Inhalation Of Asbestos Fibers Research Articles

The diagnosis of asbestosis in the 21st century: a clinicopathological correlation of 102 cases

ABSTRACT Asbestosis, defined as diffuse pulmonary fibrosis caused by inhalation of asbestos fibers, occurs after heavy exposures to asbestos dust over several decades. Because workplace exposures have been significantly curtailed since the banning of asbestos in insulation products, we were interested in examining the clinicopathological characteristics of cases diagnosed in the 21st century. The consultation files of one of the authors (VLR) were reviewed for cases of asbestosis diagnosed since 1/1/2001. 102 cases were identified, with a median age of 75 years (range: 45–89). There were 100 men and 2 women. The women were from Turkey and Brazil (none from the United States). Malignancies were present in 78 cases, including 38 lung cancers, 29 pleural mesotheliomas, and 8 peritoneal mesotheliomas. The grade of asbestosis was available in 88 cases (median severity of 2; scale: 1–4). Pleural plaque was present in 94% of cases. The most common exposure categories were insulators (39), shipyard workers (16), asbestos manufacturing (9), boiler workers (8) and pipefitter/welders (6). The median duration of exposure was 33 years (range: 2–49 years). Lung fiber burden analysis was performed in 34 cases, with amosite being the predominant fiber type. Results were compared with similar information for 475 cases diagnosed prior to 1/1/2001.

Synthesis of Ni-Doped Tremolite Fibers to Help Clarify the Aetiology of the Cytotoxic Outcome of Asbestos.

Asbestos fibers act as complex crystal-chemical reservoirs susceptible of releasing potentially toxic elements (such as ions impurities) into the lung cellular environment during permanency and dissolution. To comprehend the exact pathological mechanisms that are triggered upon inhalation of asbestos fibers, in vitro studies on possible interactions between the mineral and the biological system have been carried out mostly by using natural asbestos. However, this latter comprises intrinsic impurities such as Fe2+/Fe3+ and Ni2+ ions, and other eventual traces of metallic pathogens. Furthermore, often, natural asbestos is characterized by the co-presence of several mineral phases, fiber dimensions of which are randomly distributed in width and in length. For these reasons, it is albeit challenging to precisely identify toxicity factors and to define the accurate role of each factor in the overall pathogenesis of asbestos. In this regard, the availability of synthetic asbestos fibers with accurate chemical composition and specific dimensions for in vitro screening tests would represent the perfect tool to correlate asbestos toxicity to its chemico-physical features. Herein, to palliate such drawbacks of natural asbestos, well-defined Ni-doped tremolite fibers were chemically synthesized in order to offer biologists adequate samples for testing the specific role of Ni2+ in asbestos toxicity. The experimental conditions (temperature, pressure, reaction time and water amount) were optimized to produce batches of asbestos fibers of the tremolite phase, with uniformly distributed shape and dimensions and a controlled content of Ni2+ metal ions.

Internal Transcribed Spacer and 16S Amplicon Sequencing Identifies Microbial Species Associated with Asbestos in New Zealand.

Inhalation of asbestos fibres can cause lung inflammation and the later development of asbestosis, lung cancer, and mesothelioma, and the use of asbestos is banned in many countries. In most countries, large amounts of asbestos exists within building stock, buried in landfills, and in contaminated soil. Mechanical, thermal, and chemical treatment options do exist, but these are expensive, and they are not effective for contaminated soil, where only small numbers of asbestos fibres may be present in a large volume of soil. Research has been underway for the last 20 years into the potential use of microbial action to remove iron and other metal cations from the surface of asbestos fibres to reduce their toxicity. To access sufficient iron for metabolism, many bacteria and fungi produce organic acids, or iron-chelating siderophores, and in a growing number of experiments these have been found to degrade asbestos fibres in vitro. This paper uses the internal transcribed spacer (ITS) and 16S amplicon sequencing to investigate the fungal and bacterial diversity found on naturally-occurring asbestos minerals, asbestos-containing building materials, and asbestos-contaminated soils with a view to later selectively culturing promising species, screening them for siderophore production, and testing them with asbestos fibres in vitro. After filtering, 895 ITS and 1265 16S amplicon sequencing variants (ASVs) were detected across the 38 samples, corresponding to a range of fungal, bacteria, cyanobacterial, and lichenized fungal species. Samples from Auckland (North Island, New Zealand) asbestos cement, Auckland asbestos-contaminated soils, and raw asbestos rocks from Kahurangi National Park (South Island, New Zealand) were comprised of very different microbial communities. Five of the fungal species detected in this study are known to produce siderophores.

