Evaluation of immunological, inflammatory, and oxidative stress biomarkers in gasoline station attendants

Increased oxidative stress in shoe industry workers with low-level exposure to a mixture of volatile organic compounds

This study aimed to assess the redox status and trace metal levels in 49 shoe industry workers (11 men and 38 women) occupationally exposed to a mixture of volatile organic compounds (VOCs), which includes aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, and carboxylic acids. All measured VOCs were below the permitted occupational exposure limits. The control group included 50 unexposed participants (25 men and 25 women). The following plasma parameters were analysed: superoxide anion (O2 •-), advanced oxidation protein products (AOPP), total oxidative status (TOS), prooxidant-antioxidant balance (PAB), oxidative stress index (OSI), superoxide dismutase (SOD) and paraoxonase-1 (PON1) enzyme activity, total SH group content (SHG), and total antioxidant status (TAS). Trace metal levels (copper, zinc, iron, magnesium, and manganese) were analysed in whole blood. All oxidative stress and antioxidative defence parameters were higher in the exposed workers than controls, except for PON1 activity. Higher Fe, Mg, and Zn, and lower Cu were observed in the exposed vs control men, while the exposed women had higher Fe and lower Mg, Zn, and Cu than their controls. Our findings confirm that combined exposure to a mixture of VOCs, even at permitted levels, may result in additive or synergistic adverse health effects and related disorders. This raises concern about current risk assessments, which mainly rely on the effects of individual chemicals, and calls for risk assessment approaches that can explain combined exposure to multiple chemicals.

Occupational exposure to organic solvents and risk of bladder cancer

BACKGROUND

Bladder cancer has been linked to several occupations that involve the use of solvents, including those used in the dry-cleaning industry.

OBJECTIVES

We evaluated exposure to solvents and risk of bladder cancer in 1182 incident cases and 1408 controls from a population-based study.

METHODS

Exposure to solvents was quantitatively assessed using a job-exposure matrix (CANJEM). Exposure to benzene, toluene and xylene often co-occur. Therefore, we created two additional sets of metrics for combined benzene, toluene and xylene (BTX) exposure: (1) CANJEM-based BTX metrics and (2) hybrid BTX metrics, using an approach that integrates the CANJEM-based BTX metrics together with lifetime occupational histories and exposure-oriented modules that captured within-job, respondent-specific details about tasks and chemicals. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using logistic regression.

RESULTS

Bladder cancer risks were increased among those ever exposed to benzene (OR = 1.63, 95% CI: 1.14-2.32), toluene (OR = 1.60, 95% CI: 1.06-2.43), and xylene (OR = 1.67, 95% CI: 1.13-2.48) individually. We further observed a statistically significant exposure-response relationship for cumulative BTX exposure, with a stronger association using the hybrid BTX metrics (ORQ1vsUnexposed = 1.26, 95% CI: 0.83-1.90; ORQ2vsUnexposed = 1.52, 95% CI: 1.00-2.31; ORQ3vsUnexposed = 1.88, 95% CI: 1.24-2.85; and ORQ4vsUnexposed = 2.23, 95% CI: 1.35-3.69) (p-trend=0.001) than using CANJEM-based metrics (p-trend=0.02).

IMPACT

There is limited evidence about the role of exposure to specific organic solvents, alone or in combination on the risk of developing bladder cancer. In this study, workers with increasing exposure to benzene, toluene, and xylene as a group (BTX) had a statistically significant exposure-response relationship with bladder cancer. Future evaluation of the carcinogenicity of BTX and other organic solvents, particularly concurrent exposure, on bladder cancer development is needed.

