Toluene concentrations in the blood and risk of thyroid cancer among residents living near national industrial complexes in South Korea: A population-based cohort study

Application of fluorescent carbon quantum dots functional modified carboxymethyl cellulose film in toluene gas specific detection

With the increasing consumption of organic solvents in chemical and pharmaceutical industries, the environment pollution of volatile organic compounds (VOCs) has become an urgent problem. Therefore, the rapid-visual detection method is of great significance in the analysis of VOCs. Based on the fluorescence quenching/enhancement mechanism of carbon quantum dots (CQDs), with the help of carboxymethyl cellulose membrane with porous and large specific surface area structure, a series of green CQDs@carboxymethyl cellulose composite film (CQDs@CMC composite film) was prepared in this study. In the typical-targeted pollutants (toluene) detection application, a fluorescence spectroscopy method was established which could achieve the high sensitivity and strong specificity detection. The mainly conclusions were as follows: The fluorescence spectrometric detection method for toluene: A kind of hydrophobic Lmi/Bet CQDs@CMC composite film was prepared and characterized with imidazole/betaine CQDs and porous carboxymethyl cellulose composite film as raw materials. The toluene detection performance was studied, and the recognition mechanism was explored. The results showed that toluene enhanced the fluorescence of Lmi/Bet CQDs@CMC composite film. The fluorescence intensity of composite films was proportional to toluene concentration when the toluene concentration ranged from 200 to 2200 mg/L. The detection limit of toluene was 1.169 mg/L, which provides a theoretical basis for the detection of toluene by fluorescence spectrometry.

Risk assessment of Benzene, Toluene, Ethyl benzene, and Xylene (BTEX) in the atmospheric air around the world: A review

Volatile organic compounds, such as BTEX, have been the subject of numerous debates due to their detrimental effects on the environment and human health. Human beings have had a significant role in the emergence of this situation. Even though US EPA, WHO, and other health-related organizations have set standard limits as unhazardous levels, it has been observed that within or even below these limits, constant exposure to these toxic chemicals results in negative consequences as well. According to these facts, various studies have been carried out all over the world - 160 of which are collected within this review article, so that experts and governors may come up with effective solutions to manage and control these toxic chemicals. The outcome of this study will serve the society to evaluate and handle the risks of being exposed to BTEX. In this review article, the attempt was to collect the most accessible studies relevant to risk assessment of BTEX in the atmosphere, and for the article to contain least bias, it was reviewed and re-evaluated by all authors, who are from different institutions and backgrounds, so that the insights of the article remain unbiased. There may be some limitations to consistency or precision in some points due to the original sources, however the attempt was to minimize them as much as possible.

Highly sensitive serum volatolomic biomarkers for pancreatic cancer diagnosis

The discovery of new diagnostic tools for the early detection of diseases with poor prognosis such as pancreatic adenocarcinoma (PAC) is of high importance. The results from a control-case study (20 PAC patients, 19 healthy controls) for the search of new biomarkers of pancreatic cancer based in differences in the serum volatolome are presented in this work. Volatolomics were performed following a non-targeted HS-SPME-GC/MS approach, and a total of 433 volatile organic compounds (VOCs) was detected in the human serum samples. Of these, 125 VOC indexes showed a significant variation when controls and patients were compared (p-value < 0.05). Bonferroni corrected p-values < 0.05 were found for 40 features. PCA analysis showed the control-PAC discrimination capability of VOCs in serum, and PLS-DA was performed to select the best candidate biomarkers for the diagnosis of PAC. For the 40 selected VOCs, calculated areas under the curve (AUC) ranged from 0.98 to 0.85, and 11 of them were successfully validated using an independent set of samples (5 PAC patients, 5 healthy controls). Four of the proposed PAC biomarkers were identified as toluene, 2-ethyl-1-hexanol, pentylbenzene, and butoxymethylbenzene. Combinations of the identified PAC biomarkers were tested and showed AUC > 0.90, with the more promising candidate being butoxymethylbenzene (AUC = 0.98).

