Bilateral diffuse pulmonary infiltrates secondary to malignant peritoneal mesothelioma - A rare clinical presentation

Diffuse pulmonary metastasis secondary to primary peritoneal malignant mesothelioma is rarely reported in the literature. In this report we describe a 59-year-old Caucasian women with no known previous asbestos exposure presenting with bilateral diffuse pulmonary opacities in association with primary malignant peritoneal mesothelioma. The diagnosis was confirmed by ultrasound guided abdominal and bronchoscopy, trans-bronchial lung biopsy. The biopsy demonstrated positive staining with AE1/3, CK7, CK5/6, WT1, calretinin and D2 40. The cells were negative for BerEP4, PAX8, CA125, ER, CD34, ERG, P63, P40, Melan A, Gata3 and mammaglobin. The morphology and immunohistochemical profile supported a diagnosis of epithelioid malignant mesothelioma.

Biodurability and release of metals during the dissolution of chrysotile, crocidolite and fibrous erionite

BACKGROUND

The mechanisms by which mineral fibers induce adverse effects in vivo are still not well understood. The mechanisms of fiber dissolution in the lungs and subsequent release of metals in the extracellular/intracellular environment must be taken into account.

AIM

For the first time, the kinetics of release of metals during the acellular in vitro dissolution of chrysotile, crocidolite and fibrous erionite were determined.

METHODS

In vitro acellular dissolution of chrysotile, crocidolite, and fibrous erionite-Na was conducted using a solution mimicking the phagolysosome environment active during the phagocytosis process (pH=4.5, at 37 °C). The kinetics of release of a representative selection of metals were determined over a period of three months.

RESULTS

Despite the fact that the difference in Fe content between chrysotile and crocidolite is one order of magnitude, the much faster dissolution rate of chrysotile compared to crocidolite prompts greater release of available active surface Fe in the first weeks of the dissolution experiment and comparable amounts after 90 d. Such active iron may promote the formation of toxic hydroxyl radicals. The fast release of metals like Cr, Ni and Mn from chrysotile is also a source of concern whereas the release of V in solution is negligible.

CONCLUSION

Because chrysotile undergoes fast dissolution with respect to crocidolite and fibrous erionite, it behaves like a carrier that releases its metals' cargo in the lung environment, mimicking the phenomenon that explains the toxicity of nanoparticles. Hence, the toxicity paradigm of a non biodurable fiber like chrysotile should also take into account the release of toxic metals in the intracellular/extracellular medium during the rapid dissolution process.

Asbestos fiber identification in liver from cholangiocarcinoma patients living in an asbestos polluted area: a preliminary study

PURPOSE

To assess whether asbestos fibers may be observed in liver tissue of patients with cholangiocarcinoma (CC) with environmental or working asbestos exposure.

METHODS

Detection of fibers was performed directly on histologic sections of liver from 7 patients with CC using optical microscope and variable pressure scanning electron microscopy equipped with energy-dispersive spectroscopy (VP-SEM/EDS). All patients were from Casale Monferrato, Italy, a highly asbestos-polluted town. Due to ethical constraints, observers were blinded to patients' clinical features.

RESULTS

Fibers/bundles of fibers of chrysotile were detected in 5 out of 7 patients (71%). The boundary between healthy and neoplastic tissue or the fibrocollagen tissue produced by the neoplasia were identified as areas of fiber incorporation.

CONCLUSIONS

This study is the first report about the detection of chrysotile asbestos fibers in the liver of patients with CC. Further studies on larger cohorts are needed to corroborate our preliminary findings.

