Study on the underlying molecular mechanism of benzene-induced nervous system damage in mice based on tandem mass tag (TMT) proteomics

Benzene is known to be a common toxic industrial chemical, and prolonged benzene exposure may cause nervous system damage. At present, there were few studies on benzene-induced neurological damage. This research aimed to identify the protein biomarkers to explore the mechanism of nervous system damage caused by benzene. We established a benzene poisoning model of C57 mice by gavage of benzene-peanut oil suspension and identified differentially expressed proteins (DEPs) in brain tissue using tandem mass tag (TMT) proteomics. The results showed a significant weight loss and decrease in leukocyte and neutrophil counts in benzene poisoning mice compared to the control group. We also observed local cerebral oedema and small vessel occlusion in the cerebral white matter of benzene poisoning mice. TMT proteomic results showed that a total 6,985 proteins were quantified, with a fold change (FC) > 1.2 (or < 1/1.2) and P value <0.05 were considered as DEPs. Compared with the control group, we identified 43 DEPs, comprising 14 upregulated and 29 downregulated proteins. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis results showed that the candidate proteins were mainly involved in cholesterol metabolism, complement and coagulation cascades, african trypanosomiasis, PPAR signaling pathway, and vitamin digestion and absorption. Three proteins, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (UGT8), Apolipoprotein A-I (APOA1) and Complement C3 (C3) were validated using immunoblotting and immunohistochemical. In conclusion, our study preliminarily investigated the mechanism of benzene toxicity to the nervous system by analyzing DEPs changes in the brain.

Impact of chronic benzene poisoning on aberrant mitochondrial DNA methylation: A prospective observational study

Benzene is used as an industrial solvent, which may result in chronic benzene poisoning (CBP). Several studies suggested that CBP was associated with mitochondrial epigenetic regulation. This study aimed to explore the potential relation between CBP and mitochondrial DNA (mtDNA) methylation. This prospective observational study enrolled CBP patients admitted to Shenzhen Prevention and Treatment Center for Occupational Diseases hospital and healthy individuals between 2018 and 2021. The white blood cell (WBC), red blood cell (RBC), hemoglobin (HB), and platelet (PLT) counts and mtDNA methylation levels were measured using blood flow cytometry and targeted bisulfite sequencing, respectively. A total of 90 participants were recruited, including 30 cases of CBP (20 females, mean age 43.0 ± 8.0 years) and 60 healthy individuals (42 females, mean age 43.5 ± 11.5 years). This study detected 168 mitochondrial methylation sites >0 in all study subjects. The mtDNA methylation levels in the CBP cases were lower than the healthy individuals [median ± interquartile-range (IQR), 25th percentile, 75th percentile: (1.140 ± 0.570, 0.965, 1.535)% vs. median ± IQR, 25th percentile, 75th percentile: (1.705 ± 0.205,1.240,2.445)%, P < 0.05]. Additionally, the spearman correlation analysis showed that the mtDNA methylation levels were positively correlated with the counts of circulating leukocytes [WBC (r = 0.048, P = 0.036)] and platelets [PLT (r = 0.129, P < 0.01)]. We provided solid evidence of association between CBP and aberrant mtDNA methylation.

Health Risks Associated With Benzene Exposure in Children: A Systematic Review

Currently, there is a paucity of studies evaluating the adverse health effects of benzene exposure in children or clinical findings of those children who have been exposed. However, emerging studies show that benzene exposure can cause deleterious health effects in children. The objective of this study was to evaluate and summarize published studies on the adverse health effects of benzene exposure in children. More than 77 articles were examined and only the articles that dealt with adverse health effects on pediatric populations were included in the study. The evaluation of those studies provided current understanding of the health effects of benzene exposure in children. Findings from the currently available studies reveal that benzene exposure is associated with abnormalities in hematologic, hepatic, respiratory, and pulmonary functions in children. Published studies clearly support the need for further assessment of the potential adverse effects of benzene exposure in children, and clinical and laboratory findings of these children.

Adverse Health Complaints of Adults Exposed to Benzene After a Flaring Disaster at the BP Refinery Facility in Texas City, Texas

OBJECTIVE

The objective of this study was to assess the adverse health symptoms experienced by adult subjects who were exposed to benzene after a flaring disaster at the BP refinery in Texas City, Texas.