Near Missed Case of Occupational Pleural Malignant Mesothelioma, a Case Report and Latest Therapeutic Options

Asbestos use started to be gradually banned in Europe from 1991 onwards, and there are currently strict occupational exposure limits for asbestos. However, malignant mesothelioma has a long latency time (in some cases up to 50-60 years), so the risks related to asbestos exposure should not be forgotten. Considering the increased risk of lung cancer following the inhalation of asbestos fibers, lifetime health monitoring should be considered in people occupationally exposed to asbestos, with an emphasis on the respiratory system. An assessment of their occupational history should be performed rigorously, especially in the areas with a history of asbestos production/use, as this is a key element for an early diagnosis and appropriate treatment. This case report presents a near-missed case of occupational pleural malignant mesothelioma. The latency time between the first asbestos exposure and the diagnosis of occupational pleural malignant mesothelioma was 49 years. The accurate diagnosis was made two years after the first symptoms appeared.

Mesotelioma pleural

Pleural mesothelioma is the main malignant pleural tumor. Most cases are associated with inhalation of asbestos fibers. The most frequent manifestations are dyspnea and chest pain in patients in pleural effusion and/or nodular pleural thickening. The diagnosis is histological, distinguishing between three big subgroups: epithelioid, sarcomatoid, and biphasic. The most used staging is based on the TNM staging system and proposed by the International Association for the Study of Lung Cancer (IASLC). The principal prognostic factors, in addition to TNM stage, are the histological type, age, and the patient's overall condition. In select patients, surgery may be indicated as part of multimodal treatment. In order to determine which patients are candidates for surgery, in addition to the epithelial histological type, an adequate cardiopulmonary reserve, an extension study with a computed tomography scan of the chest and abdomen, magnetic resonance imaging, positron emission tomography, and an examination of the mediastinum with endobronchial ultrasound or mediastinoscopy should be taken into account. In patients who are not candidates for surgery, chemotherapy in a platinum/pemetrexed regimen and/or symptomatic treatment that includes pleurodesis and control of pain and dyspnea should be considered.

Molecular and immunological changes in blood of rats exposed to various doses of asbestos dust.

Asbestos-related diseases are a group of diseases resulting from the inhalation of asbestos fibres and their subsequent deposition in the lung parenchyma, which causes the development of inflammatory and fibrotic processes in the respiratory system. Cases of the disease often occur in the practice of doctors. The purpose of the study was to examine the level of circulating-free mitochondrial DNA (cf mtDNA), pro-inflammatory cytokines, immunological status and structural changes in the lung of rats exposed to various doses of asbestos dust. Immune monitoring was performed using the peripheral blood samples of 40 male Wistar rats exposed and unexposed to asbestos dust. cf mtDNA copy numbers were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and cytokines were determined using a rat Enzyme Linked Immuno Sorbent Assay (ELISA) kit. A comprehensive assessment of the histopathological study performed under exposure to asbestos at a dose of 25mg and 50mg showed the presence of pronounced structural defects in the lung tissue of laboratory rats. The level of cf mtDNA in plasma of rats exposed to asbestos at a dose of 25mg was reliably higher than that of control rats, and animals exposed to asbestos at a dose of 50mg. The highest levels of pro-inflammatory cytokines IL-6 and TNF-a were also observed after asbestos dusting at a dose of 25mg. According to the results of the immunological status obtained, the decrease in the levels of pro-inflammatory cytokines in the blood plasma at 50mg is due to the immunosuppressive effect in the rat immune system at this dose. A positive correlation was found between TNF-a level and copy numbers of cf mtDNA at a dose of 25mg.

Disturbance of the Warburg effect by dichloroacetate and niclosamide suppresses the growth of different sub-types of malignant pleural mesothelioma in vitro and in vivo.