A theoretical study on toluene oxidization by OH radical

Toluene, a prominent member of volatile organic compounds (VOCs), exerts a substantial adverse influence on both human life and the environment. In the context of advanced oxidation processes, the ·OH radical emerges as a highly efficient oxidant, pivotal in the elimination of VOCs. This study employs computational quantum chemistry methods (G4MP2//B3LYP/6-311++G(d,p)) to systematically investigate the degradation of toluene by ·OH radicals in an implicit solvent model, and validates the rationale of choosing a single-reference method using T1 diagnostics. Our results suggest three possible reaction mechanisms for the oxidation of toluene by ·OH: firstly, the phenyl ring undergoes a hydrogen abstraction reaction followed by direct combination with ·OH to form cresol; secondly, ·OH directly adds to the phenyl ring, leading to ring opening; thirdly, oxidation of sidechain to benzoic acid followed by further addition and ring opening. The last two oxidation pathways involve the ring opening of toluene via the addition of ·OH, significantly facilitating the process. Therefore, both pathways are considered feasible for the degradation of toluene. Subsequently, the UV-H2O2 system was designed to induce the formation of ·OH for toluene degradation and to identify the optimal reaction conditions. It was demonstrated that ·OH and 1O2 are the primary active species for degrading toluene, with their contribution ranking as ·OH > 1O2. The intermediates in the mixture solution after reactions were characterized using GC-MS, demonstrating the validity of theoretical predictions. A comparative study of the toluene consumption rate revealed an experimental comprehensive activation energy of 10.33 kJ/mol, which is consistent with the preliminary activation energies obtained via theoretical analysis of these three mechanisms (0.56 kJ/mol to 13.66 kJ/mol), indicating that this theoretical method can provide a theoretical basis for experimental studies on the oxidation of toluene by ·OH.

Association between oil spill clean-up work and thyroid cancer: Nine years of follow-up after the Hebei Spirit oil spill accident

In 2007, an unprecedented oil spill occurred in Taean, Korea. Although crude oil contains chemicals that could increase thyroid cancer risk, few studies have examined the long-term effects of oil exposure during clean-up and thyroid cancer incidence. We investigated the long-term thyroid cancer incidence among participants involved in clean-up work. 1798 participants engaged in at least two surveys since the baseline was tracked from 2008 to 2018. Participants reported the days they participated in oil clean-up works and cancer diagnoses. Cox proportional hazard models were used to estimate the hazard ratios between clean-up work duration and thyroid cancer. Over the 9-year follow-up, 30 thyroid cancer cases were diagnosed. A positive association was observed between clean-up duration and thyroid cancer risk. This effect was more pronounced among residents living <50 m from traffic roads. Our results indicate that crude oil clean-up work participation may increase the thyroid cancer risk.

Machine learning-aided metallomic profiling in serum and urine of thyroid cancer patients and its environmental implications

The incidence rate of thyroid cancer has been growing worldwide. Thyroid health is closely related with multiple trace metals, and the nutrients are essential in maintaining thyroid function while the contaminants can disturb thyroid morphology and homeostasis. In this study, we conducted metallomic analysis in thyroid cancer patients (n = 40) and control subjects (n = 40) recruited in Shenzhen, China with a high incidence of thyroid cancer. We found significant alterations in serumal and urinary metallomic profiling (including Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, I, Ba, Tl, and Pb) and elemental correlative patterns between thyroid cancer patients and controls. Additionally, we also measured the serum Cu isotopic composition and found a multifaceted disturbance in Cu metabolism in thyroid disease patients. Based on the metallome variations, we built and assessed the thyroid cancer-predictive performance of seven machine learning algorithms. Among them, the Random Forest model performed the best with the accuracy of 1.000, 0.858, and 0.813 on the training, 5-fold cross-validation, and test set, respectively. The high performance of machine learning has demonstrated the great promise of metallomic analysis in the identification of thyroid cancer. Then, the Shapley Additive exPlanations approach was used to further interpret the variable contributions of the model and it showed that serum Pb contributed the most in the identification process. To the best of our knowledge, this is the first study that combines machine learning and metallome data for cancer identification, and it supports the indication of environmental heavy metal-related thyroid cancer etiology.

