Cause specific mortality in an Italian pool of asbestos workers cohorts.

BACKGROUND: Asbestos is a known human carcinogen and is causally associated with malignant mesothelioma, lung, larynx and ovarian cancers. METHODS: Cancer risk was studied among a pool of formerly asbestos-exposed workers in Italy. Fifty-two Italian asbestos cohorts (asbestos-cement, rolling-stock, shipbuilding, and other) were pooled and their mortality follow-up was updated to 2018. Standardized mortality ratios (SMRs) were computed for major causes of death considering duration of exposure and time since first exposure (TSFE), using reference rates by region, age and calendar period. RESULTS: The study included 63,502 subjects (57,156 men and 6346 women): 40% who were alive, 58% who died (cause known for 92%), and 2% lost to follow-up. Mortality was increased for all causes (SMR: men = 1.04, 95% confidence interval [CI] 1.03-1.05; women = 1.15, 95% CI 1.11-1.18), all malignancies (SMR: men = 1.21, 95% CI 1.18-1.23; women = 1.29, 95% CI 1.22-1.37), pleural and peritoneal malignancies (men: SMR = 10.46, 95% CI 9.86-11.09 and 4.29, 95% CI 3.66-5.00; women: SMR = 27.13, 95% CI 23.29-31.42 and 7.51, 95% CI 5.52-9.98), lung (SMR: men = 1.28, 95% CI 1.24-1.32; women = 1.26, 95% CI 1.02-1.53), and ovarian cancer (SMR = 1.42, 95% CI 1.08-1.84). Pleural cancer mortality increased during the first 40 years of TSFE (latency), reaching a plateau thereafter. CONCLUSIONS: Analyses by time-dependent variables showed that the risk for pleural neoplasms increased with latency and no longer increases at long TSFE, consistent with with asbestos clearance from the lungs. Peritoneal neoplasm risk increased over all observation time.

[Malignant mesothelioma in two married couples exposed to asbestos]. / Mesotelioma maligno in due coppie di coniugi esposte ad amianto.

BACKGROUND: the relationship between past asbestos exposure and the onset of malignant mesothelioma (MM) is well established. However, defining the exposure is not always easy, as it occurs decades before the onset of the disease. OBJECTIVES: this report describes four cases of MM diagnosed in two different married couples, both exposed to asbestos fibers: husbands at work and wives for cohabiting and washing their work overalls. DESIGN: case report. METHODS: the information was collected through interviews using a semi-structured questionnaire and analyzed by occupational hygienists during the activity of epidemiological surveillance of this disease. The results of the mineral content of asbestos fibers performed on lung parenchymal from one of the female cases are available. RESULTS: these two cases show a longer latency in the lesser exposed confirming what an occupational epidemiological study has recently highlighted. CONCLUSIONS: whenever good quality information collected during interviews are available, skilled occupational hygienists are able to reconstruct past exposures in quali-quantitative terms.

Incidence of mesothelioma in young people and causal exposure to asbestos in the Italian national mesothelioma registry (ReNaM).

INTRODUCTION: The epidemiological surveillance of mesothelioma incidence is a crucial key for investigating the occupational and environmental sources of asbestos exposure. The median age at diagnosis is generally high, according to the long latency of the disease. The purposes of this study are to analyse the incidence of mesothelioma in young people and to evaluate the modalities of asbestos exposure. METHODS: Incident malignant mesothelioma (MM) cases in the period 1993-2018 were retrieved from Italian national mesothelioma registry and analysed for gender, incidence period, morphology and exposure. Age-standardised rates have been calculated and the multiple correspondence analysis has been performed. The association between age and asbestos exposure has been tested by χ2 test. RESULTS: From 1993 to 2018, 30 828 incident MM cases have been collected and 1278 (4.1%) presented diagnosis at early age (≤50 years). There is a substantial association between age at diagnosis and the type of asbestos exposure and a significantly lower frequency of cases with occupational exposure to asbestos (497 cases vs 701 expected) in young people has been documented. Paraoccupational and environmental exposure to asbestos have been found more frequent in young MM cases (85 and 93 observed cases vs 52 and 44 expected cases, respectively). CONCLUSIONS: Mesothelioma incidence surveillance at population level and the anamnestic individual research of asbestos exposure is a fundamental tool for monitoring asbestos exposure health effects, supporting the exposure risks prevention policies. Clusters of mesothelioma incident cases in young people are a significant signal of a potential non-occupational exposure to asbestos.