Multi-walled carbon nanotubes induce stronger migration of inflammatory cells in vitro than asbestos or granular particles but a similar pattern of inflammatory mediators

Biopersistent pro-inflammatory fibers are suspected human carcinogens. Cytotoxicity and transcription of pro- and anti-inflammatory mediators of different fibers were investigated in functional relationship to chemotaxis in vitro as a model for fiber-induced inflammation of the lung. We challenged NR8383 rat macrophages with multi-walled carbon nanotubes (MWCNT) and various asbestos fibers. The resulting cell supernatants were than studied using the Particle-induced Cell Migration Assay (PICMA) and cytotoxicity was determined using the LDH test. Expression of inflammatory mediators was analyzed with qPCR and verified by ELISA. Chrysotile A and the rigid, needle-shaped NM-401 caused the strongest cytotoxic effects and the largest number of migrated cells. In contrast, the MWCNT NM-400, NM-402, and NM403 were apparently non-cytotoxic but induced pronounced cell migration showing a very steep dose response. However, the strength of cell migration and cytotoxicity of the asbestos fibers were correlated. The expression profile of inflammatory mediators was comparable, although cytotoxicity of the MWCNT NM-401 and NM-403 differed strongly. Induction of the corresponding proteins was confirmed for CCL2, CCL3, CXCL1, CXCL3, IL1RA (IL1RN), CSF1, GDF15 and TNFa. Chrysotile A and NM-401 induced much stronger chemotaxis than the non-fibrous particles reported in our previous study. Cytotoxic and chemotactic effects correspond to the induction of inflammatory mediators.

Malignant Peritoneal Mesothelioma Without Asbestos Exposure

Malignant mesothelioma is a rare neoplasm of the serosal linings. Mesothelioma has been linked to asbestos exposure, with prior asbestos exposure linked to 33-50% of malignant peritoneal mesotheliomas. We describe a case of malignant peritoneal mesothelioma (MPM) without any prior exposure to asbestos in a 40-year-old Hispanic female who presented to the emergency department with worsening abdominal pain and distension. She had a history of beta thalassemia trait and iron deficiency anemia. Examination revealed a distended abdomen with protruding umbilicus and positive shifting dullness. Laboratory tests showed anemia. Computed tomography (CT) of the abdomen revealed massive complex ascites suspicious of a malignant process. Ascitic fluid analysis showed serum ascites albumin gradient (SAAG) of 1.1 g/dL with a total protein of 5.2 g/dL. She underwent laparoscopic peritoneal biopsy which yielded epithelioid type malignant mesothelioma. She was started on chemotherapy with cisplatin and pemetrexed. The last follow-up was 27 months after the diagnosis. MPM is a rare and life-threatening malignancy. Frequently, the symptoms are non-specific. This poses a diagnostic challenge for physicians and probably the reason why the diagnosis is often delayed, especially in the absence of risk factors.

Iron addiction with ferroptosis-resistance in asbestos-induced mesothelial carcinogenesis: Toward the era of mesothelioma prevention

Cancer is the primary cause of human mortality in most countries. This tendency has increased as various medical therapeutics have advanced, which suggests that we cannot escape carcinogenesis, although the final outcome may be modified by exposomes and statistics. Cancer is classified by its cellular differentiation. Mesothelial cells are distinct in that they line somatic cavities, facilitating the smooth movement of organs, but are not exposed to the external environment. Malignant mesothelioma, or simply mesothelioma, develops either in the pleural, peritoneal or pericardial cavities, or in the tunica vaginalis testes. Mesothelioma has been a relatively rare cancer but is socially important due to its association with asbestos exposure, caused by modern industrial development. The major pathogenic mechanisms include oxidative stress either via catalytic reactions against the asbestos surface or frustrated phagocytosis of macrophages, and specific adsorption of hemoglobin and histones by asbestos fibers in the presence of phagocytic activity of mesothelial cells. Multiwall carbon nanotubes of ~50 nm-diameter, additionally adsorbing transferrin, are similarly carcinogenic to mesothelial cells in rodents and were thus classified as Group 2B carcinogens. Genetic alterations found in human and rat mesothelioma notably contain changes found in other excess iron-induced carcinogenesis models. Phlebotomy and iron chelation therapies have been successful in the prevention of mesothelioma in rats. Alternatively, loading of oxidative stress by non-thermal plasma to mesothelioma cells causes ferroptosis. Therefore, carcinogenesis by foreign fibrous inorganic materials may overlap the uncovered molecular mechanisms of birth of life and its evolution.