Background: Inhalation of asbestos fibers is the most common cause of malignant pleural mesothelioma (MPM). In 2004, the United States Food and Drug Administration approved a combination of cisplatin with pemetrexed to treat unresectable MPM. Nonetheless novel treatment is urgently needed. The objective of this study is to report the combination effect of dichloroacetate (DCA) or niclosamide (Nic) Nic in MPM. Materials and methods: The effect of a combination of DCA and Nic was studied using a panel of MPM cell lines (H28, MSTO-211H, H226, H2052, and H2452). Cell viability was monitored by MTT assay. Glycolysis, oxidative phosphorylation, glucose, glycogen, pyruvate, lactate, citrate, succinate and ATP levels were determined by corresponding ELISA. Apoptosis, mitochondrial transmembrane potential, cell cycle analysis, hydrogen peroxide and superoxide were investigated by flow cytometry. Cell migration and colony formation were investigated by transwell migration and colony formation assays respectively. The in vivo effect was confirmed using 211H and H226 nude mice xenograft models. Results and conclusion: Cell viability was reduced. Disturbance of glycolysis and/or oxidative phosphorylation resulted in downregulation of glycogen, citrate and succinate. DCA and/or Nic increased apoptosis, mitochondrial transmembrane depolarization, G2/M arrest and reactive oxygen species. Moreover, DCA and/or Nic suppressed cell migration and colony formation. Furthermore, a better initial tumor suppressive effect was induced by the DCA/Nic combination compared with either drug alone in both 211H and H226 xenograft models. In H226 xenografts, DCA/Nic increased median survival of mice compared with single treatment. Single drug and/or a combination disturbed the Warburg effect and activated apoptosis, and inhibition of migration and proliferation in vivo. In conclusion, dichloroacetate and/or niclosamide showed a tumor suppressive effect in MPM in vitro and in vivo, partially mediated by disturbance of glycolysis/oxidative phosphorylation, apoptosis, ROS production, G2/M arrest, and suppression of migration and proliferation.

Sera from Patients with Malignant Pleural Mesothelioma Tested Positive for IgG Antibodies against SV40 Large T Antigen: The Viral Oncoprotein.

Malignant pleural mesothelioma (MPM), a fatal tumor, is mainly linked to the asbestos exposure. It has been reported that together with the inhalation of asbestos fibers, other factors are involved in the MPM onset, including simian virus 40 (SV40). SV40, a polyomavirus with oncogenic potential, induces (i) in vitro the mesenchymal cell transformation, whereas (ii) in vivo the MPM onset in experimental animals. The association between MPM and SV40 in humans remains to be elucidated. Sera (n = 415) from MPM-affected patients (MPM cohort 1; n = 152) and healthy subjects (HSs, n = 263) were investigated for their immunoglobulin G (IgG) against simian virus 40 large tumor antigen (Tag), which is the transforming protein. Sera were investigated with an indirect enzyme-linked immunosorbent assay (ELISA) using two synthetic peptides from SV40 Tag protein. SV40 Tag protein was evaluated by immunohistochemical (IHC) staining on MPM samples (MPM cohort 2; n = 20). Formalin-fixed and paraffin-embedded (FFPE) samples were obtained from MPM patients unrelated to MPM serum donors. The proportion of sera, from MPM patients, showing antibodies against SV40 Tag (34%) was significantly higher compared to HSs (20%) (odds ratio 2.049, CI 95% 1.32–3.224; p=0.0026). Immunohistochemical staining (IHS) assays showed SV40 Tag expression in 8/20, 40% of MPM specimens. These results indicate that SV40 is linked to a large fraction of MPM. It is worth noting that the prevalence of SV40 Tag antibodies detected in sera from cohort 1 of MPM patients is similar to the prevalence of SV40 Tag found to be expressed in FFPE tissues from MPM cohort 2.

Malignant Mesothelioma Mortality in Women - United States, 1999-2020.

Inhalation of asbestos fibers can cause malignant mesothelioma, a rapidly progressing and lethal cancer of the mesothelium, the thin layer of tissues surrounding internal organs in the chest and abdomen. Patients with malignant mesothelioma have a poor prognosis, with a median survival of 1 year from diagnosis. The estimated median interval from initial occupational asbestos exposure to death is 32 years (range = 13-70 years) (1). Occupational asbestos exposure is most often reported in men working in industries such as construction and manufacturing; however, women are also at risk for exposure to asbestos fibers, and limited data exist on longer-term trends in mesothelioma deaths among women. To characterize deaths associated with mesothelioma and temporal trends in mesothelioma mortality among women in the United States, CDC analyzed annual Multiple Cause of Death records from the National Vital Statistics System for 1999-2020, the most recent years for which complete data are available. The annual number of mesothelioma deaths among women increased significantly, from 489 in 1999 to 614 in 2020; however, the age-adjusted death rate per 1 million women declined significantly, from 4.83 in 1999 to 4.15 in 2020. The largest number of deaths was associated with the health care and social assistance industry (89; 15.7%) and homemaker occupation (129; 22.8%). Efforts to limit exposure to asbestos fibers, including among women, need to be maintained.