Mesothelioma Risk among Construction Workers According to Job Title: Data from the Italian Mesothelioma Register.

BACKGROUND: An increased risk of mesothelioma has been reported in various countries for construction workers. The Italian National Mesothelioma Registry, from 1993 to 2018, reported exposure exclusively in the construction sector in 2310 cases. We describe the characteristics of these cases according to job title. METHODS: We converted into 18 groups the original jobs (N=338) as reported by ISTAT codes ('ATECO 91'). The exposure level was attributed at certain, probable and possible in accordance with the qualitative classification of exposure as reported in the Registry guidelines. Descriptive analysis by jobs highlights the total number of subjects for each single job and certain exposure, in descending order, insulator, plumbing, carpenter, mechanic, bricklayer, electrician, machine operator, plasterer, building contractor, painter and labourer. RESULTS: The cases grow for plumbing in the incidence periods 1993-2018, while, as expected, it decreases for insulator. Within each period considered the most numerous cases are always among bricklayers and labourers, these data confirm the prevalence of non-specialised "interchangeable" jobs in Italian construction sector in the past. CONCLUSIONS: Despite the 1992 ban, the construction sector still presents an occupational health prevention challenge, circumstances of exposure to asbestos may still occur due to incomplete compliance with prevention and protection measures.

Rate advancement measurement for lung cancer and pleural mesothelioma in asbestos-exposed workers.

INTRODUCTION: Exposure to asbestos increases the risk of lung cancer and mesothelioma. Few studies quantified the premature occurrence of these diseases in asbestos-exposed workers. Focus on premature disease onset (rate advancement or acceleration) can be useful in risk communication and for the evaluation of exposure impact. We estimated rate advancement for total mortality, lung cancer and pleural mesothelioma deaths, by classes of cumulative asbestos exposure in a pooled cohort of asbestos cement (AC) workers in Italy. METHOD: The cohort study included 12 578 workers from 21 cohorts, with 6626 deaths in total, 858 deaths from lung cancer and 394 from pleural malignant neoplasm (MN). Rate advancement was estimated by fitting a competitive mortality Weibull model to the hazard of death over time since first exposure (TSFE). RESULT: Acceleration time (AT) was estimated at different TSFE values. The highest level of cumulative exposure compared with the lowest, for pleural MN AT was 16.9 (95% CI 14.9 to 19.2) and 33.8 (95% CI 29.8 to 38.4) years at TSFE of 20 and 40 years, respectively. For lung cancer, it was 13.3 (95% CI 12.0 to 14.7) and 26.6 (95% CI 23.9 to 29.4) years, respectively. As for total mortality, AT was 3.35 (95% CI 2.98 to 3.71) years at 20 years TSFE, and 6.70 (95% CI 5.95 to 7.41) at 40 years TSFE. CONCLUSION: The current study observed marked rate advancement after asbestos exposure for lung cancer and pleural mesothelioma, as well as for total mortality.

Asbestos Removal Acceleration for New Jobs and Fossil Fuel Use Reduction for Public Health and Climate Readiness: A Contribution to the Revival of the Italian Economy Post-COVID-19.

The Italian economy has been battered by the SARS-CoV-2/COVID-19 pandemic. European Union and Italian government economic recovery funds will provide special economic recovery loans aimed toward energy saving and the consequent reduction of greenhouse gas emissions (GHG) to meet the Paris Agreement climate goals. In, Italy, millions of square meters of asbestos cement (AC) roofing cover industrial and civic buildings. Removal of this asbestos containing material (ACM) would contribute to three pandemic and economic recovery objectives: job creation, reduction of greenhouse gasses (thru energy savings), and public health improvements. Though asbestos was used for its excellent thermal insulation properties, we provide calculations that demonstrate that the cement binding in AC roofing negates the asbestos insulation function. Therefore, replacing AC roofing with roofs made with alternative materials with better thermal transmission coefficients can contribute significantly to energy savings, reduce the risk of asbestos-related morbidity and mortality, and establish substantial economic activity.

