Environmental asbestos exposure and risk of mesothelioma

Asbestos-related cancers: the 'Hidden Killer' remains a global threat

Introduction: Asbestos, the most frequent cause of occupational cancer, continues to be consumed on a massive scale, with millions of people exposed on a daily basis. This review explains why we have failed in curtailing the silent epidemic of asbestos-related disease and why the numbers of asbestos victims are likely to remain high. Emerging and developed countries have to be reminded that asbestos exposure has yet to become a problem of the past. The worldwide spread of asbestos, followed by the surge of asbestos-related cancers, resembles the lung cancer epidemic caused by smoking and stimulated by manufacturers.Areas covered: Underreporting of malignant mesothelioma and asbestos-induced lung cancer, frequently-used arguments in the amphibole/chrysotile debate and the conclusion from bona-fide research organizations, that all forms of asbestos are carcinogenic, are reviewed. Special attention is paid to the consequences of ubiquitous environmental asbestos and the 'changing face' of malignant mesothelioma in countries with heavy asbestos use in the past.Expert opinion: Experts in oncology, respiratory medicine, occupational and public health, and basic researchers must take responsibility and acknowledge the ongoing silent epidemic of asbestos-related diseases. The call for a world-wide asbestos ban is more urgent than ever.

Assessment of the future mesothelioma disease burden from past exposure to asbestos in ship recycling yards in India

The recycling of end-of-life vessels is a complex activity that generates an enormous amount of hazardous waste, including asbestos-containing materials (ACM). Efforts by the Government of India to comply with national and international regulations and improved standard operating procedures are expected to lower the exposure risk of the workforce to hazardous substances, including asbestos. The current workers are likely to face lesser risks than did those exposed in the past. The present study assesses the health risks from past exposure of asbestos for those workers engaged in handling and removing ACM in ship recycling yards before environmentally sound recycling of obsolete ships was introduced in the early 2000s. Estimates were made of the number of workers exposed, and the intensity of exposure and these data were used to estimate the likely number of mesothelioma deaths in the future. It was estimated that nearly 15% of the total workforce engaged in ship recycling will suffer from mesothelioma which translates to about 4,513 mesothelioma deaths among the total of 31,000 workers estimated to be ever employed in the yards from 1994 till 2002. Recommendations are made for a practical approach to the safe handling of ACMs in Indian ship recycling yards.

Epidemiology of mesothelioma in the 21st century in Europe and the United States, 40 years after restricted/banned asbestos use

Research has established a strong association between asbestos exposure and malignant mesothelioma, a deadly form of cancer. Since the early 1980’s many countries have restricted or banned the production of asbestos, leading to a decline of occupational asbestos exposure in many industrialized countries. However, some countries continue to use asbestos, and worldwide rates of mesothelioma are still increasing. Because of the long latency between exposure and mesothelioma occurrence and the persistence of environmental exposure, incidence rates (IR) may decrease very slowly for several years ahead. In this review, we examine estimates of asbestos consumption before widespread asbestos regulations and the trends in incidence and mortality rates, as well as changes over time for the United States and Europe. In some countries with earlier asbestos restrictions, mesothelioma incidence has been in a modest decline over time. However, asbestos exposure is still a burden worldwide and legislative action is needed to obtain a full ban. The pattern of mesothelioma is shifting from a mostly male disease to a disease that affects females as well in substantial numbers. Studies on unknown sources of asbestos exposure, of other sources of natural exposure to asbestos and asbestos-like fibers, as well as of individual genetic susceptibility to asbestos fibers are needed.