Asbestos in the ambient air from rural, urban, residential, baseball and mining areas in South Korea

Asbestos is a naturally occurring fibrous silicate that has been widely used as electrical insulator and heat-resistant material in buildings, yet inhalation of asbestos fibers can lead to serious lung diseases such as asbestosis and cancer. Practically no research has been conducted on the size distribution and morphological characteristics of airborne asbestos, and airborne asbestos concentrations in South Korea are unknown. Here we studied type, concentration, size, morphology and composition of asbestos fibers in the ambient air of several regions in South Korea. Asbestos concentrations were analyzed in 7 urban areas, 7 rural areas including agricultural and fishing areas, 17 mines and their surrounding areas, 7 residential areas constructed with asbestos-containing stones near rivers, 2 baseball fields and 2 background sites. Results show that the highest air asbestos concentrations were 0.00161 for residential areas and 0.00122 for baseball fields according to phase-contrast microscopy, and 0.00057 for asbestos mines and 0.00055 for baseball fields, according to transmission electron microscopy. Asbestos types included chrysotile, tremolite, and actinolite. Chrysotile fibers measured 5.24–35.5 µm in length with aspect ratios of 12.6–202.6; tremolite fibers measured 6.07–40.2 µm in length with aspect ratios of 5.7–81.2; and actinolite fibers measured 5.01–28.5 µm in length with aspect ratios of 3.2–108.9. Chrysotile was distributed in bundles or single fibers, whereas tremolite and actinolite exhibited fibrous, acicular, and cleavage forms.

Predicting Long-Term Asbestos Prevalence in Human Lungs, Lymph Nodes, and Remote Organs from Short-Term Murine Experiments.

Inhalation of asbestos fibers leads to a suite of fatal diseases that can manifest years, if not decades, after cessation of exposure. The first phase of disease progression occurs as fibers are transported from point of entry in the lungs throughout the entire body. A mathematical model is developed for the disposition of non-chrysotile asbestos in the body and, except for exposure levels, is parameterized by published data on short-term rat experiments. Asbestos exposure in individual humans is determined by matching published long-term lung data for nine patients. The resulting model predicts transport of fibers within the lymphatic system and prevalence of fibers in lymph nodes for these patients with reasonable accuracy. Model predictions for remote organs are compared against published observations. The model consists of a system of globally stable differential equations, and a sensitivity analysis was conducted. The model indicates that fiber density in lymph nodes is correlated with total exposure, level times duration, no matter whether there is a long-term, low-level exposure or short-term, high-level exposure. The model predicts that levels of sequestered asbestos reach steady state within five years of cessation of exposure, a timeline previously not known. The model suggests that the time to steady state is short compared to onset of disease, and that delayed onset of related disease may be a function of chemical and biological processes not in this model.

Osteopontin mRNA expression by rat mesothelial cells exposed to multi-walled carbon nanotubes as a potential biomarker of chronic neoplastic transformation in vitro

Mesothelioma is a cancer of the lung pleura primarily associated with inhalation of asbestos fibers. Multi-walled carbon nanotubes (MWCNTs) are engineered nanomaterials that pose a potential risk for mesothelioma due to properties that are similar to asbestos. Inhaled MWCNTs migrate to the pleura in rodents and some types cause mesothelioma. Like asbestos, there is a diversity of MWCNT types. We investigated the neoplastic potential of tangled (tMWCNT) versus rigid (rMWCNT) after chronic exposure using serial passages of rat mesothelial cells in vitro. Normal rat mesothelial (NRM2) cells were exposed to tMWCNTs or rMWCNTs for 45 weeks over 85 passages to determine if exposure resulted in transformation to a neoplastic phenotype. Rat mesothelioma (ME1) cells were used as a positive control. Osteopontin (OPN) mRNA was assayed as a biomarker of transformation by real time quantitative polymerase chain reaction (qPCR) and transformation was determined by a cell invasion assay. Exposure to rMWCNTs, but not tMWCNTs, resulted in transformation of NRM2 cells into an invasive phenotype that was similar to ME1 cells. Moreover, exposure of NRM2 cells to rMWCNTs increased OPN mRNA that correlated with cellular transformation. These data suggest that OPN is a potential biomarker that should be further investigated to screen the carcinogenicity of MWCNTs in vitro.