[Mortality study in a cohort of entertainment workers]. / Studio di mortalità su una coorte di addetti al settore dello spettacolo.

SUMMARY: Introduction. Malignant mesotheliomas have been observed in entertainment workers in the last decades. They have been evaluated as occupationally exposed to asbestos contained in tools used for fireproof and sound-absorbing purposes. Aim of the study. To evaluate the mortality of workers engaged in a Florentine theatre where a large quantity of asbestos was found in the '80s, put in place 20 years earlier. Methods. It is a cohort study on entertainment workers with follow-up period ranged from 1-1-1970 till 31-12-2018. Standardized Mortality Ratios (SMRs) and their 95% Confidence Intervals (95% IC) were calculated by gender and job ("manual workers" and "all other jobs"), using age and sex specific mortality rates of Tuscan population. Results. The cohort includes 826 workers (389 manual workers and 437 engaged in other jobs) engaged by the Florentine theatre between 01/01/1937 and 31/12/1990. Excesses of mortality for all causes are observed in manual workers, either males (301 cases; SMR 304,0; 95% IC 271,5-340,3) or females (86 cases; SMR 429,8; 95% IC 348,0-531,0). The group of the other workers presents deficits of mortality by all causes, cancers and cardiovascular diseases in both genders. One death for pleural cancer is observed in a manual worker. Discussion. The results are in line with previous observations in similar occupations. In the examined Florentine theatre the asbestos exposures were important only for the manual workers who worked in the technical rooms characterized by the presence of friable asbestos sprinkled and in a bad state of maintenance.

[Inventory of occupational exposure to asbestos with particular reference to Tuscan workers]. / Repertorio delle esposizioni occupazionali ad amianto con particolare riferimento ai lavoratori toscani.

This Catalogue is a collection of information on the use of raw asbestos and asbestos-containing materials used in several industries and occupational activities, with particular attention to the situation of Tuscany, a region of Central Italy. The work was developed at the Institute for Cancer Research, Prevention and Clinical Network (ISPRO) of Florence, where epidemiologic research and surveillance activities have been developing since 1988 and where the coordination and evaluation of the regional health surveillance programme provided to past asbestos workers started in 2016 and is still ongoing. The Catalogue aims at being a working tool for all health professionals engaged in examining and classifying the occupational asbestos exposures of subjects both affected by diseases that could be associated to this carcinogen and examined within the regional health surveillance programme. It is necessary for the health personnel engaged in the above-mentioned activities to know or to have the possibility to find exact and detailed data on asbestos exposure by occupational sector. These data are briefly described in the 29 factsheets this Catalogue consists of. In each factsheet, the presence and every use of asbestos are described, with reference to a precise occupational sector. Several occupational sectors can be considered together because of analogies on asbestos exposure. Occupations are considered on the basis of existing evidence on the use of raw asbestos or asbestos-containing materials (as semi-finished or finished products or as auxiliary materials in production processes). Besides the presence and use of asbestos, a description of the possible exposures of workers is reported. Sources of information were scientific and grey literature as well as the 7,187 occupational histories of mesothelioma registered by the specific Tuscan registry. Some factsheets have been revised and enhanced by Italian experts on the asbestos exposure with a specific competence in the examined sectors. Each factsheet includes also questions to be addressed to workers in order to examine in depth their possible asbestos exposure. For those who would like to expand their knowledge on this topic, references are reported both at the end of each factsheet and at the end of the volume. In all industrialized countries, also in those which have not already banned asbestos use, a decrease in the use of this material and in the relative exposure have been observing since the end of the Seventies, few years after the general consensus within the scientific community on asbestos carcinogenicity. This decreasing trend has been becoming greater and greater since the end of the Eighties, when more restrictive regulations have been approved and applied, especially in occupational settings. Nevertheless, nowadays asbestos-related diseases are still diagnosed due to past exposures, although during next decade a decreasing incidence of malignant mesothelioma - the cancer most specifically related to this carcinogen and characterized by a very bad prognosis and the longest latency - could be observed. Particular attention will be paid to jobs regarding renovation of old buildings containing asbestos and to decontamination activities. In conclusion, this Catalogue is a working tool - although it is not exhaustive and could be upgraded with new information - for all professionals engaged in asbestos risk prevention activities as health personnel, personnel of insurance companies, employers, and employee representatives.