Breast Cancer Cell-Derived Soluble CD44 Promotes Tumor Progression by Triggering Macrophage IL1β Production

IL1β is a central regulator of systemic inflammatory response in breast cancer, but the precise regulatory mechanisms that dictate the overproduction of IL1β are largely unsolved. Here, we show that IL1β secretion is increased by the coculture of human monocyte-like cells and triple-negative breast cancer (TNBC) cells. In addition, macrophages robustly produced IL1β when exposed to the conditioned media of TNBC cells. Consistent with these observations, macrophage depletion decreased serum IL1β and reduced breast cancer progression in an orthotopic breast cancer mouse model. Profiling the secretome of human breast cancer cells revealed that the CD44 antigen was the most differentially released protein in basal conditions of TNBC cells. Antibody-mediated neutralization of CD44 abrogated IL1β production in macrophages and inhibited the growth of primary tumors. These results suggest IL1β-mediated oncogenic signaling is triggered by breast cancer cell membrane-derived soluble CD44 (sCD44) antigen, and targeting sCD44 antigen may provide an alternative therapeutic strategy for breast cancer treatment by modulating inflammatory tumor microenvironment. SIGNIFICANCE: A novel positive feedback loop between IL1β and CD44 promotes TNBC malignant progression.

Geographic Co-Occurrence of Mesothelioma and Ovarian Cancer Incidence

Background: Asbestos is an established cause of several cancers, including mesothelioma and ovarian cancer. Incidence of mesothelioma, the sentinel asbestos-associated cancer, varies by state, likely reflecting different levels of asbestos exposure. We hypothesized that states with high mesothelioma incidence may also have high ovarian cancer incidence. Materials and Methods: Using data from the Centers for Disease Control and Prevention National Program for Cancer Registries and the National Cancer Institute Surveillance, Epidemiology, and End Results Program, we examined the geographic co-occurrence of mesothelioma and ovarian cancer incidence rates by U.S. state for 2003-2015. Results: By state, mesothelioma incidence ranged from 0.5 to 1.3 cases per 100,000 persons and ovarian cancer incidence ranged from 9 to 12 cases per 100,000 females. When states were grouped by quartile of mesothelioma incidence, the average ovarian cancer incidence rate was 10% higher in states with the highest mesothelioma incidence than in states with the lowest mesothelioma incidence. Ovarian cancer incidence tended to be higher in states with high mesothelioma incidence (Pearson correlation r = 0.54; p < 0.0001). Conclusions: Data from state cancer registries show ovarian cancer incidence was positively correlated with mesothelioma incidence, suggesting asbestos may be a common exposure. The potential for asbestos exposure has declined since the 1970s because fewer products contain asbestos; however, some products, materials, and buildings may still release asbestos and thousands of workers may be exposed. Ensuring that people are protected from exposure to asbestos in their workplaces, homes, schools, and communities may reduce the risk of several cancers.

A Comparison of Environmental Concerns in Two Disparate Montana and Nevada Communities

Asbestos refers to six fibrous minerals that occur naturally in the environment in the United States and throughout the world. Deposits may be found in soil, rocks, and deposits of other minerals such as vermiculite and talc. These naturally occurring asbestos (NOA) minerals belong to the serpentine and amphibole family of minerals. This chapter reports shared components of community-driven environmental concerns related to exposure to NOA in a rural Montana and a suburban Nevada community. The specific aim is to establish an understanding of the community and community member's primary concern(s) related to NOA in both communities. The knowledge that NOA is commonly found in areas across the United States supports the need for additional research into the health effects of environmental exposure and best-practices to reduce exposure risk while allowing communities to thrive economically.

Using a Mobile Phone App to Identify and Assess Remaining Stocks of In Situ Asbestos in Australian Residential Settings

Asbestos-containing materials (ACMs) were used extensively throughout much of the 20th century and can still be found in many Australian homes. Therefore, we developed a mobile application (“app”), called ACM Check, which guides users through a home inspection to identify and assess certain types of in situ ACM. A cross-sectional study was conducted using the app to collect data on the type and condition of in situ asbestos in Australian residential settings. Since being released in June 2017, we have received data for 702 home inspections. Of these, 578 (82.3%) houses contained a total of 1895 in situ materials categorised as positive for asbestos by the app. The most prevalent ACMs were used for the backing board to electrical meter boxes (50% of homes), eaves and soffit linings (44.2% of homes), and fencing (28.1% of homes). While the majority of ACMs were categorised as ‘very low’ or ‘low’ priority for removal or remediation, 6.6% of all ACMs were considered to be of ‘high’ priority. Mobile apps offer a platform to help increase people’s awareness of possible health hazards found in the residential environment, such as asbestos, while also being used to collect data for public and environmental health research.