Zdravstveni učinci vlakana azbesta u vazduhu

Since the beginning of the 20th century, thousands of tons of asbestos were used in all developed countries in industry and construction. After the serious illnesses and deaths caused by inhalation of asbestos fibers were reliably identified, the first asbestos use ban was prescribed by the World Health Organization (WHO) in 1972. Asbestos in the last 100 years to blame for the death of a large number of workers in industry and construction as well as the population. According to the World Health Organization in the next 40 years in the world is expected to illness and death of more than 500 000 people as a consequence of inhaling airborne particles of asbestos. That fact has led to a complete ban on any use of asbestos in most countries. The paper is particularly pronounced approach applied in the US, according to which each of respirable difficult soluble fiber is considered fibrinogen, and every fiber diameter ≤1mm and length ≥10mm potentially fibrinogen and carcinogenic, and in Germany that any inorganic fiber diameter of 5mm and the ratio length and diameter of> 3: 1 is considered potentially carcinogenic. The question is whether it is justified to carcinogenic fibers prescribe and apply the limit values, and whether in BiH differently treated with carcinogens acting genotoxic than those operating epigenetic mechanisms.

Mesothelioma: are nurses being put at risk in the workplace?

Malignant mesothelioma is an aggressive, rare cancer caused by exposure to and inhalation of asbestos fibres. The cancer is associated with traditionally male-dominated industries that use asbestos, including asbestos mining and disposal, and the construction industry.

Attenuation of oxidative stress and chromosomal aberrations in cultured macrophages and pulmonary cells following self-sustained high temperature synthesis of asbestos

Inhalation of asbestos fibres can cause lung and pleural diseases in humans and constitutes a severe public health threat worldwide. The aim of the present study was to assess the biological effects induced in both pulmonary cells (A549) and monocyte/macrophage (RAW 264.7) cell lines by combustion slags obtained from asbestos through a self-sustained high-temperature synthesis (SHS) reaction. The SHS reaction involves rapid thermal treatment and displays great ability to neutralise asbestos. Cytotoxicity, redox status imbalance, lipid peroxide production, DNA strand breaks (comet assay) and chromosomal aberrations (cytokinesis block micronucleus test) were evaluated in cells exposed either to untreated asbestos fibres or to grinded SHS-generated slags of different granulometry, tested in cultured cells at varying doses and for varying exposure times. Our results show that asbestos fibres cause redox status imbalance, especially in monocyte/macrophage cell lines. Moreover, they promote lipid peroxidation and trigger genomic alterations. When the cells were exposed to slag powders, which are the products of SHS asbestos treatment, generation of lipid peroxides and induction of DNA strand breaks still persisted, due to the high content in iron and other metals detected in these samples. However, there was an attenuation of redox status imbalance and an absence of chromosomal aberrations, which probably reflects the loss of the asbestos fibrous structure following SHS reaction, as demonstrated by electron microscopy analyses. In conclusions, SHS-treated asbestos wastes can potentially have deleterious health effects due to the oxidative stress induced by inhaled powders but they loose the asbestos ability to induce chromosomal alterations.

MicroRNAs diagnostic and prognostic value as predictive markers for malignant mesothelioma

Malignant mesothelioma is an aggressive tumor resistant to current therapies with a latency period ranging between 20 and 60 years, caused by inhalation of asbestos fibers, that continues to represent a social and healthcare issue. The high percentage of people exposed to asbestos for professional or environmental reasons is associated with the high biopersistence of its fibers and with its widespread use in the last century. Approximately 20-40% of men report an occupational history that might have caused the workplace exposure (criteria Helsinki, 1997). Some authors are evaluating the possible use of bioindicators as a screening and early diagnosis tool. In this regard, the use of microRNAs has been proposed as powerful diagnostic and prognostic biomarkers for many tumors and human diseases. This review focuses on the current state of knowledge on the key role of microRNAs expression as new malignant mesothelioma biomarkers, in early clinical diagnostic applications.

Occupational exposures and idiopathic pulmonary fibrosis.

A recent meta-analysis of data from international case-control studies reports a population attributable fraction of 16% for occupational factors in the cause of idiopathic pulmonary fibrosis (IPF). Smoking, genetic factors and other prevalent diseases only partly explain IPF, and so this review aims to summarize recent progress in establishing which occupational exposures are important in cause. IPF is a rare disease, although it is the commonest idiopathic interstitial pneumonia. Epidemiological study suggests that incidence of IPF is increasing, particularly in older men. There are significant associations with IPF and occupational exposures to organic dust, including livestock, birds and animal feed, metal dust, wood dust and silica/minerals. Estimates of effect vary between studies, and are influenced by the distribution of employment, study design and case definition. Inhalation of asbestos fibres is a known cause of usual interstitial pneumonia (as seen histologically in IPF), though there are significant linear relationships between asbestos consumption, and mortality from both IPF and mesothelioma, leading to the hypothesis that low-level asbestos exposure may cause IPF. Research must focus on exposure-response relationships between asbestos and other occupational inhaled hazards, and IPF. Funding bodies and policy makers should acknowledge the significant occupational burden on IPF.