Asbestos neglect: Why asbestos exposure deserves greater policy attention

While many public health threats are now widely appreciated by the public, the risks from asbestos exposure remain poorly understood, even in high-risk groups. This article makes the case that asbestos exposure is an important, ongoing global health threat, and argues for greater policy efforts to raise awareness of this threat. It also proposes the extension of asbestos bans to developing countries and increased public subsidies for asbestos testing and abatement.

Systematic screening for occupations and occupational exposures in head and neck squamous cell carcinoma patients

PURPOSE

The importance of occupational exposures in patients with head and neck squamous cell carcinomas (HNSCC) has received little attention.

METHODS

In a single-center study, we prospectively characterized occupational exposures in 154 HNSCC cancer patients in a systematic occupational consultation and examined the association between most frequent exposures, HNSCC stage and localization.

RESULTS

Patients occupied a mean of 3.3 different positions during their working life. The prevalence of asbestos, the most frequent exposure (46 patients; 29.9%) was higher than in the French population > 50 years. Other frequent exposures were solvents (n = 26; 16.9%) and silica (n = 19; 12.3%). For 37 patients (24%) a possible link was identified between occupational exposures and HNSCC. Duration of asbestos exposure was significantly higher (p = 0.04) in patients with hypopharyngeal and laryngeal cancer compared to other localizations.

CONCLUSIONS

Occupational exposures are frequent in patients with HNSCC and should receive increased attention by physicians.

The significance of non-occupational asbestos exposure in women with mesothelioma

Malignant mesothelioma is a rare and aggressive pleural or peritoneal tumour almost always caused by exposure to asbestos fibres. Exposure to asbestos can cause malignant mesothelioma 30-40 years after exposure. A description of sources of exposure is important for prevention and possible financial compensation. Three women with cases of histologically confirmed malignant mesothelioma diagnosed from non-occupational asbestos exposure are described. Patients were contacted for an interview to assess their exposure history to asbestos. All three cases had mixed exposure histories related to secondary, environmental contamination, and domestic exposure. This case series highlight how ubiquitous asbestos is in the environment and how diverse the exposures may be. It is anticipated that a significant number of cases of non-occupational mesothelioma will be seen in many countries for several decades given the extent of asbestos containing materials.

Current Asbestos Exposure and Future Need for Palliative Care in India

Asbestos-related diseases (ARDs) are incurable but entirely preventable. Due to India's continuing use of asbestos, ARD patients will increase to a high number in the next three to four decades. This will increase the burden on palliative care system which is in nascent stage presently. Palliative care is the mainstay of the management of ARDs. Unfortunately, the burden on palliative care is likely to increase due to multiple factors contributed by India's demographic and economic changes. In the near future, there will be at least 12.5 million ARD patients and 1.25 million asbestos-related cancer patients worldwide, and half of these will be in India. It is high time to introspect about our ability to engage with this future problem. The paper also discusses the organization of this future problem of ARDs and possible action points toward future access to palliative care for ARD patients.

Mortality among workers exposed to asbestos at the shipyard of Genoa, Italy: a 55 years follow-up

BACKGROUND

Exposure to asbestos remains a global issue due to its massive use in the twentieth century and its long environmental persistence. Exposure to asbestos still occurs during dismantling of ships and vessels, buildings renovation, mining operations, and is reported in developing countries. Current estimate report exposure of hundreds of million people in occupational settings in countries where its use remains unregulated.

