from instructors from the training fire study before the first and 3 h after the last training scenario for each day (instructors led three training scenarios per day). Samples were analyzed for metabolites of VOCs to which firefighters may be exposed.

RESULTS

In the residential fire study, urinary metabolites of xylenes (2MHA), toluene (BzMA), and styrene (MADA) increased significantly (at 0.05 level) from pre- to post-fire. In the training fire study, MADA concentrations increased significantly from pre- to post-fire for both firefighter students and instructors. Urinary concentrations of benzene metabolites (MUCA and PhMA) increased significantly from pre- to post-fire for instructors, while metabolites of xylenes (3MHA+4MHA) and acrolein (3HPMA) increased significantly for firefighter students. The two highest MUCA concentrations measured post-shift from instructors exceeded the BEI of 500 μg/g creatinine.

CONCLUSIONS

Some of the metabolites that were significantly elevated post-fire are known or probable human carcinogens (benzene, styrene, acrolein); thus, exposure to these compounds should be eliminated or reduced as much as possible through the hierarchy of controls. Given stringent use of SCBA, it appears that dermal exposure contributes in part to the levels measured here.

Factors affecting prevalence of neurological symptoms among workers at gasoline stations in Rayong Province, Thailand

This cross-sectional study was aimed at assessing the exposure to organic solvents and the factors affecting prevalence of neurological symptoms among workers at gas stations in Rayong Province. The sample included 200 workers at gas stations, including refueling staff, cashiers, food shop, coffee shop, and convenience store employees. Interview questionnaire included general information, work history, and neurological symptoms. Urine collection devices were used to detect organic solvents metabolized in urine, including t,t-muconic acid (t,t-MA), hippulic acid (HA), mandelic acid (MA), and methylhppuric acid (MHA).The results showed that the workers’ medians (interquartile range: IQR) of the metabolized organic solvents were as follows: t,t-MA was 393.62 (244.59) µg/g Cr, HA was 0.32 (0.14) g/g Cr, MA was 0.06 (0.02) g/g Cr, and MHA was 0.40 (0.13) g/g Cr. For prevalence of neurological symptoms, top three symptoms were headache (49.0%), dizziness (42.5%), and stress/irritability (38.5%). Working at a gas station present was neurological symptoms more than in the past was 32.5%. According to the assessment of exposure to metabolized organic solvents and factors affecting the prevalence of neurological symptoms, overtime work ≥ 6 hours and HA content greater than quartiles Q3 had an effect on neurologic symptoms (OR=2.17; 95%CI=1.23-5.10 and OR=2.15; 95%CI=1.18- 4.76, respectively). In summary, time spent working in gas stations and exposure to toluene organic solvents can cause neurological symptoms. It is recommended to reduce overtime or add breaks during work shifts or shift changes. In addition, workers should be away from the solvent.

Factors Affecting Adverse Health Effects of Gasoline Station Workers

This cross-sectional study examined the risk factors affecting adverse health effects from benzene exposure among gasoline station workers in Khon Kean province, Thailand. An interview questionnaire of adverse symptoms relating to benzene toxicity was administered to 151 workers. Area samplings for benzene concentration and spot urine for tt-muconic acid (tt-MA), a biomarker of benzene exposure, were collected. The factors associated with adverse symptoms were analysed by using multiple logistic regression. It was found that these symptoms mostly affected fuelling workers (77.5%), and the detected air benzene reached an action level or higher than 50% of NIOSH REL (>50 ppb). The top five adverse symptoms, i.e., fatigue, headache, dizziness, nasal congestion, and runny nose, were reported among workers exposed to benzene. More specific symptoms of benzene toxicity were chest pain, bleeding/epistaxis, and anaemia. The detected tt-MA of workers was 506.7 ug/g Cr (IQR), which was a value above the BEI and higher than that of asymptomatic workers. Risk factors significantly associated with adverse symptoms, included having no safety training experience (OR_adj = 5.22; 95% CI: 2.16–12.58) and eating during work hours (OR_adj = 16.08; 95% CI: 1.96–131.74). This study urges the tightening of health and safety standards at gasoline stations to include training and eating restrictions while working in hazardous areas.