Characterization of lymphocyte subsets and intestinal short-chain fatty acids in benzene-induced immunosuppressive mice

Exposure to benzene causes immunosuppression, but the mechanism has not been clarified. In this study, mice were subcutaneously injected with different concentrations (0, 6, 30 and 150 mg/kg) of benzene for four weeks. The lymphocytes of bone marrow (BM), spleen and peripheral blood (PB) and the level of short-chain fatty acids (SCFAs) in mouse intestine were measured. The results showed that benzene exposure led to a reduction in CD3+ and CD8+ lymphocytes in mouse BM, spleen and PB, and CD4+ lymphocytes were increased in mouse spleen but decreased in mouse BM and PB after 150 mg/kg benzene exposure. In addition, Pro-B lymphocytes were reduced in mouse BM in the 6 mg/kg group. Besides, the levels of IgA, IgG, IgM, IL-2, IL-4, IL-6, IL-17a, TNF-α and IFN-γ in mouse serum were reduced after benzene exposure. Furthermore, the levels of acetic, propionic, butyric and hexanoic acid were reduced in mouse intestine, and the AKT-mTOR signaling pathway was activated in mouse BM cells after benzene exposure. Our results demonstrate that benzene induced immunosuppression in mice, and the B lymphocytes in BM are more sensible to benzene-induced toxicity. The reduction in mouse intestinal SCFAs as well as the activation of AKT-mTOR signaling may be related to the occurrence of benzene immunosuppression. Our study provides new insight for further mechanistic research on benzene-induced immunotoxicity.

Registered human trials addressing environmental and occupational toxicant exposures: Scoping review of immunological markers and protective strategies

Exposure to pollution is a worldwide societal challenge participating in the etiology and progression of different diseases. However, the scarce information hinders our understanding of the actual level of human exposure and its specific effects. Inadequate and excessive immune responses underlie diverse chronic diseases. Yet, it is unclear which and how toxicant exposures affect the immune system functions. There is a multiplicity of immunological outcomes and biomarkers being studied in human trials related to exposure to different toxicants but still without clear evidence of their value as biomarkers of exposure or effect. The main aim of this study was to collect scientific evidence and identify relevant immunological biomarkers used at the clinical level for toxicant exposures. We used the platform clinical trials.gov as a database tool. First, we performed a search combining research items related to toxicants and immunological parameters. The resulting117 clinical trials were examined for immune-related outcomes and specific biomarkers evaluated in subjects exposed to occupational and environmental toxicants. After categorization, relevant immunological outcomes and biomarkers were identified related to systemic and airway inflammation, modulation of immune cells, allergy and autoimmunity. In general, the immune markers related to inflammation are more frequently investigated for exposure to pollutants, namely IL-6, C-reactive protein (CRP) and nitric oxide (NO). Nevertheless, the data also indicated that prospective biomarkers of effect are gaining ground and a guiding representation of the established and novel biomarkers is suggested for upcoming trials. Finally, potential protective strategies to mitigate the adverse effects of specific toxicants are underlined for future studies.

Evaluation of the in vitro and in vivo antioxidant potential of Punica granatum L. against toluene-induced liver injuries in rats

Background and Aim:

Humans are more frequently exposed to chemicals in daily life by inhalation of indoor and outdoor air. However, abusers and workers are the most exposed to those chemicals and their health risks particularly, liver diseases. The present study investigated the protective effects of pomegranate juice (PJ) (Punica granatum) and pomegranate peel aqueous extract (PAE) supplementation against toluene (Tol)-induced hepatotoxicity in Wistar rats.

Materials and Methods:

A phytochemical analysis and assessment of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity were performed for the PJ and the PAE. The invivo study was carried out using 70 Wistar rats that were divided into seven groups, each consisting of 10 rats. All groups were treated orally for 6 weeks as follows: Control (C), positive controls (CO: 1.25 mL/kg body weight [BW]; PJ: 4 mL/kg BW; and PAE: 400 mg/kg BW), Tol (550 mg/kg BW), and a mixture each of PJ-Tol and PAE-Tol. At the end of the 45^th day of study, the hepatic biochemical markers (transaminases, alkaline phosphatase, total bilirubin, albumin, and total proteins) were auto-analyzed, as well as histology and oxidative stress markers of the liver were evaluated.

Results:

The phytochemical analysis revealed that the DPPH scavenging activity and the total phenolic, flavonoid, and tannin contents were higher in the pomegranate peel extract versus the juice. The results also showed that Tol significantly increased liver enzyme activities and total bilirubin levels, whereas albumin and total proteins were significantly decreased. Similarly, Tol provoked a significant increase in hepatic malondialdehyde levels, with a decrease in glutathione content and glutathione peroxidase activity. The biochemical changes agreed with the hepatic histological alterations. A significant improvement in all parameters was observed in the PAE-Tol group compared with the PJ-Tol group.