METHODS

We conducted a historical prospective cohort mortality study aimed at estimating mortality from specific causes, the temporal changes of pleural and lung cancer mortality, and the attributable fraction (AF) of lung cancer deaths following asbestos exposure. The study included 3984 shipyard workers employed at the shipyard of Genoa, Italy, between 1960 and 1981 and followed up to December 2014. Standardized Mortality Ratios (SMR) and their 95% confidence intervals (95%CI) were computed.

RESULTS

Overall deaths recorded were 3331 (83.6%). Excess mortality was observed for all cancers (SMR = 127, 95%CI:120-134), pleural mesothelioma (575, 469-697), cancers of the larynx (183, 134-244) and of the lung (154, 139-170), and for respiratory tract diseases (127, 114-141), including asbestosis (2277, 1525-3270). Ninety out of 399 deaths (22.6%) from lung cancer were attributed to asbestos exposure. The estimated lung cancer AF was 49.3% in workers with the highest SMR for pleural cancer. Median latency times for pleural and lung cancer were 42.8 years (minimum latency: 9.3 years) and 38.7 years (minimum latency: 6 years). The peak of mesothelioma incidence, expected in Italy in the period 2015-2024, was confirmed.

CONCLUSIONS

The long follow-up period of our study allowed the detection of a substantial disease burden following asbestos exposure. These findings support the urgent need for the prevention of asbestos related diseases through the implementation of asbestos ban worldwide, including those countries where asbestos is still mined, manufactured and used.

Impact of asbestos on public health: a retrospective study on a series of subjects with occupational and non-occupational exposure to asbestos during the activity of Fibronit plant (Broni, Italy)

The goal of this study is to understand more about the role of asbestos in causing human diseases, first of all mesothelioma, by investigating a large series of deaths due to asbestos-related diseases (ARDs). The main aim is to clarify if even very low amounts of asbestos can cause mesothelioma and other ARDs, as well as to find out if a different individual vulnerability can be important. This retrospective study included 188 subjects who died from asbestos related diseases in 2000-2017 in the area around Broni, Italy, where an important asbestos cement factory had been active from 1932 until 1993. In each case, a forensic autopsy has been performed. In order to perform the present study, the records were retrieved, including the clinical files, the autopsy, and the histological report. The statistical analysis performed showed that there was a significant relation between the cause of death (mesothelioma, lung cancer or asbestosis) and the kind of exposure (occupational, neighborhood or household), showing that all the subjects not exposed occupationally (and, therefore, exposed to lower amounts of asbestos) died from mesothelioma, whereas the individuals who used to work at the plant died also from other caused (asbestosis, lung cancer). Significant differences were highlighted examining the distribution of the causes of death according to the smoking habits. Moreover, among the mesothelioma patients, the survival time was shorter in the subjects with a neighborhood or household exposure than in the occupationally exposed individuals. The study provided meaningful data about the role of asbestos in causing human pathologies. In particular, the present data appear to support the hypothesis that even an exposure to a very little amount of asbestos can cause mesothelioma in hypersusceptible subjects (probably, on a genetic basis).

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.

[Asbestos in the National Navy: Employment-exposure matrix]

INTRODUCTION

The odd risk ratio for an asbestos-related disease is 6.9 for National Defense personnel and 94% of the victims who are compensated belong to the French Navy. While employment-exposure matrices exist for the civilian environment, none are available to the military. Our work consists of the creation of the first employment-exposure matrix in the French Navy, in order to optimize post-occupational medical surveillance.

METHOD

We conducted a bibliographic search for asbestos in naval repair, naval embarking and foreign navies. From databases such as Medline, Pubmed, we used the following keywords "Navy", "Asbestos", "Shypyard" and "Military" and we have extended ourselves to the registers of existing theses on the subject.

RESULTS

Epidemiological and bibliographic data confirm the increased risk in the French Navy. Three variables are important in the proposal of this employment-exposure matrix: employment, year of arming the ship and duration of embarkation. There is a major risk for personnel whose work is in direct contact with asbestos, in particular machine personnel, irrespective of their duration of exposure. For embarked personnel who do not have direct contact with asbestos in their jobs, the increase in risk depends essentially on the ship's year of arming and the presence of asbestos, whether or not on board, as well as the duration of exposure of seafarers.