METHODS

A total of 2162 adults aged 18 years or older and exposed to benzene were included. Using the patients' medical charts, we collected and analyzed data on health complaints as well as the patients' serum levels of beta-2-microglobulin and urinary excretion of phenol.

RESULTS

A total of 11,368 health symptom complaints were reported in 2162 adults exposed to benzene. Neurological symptoms occurred most frequently (174%), followed upper respiratory symptoms (115%), cough (31%), painful joints (30%), cardiac symptoms (28%), dermatological symptoms (28%), gastrointestinal symptoms (27%), diarrhea (25%), vision symptoms (21%), and nausea/vomiting (19%). Logistic regression analysis indicated that urinary symptoms (R2=0.65) and painful joints (R2=0.44) were positively associated with increasing age in benzene-exposed subjects.

CONCLUSION

Adult subjects exposed to benzene experience a range of adverse health symptoms and an altered profile of urinary phenol, thus indicating they are at high risk of developing serious future health complications. (Disaster Med Public Health Preparedness. 2018;12:232-240).

Illness Symptoms Experienced by Children Exposed to Benzene After a Flaring Incident at the BP Refinery Facility in Texas City

Objective To evaluate the illness symptoms experienced by children who were exposed to benzene following a flaring incident at the BP refinery in Texas City, Texas. Methods A total of 641 children, aged <17 years, exposed to benzene were included. Using medical charts, data on the children's illness symptoms as well as the serum levels of β-2-microglobulin and the amount of urinary excretion of phenol were reviewed and analyzed. Results A total of 1790 illness symptoms were reported in 641 children exposed to benzene. Upper respiratory symptoms were the most (67%) frequently reported, followed by neurological symptoms (57%), diarrhea (25%), and cough (24%). Logistic regression analysis indicated that neurological symptoms (R(2) = 0.75), chest pain (R(2) = 0.64), joint pain (R(2) = 0.57), and vision difficulty (R(2) = 0.54) were positively associated with increasing age. β-2-Microglobulin levels were significantly higher in children <5 years compared with those >5 year (P = .04). Conversely, urinary phenol levels were significantly lower in children <5 years compared with those >5 years (P = .00). Conclusion Together, these findings reveal that children exposed to benzene experience a range of illness symptoms and an altered profile of urinary phenol indicating their vulnerability to potentially increased health complications.

Adverse Health Effects of Benzene Exposure Among Children Following a Flaring Incident at the British Petroleum Refinery in Texas City

This study examined the health effects of benzene exposure among children from a flaring incident at the British Petroleum (BP) refinery in Texas City, Texas. A total of 899 children (benzene exposed, n = 641 and unexposed, n = 258), aged <17 years, were included. Hematological analysis showed that white blood cell (×10(3)/µL) counts were significantly decreased in the exposed children compared with the unexposed children (7.1 ± 2.2 versus 7.6 ± 2.1, P = .001). Similarly, the hemoglobin (g/dL) levels were decreased significantly in the exposed group compared with the unexposed group (12.7 ± 1.3 vs 13.1 ± 1.5, P = .001). Conversely, platelet (×10(3)/µL) counts were increased significantly in the exposed group compared with the unexposed group (318.6 ± 79.8 versus 266.9 ± 58.8, P = .001). Hepatic enzymes were also significantly elevated among exposed children compared with the unexposed children. These findings suggest that children exposed to benzene are at a higher risk of developing both hepatic and bone marrow-related disorders.

Detrimental Health Effects of Benzene Exposure in Adults After a Flaring Disaster at the BP Refinery Plant in Texas City

OBJECTIVE

To examine the adverse effects of benzene exposure in adults from a prolonged flaring disaster at the BP refinery in Texas City, Texas.

METHODS

Adults aged 18 years and older who had been exposed and unexposed to benzene were included. We reviewed medical charts and compared measures of white blood cells (WBCs), platelets, hemoglobin, hematocrit, blood urea nitrogen (BUN), creatinine, alkaline phosphatase (ALP), aspartate amino transferase (AST), and alanine amino transferase (ALT) in exposed and unexposed adults.