The environmental burden on endocrine neoplasia: a review on the documented impact of endocrine disrupting chemicals

INTRODUCTION

Endocrine-disrupting chemicals (EDCs) have gained more importance in the past decade, mostly due to their role in the pathogenesis of disease, especially in carcinogenesis. However, there is limited literature on the environmental burden on some of the less common endocrine neoplasia.

AREAS COVERED

This review focuses on both observational and experimental studies linking exposure to EDCs and endocrine neoplasia specifically pituitary, thyroid, adrenal and neuroendocrine tumors. Following PRISMA guidelines, a search of English peer-reviewed literature was performed using Medline and Google Scholar, giving preference to recent publications.

EXPERT OPINION

Exposure to EDC occurs not only in the household but also at work, whether it is in the office, factory, or farm and during transport from one location to another. Many studies have evaluated the effect of single environmental agents; however, humans are rarely exposed to only one EDC. Different EDCs and different levels of exposure may interact together to provide either a synergistic and/or an antagonistic disruption on human health, and hence a complex mechanism to elucidate. The ultimate adverse effect is difficult to predict, as it is not only influenced by the degree of exposure, but also by genetics, lifestyle, comorbidities, and other stressors.

Blood Concentrations of Volatile Organic Compounds Among US Workers From Various Trades

OBJECTIVE

This study aimed to examine blood benzene, toluene, ethylbenzene, o-xylene, and m-/p-xylene (BTEX) concentrations and their trends contrasting construction workers with workers in other occupations from 1999 to 2014 in the United States. Methods: Using data from the National Health and Nutrition Examination Survey, quantile regressions were performed to investigate associations between occupation and blood BTEX concentrations. Results: We found that high-risk and construction occupations were associated with increased blood concentrations of toluene, o-xylene, and m-/p-xylene at the 50-90th percentiles (P 50-90 ), and ethylbenzene at P 70-90 . Moreover, although blood concentrations of ethylbenzene, o-xylene, and m-/p-xylene trended down among all US workers, no decreasing trend was observed for benzene and toluene among construction workers. Conclusions: Future studies are warranted to address questions about specific tasks to better assess VOC exposure from various trades.

Emission inventories, emission factors, and composition profiles of volatile organic compounds (VOCs) and heavy metals (HMs) from an electronic waste dismantling park in southern China

Electronic waste (e-waste) dismantling is a significant source of atmospheric pollutants, including volatile organic compounds (VOCs) and heavy metals (HMs), which may have adverse effects on the surrounding environment and residents. However, the organized emission inventories and emission characteristics of VOCs and HMs from e-waste dismantling are not well documented. In this study, the concentrations and components of VOCs and HMs were monitored at the exhaust gas treatment facility from two process areas of a typical e-waste dismantling park in southern China in 2021. Emission inventories of VOCs and HMs were established, with total emissions of 8.85 t/a and 18.3 kg/a for VOCs and HMs in this park, respectively. The cutting & crushing (CC) area was the largest emissions source, accounting for 82.6% of VOCs and 79.9% of HMs, respectively, while the baking plate (BP) area had higher emission factors. Additionally, the concentration and composition of VOCs and HMs in the park were also analyzed. For VOCs, the concentrations of halogenated hydrocarbons and aromatic hydrocarbons were comparable in the park, while m/p-xylene, o-xylene, and chlorobenzene were the key VOC species. The HM concentrations followed the order of Pb > Cu > Mn > Ni > As > Cd > Hg, with Pb and Cu being the main heavy metals released. This is the first VOC and HM emission inventory for the e-waste dismantling park, and our data will lay a solid ground for pollution control and management for the e-waste dismantling industry.