CONCLUSION

These results allow us to recommend a classification of the risk in accordance with the recommendations of the French Health Authority and to propose an adequate post-professional follow-up for the personnel of the Navy.

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.

Work-related laryngeal cancer: Trends in France from 2001 to 2016

OBJECTIVES

As part of the 2014-2019 cancer plan and in order to improve our knowledge of work-related cancers, we analysed the work-related laryngeal cancer risk situations identified in the French national occupational disease surveillance and prevention network (rnv3p) from 2001 to 2016.

MATERIAL AND METHODS

This study focused on cases of work-related laryngeal cancer, which the expert physician considered to be directly related to exposure (intermediate or strong causal relationship). Demographic data, occupational exposure circumstances (hazards, occupation, business sector), non-occupational risk factors and the occupational physician's opinion concerning notification as an occupational disease were analysed.

RESULTS

Two hundred forty-four cases of laryngeal cancer were registered between 2001 and 2016. One hundred and forty seven cases were considered to be work-related, with an intermediate or strong causal relationship in 87 cases. This exclusively male population had a median age of 59 years. Ninety-seven different forms of exposure were identified, including asbestos in 78 cases. The main business sectors concerned were specialized construction (14 cases) and metallurgy (7 cases). Occupational disease notification was recommended in 60 patients, corresponding to asbestos exposure in 80% of cases.

CONCLUSIONS

Asbestos is the laryngeal cancer risk factor most commonly reported in the network from 2001 to 2016. This study confirms the role of asbestos in laryngeal carcinogenesis. Laryngeal cancer may therefore need to be compensated as an occupational disease in France, as in other European countries.

A meta-analysis of airborne asbestos fiber concentrations from work with or around asbestos-containing floor tile

In this meta-analysis, exposures to airborne asbestos during work with or around floor tiles were characterized according to several variables: study, sample type, activity, and task. Personal breathing zone, bystander, and area sample exposure concentrations were differentiated and compared against current occupational exposure limits to asbestos. In total, 22 studies, including 804 personal, 57 bystander, and 295 area samples, were included in the analysis. The arithmetic mean airborne fiber concentrations were 0.05, 0.02, and 0.01 f/cm³ for personal, bystander, and area samples, respectively. Arithmetic mean time-weighted-average fiber concentrations over an 8-h working day were 0.02 and 0.01 f/cm³ for personal and bystander samples, respectively. Phase contrast microscopy (PCM) personal airborne fiber concentrations were highest for maintenance activities, followed by removal and installation. Tasks that involved buffing or burnishing, scoring or snapping, and scraping or lifting had the highest personal PCM concentrations, while stripping floor tile and removing it with chemical solvent had the lowest concentrations. Exposures associated with handling asbestos floor tiles, under working conditions normally encountered, do not generally produce airborne concentrations at levels that exceed the current OSHA PEL nor do they appear to approach the threshold cumulative asbestos dose concentrations that have been previously associated with an increased risk of asbestos-related disease.

Elongate mineral particles in the natural environment

When considering elongate mineral particles (EMPs) in the natural environment it is important to first: 1) define what an elongate mineral is and 2) present what we as mineralogists and geologists know about their distribution. However, it is often very difficult to define the natural world, instead we physical scientists resort to describing it. For instance, we used 1,419 words spread over two pages of our mineralogy textbook (Dyar and Gunter, 2008) to describe a mineral. On the other hand, elongate has a rather simple non-quantitative definition as a particle longer than it is wide; however, to quantify it, we must select an aspect ratio. Cleary the term EMP was coined with the hopes to simplify some of the confusion resulting in the differing "meanings" of such words as asbestos, asbestiform, acicular, and most importantly "fiber" in the natural vs. built environment, especially when applied to amphiboles (Gunter, 2010), and non-regulated asbestiform amphibole species. This paper draws on three sources: 1) the USDA-NRCS soil database (Thompson et al., 2011), 2) soil mineralogical data from USGS (Smith et al., 2013), and 3) the mineral database created in conjunction with the Dyar and Gunter (2008) textbook in an attempt to show issues created by use of the term EMP.