Conclusion:

Exposure to Tol altered the hepatic antioxidant and biochemical parameters and histological profile of the rats, and PAE was more powerful than PJ in reducing Tol liver injuries through its antioxidant activity.

Induced sputum abnormalities in gas station attendants

PURPOSE

To investigate inflammatory changes in the induced sputum (IS) of gas station attendants (GSAs) at risk of exposure to fuel vapors through inhalation and susceptible to respiratory complaints and impaired lung function.

METHODS

Hypertonic saline-IS was collected from 52 GSAs who had never smoked (42 men, age = 35.9 ± 8.9 years) and had no known comorbidities. A group of 22 non-smokers (11 men, age = 30.5 ± 5.1 years) selected from the University staff served as control. The GSAs answered a questionnaire and underwent spirometry and chest tomography. A total of 15 inflammatory biomarkers associated with inflammation, including cytokines, chemokines, and mediators of immunological response, were also measured.

RESULTS

The most common symptoms of GSAs were coughing (42.3%) and dyspnea (59.6%) based on the New York Heart Association (NYHA; Class II) classification. Significant elevations (p < 0.05) in forced vital capacity and forced expiratory volume within the first second were observed in the GSAs relative to those in the controls (GSA vs. control: 99 ± 12% vs. 90 ± 9% and 94 ± 11% vs. 87 ± 10%, respectively). The GSAs had a lower percentage of IS lymphocytes than that in the control group (4.5 ± 5.7% vs. 7.7 ± 9.8%). The GSAs also had significantly lower concentrations of IL-4, IL-5, IL-10, IL-12_P70, IFN-γ, and MIP-1α, but IL-3 levels were higher. No differences were observed in the airway thickness and the amount of emphysema between the GSAs and the controls.

CONCLUSION

Despite normal lung function and absence of abnormalities on HRCT, GSAs have a higher frequency of respiratory complaints, with evidence of impairment of lymphocytic activity in the airways.

Clastogenicity and Aneugenicity of 1,4-Benzoquinone in Different Lineages of Mouse Hematopoietic Stem/Progenitor Cells

Previous reports on hematotoxicity and leukemogenicity related to benzene exposure highlighted its adverse effects on hematopoiesis. Despite the reported findings, studies concerning the mechanism of benzene affecting chromosomal integrity in lineage-committed hematopoietic stem/progenitor cells (HSPCs) remain unclear. Here, we studied the clastogenicity and aneugenicity of benzene in lineage-committed HSPCs via karyotyping. Isolated mouse bone marrow cells (MBMCs) were exposed to the benzene metabolite 1,4-benzoquinone (1,4-BQ) at 1.25, 2.5, 5, 7, and 12 μM for 24 h, followed by karyotyping. Then, the chromosomal aberration (CA) in 1,4-BQ-exposed hematopoietic progenitor cells (HPCs) comprising myeloid, Pre-B lymphoid, and erythroid lineages were evaluated following colony-forming cell (CFC) assay. Percentage of CA, predominantly via Robertsonian translocation (Rb), was increased significantly (p < 0.05) in MBMCs and all progenitors at all concentrations. As a comparison, Pre-B lymphoid progenitor demonstrated a significantly higher percentage of CA (p < 0.05) than erythroid progenitor at 1.25, 2.5, and 7 μM as well as a significantly higher percentage (p < 0.05) than myeloid progenitor at 7 μM of 1,4-BQ. In conclusion, 1,4-BQ induced CA, particularly via Rb in both MBMCs and HPCs, notably via a lineage-dependent response. The role of lineage specificity in governing the clastogenicity and aneugenicity of 1,4-BQ deserves further investigation.