Low-Level Environmental Mercury Exposure and Thyroid Cancer Risk Among Residents Living Near National Industrial Complexes in South Korea: A Population-Based Cohort Study

Background: Previous studies suggested that mercury may be linked to thyroid cancer due to its bioaccumulation in the thyroid gland, but no studies have evaluated the association between mercury exposure and thyroid cancer risk. We examined the relationship between mercury exposure and thyroid cancer risk, with the potential modification of hematological parameters. Methods: We performed a secondary analysis of a prospective cohort study among residents living near industrial complexes in South Korea (recruited from 2003 to 2011). Incident thyroid cancer cases (C73, ICD-10 code) were identified from the National Cancer Registry and Statistics Korea. Urinary mercury concentrations were measured using thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). Cox proportional hazards regression models (adjusted for age, sex, educational level, smoking status, and employment) were used to estimate the hazard ratio (HR) and confidence interval [CI] between mercury exposure and the incidence of thyroid cancer. Results: We documented 69 cases of thyroid cancer in a total of 5213 participants during follow-up (median 8.7 years). The geometric mean of urinary mercury concentration was 1.8 μg/L for thyroid cancer cases and 1.2 μg/L for noncases (p for difference = 0.001). After adjusting for potential confounders, those in the highest tertile of urinary mercury levels had a twofold higher risk of thyroid cancer (HR = 1.97 [CI 1.03 - 3.80] in the highest tertile vs. the lowest tertile, p for trend = 0.043). This association was stronger for those with lower mean corpuscular volume and mean corpuscular hemoglobin status. Conclusions: Urinary mercury concentration was positively associated with the risk of thyroid cancer among residents living near national industrial complexes, and this association was influenced by red blood cell indices status. These results provide some evidence suggesting the adverse effects of environmental metal pollution in the development of thyroid cancer.

A sustainable Decision Support System for soil bioremediation of toluene incorporating UN sustainable development goals

Decision Support System (DSS) is a novel approach for smart, sustainable controlling of environmental phenomena and purification processes. Toluene is one of the most widely used petroleum products, which adversely impacts on human health. In this study, Fusarium Solani fungi are utilized as the engine of the toluene bioremediation procedure for the monitoring part of DSS. Experiments are optimized by Central Composite Design (CCD) - Response Surface Methodology (RSM), and the behavior of the mentioned fungi is estimated by M5 Pruned model tree (M5P), Gaussian Processes (GP), and Sequential Minimal Optimization (SMOreg) algorithms as the prediction section of DSS. Finally, the control stage of DSS is provided by integrated Petri Net modeling and Failure Modes and Effects Analysis (FMEA). The findings showed that Aeration Intensity (AI) and Fungi load/Biological Waste (F/BW) are the most influential mechanical and biological factors, with P-value of 0.0001 and 0.0003, respectively. Likewise, the optimal values of main mechanical parameters include AI, and the space between pipes (S) are equal to 13.76 m³/h and 15.99 cm, respectively. Also, the optimum conditions of biological features containing F/BW and pH are 0.001 mg/g and 7.56. In accordance with the kinetic study, bioremediation of toluene by Fusarium Solani is done based on a first-order reaction with a 0.034 s-1 kinetic coefficient. Finally, the machine learning practices showed that the GP (R2 = 0.98) and M5P (R2 = 0.94) have the most precision for predicting Removal Percentage (RP) for mechanical and biological factors, respectively. At the end of the present research, it is found that by controlling seven possible risk factors in bioremediation operation through the FMEA- Petri Net technique, efficiency of the process can be adjusted to optimum value.