WHO/ILO work-related burden of disease and injury: Protocol for systematic reviews of occupational exposure to dusts and/or fibres and of the effect of occupational exposure to dusts and/or fibres on pneumoconiosis

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing a joint methodology for estimating the national and global work-related burden of disease and injury (WHO/ILO joint methodology), with contributions from a large network of experts. In this paper, we present the protocol for two systematic reviews of parameters for estimating the number of deaths and disability-adjusted life years attributable to pneumoconiosis from occupational exposure to dusts and/or fibres, to inform the development of the WHO/ILO joint methodology.

OBJECTIVES

We aim to systematically review studies on occupational exposure to dusts and/or fibres (Systematic Review 1) and systematically review and meta-analyse estimates of the effect of occupational exposure to dusts and/or fibres on pneumoconiosis (Systematic Review 2), applying the Navigation Guide systematic review methodology as an organizing framework.

DATA SOURCES

Separately for Systematic Reviews 1 and 2, we will search electronic academic databases for potentially relevant records from published and unpublished studies, including Medline, EMBASE, Web of Science and CISDOC. We will also search electronic grey literature databases, Internet search engines and organizational websites; hand-search reference list of previous systematic reviews and included study records; and consult additional experts.

STUDY ELIGIBILITY AND CRITERIA

We will include working-age (≥15 years) study participants in the formal and informal economy in any WHO and/or ILO Member State but exclude children (<15 years) and unpaid domestic workers. Eligible risk factors will be dusts and/or fibres from: (i) asbestos; (ii) silica; and/or (iii) coal (defined as pure coal dust and/or dust from coal mining). Included outcomes will be (i) asbestosis; (ii) silicosis; (iii) coal worker pneumoconiosis; and (iv) unspecified pneumoconiosis. For Systematic Review 1, we will include quantitative prevalence studies of occupational exposure to dusts and/or fibres (i.e. no versus any exposure) stratified by country, sex, age and industrial sector or occupation. For Systematic Review 2, we will include randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of any occupational exposure to dusts and/or fibres on the prevalence of, incidence of or mortality due to pneumoconiosis, compared with the theoretical minimum risk exposure level of no exposure.

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors will independently screen titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. At least two review authors will assess risk of bias and the quality of evidence, using the most suited tools currently available. For Systematic Review 2, if feasible, we will combine relative risks using meta-analysis. We will report results using the guidelines for accurate and transparent health estimates reporting (GATHER) for Systematic Review 1 and the preferred reporting items for systematic reviews and meta-analyses guidelines (PRISMA) for Systematic Review 2.

PROSPERO REGISTRATION NUMBER

CRD42018084131.

Hotspots of malignant pleural mesothelioma in Western Europe

Malignant pleural mesothelioma, a highly invasive tumour, has been epidemiologically linked to an occupational or environmental exposure to asbestos. Although asbestos has been widely used in diverse industrial applications and in construction, some industrial sectors have been affected much more than others. The objective of this review was to describe the existence of clusters of malignant pleural mesothelioma in Western European countries, based on epidemiological studies published between 2000 and 2015. MEDLINE (PubMed) and Embase were searched for relevant studies on spatial clustering of mesothelioma in Western European countries. Eventually, 16 different studies published between 2000 and 2015 were selected for a comprehensive analysis. Relevant studies on spatial clustering of mesothelioma were found for Belgium, the Netherlands, the United Kingdom, Germany, France, Spain, Italy and Denmark. Clustering of pleural mesothelioma was found mainly around shipyards (16 studies) and asbestos cement industries (10 studies). Although malignant pleural mesothelioma may be found throughout Western Europe, the present study indicates specific areas with higher past and also probable future incidence.