Is Mesothelioma Unrelated to the Lung Asbestos Burden? Comment on Visonà et al. Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples. Int. J. Environ. Res. Public Health 2021, 18, 2053.

We read with interest the report by Visonà and coworkers on the lung asbestos fiber burden in an autopsy series of decedents from mesothelioma (MM: 59 cases) and individuals who "suffered from asbestosis and died of its complications" (13 cases) [...].

[The Tuscan experience on the asbestos discharge process 28 years after the ban: critical issues and future perspectives]. / L'esperienza toscana sul processo di dismissione dell'amianto a 28 anni dal bando: criticità e prospettive future.

OBJECTIVES: to examine the progress of the remediation and disposal of asbestos containing materials (ACMs) in Tuscany Region (Central Italy), the relative workforce employed, and how these activities are framed and reflected in the Italian panorama. DESIGN: descriptive study on the asbestos removal process in Tuscany. SETTING AND PARTICIPANTS: Reports drawn up according to article No. 9 of Law No. 257/92 received by the Tuscany Region from 1993 to 2019. The on-line submission of the reports has been available since 2011. MAIN OUTCOME MEASURES: quantities and characteristics of used or removed ACMs by compact and friable matrix, the ones transferred to temporary storage and/or landfill plants during 1995-2019; number of employees engaged in activities with asbestos presence, by type and duration of activity during 2015-2019. RESULTS: from 1993 to 2019, the Tuscany Region received a total of 5,284 reports. From 1995 to 2019, a total of 423,487 tons of ACMs were removed in Tuscany, 402,897 in a compact matrix and 20,590 in a friable matrix. Over the past five years, the workers employed in these activities were on average 1,500, with around 182,000 hours per year in contact with ACMs. CONCLUSIONS: Reports article No. 9 are an essential tool to monitor and evaluate the impact of political choices to incentivize the process of ACM removal, which is still proceeding too slowly: still 3/4 of installed ACMs remain in place 28 years after the ban. Furthermore, Reports article No. 9 are a source to identify workers who are potentially exposed to lower doses than in the past; they can be included in epidemiological cohort studies as well as in health surveillance programmes of past asbestos workers, an essential assistance level of collective prevention.

Asbestos Exposure and Malignant Mesothelioma in Construction Workers-Epidemiological Remarks by the Italian National Mesothelioma Registry (ReNaM).

Notwithstanding the ban in 1992, asbestos exposure for workers in the construction sector in Italy remains a concern. The purpose of this study is to describe the characteristics of malignant mesothelioma (MM) cases recorded by the Italian registry (ReNaM) among construction workers. Incident mesothelioma cases with a definite asbestos exposure have been analyzed. Characteristics of cases and territorial clusters of crude rates of MM in construction workers have been described, as well as the relation between asbestos use before the ban and the historical trend of workforce in the construction sector in Italy. ReNaM has collected 31,572 incident MM cases in the period from 1993 to 2018 and asbestos exposure has been assessed for 24,864 (78.2%) cases. An occupational exposure has been reported for 17,191 MM cases (69.1% of subjects with a definite asbestos exposure). Among them, 3574 had worked in the construction sector, with an increasing trend from 15.8% in the 1993-98 period to 23.9% in 2014-2018 and a ubiquitous territorial distribution. The large use of asbestos in construction sector before the ban makes probability of exposure for workers a real concern still today, particularly for those working in maintenance and removal of old buildings. There is a clear need to assess, inform, and prevent asbestos exposure in this sector.