Neurotoxicity induced by toluene: In silico and in vivo evidences of mitochondrial dysfunction and dopaminergic neurodegeneration

Toluene is an air pollutant widely used as an organic solvent in industrial production and emitted by fossil fuel combustion, in addition to being used as a drug of abuse. Its toxic effects in the central nervous system have not been well established, and how and which neurons are affected remains unknown. Hence, this study aimed to fill this gap by investigating three central questions: 1) How does toluene induce neurotoxicity? 2) Which neurons are affected? And 3) What are the long-term effects induced by airborne exposure to toluene? To this end, a Caenorhabditis elegans model was employed, in which worms at the fourth larval stage were exposed to toluene in the air for 24 h in a vapor chamber to simulate four exposure scenarios. After the concentration-response curve analysis, we chose scenarios 3 (E3: 792 ppm) and 4 (E4: 1094 ppm) for the following experiments. The assays were performed 1, 48, or 96 h after removal from the exposure environments, and an irreversible reduction in neuron fluorescence and morphologic alterations were observed in different neurons of exposed worms, particularly in the dopaminergic neurons. Moreover, a significant impairment in a dopaminergic-dependent behavior was also associated with negative effects in healthspan endpoints, and we also noted that mitochondria may be involved in toluene-induced neurotoxicity since lower adenosine 5'-triphosphate (ATP) levels and mitochondrial viability were observed. In addition, a reduction of electron transport chain activity was evidenced using ex vivo protocols, which were reinforced by in silico and in vitro analysis, demonstrating toluene action in the mitochondrial complexes. Based on these findings model, it is plausible that toluene neurotoxicity can be initiated by complex I inhibition, triggering a mitochondrial dysfunction that may lead to irreversible dopaminergic neuronal death, thus impairing neurobehavioral signaling.

Crinum jagus (J. Thomps. Dandy): Antioxidant and protective properties as a medicinal plant on toluene-induced oxidative stress damages in liver and kidney of rats

Crinum jagus (C. jagus; J. Thomps.) Dandy (Liliaceae) is a pantropical plant known for its medicinal values and pharmacological properties. The study assessed the protective effects and changes in oxidative stress indices due to C. jagus leaf extracts on the toluene-induced liver and kidney injuries in rats. The study was conducted on 8-week-old male Wistar rats (n = 80), weighing 243.3 ± 1.42 g. Group I, 1 ml/kg distilled water for 7 days; Group II, 4.5 ml/kg toluene once, 1 ml/kg distilled water for 7 days; Group III, 4.5 ml/kg toluene once, 500 mg/kg methanolic extract for 7 days; Group IV, 4.5 ml/kg toluene once, 500 mg/kg aqueous extract for 7 days; Group V, 500 mg/kg methanolic extract for 7 days; Group VI, 500 mg/kg aqueous extract for 7 days; Group VII, 500 mg/kg of vitamin C for 7 days; Group, VIII, 4.5 ml/kg toluene once, 500 mg/kg vitamin C for 7 days, all administrations were given by oral gavage. The phytochemical contents, absolute and relative organ weights of liver and kidneys, liver and kidney function tests, antioxidant status, as well as histological tests were analyzed using standard protocols. The tannins, flavonoids, and polyphenols were in highest concentration in both extracts, content in methanol extract (57.04 ± 1.51 mgg-1, 35.43 ± 1.03 mgg-1, 28.2 ± 0.34 mgg-1 respectively) > aqueous extract (18.74 ± 1.01 mgg-1, 13.43 ± 0.47 mgg-1, 19.65 ± 0.21 mgg-1 respectively). In the negative control group (II), bodyweights significantly (P < 0.05) reduced by 22%, liver weight and kidney weight significantly (P < 0.05) increased by 42% and 83% respectively, liver-to-bodyweight and kidney-to-bodyweight ratios increased significantly (P < 0.05); serum liver function tests (LFTs) i.e., bilirubin, alkaline phosphatase (ALP), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Gamma-glutamyl transferase (GGT), and serum kidney function tests (creatinine and urea) were significantly (P < 0.05) elevated; oxidant status (tissue malondialdehyde; MDA) was significantly (P < 0.05) elevated, antioxidant status i.e., tissue superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels was significantly (P < 0.05) reduced; with markedly visible renal and hepatic histopathological findings, compared to the normal control group. In C. jagus extract test groups (III and IV), the parameters were significantly (P < 0.05) alleviated and reversed to normal/near normal compared to the negative control. The LFTs, kidney function tests, and antioxidant status were significantly (P < 0.05) more improved with the methanol extract test and standard control groups compared to the aqueous extract test group; Also, the methanol extract test group showed better histological features than the aqueous extract test and standard control groups. The methanolic extract shows better antioxidant potential due to the availability of more nonenzymatic antioxidants (tannins, flavonoids, and polyphenols). The findings showed that toluene is a very aggressive xenobiotic due to the promotion of oxidative stress and peroxidation of cellular lipids, but C. jagus leaves provide significant protection through the reducing power of nonenzymatic antioxidants and their ability to induce endogenous antioxidant enzymes (SOD, CAT, and glutathione reductase or GR) causing reduced cellular lipid peroxidation and tissue damages, quickened tissue repair, and improved cell biology of liver and kidneys during toluene toxicity. The methanol leaf extract provides better protection and should be advanced for more experimental and clinical studies to confirm its efficacy in alleviating oxidative stress tissue injuries, specifically due to toluene.