Imaging of asbestos-related lung and pleural diseases as an endemic exposure in Egypt

BackgroundAsbestos refers to a group of naturally occurring silicate minerals which have been traditionally used in building materials and household products. Inhalation of asbestos fibers, however, has been associated with adverse health outcomes, with the disease manifestations principally affecting the thorax. The aim of our study is to detect and evaluate the different radiological patterns of asbestos-related lung and pleural disease and its complicationsResultsMDCT examination was able to assess and distinguish asbestosis as well as asbestos-related lung and pleural disease besides detection of any associated complications.ConclusionThis study demonstrates that while reporting of malignant asbestos-related pleural disease is adequate, there is room for improvement in the reporting of more benign disease.

Discerning Erionite from Other Zeolite Minerals During Analysis

ABSTRACT Erionite, a naturally occurring fibrous mineral that belongs to the zeolite group has been designated by the International Agency for Research on Cancer (IARC) as a Group 1 Carcinogen on the basis of mesothelioma, a disease also resulting from the inhalation of asbestos fibers. Significant outcrops of fibrous erionite have been reported in California, North Dakota, Nevada, Oregon, and other states. For geologists and industrial hygienists dealing with mining, construction, or various aspects of community protection, it is vital to understand the basics of detecting and handling erionite, since it is similar to asbestos and can cause similar disease. There are many fibrous zeolites, and discerning erionite from these other minerals requires modifications to current asbestos analysis methods. Without these modifications, identification and quantification are questionable and could increase the likelihood of both false negatives and false positives. There is currently no published method specific to erionite analysis; without guidance standards, each laboratory has approached erionite analysis independently. With a few small but significant changes to asbestos analysis methodologies, we developed a reproducible analytical procedure for rapid identification of erionite fibers in air, bulk, and soil samples by transmission electron microscopy (TEM). Using specialized preparation techniques, energy dispersive Spectrometry (EDS) calibrations, and a liquid nitrogen cryo-holder (cold stage), we were able to overcome the difficulties associated with erionite analysis. By incorporating these changes, commercial analytical laboratories can contribute reliable data to air-exposure studies and characterization guidelines, which may help in determining regulations and further understanding the health risks of erionite.

Evaluation of paraoxonase-1 enzyme activity and oxidative stress relations in malignant mesothelioma cases

BACKGROUND: Malignant pleural mesothelioma (MPM) is the most common cancer in the pleura and highly aggressive with a very poor prognosis. Asbestos, known as a carcinogenic mineral with fiber structures, is the main cause of MPM formation. Exposure to asbestos causes an increase in reactive oxygen species, deficiency of antioxidant enzyme levels, and DNA damage. As a result of asbestos pathogenesis, all of these changes cause pulmonary fibrosis, pleural diseases, and malignancies. The endogenous antioxidant paraoxonase-1 (PON-1) is a calcium-dependent esterase involved in the hydrolysis of lipid peroxides, and PON-1 has been shown to have protective properties in oxidative stress and inflammatory diseases in various studies. OBJECTIVE: The study aimed to examine the relationship of MPM with PON-1 enzyme activity and oxidative status using total oxidant status (TOS) and total antioxidant status (TAS). MATERIALS AND METHODS: The study population was formed of 33 retrospectively examined mesothelioma patients as MPM group and 33 age- and sex-matched healthy individuals as controls. PON-1 activity was measured spectrophotometrically by enzyme-linked immunosorbent assay method. Total antioxidant and oxidant status was determined using Rel Assay Diagnostics kit. Oxidative stress index (OSI) was estimated as the ratio of the TOS to the TAS levels. RESULTS: In the present study, PON-1, TOS, TAS, and OSI levels were adjusted by comorbidity and smoking. The results indicated that TOS and OSI of MPM patients increased compared to healthy controls (P CONCLUSION: These results suggested that oxidative stress occurring as a result of inhalation of asbestos fibers may reduce the level of PON-1.