Deep learning-based classification of mesothelioma improves prediction of patient outcome

Malignant mesothelioma (MM) is an aggressive cancer primarily diagnosed on the basis of histological criteria¹. The 2015 World Health Organization classification subdivides mesothelioma tumors into three histological types: epithelioid, biphasic and sarcomatoid MM. MM is a highly complex and heterogeneous disease, rendering its diagnosis and histological typing difficult and leading to suboptimal patient care and decisions regarding treatment modalities². Here we have developed a new approach-based on deep convolutional neural networks-called MesoNet to accurately predict the overall survival of mesothelioma patients from whole-slide digitized images, without any pathologist-provided locally annotated regions. We validated MesoNet on both an internal validation cohort from the French MESOBANK and an independent cohort from The Cancer Genome Atlas (TCGA). We also demonstrated that the model was more accurate in predicting patient survival than using current pathology practices. Furthermore, unlike classical black-box deep learning methods, MesoNet identified regions contributing to patient outcome prediction. Strikingly, we found that these regions are mainly located in the stroma and are histological features associated with inflammation, cellular diversity and vacuolization. These findings suggest that deep learning models can identify new features predictive of patient survival and potentially lead to new biomarker discoveries.

Cancer incidence and mortality associated with non-occupational and low dose exposure to Libby vermiculite in Minnesota

BACKGROUND

A vermiculite processing plant in a Minneapolis, Minnesota neighborhood utilized asbestos-containing ore from Libby, Montana from the late 1930's until 1989. Multiple pathways of exposure to Libby asbestos were characterized in a cohort of over 6000 plant workers and residents living near the plant.

OBJECTIVE

We conducted a cohort linkage study to assess the impact of cumulative low dose exposure and the role of occupational history on asbestos-related mortality and cancer morbidity among cohort members residing near a vermiculite plant.

METHODS

Cohort members alive in 1988 (n = 5848) were linked to the Minnesota Cancer Surveillance System to identify incident cases of mesothelioma, lung cancer, and all-cancer diagnosed from 1988 to 2010. Proportional incidence ratios (PIRs) were calculated for mesothelioma and lung cancer. Vital status and cause of death were ascertained from Minnesota vital records and the National Death Index (1988-2011). Mortality rates of the cohort (2001-2011) for asbestos-related outcomes were compared to the Minnesota population to estimate standardized mortality ratios (SMRs) and stratified by gender, exposure, and occupational history categories.

RESULTS

We identified seven cases of mesothelioma, with elevated incidence only in females (PIR = 11.76, 95% CI: 3.17, 30.12). Lung cancer was elevated in both genders: PIR = 1.54 (95% CI: 1.19, 2.0) in males and 1.62 (95% CI: 1.21, 2.12) in females. We found elevated mortality from COPD, lung cancer, and mesothelioma among females (SMR for mesothelioma in females = 18.97, CI: 3.91, 55.45), among the 546 deaths identified. All four deaths from mesothelioma occurred in the >75th percentile of exposure (>0.0156 fiber/cc x months). The SMR for lung cancer and all respiratory cancer was elevated even after controlling for occupation.

CONCLUSIONS

Community exposure to Libby amphibole asbestos from a vermiculite processing plant is associated with increased risk of COPD, lung cancer and mesothelioma incidence and mortality, most notably among females, and is likely to remain a public health issue for years to come.

Environmental and Occupational Exposure to Asbestos as a Result of Consumption and Use in Poland

Asbestos is harmful to human health; exposure to asbestos causes a wide range of asbestos-related diseases.