Volatile Chemical Profile of Ethanol-Based Hand Sanitizer marketed in Brazil by HS-SPME/GC-MS

Aim:

This study aims to determine the volatile chemical profile of ethanol-based hand sanitizer marketed in Brazil by HS-SPME/GC-MS.

Background:

Ethanol-based hand sanitizer has been used to protect against coronavirus disease (COVID-19). In general, these formulations are prepared using a carbomer. In 2020 and 2021, the production of hand sanitizer has increased due to the COVID-19 epidemic. Therefore, it is important to know the composition of this formulation because certain molecules present in some alcoholic mixtures can cause health problems

Method:

Ethanol-based hand sanitizer, AL1, AL2, BL1, CL1, DL1, EL1, FL1, and GL1 (ethanol derivative of fuel station), was purchased from manufacturers commercialized in Araguaína-TO and analyzed by HS-SPME/GC-MS for determining volatile chemical profile.

Results:

The analyses showed different compositions for the ethanol-based hand sanitizers. Samples AL1 and AL2 contained isopropyl alcohol, ethyl acetate, benzene, ethane-1,1-diethoxy, limonene, and other compounds. Linear alkanes were also detected. Only ethyl acetate and ethane-1,1-diethoxy were detected in CL1, in addition to ethanol. Thus, it is the most suitable sample among those analyzed. The presence of benzene, alkanes, and other hydrocarbons may be associated with the use of fuel ethanol to prepare these sanitizers, as shown in the sample GL1. Benzene, xylene, and toluene were found in FL1. This sample is the most contaminated among those analyzed.

Conclusion:

The chemical profile of commercial ethanol-based hand sanitizer from eight different samples sold in Araguaína-Brazil was established by GC-MS. Compounds like benzene and other alkanes were found in some samples. These results suggested possible contamination by alcohols unqualified in producing pharmaceutical substances. These analyzes are particularly relevant due to the pandemic situation to avoid COVID-19 proliferation. Benzene and other alkanes are harmful to human health and should be avoided in hand sanitizer production.

Production of Gasolines and Monocyclic Aromatic Hydrocarbons: From Fossil Raw Materials to Green Processes

The properties and the applications of the main monocyclic aromatic hydrocarbons (benzene, toluene, ethylbenzene, styrene, and the three xylene isomers) and the industrial processes for their manufacture from fossil raw materials are summarized. Potential ways for their production from renewable sources with thermo-catalytic processes are described and discussed in detail. The perspectives of the future industrial organic chemistry in relation to the production of high-octane bio-gasolines and monocyclic aromatic hydrocarbons as renewable chemical intermediates are discussed.