RESULTS

Records from 2213 adults (benzene exposed, n=1826; unexposed, n=387) were reviewed. Benzene-exposed subjects had significantly higher WBC counts (7.9±2.3 vs 6.8±1.6×10(3) per µL, P=0.0000) and platelet counts (270.8±60.9 vs 242.5±53.7×10(3) per µL, P=0.0000) than did the unexposed subjects. Serum creatinine levels were also significantly higher in the exposed group than in the unexposed group (1.0±0.2 vs 0.8±0.2 mg/dL, P=0.000). Serum levels of ALP were significantly higher in the exposed subjects than in the unexposed subjects (82.1±15.6 vs 71.8±8.2 IU/L, P=0.000). Similarly, benzene-exposed subjects had significantly higher levels of AST (26.2±6.4 vs 19.7±5.3 IU/L, P=0.000) and ALT (30.6±10.8 vs 20.9±9.6 IU/L, P=0.000) than in those unexposed to benzene.

CONCLUSION

Benzene exposure resulted in significant alterations in hematologic and liver profiles in adults.

Metabolic Polymorphisms and Clinical Findings Related to Benzene Poisoning Detected in Exposed Brazilian Gas-Station Workers

Benzene is a ubiquitous environmental pollutant and an important industrial chemical present in both gasoline and motor vehicle emissions. Occupational human exposure to benzene occurs in the petrochemical and petroleum refining industries as well as in gas-station workers, where it can lead to benzene poisoning (BP), but the mechanisms of BP are not completely understood. In Brazil, a significant number of gas-station service workers are employed. The aim of the present study was to evaluate alterations related to BP and metabolic polymorphisms in gas-station service workers exposed to benzene in the city of Rio de Janeiro, Brazil. Occupational exposure was based on clinical findings related to BP, and metabolic polymorphisms in 114 Brazilian gas-station attendants. These workers were divided into No Clinical Findings (NCF) and Clinical Findings (CF) groups. Neutrophil and Mean Corpuscular Volume (MCV) showed a significant difference between the two study groups, and neutrophil has the greatest impact on the alterations suggestive of BP. The clinical findings revealed higher frequencies of symptoms in the CF group, although not all members presented statistical significance. The frequencies of alleles related to risk were higher in the CF group for GSTM1, GSTT1, CYP2E1 7632T > A, but lower for NQO1 and CYP2E1 1053C > T genotypes. Moreover, an association was found between GSTM1 null and alterations related to BP, but we did not observe any effects of other polymorphisms. Variations in benzene metabolizing genes may modify benzene toxicity and should be taken into consideration during risk assessment evaluations.

Hematological and hepatic alterations in nonsmoking residents exposed to benzene following a flaring incident at the British petroleum plant in Texas City

OBJECTIVE

Human exposure to benzene is associated with multiple adverse health effects with an increased risk of developing carcinogenesis. Benzene exposure is known to affect many critical organs including the hematological, hepatic, renal, lung, and cardiac functions. The purpose of this study is to examine the health effects of benzene exposure among nonsmoking subjects from a prolonged flaring incident that occurred at the British petroleum (BP) refinery in the Texas City, Texas.

METHODS

The study included nonsmoking subjects who had been exposed and unexposed to benzene. Using medical charts, clinical data including white blood cell (WBC) counts, platelet counts, hemoglobin, hematocrit, blood urea nitrogen (BUN), creatinine, alkaline phosphatase (ALP), aspartate amino transferase (AST), and alanine amino transferase (ALT) in nonsmoking subjects exposed to benzene were reviewed and analyzed and compared with unexposed adults.

RESULTS

A total of 1422 nonsmoking subjects (benzene exposed, n=1093 and unexposed, n=329) were included. Benzene exposed subjects had significantly higher levels of WBC (×10(3) per μL) counts (7.7±2.2 versus 6.8±1.7, P=0.001) and platelet (×10(3) per μL) counts (288.8±59.0 versus 245.3±54.4, P=0.001) compared with the unexposed subjects. The mean serum creatinine (mg/dL) levels were also significantly increased in the benzene exposed group compared with the unexposed group (1.1±0.4 versus 0.8±0.2, P=0.001). Serum levels of ALP (IU/L) was significantly elevated in the benzene exposed subjects compared with the unexposed subjects (87.3±22.6 versus 69.6±16.5, P=0.001). Similarly, benzene exposed subjects had significantly higher levels of AST and ALT compared with those unexposed subjects.

CONCLUSION

Benzene exposure from the prolonged BP flaring incident caused significant alterations in hematological and liver markers indicating that these nonsmoking residents exposed to refinery chemicals may be at a higher risk of developing hepatic or blood related disorders.