AIM

Malignant mesothelioma (MM) is unique to occupational and environmental asbestos exposure.

METHODS

Environmental asbestos exposure was examined in relation to asbestos use and manufacturing, the quantity of the asbestos-containing products still in use, the concentrations of asbestos fibres in the air and the number of MM cases diagnosed each year per county.

RESULTS

The correlation coefficient of the measurements of the asbestos fibre concentrations in the air and the quantity of asbestos-cement products in use is high and amounts to 0.68. Meanwhile, the correlation coefficient of the measurements of asbestos fibre concentrations in air and MM morbidity rate resulting from environmental exposure calculated for particular counties in provinces is low and amounts to 0.37. The highest MM morbidity rate was observed for Małopolskie and Śląskie, a typical industrial area of Poland.

CONCLUSIONS

There are MM cases which are still attributable to occupational asbestos exposure, although MM cases resulting from environmental exposure to asbestos have an increased MM risk. Poland is among those countries with a low MM incidence rate, which seems to be an underestimation of environmental asbestos exposure. As long as asbestos-cement products are used in the environment, actions should be undertaken to protect public health.

Environmental asbestos exposure in childhood and risk of mesothelioma later in life: a long-term follow-up register-based cohort study

OBJECTIVE

To examine the risk of malignant mesothelioma (MM) in former pupils who attended primary school near an asbestos cement plant.

METHODS

A cohort of 12 111 former pupils, born 1940-1970, was established from individual historical records from four primary schools located at a distance of 100-750 m in the prevailing wind direction from an asbestos cement plant operating from 1928 to 1984 in Aalborg, Denmark. The school cohort and a comparison cohort consisting of 108 987 gender and 5-year frequency-matched subjects were followed up (2015) for MM in the Danish Cancer Registry. Using Cox regression, HRs were estimated for the incidence of MM. Adjustments for occupational and familial asbestos exposure were made with a job exposure matrix. An SIR analysis including latency periods testing the cancer incidence rate was performed with the comparison cohort as the reference rate.

RESULTS

The median person-years of follow-up were 62.5 years in the school cohort and 62.2 years in the comparison cohort. There were 32 males and 6 females of the former pupils who developed MM during the follow-up: HR_male 7.01 (95% CI 4.24 to 11.57), HR_female 7.43 (95% CI 2.50 to 22.13). Those who attended school 250 m north of the plant had the highest HR for MM, 10.65 (95% Cl 5.82 to 19.48). No significant trend between school distance and risk of MM was established (p=0.35).

CONCLUSION

Our results suggest that boys and girls who attended schools and lived in the neighbourhood of an asbestos cement plant later in life have a significantly increased risk of MM.

Association between mesothelioma and non-occupational asbestos exposure: systematic review and meta-analysis

BACKGROUND

The risk of mesothelioma has been shown to be associated with exposure to asbestos fibers. Most of the existing literature focuses on occupational exposure; however, non-occupational asbestos exposure has also been identified as an important risk factor.

OBJECTIVE

To estimate the association between mesothelioma and non-occupational asbestos exposure, and evaluate control recruitment and exposure measurement methods.

METHODS

A systematic literature review was conducted to identify case-control (CC) and cohort studies that examined the association between mesothelioma and non-occupational exposure to asbestos, including neighborhood, domestic, and household exposure. Meta-analysis was performed to estimate a summary relative risk estimate (SRRE) and 95% confidence interval using random-effects models. Subgroup analyses were also conducted by exposure type, gender, region, and fiber type.

RESULTS

Twenty CC and 7 cohort studies were selected. Controls in CC studies were selected from the general population (55%), hospital records (18%), cancer registry (23%) and a combination of population and hospital records (5%). Multiple methods were used to measure neighborhood exposure (e.g., linear distance and direction of residence from an asbestos factory), domestic (e.g., whether living with an asbestos worker) and household exposure (e.g., whether involved in asbestos-containing home improvement projects). Primary meta-analyses suggested a SRRE of mesothelioma of 5.33 (95%CI: 2.53, 11.23) from neighborhood exposure, 4.31 (95%CI, 2.58, 7.20) from domestic exposure, and 2.41 (95%CI, 1.30, 4.48) from household exposure with large I² statistics ranging from 83-99%.