Types and Health Hazards of Fibrous Materials Used as Asbestos Substitutes

Asbestos has been banned in many countries but many countries, including developing countries, are still using asbestos or materials containing asbestos. Substitute materials have been studied and developed over a long period of time because of the hazards of asbestos, and many people have recently shown interest in the hazards of substitute materials. However, comprehensive information about the types of asbestos substitutes, their use and health hazards, and references for the protection for the health of workers is limited. The purpose of this study is to provide people in the related industries with information on the types and health hazards of fibrous materials that can be used as asbestos substitutes. According to the patent resources from the United States and Europe, fibrous materials have been used to develop asbestos-free products since before 1980. Recently, the health hazards of asbestos substitutes have been assessed and many additional researches are required. However, only some of the substitute materials have been assessed for health hazards, and health hazard data has not been sufficient in many cases. Therefore, efforts should be made to minimize workers' exposure to substitute materials that do not contain asbestos.

Occupational Burden of Asbestos-Related Diseases in Korea, 1998-2013: Asbestosis, Mesothelioma, Lung Cancer, Laryngeal Cancer, and Ovarian Cancer

BACKGROUND

Asbestos exposure causes asbestos-related diseases (ARDs) including asbestosis, malignant mesothelioma, lung cancer, laryngeal cancer, and ovarian cancer. Although Korea used substantial amounts of asbestos in the past, no study has focused on its occupational burden of disease (OBD). Therefore, this study aimed to determine the OBDs of ARDs in Korea.

METHODS

The CARcinogen Exposure (CAREX) database was used to determine the proportion of exposed population. Relative risks for lung cancer, laryngeal cancer, and ovarian cancer were used to determine the population-attributable fraction. Data for deaths caused by ARDs during 1998-2013 were obtained from the World Health Organization mortality database. The potential years of life lost (PYLL) and annual average PYLL (APYLL) indicated OBDs.

RESULTS

In Korea, the number of ARD-attributable deaths and PYLL due to all ARDs during 1998-2013 were 4,492 and 71,763.7, respectively. The number of attributable deaths and PYLL due to asbestosis, malignant mesothelioma, lung cancer, laryngeal cancer, and ovarian cancer were 37 and 554.2, 808 and 15,877.0, 3,256 and 47,375.9, 120 and 1,605.5, and 271 and 6,331.1, respectively; additionally, the APYLL were 15.0, 19.7, 14.6, 13.4, and 23.4, respectively, and the average age at death was 70.4, 62.6, 69.1, 69.9, and 61.8, respectively. Our study showed that although the use of asbestos has ceased in Korea, the incidence of ARDs tends to increase.

CONCLUSION

Therefore, efforts to reduce future OBDs of ARDs, including early detection and proper management of ARDs, are needed in Korea.

Measurement of elongate mineral particles: What we should measure and how do we do it?

The length distributions of single fibrils of Coalinga, UICC-B and wet dispersed chrysotile were measured by transmission electron microscopy (TEM). It was found that the distributions significantly diverged above approximately 10 μm (μm) in length, corresponding to differences in published results of animal experiments. This result is in contrast to published data in which counting of an insufficient number of fibers resulted in an erroneous conclusion that the length distribution of Coalinga chrysotile fibrils was indistinguishable from those of other sources of chrysotile. The size distributions of the respirable particle size fractions from acknowledged tremolite asbestos samples were found to be dominated by elongate particles longer than 5 μm that are within the dimensional range of non-asbestiform amphiboles. Prior studies have shown that these elongate particles obscure a correlation between a specific size range of particles and results of animal implantation studies that used tremolite of various morphologies. In the prior studies, a reference protocol was developed from four crushed non-asbestiform amphiboles to differentiate the size range of amphibole particles that correlates with the mesothelioma frequencies observed in the animal studies. In the work reported here, this correlation was tested with TEM analyses of amphiboles from Libby, MT, Sparta, NJ and Homestake mine, Lead, SD, which represent known environmental/occupational situations. Further TEM analyses of the tremolite samples used in the original animal implantation studies have also shown that the numbers of elongate tremolite particles with lengths ≤5 μm implanted into the animals are not correlated with the observed mesothelioma frequencies.