Evaluation of Exposure to Toluene and Xylene in Gasoline Station Workers

The main volatile organic compounds found at gasoline stations are benzene, toluene, ethylbenzene, and xylene isomers (BTEX). They cause several harmful effects on human health. Regulatory Norm 7 (1978) provides that, in Brazil, biological monitoring of toluene and xylene is carried out by measuring the urinary metabolites hippuric acid (HA) and methylhippuric acid (MHA), respectively. The objective of this study was to assess the exposure to toluene and xylene and to identify related signs and symptoms in gasoline station workers. A cross-sectional epidemiological study was conducted with workers occupationally exposed to fuels. These gasoline station workers were divided into two groups: 94 workers exposed mainly by inhalation (convenience store workers (CSWs)) and 181 workers exposed by inhalation and dermal route (filling station attendants (FSAs)). A comparison group was formed by 119 workers not occupationally exposed to fuels (office workers (OWs)). Workers exposed to fuels had higher average levels of these exposure biomarkers (HA and MHA), which were also higher in convenience store workers than in filling station attendants. In addition, individuals exposed to the solvents present in gasoline had altered mood/depression, cramps, dizziness, drowsiness, headaches, irritability/nervousness, weakness, weight loss, and other symptoms more frequently and had higher urinary levels of HA and MHA compared to the comparison group. Gasoline station workers showed high levels of HA and MHA, reflecting high occupational exposure to the solvents toluene and xylene present in gasoline, demonstrating that changes in the current legislation and in the work environment are necessary to ensure better health protection for these workers.

Covalent-coordination tandem functionalization of a metal-organic framework (UiO-66) as a hybrid probe for luminescence detection of trans,trans-muconic acid as a biomarker of benzene and Fe3

By means of post-synthetic treatment on the UiO-66 derivative with -SO3H, a novel luminescent hybrid material named Tb3+@UiO-66-SO3H has been prepared simply and efficiently. Given its wonderful luminescence properties like intense green emission, a long lifetime, a robust structure and photostability, it is further developed as a fluorescent probe for the sensing of trans,trans-muconic acid (tt-MA, a biomarker of benzene) and Fe3+, which are closely related to human health. Notably, Tb3+@UiO-66-SO3H shows an outstanding recognition ability for Fe3+ among common cations with a low detection limit (0.11 μM, 0.006 ppm). More importantly, Tb3+@UiO-66-SO3H can realize highly sensitive and selective detection of tt-MA (detection limit, 0.58 μM, 0.083 ppm). Besides, this rapid response probe is facilely prepared, non-toxic and reusable, showing the potential of Tb3+@UiO-66-SO3H in the practical monitoring of tt-MA and Fe3+.

Gasoline-station workers in Brazil: Benzene exposure; Genotoxic and immunotoxic effects

Chronic exposure to benzene is a risk factor for hematological malignancies. Gasoline-station workers are exposed to benzene in gasoline, via both inhalation and dermal contact (attendants and managers) or inhalation (workers in the on-site convenience stores and offices). We have studied the exposure of these workers to benzene and the resulting genotoxic and immunotoxic effects. Levels of urinary trans, trans-muconic acid were higher among gasoline-station workers than among office workers with no known exposure to benzene (comparison group). Among the exposed workers, we observed statistically significant biological effects, including elevated DNA damage (comet assay); higher frequencies of micronuclei and nuclear buds (CBMN assay); lower levels of T-helper lymphocytes and naive Th lymphocytes; lower CD4 / CD8 ratio; and higher levels of NK cells and memory Th lymphocytes. Both groups of exposed workers (inhalation and inhalation + dermal routes) showed similar genotoxic and immunotoxic effects.