CONCLUSIONS

Non-occupational asbestos exposure is significantly associated with an elevated risk of mesothelioma. Funnel plots indicated a potential of publication bias. Some SRREs should be interpreted with cautions because of high between-studies heterogeneity.

Ovarian cancer in a former asbestos textile factory worker: a case report

Background

The International Agency for Research on Cancer (IARC) defined that asbestos is a group 1 substance that causes lung cancer, mesothelioma (pleura and peritoneum), laryngeal cancer, and ovarian cancer in humans. Many studies on lung cancer, and mesothelioma caused by asbestos exposure have been conducted, but there was no case report of ovarian cancer due to asbestos exposure in Korea. We describe a case of ovarian cancer caused by asbestos exposure in a worker who worked at an asbestos textile factory for 3 years and 7 months in the late 1970s.

Case presentation

A 57-year-old woman visited the hospital because she had difficulty urinating. Ovarian cancer was suspected in radiologic examination, and exploratory laparotomy was performed. She was diagnosed with epithelial ovarian cancer. The patient did not undergo postoperative chemotherapy and recovered. She joined the asbestos factory in March 1976 and engaged in asbestos textile twisting and spinning for 1 year, 2 years and 7 months respectively. In addition, she lived near the asbestos factory for more than 20 years. There was no other specificity or family history.

Conclusion

Considering the patient’s occupational and environmental history, it is estimated that she had been exposed to asbestos significantly, so we determined that ovarian cancer in the patient is highly correlated with the occupational exposure of asbestos and environmental exposure is a possible cause as well. Social devices are needed to prevent further exposure to asbestos. It is also necessary to recognize that ovarian cancer can occur in workers who have previously been exposed to asbestos, and the education and social compensation for those workers are needed.

Factors influencing malignant mesothelioma survival: a retrospective review of the National Mesothelioma Virtual Bank cohort

Background: Malignant mesothelioma (MM) is a rare but deadly malignancy with about 3,000 new cases being diagnosed each year in the US.  Very few studies have been performed to analyze factors associated with mesothelioma survival, especially for peritoneal presentation. The overarching aim of this study is to examine survival of the cohort of patients with malignant mesothelioma enrolled in the National Mesothelioma Virtual Bank (NMVB).   Methods:  888 cases of pleural and peritoneal mesothelioma cases were selected from the NMVB database, which houses data and associated biospecimens for over 1400 cases that were diagnosed from 1990 to 2017. Kaplan Meier's method was performed for survival analysis. The association between prognostic factors and survival was estimated using Cox Hazard Regression method and using R software for analysis. Results: The median overall survival (OS) rate of all MM patients, including pleural and peritoneal mesothelioma cases is 15 months (14 months for pleural and 31 months for peritoneal).  Significant prognostic factors associated with improved survival of malignant mesothelioma cases in this NMVB cohort were younger than 45, female gender, epithelioid histological subtype, stage I, peritoneal occurrence, and having combination treatment of surgical therapy with chemotherapy. Combined surgical and chemotherapy treatment was associated with improved survival of 23 months in comparison to single line therapies. Conclusions: There has not been improvement in the overall survival for patients with malignant mesothelioma over many years with current available treatment options. Our findings show that combined surgical and chemotherapy treatment in peritoneal mesothelioma is associated with improved survival compared to local therapy alone.