Italian pool of asbestos workers cohorts: asbestos related mortality by industrial sector and cumulative exposure.

OBJECTIVE: Italy has been a large user of asbestos and asbestos containing materials until the 1992 ban. We present a pooled cohort study on long-term mortality in exposed workers. METHODS: Pool of 43 Italian asbestos cohorts (asbestos cement, rolling stock, shipbuilding, glasswork, harbors, insulation and other industries). SMRs were computed by industrial sector for the 1970-2010 period, for the major causes, using reference rates by age, sex, region and calendar period. RESULTS: The study included 51 801 subjects (5741 women): 55.9% alive, 42.6% died (cause known for 95%) and 1.5% lost to follow-up. Asbestos exposure was estimated at the plant and period levels. Asbestos related mortality was significantly increased. All industrial sectors showed increased mortality from pleural malignancies, and most also from peritoneal and lung cancer and asbestosis, with exposure related trend. Increased mortality was also observed for ovarian cancer and for bladder cancer. DISCUSSION: The study confirmed the increased risk for cancer of the lung, ovary, pleura and peritoneum but not of the larynx and the digestive tract. A large increase in mortality from asbestosis was observed.

Reconstruction of the asbestos exposure in a textile company producing sewing threads through the use of an unusual information source.

BACKGROUND: The Tuscan Regional Operating Center (ROC) of Malignant Mesotheliomas has identified a cluster of 11 cases of malignant mesothelioma occurred in a textile plant manufacturing sewing thread. Using the common research method, the ROC had not previously been able to identify the specific sources of asbestos exposure causing such a large cluster. OBJECTIVES: The ROC's objective was to review all cases of the cluster and to better identify their occupational asbestos exposures. METHODS: The cases' occupational histories of asbestos exposure have been reviewed, using information deriving from the annual reports sent to the Tuscany Region since 1988 by all the asbestos removal companies according to the Law no. 257/1992, article 9, and from interviews to former employees of the plant. RESULTS: The work cycle has been reconstructed and enriched with the new information about the asbestos presence and its uses in the plant. The eleven cases were all reclassified as "certainly occupational exposed" given that the new collected information depicted a widespread asbestos pollution of the workplace during the period of employment of all cases. CONCLUSIONS: Using different sources of information, in addition to those traditionally collected through questionnaires, to reconstruct past asbestos exposuresallowed us to clarify the existence of the cluster of mesothelioma cases and the highest level of occupational asbestos exposure was attributed to all cases with consequent activation of the medico-legal procedure.

[About the asbestos and the Position Paper on asbestos of the Italian Society of Occupational Medicine]. / A proposito dell'amianto e del Position Paper della Società italiana di medicina del lavoro sull'amianto.

The SIML Position Paper dedicated to asbestos (PPA) is addressed (mainly) to competent practitioners (CP) for the purposes to provide a guidance about a set of items classified as markedly interesting: the actuality of asbestos exposure and the evaluation of the related risk; the diagnosis of the asbestos related diseases; the shape of the risk functions (namely about mesotheliomas); the causal relationship between exposure and disease; the medical surveillance of the workers currently and previously exposed. The scientific literature doesn't acknowledge the idea that nowadays in Italy the frequency of pleural mesotheliomas deriving from environmental asbestos from outdoor sources exposures is really a relevant item. Inside the SIML PPA the chapter concerning industrial hygiene and environmental monitoring themes shows inaccuracies and deficiencies, so resulting of scarce utility for the CPs that should be called for a more cooperative role in front of the employers. The arguments of the diagnosis of the asbestos related diseases is developed with an undue emphasis upon the differential histological diagnosis of asbestosis and, especially, of pleural mesothelioma: nosographic aspects that hardly are posed to the attention of the CP. A similar emphasis is posed towards the shape of the risk function for pleural mesothelioma, a theme absent from the current practice of the CP such as of other occupational practitioners. In conclusion, next to themes of undoubted interest for the PC, the SIML PPA dwells on the scrutiny of some topics representing critical elements of the current contrast between consultants and valuers in the context of criminal prosecutions: subjects having forensic relevance but far from the "application actuality" for the CP invoked in the PPA. A greater transparency, last but not least, was to have been posed, inside the SIML PPA, in the disclosure of the conflict of interests (COIs) of some Authors, declaring their consultancy in favour of companies.