Combine effect of exposure to petrol, kerosene and diesel fumes: On hepatic oxidative stress and haematological function in rats

Petroleum product fumes (PPFs) containing toxic organic components are pervasive in the environment, emanating from anthropogenic activities, including petroleum exploration and utilization by end-user activities from petrol-gasoline stations. Petrol station attendants are exposed to PPF through inhalation and dermal contact with consequent toxicological implications. We investigated the effects of chronic exposure (60 and 90 days) to petrol (P), kerosene (K) and diesel (D) alone and combined exposure to petrol, kerosene and diesel (PKD) fumes on hepatotoxicity, haematological function and oxidative stress in rats. Following sacrifice, we evaluated hepatic damage biomarkers, blood glucose, oxidative stress and haematological function. Chronic exposure to PPF significantly increased organo-somatic indices, blood glucose, biomarkers of hepatic toxicity and oxidative stress in an exposure duration-dependent manner. There was a simultaneous decrease in the protective capacity of antioxidants. Furthermore, exposure to PPF increased pro-inflammatory biomarkers in rats (90 > 60 days). Regardless of exposure duration, plateletcrit, mean platelet volume, platelet distribution width and red cell distribution width in the coefficient of variation increased, whereas red blood cell count, haemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, white blood cell, lymphocyte, monocyte-basophil-eosinophil mixed counts and platelet count decreased after 60 and 90 days exposure. Microscopic examination of the liver demonstrated hepatic pathological changes paralleling the duration of exposure to PKD fumes. However, the injury observed was lesser to that of rats treated with the diethylnitrosamine - positive control. Our results expanded previous findings and further demonstrated the probable adverse effect on populations' health occasioned by persistent exposure to PPF. Individuals chronically exposed by occupation to PPF may be at greater risk of developing disorders promoted by continuous oxido-inflammatory perturbation and suboptimal haematological-immunologic function - thereby enabling a permissive environment for pathogenesis notwithstanding the limitation of quantifying PPF absolute values in our model system.

Buckwheat, rooibos, and vitex extracts can mitigate adverse effects of xylene on ovarian cells in vitro

This study examines whether selected functional food and medicinal plants can mitigate the adverse effects of xylene on ovarian cells. The influences of xylene (0, 10, 100, or 1000 ng/mL), buckwheat (Fagopyrum esculentum), rooibos (Aspalathus linearis), vitex (Vitex agnus-castus), extracts (10 μg/mL each), and a combination of xylene with these plant additives on cultured porcine ovarian granulosa cells are compared. Cell viability, proliferation (PCNA accumulation), apoptosis (accumulation of bax), and release of progesterone (P4) and estradiol (E2) were analyzed by the trypan blue tests, quantitative immunocytochemistry, and enzyme-linked immunosorbent assays, respectively. Xylene suppressed all measures of ovarian cell function. Rooibos prevented all of xylene's effects, whereas buckwheat and vitex prevented four of five of the analyzed effects (buckwheat prevented xylene influence on viability, PCNA, bax, and E2; vitex prevented xylene action on viability, PCNA, and P4 and E2). These observations show that xylene has the potential to suppress ovarian cell functions, and that buckwheat, rooibos, and vitex can mitigate those effects, making them natural protectors against the adverse effects of xylene on ovarian cells.

Assessment of hepatic functions, hematopoietic cytokines and haematological parameters in people occupationally exposed to volatile petroleum hydrocarbons

Humans are occupationally exposed to volatile petroleum hydrocarbons through inhalation and ingestion. To access the effect of exposure to volatile hydrocarbons, hematopoietic cytokines, haematological parameters and hepatic functions were assayed for in 100 subjects. Male participants showed significant increase (p < 0.05) in erythropoietin, interleukin-3, alanine transaminase (ALT), alkaline phosphatase (ALP), mean cell hemoglobin concentration (MCHC), mean cell volume (MCV) and significant decrease (p < 0.05) in mean cell hemoglobin (MCH). Female participants showed significant increase (p < 0.05) in interleukin-3, ALT, AST, ALP, MCHC, MCV and significant decrease (p < 0.05) in MCH, platelets, hemoglobin and hematocrit compared to their controls. Exposure to volatile petroleum hydrocarbons raised the absolute red blood cell indices and liver enzymes and could stimulate combined increase in the release of erythropoietin and interleukin-3 leading to ineffective hematopoiesis.