Factors influencing malignant mesothelioma survival: a retrospective review of the National Mesothelioma Virtual Bank cohort

Background: Malignant mesothelioma (MM) is a rare but deadly malignancy with about 3,000 new cases being diagnosed each year in the US.  Very few studies have been performed to analyze factors associated with mesothelioma survival, especially for peritoneal presentation. The overarching aim of this study is to examine survival of the cohort of patients with malignant mesothelioma enrolled in the National Mesothelioma Virtual Bank (NMVB).   Methods:  888 cases of pleural and peritoneal mesothelioma cases were selected from the NMVB database, which houses data and associated biospecimens for over 1400 cases that were diagnosed from 1990 to 2017. Kaplan Meier's method was performed for survival analysis. The association between prognostic factors and survival was estimated using Cox Hazard Regression method and using R software for analysis. Results: The median overall survival (OS) rate of all MM patients, including pleural and peritoneal mesothelioma cases is 15 months (14 months for pleural and 31 months for peritoneal).  Significant prognostic factors associated with improved survival of malignant mesothelioma cases in this NMVB cohort were younger than 45, female gender, epithelioid histological subtype, stage I, peritoneal occurrence, and having combination treatment of surgical therapy with chemotherapy. Combined surgical and chemotherapy treatment was associated with improved survival of 23 months in comparison to single line therapies. Conclusions: There has not been improvement in the overall survival for patients with malignant mesothelioma over many years with current available treatment options. Our findings show that combined surgical and chemotherapy treatment in peritoneal mesothelioma is associated with improved survival compared to local therapy alone.

Factors influencing malignant mesothelioma survival: a retrospective review of the National Mesothelioma Virtual Bank cohort

Background: Malignant mesothelioma (MM) is a rare but deadly malignancy with about 3,000 new cases being diagnosed each year in the US.  Very few studies have been performed to analyze factors associated with mesothelioma survival, especially for peritoneal presentation. The overarching aim of this study is to examine survival of the cohort of patients with malignant mesothelioma enrolled in the National Mesothelioma Virtual Bank (NMVB).  

Methods:  888 cases of pleural and peritoneal mesothelioma cases were selected from the NMVB database, which houses data and associated biospecimens for over 1400 cases that were diagnosed from 1990 to 2017. Kaplan Meier’s method was performed for survival analysis. The association between prognostic factors and survival was estimated using Cox Hazard Regression method and using R software for analysis.

Results: The median overall survival (OS) rate of all MM patients, including pleural and peritoneal mesothelioma cases is 15 months (14 months for pleural and 31 months for peritoneal).  Significant prognostic factors associated with improved survival of malignant mesothelioma cases in this NMVB cohort were younger than 45, female gender, epithelioid histological subtype, stage I, peritoneal occurrence, and having combination treatment of surgical therapy with chemotherapy. Combined surgical and chemotherapy treatment was associated with improved survival of 23 months in comparison to single line therapies.

Conclusions: There has not been improvement in the overall survival for patients with malignant mesothelioma over many years with current available treatment options. Our findings show that combined surgical and chemotherapy treatment in peritoneal mesothelioma is associated with improved survival compared to local therapy alone.

Accuracy of a mobile app to identify suspect asbestos-containing material in Australian residential settings

In situ asbestos in the built environment is a remaining source of exposure in countries that have prohibited the manufacture and use of asbestos. However, it is difficult to identify in situ asbestos-containing material in residential settings. The objective of this study was to evaluate the accuracy of the mobile phone application ("app"), ACM Check, in identifying in situ asbestos located inside and outside of homes compared with onsite inspections conducted by an experienced environmental consultant. A cross-sectional study was undertaken that involved participants completing ACM Check on their homes built pre-1990 and located throughout metropolitan Perth, Western Australia, and an onsite inspection conducted at each home by an environmental consultant. Cohen's kappa statistic was calculated to evaluate the strength of agreement between the two methods. The 40 houses sampled were built between 1898 and 1988 with a median year of 1966. Thirty-eight (95%) homes had at least one type of material categorized as positive for asbestos by both ACM Check and the environmental consultant (κ = 1.00). Agreement between the two methods differed when categorizing specific materials as positive or negative for asbestos with substantial agreement for fencing (κ = 0.918), outbuilding walls (κ = 0.844), backing board to electrical meter box (κ = 0.826), exterior wall cladding (κ = 0.771), and interior walls (κ = 0.754), and fair agreement for outbuilding roofs (κ = 0.375) and interior flooring (κ = 0.304). ACM Check is a tool that can be used by tradespeople, home renovators, and householders to screen residential settings for the presence of in situ asbestos-containing material. Mobile phone apps have the potential to be developed or modified for use in other countries to help users identify asbestos and reduce their risk of asbestos exposure.