Factors Affecting Asbestosis Mortality Among Asbestos-Cement Workers in Italy.

OBJECTIVES: This study was performed with the aim of investigating the temporal patterns and determinants associated with mortality from asbestosis among 21 cohorts of Asbestos-Cement (AC) workers who were heavily exposed to asbestos fibres. METHODS: Mortality for asbestosis was analysed for a cohort of 13 076 Italian AC workers (18.1% women). Individual cumulative asbestos exposure index was calculated by factory and period of work weighting by the different composition of asbestos used (crocidolite, amosite, and chrysotile). Two different approaches to analysis, based on Standardized Mortality Ratios (SMRs) and Age-Period-Cohort (APC) models were applied. RESULTS: Among the considered AC facilities, asbestos exposure was extremely high until the end of the 1970s and, due to the long latency, a peak of asbestosis mortality was observed after the 1990s. Mortality for asbestosis reached extremely high SMR values [SMR: males 508, 95% confidence interval (CI): 446-563; females 1027, 95% CI: 771-1336]. SMR increased steeply with the increasing values of cumulative asbestos exposure and with Time Since the First Exposure. APC analysis reported a clear age effect with a mortality peak at 75-80 years; the mortality for asbestosis increased in the last three quintiles of the cumulative exposure; calendar period did not have a significant temporal component while the cohort effect disappeared if we included in the model the cumulative exposure to asbestos. CONCLUSIONS: Among heaviest exposed workers, mortality risk for asbestosis began to increase before 50 years of age. Mortality for asbestosis was mainly determined by cumulative exposure to asbestos.

[Martinite: an alternative to asbestos insulation available since XIX Century]. / Martinite: un materiale isolante alternativo all'amianto disponibile dal XIX secolo.

New findings and technical investigations carried out on the material called Martinite have found that, already at the end of the Nineteenth century, this material, with excellent insulating properties, free from asbestos and other substances harmful to human health, was available on the national and international markets. At the beginning of the Twentieth century, Martinite was used in warships of the Italian Royal Navy and, in 1950, the Italian national naval certification body (UNAV) authorized it to be used on all ships. It also had other uses, including the construction of civil power plants. If properly advertised and distributed, Martinite could have been used all over the world in place of asbestos in different applications, avoiding the catastrophic consequences on the health of thousands of people. The product did not receive the desired commercial development, because of the small size of the company, which could not compete with the large asbestos multinationals. KEYWORDS: asbestos; Martinite; asbestos substitutes; insulation.

Martinite: An Alternative to Asbestos Insulation Available Since the Nineteenth Century.

The asbestos industry has always claimed that asbestos is a 'magic mineral', which is not replaceable. New findings, however, contradict this because asbestos-free alternatives, with excellent insulating properties, have been available since the end of the nineteenth century. The aim of this current research is to gather evidence of the potential of 'Martinite' to replace asbestos. We identified references to 'Martinite' in documents and brochures pertaining to insulation of ships, dating back as far as possible by acquiring recent interviews, utilizing records in public libraries and in archives, and conducting web searches. Martinite was produced by a small company called 'Manifatture Martiny', founded at the end of the nineteenth century in Turin, Italy. This company was specialized in insulation materials production, such as cork, rubber, foams, and even asbestos. In the early twentieth century, Martinite was utilized in warships of the Royal Italian Navy. During this time, it was patented in Italy and in many other industrialized nations. It was also utilized in construction of civilian power plants and was approved by the Architects Corporation in 1940. Furthermore, it was licenced in 1950 by the Italian National Naval Certification Body (UNAV) to be used on ships. We argue that had Martinite been properly advertised and distributed, it could have been used worldwide in place of asbestos for some applications, resulting in a lower incidence of serious and fatal diseases. The small scale of the company, compared to those of the asbestos multinationals, contributed to the lack of commercial development of the product.