Talc exposure and risk of stomach cancer: Systematic review and meta-analysis of occupational cohort studies

BACKGROUND/PURPOSE

Talc powder is widely used in various industries, but the carcinogenic effects associated with talc are not well understood. The objective of this study was to estimate the risk of stomach cancer after occupational talc exposure.

METHODS

We conducted a meta-analysis was performed to calculate the meta-relative risk (mRR) of stomach cancer. We searched the MEDLINE, EMBASE, CNKI and Wanfang Data databases for publications prior to January 1, 2017 using talc, cancer, and mortality as the search terms. Only cohort studies with occupational talc exposure and stomach cancer statistics were included.

RESULTS

All pooled analyses were based on random-effects models. We selected 13 observational studies (12 publications) for the meta-analysis, and heterogeneity was observed among studies. Workers exposed to all forms of talc had a significantly increased mRR of 1.21 (95% CI: 1.03-1.42, p = 0.02) for stomach cancer. Workers exposed to talc not containing asbestiform fibers also had an increased mRR of 1.26 (95% CI: 0.97-1.63, p = 0.09).

CONCLUSION

The available data showed a positive association between occupational talc exposure and risk of stomach cancer. The association between talc not containing asbestiform fibers and risk of stomach cancer was not significant. Further epidemiological studies are required to evaluate the safety of talc.

Adverse health effects of asbestos: solving mysteries regarding asbestos carcinogenicity based on follow-up survey of a Chinese factory

The present review summarizes the results of several follow-up studies assessing an asbestos product manufacturing plant in Chongqing, China, and discusses three controversial issues related to the carcinogenicity of asbestos. The first issue is the amphibole hypothesis, which asserts that the carcinogenicity of asbestos is limited to amphiboles, such as crocidolite, but not serpentines, such as chrysotile. However, considering the possible multiple component of asbestos carcinogenicity in the presence of tobacco smoke or other carcinogens, chrysotile cannot be regarded as non-carcinogenic. Additionally, in a practical sense, it is not possible to assume "pure" chrysotile due to its ubiquitous contamination with tremolite, which is a type of amphibole. Thus, as the International Agency for Research on Cancer (IARC) assessed, all forms of asbestos including chrysotile should be regarded carcinogenic to humans (Group 1). The second issue is the chrysotile/tremolite paradox, which is a phenomenon involving predominant levels of tremolite in the lung tissues of individuals who worked in locations with negligible levels of tremolite due to the exclusive use of chrysotile. Four possible mechanisms to explain this paradox have been proposed but this phenomenon does not support the claim that amphibole is inert. The final issue discussed is the textile mystery, i.e., the higher incidence of cancer in asbestos textile plants compared to asbestos mines where the same asbestos was produced and the exposure levels were comparable. This phenomenon was first reported in North America followed by UK and then in the present observations from China. Previously, levels of fiber exposure were calculated using a universal converting coefficient to estimate the mass concentration versus fiber concentration. However, parallel measurements of fiber and mass concentrations in the workplace and exposed air indicated that there are wide variations in the fiber/mass ratio, which unjustifies the universal conversion. It is possible that contamination by airborne non-fibrous particles in mines with mass fiber conversion led to the overestimation of fiber concentrations and resulted in the textile mystery. Although the use and manufacturing of asbestos has been banned in Japan, more than 10 million tons of asbestos had been imported and the majority remains in existing buildings. Thus, efforts to control asbestos exposure should be continued.