Mesotheliomas in Genetically Engineered Mice Unravel Mechanism of Mesothelial Carcinogenesis

Malignant mesothelioma (MM), a rare and severe cancer, mainly caused as a result of past-asbestos exposure, is presently a public health concern. Current molecular studies aim to improve the outcome of the disease, providing efficient therapies based on the principles of precision medicine. To model the molecular profile of human malignant mesothelioma, animal models have been developed in rodents, wild type animals and genetically engineered mice harbouring mutations in tumour suppressor genes, especially selecting genes known to be inactivated in human malignant mesothelioma. Animals were either exposed or not exposed to asbestos or to other carcinogenic fibres, to understand the mechanism of action of fibres at the molecular level, and the role of the selected genes in mesothelial carcinogenesis. The aim of the manuscript was to compare mesothelioma models to human malignant mesothelioma and to specify the clue genes playing a role in mesothelial carcinogenesis. Collectively, MM models recapitulate the clinical features of human MM. At least two altered genes are needed to induce malignant mesothelioma in mice. Two pathways regulated by Cdkn2a and Trp53 seem independent key players in mesothelial carcinogenesis. Other genes and pathways appear as bona fide modulators of the neoplastic transformation.

Indoor release of asbestiform fibers from naturally contaminated water and related health risk

This study investigates the occurrence of airborne asbestiform fibers released in indoor ambient due to the use of asbestos naturally contaminated water. Some experiments employed a laboratory physical model using an ultrasonic humidifier charged with contaminated groundwater. Other experiments were carried out at full scale to assess the release of asbestiform fibers during showering. Obtained results show that the concentration of the airborne asbestiform fibers released in the bathroom during showering is higher than the limit value set by the European and Italian Regulations, while the concentration of fibers released by the humidifier is much lower. However, it is noteworthy that the use of the humidifier at high exposure time results in similar health risk. Strong correlations were found between the concentration of the airborne asbestiform fibers and a novel surrogate parameter (i.e. the exposure-specific-water-consumption). These correlations can be used to monitor the asbestiform fibers concentration at varying operating conditions and therefore, to control the resulting health risk.

Case series: rheumatological manifestations attributed to exposure to Libby Asbestiform Amphiboles

An increased risk for Systemic Autoimmune Diseases (SAID) has been reported in Libby, Montana, where extensive exposures to fibrous amphiboles occurred due to mining and use of asbestos-laden vermiculite. In addition, positive antinuclear autoantibody tests are associated with exposure to Libby Asbestiform Amphiboles (LAA) in both humans and mice. Among 6603 subjects who underwent health screening at the Center for Asbestos Related Diseases (CARD, Libby MT), 13.8% were diagnosed with an autoimmune disease, with prevalence values for the most common SAID being significantly higher than expected in the United States. Among the CARD screening population, serological and clinical profiles are diverse, representing symptoms and autoantibodies reflective of systemic lupus erythematosus (SLE), scleroderma, rheumatoid arthritis, and other rheumatic syndromes, including undifferentiated connective tissue disease (UCTD). Based upon screening of medical records by physicians with rheumatology expertise, the evolving nature of rheumatological disease in these patients is often atypical, with mixed diagnostic criteria and with a 1:1 male-to-female ratio. Through the Libby Epidemiology Research Program, cases were identified that illustrate clinical autoimmune outcomes with LAA exposure. Our goal was to better characterize SAID in Libby, MT in order to improve recognition of autoimmune outcomes associated with this exposure. In view of recent discoveries of widespread exposure to fibrous minerals in several areas of the U.S. and globally, it is critical to evaluate rheumatologic manifestations in other cohorts so that screening, surveillance, and diagnostic procedures are able to detect and recognize potential autoimmune outcomes of asbestos exposure.