Cumulative asbestos exposure and mortality from asbestos related diseases in a pooled analysis of 21 asbestos cement cohorts in Italy.

BACKGROUND: Despite the available information on cancer risk, asbestos is used in large areas in the world, mostly in the production of asbestos cement. Moreover, questions are raised regarding the shape of the dose response relation, the relation with time since exposure and the association with neoplasms in various organs. We conducted a study on the relationship between cumulative asbestos exposure and mortality from asbestos related diseases in a large Italian pool of 21 cohorts of asbestos-cement workers with protracted exposure to both chrysotile and amphibole asbestos. METHODS: The cohort included 13,076 workers, 81.9% men and 18.1% women, working in 21 Italian asbestos-cement factories, with over 40 years of observation. Exposure was estimated by plant and period, and weighted for the type of asbestos used. Data were analysed with consideration of cause of death, cumulative exposure and time since first exposure (TSFE), and by gender. SMRs were computed using reference rates by region, gender and calendar time. Poisson regression models including cubic splines were used to analyse the effect of cumulative exposure to asbestos and TSFE on mortality for asbestos-related diseases. 95% Confidence Intervals (CI) were computed according to the Poisson distribution. RESULTS: Mortality was significantly increased for 'All Causes' and 'All Malignant Neoplasm (MN)', in both genders. Considering asbestos related diseases (ARDs), statistically significant excesses were observed for MN of peritoneum (SMR: men 14.19; women 15.14), pleura (SMR: 22.35 and 48.10), lung (SMR: 1.67 and 1.67), ovary (in the highest exposure class SMR 2.45), and asbestosis (SMR: 507 and 1023). Mortality for ARDs, in particular pleural and peritoneal malignancies, lung cancer, ovarian cancer and asbestosis increased monotonically with cumulative exposure. Pleural MN mortality increased progressively in the first 40 years of TSFE, then reached a plateau, while peritoneal MN showed a continuous increase. The trend of lung cancer SMRs also showed a flattening after 40 years of TSFE. Attributable proportions for pleural, peritoneal, and lung MN were respectively 96, 93 and 40%. CONCLUSIONS: Mortality for ARDs was associated with cumulative exposure to asbestos. Risk of death from pleural MN did not increase indefinitely with TSFE but eventually reached a plateau, consistently with reports from other recent studies.

Role of asbestos clearance in explaining long-term risk of pleural and peritoneal cancer: a pooled analysis of cohort studies.

OBJECTIVES: Models based on the multistage theory of cancer predict that rates of malignant mesothelioma continuously increase with time since first exposure (TSFE) to asbestos, even after the end of external exposure. However, recent epidemiological studies suggest that mesothelioma rates level off many years after first exposure to asbestos. A gradual clearance of asbestos from the lungs has been suggested as a possible explanation for this phenomenon. We analysed long-term trends of pleural and peritoneal cancer mortality in subjects exposed to asbestos to evaluate whether such trends were consistent with the clearance hypothesis. METHODS: We used data from a pool of 43 Italian asbestos cohorts (51 801 subjects). The role of asbestos clearance was explored using the traditional mesothelioma multistage model, generalised to include a term representing elimination of fibres over time. RESULTS: Rates of pleural cancer increased until 40 years of TSFE, but remained stable thereafter. On the other hand, we observed a monotonic increase of peritoneal cancer with TSFE. The model taking into account asbestos clearance fitted the data better than the traditional one for pleural (p=0.004) but not for peritoneal (p=0.09) cancer. CONCLUSIONS: Rates of pleural cancer do not increase indefinitely after the exposure to asbestos, but eventually reach a plateau. This trend is well described by a model accounting for a gradual elimination of the asbestos fibres. These results are relevant for the prediction of future rates of mesothelioma and in asbestos litigations.