ABBREVIATIONS

ANA, antinuclear autoantibody; ARD, Asbestos-Related Diseases; ATSDR, Agency for Toxic Substances & Disease Registry; CARD, Center for Asbestos Related Diseases; CCP, Cyclic citrullinated peptide antibody; CREST, limited cutaneous form of scleroderma; CT, computed tomography; DIP, Distal Interphalangeal Joint; DLCO, Diffusing Capacity of the Lung for CO₂; DMARD, Disease Modifying Anti-Rheumatic Drugs; ENA, Extractable Nuclear Antigen antibodies; FVC, Forced Vital Capacity; LAA, Libby Asbestiform Amphiboles; LERP, Libby Epidemiology Research Program; MCP, Metacarpal Phalangeal Joint; PIP, Proximal Interphalangeal Joint; PIP, rheumatoid arthritis; RV, Residual Volume; SAID, Systemic autoimmune diseases; SLE, systemic lupus erythematosus; SSc, Systemic Sclerosis; TLC, Total Lung Capacity.

New Perspectives on Diagnosis and Therapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but severe form of cancer, with an incidence that varies significantly within and among different countries around the world. It develops in about one to two persons per million of the general population, leading to thousands of deaths every year worldwide. To date, the MPM is mostly associated with occupational asbestos exposure. Asbestos represents the predominant etiological factor, with approximately 70% of cases of MPM with well-documented occupational exposure to asbestos, with the exposure time, on average greater than 40 years. Environmental exposure to asbestos is increasingly becoming recognized as a cause of mesothelioma, together with gene mutations. The possible roles of other cofactors, such as viral infection and radiation exposure, are still debated. MPM is a fatal tumor. This cancer arises during its early phase without clinical signs. Consequently, its diagnosis occurs at advanced stages. Standard clinical therapeutic approaches include surgery, chemo- and radiotherapies. Preclinical and clinical researches are making great strides in the field of this deadly disease, identifying new biomarkers and innovative therapeutic approaches. Among the newly identified markers and potential therapeutic targets, circulating microRNAs and the Notch pathway represent promising avenues that could result in the early detection of the tumor and novel therapeutic approaches.

A vicious interplay between genetic and environmental insults in the etiology of blood cancers

Over the years, the etiology of cancer has been attributed alternatively to genetic and environmental insults. According to the genetic hypothesis, cancer cells arise from the acquisition of mutations that dysregulate the intrinsic mechanisms controlling normal cell growth and survival. In contrast, the environmental hypothesis holds that cancer can be caused by multiple extrinsic challenges that alter normal tissue homeostasis, but may not necessarily involve mutations. It is, however, quite possible that these two mechanisms are not mutually exclusive. According to this third hypothesis, environmental challenges, by mechanisms still poorly understood, may act by imposing a selection pressure that confers a proliferative advantage on cells carrying specific driver mutations, leading to disease initiation. The authors of a brief report published in this journal (Exp Hematol. 2017;56:1-6) tested this third hypothesis experimentally and provide new evidence that chronic inflammation, by increasing tumor necrosis factor (TNF)-α, may positively select malignant hematopoietic stem cells (HSCs) carrying loss-of-function TET2 mutations that switch the TNF-α signaling responses to activate proliferation rather than inducing quiescence. Furthermore, these mutations skew hematopoietic differentiation toward the myelomonocytic lineage and the output of macrophages producing TNF-α constitutively, promoting further environment-independent expansion of the malignant HSCs. These findings support a model in which the formation of a malignant population is triggered by a vicious interplay between genetic (TET2 mutations) and environmental (inflammation) insults, suggesting the need for strategies that target both the malignant cells and their environment.