Systematic review of epidemiological studies evaluating the association between exposure to man-made vitreous fibers and non-malignant respiratory diseases

This study aimed to systematically review and synthesize epidemiological evidence evaluating the association between occupational man-made vitreous fiber (MMVF) exposure and non-malignant respiratory disease (NMRD). We searched PubMed and Scopus databases to identify epidemiological studies evaluating the association between occupational MMVF exposure (limited to insulation wools) and at least 1 NMRD outcome published prior to January 2023. A total of 23 studies met our inclusion criteria. Studies of NMRD mortality among workers with MMVF exposure (n = 9) predominately reported null findings. Qualitative and quantitative synthesis of evidence from these studies suggests that MMVF exposure is not associated with elevated risk of NMRD mortality. The remaining 14 studies evaluated NMRD morbidity, specifically self-reported respiratory symptoms and/or subclinical measures of respiratory disease. Our review did not identify any consistent or compelling evidence of an association between MMVF exposure and any NMRD morbidity outcome; however, this body of evidence was largely limited by cross-sectional design, self-reported exposure and/or outcome ascertainment, incomplete statistical analysis and reporting, and questionable generalizability given that 13/14 studies were published over 20 years ago. We recommend that future studies aim to overcome the limitations of this literature to more accurately characterize the association between occupational MMVF exposure and NMRD morbidity.

Asbestos ingestion and gastrointestinal cancer: a possible underestimated hazard

The presence of asbestos fibres (AFs) in drinking water could be linked with gastrointestinal cancers. However, it is not regulated in several countries due to conflicting evidence. Areas covered: Some reports mainly associated AF ingestion with gastric and colorectal cancer. Experimental evidence suggested a role for timing and extent of exposure, and showed that ingested AFs induce toxic effects on the stomach, ileum and colon, histological alterations and negative effects at a molecular level, cross the placenta and enter foetal organs (including the liver), and seem able to act as a co-carcinogen agent. Occupational studies suggest associations between asbestos exposure and intrahepatic cholangiocarcinoma, and observations exist indicating the possibility that AFs could enter the liver and bile through enteric absorption. Expert commentary: A risk threshold (AF concentration in drinking water) for digestive cancers has not been convincingly identified so far and regulations, where adopted, have weak scientific basis and may not be adequate. With further and more definitive studies, evidence might become sufficient to justify monitoring plans, persuade countries with no current limits to set a maximum level of AFs in drinking water and might induce a revision of the existing legislations, pointing to efficient primary prevention policies.

Malignant Mesothelioma Mortality - United States, 1999-2015

Malignant mesothelioma is a neoplasm associated with occupational and environmental inhalation exposure to asbestos* fibers and other elongate mineral particles (EMPs) (1-3). Patients have a median survival of approximately 1 year from the time of diagnosis (1). The latency period from first causative exposure to malignant mesothelioma development typically ranges from 20 to 40 years but can be as long as 71 years (2,3). Hazardous occupational exposures to asbestos fibers and other EMPs have occurred in a variety of industrial operations, including mining and milling, manufacturing, shipbuilding and repair, and construction (3). Current exposures to commercial asbestos in the United States occur predominantly during maintenance operations and remediation of older buildings containing asbestos (3,4). To update information on malignant mesothelioma mortality (5), CDC analyzed annual multiple cause-of-death records† for 1999-2015, the most recent years for which complete data are available. During 1999-2015, a total of 45,221 deaths with malignant mesothelioma mentioned on the death certificate as the underlying or contributing cause of death were reported in the United States, increasing from 2,479 deaths in 1999 to 2,597 in 2015 (in the same time period the age-adjusted death rates§ decreased from 13.96 per million in 1999 to 10.93 in 2015). Malignant mesothelioma deaths increased for persons aged ≥85 years, both sexes, persons of white, black, and Asian or Pacific Islander race, and all ethnic groups. Despite regulatory actions and the decline in use of asbestos the annual number of malignant mesothelioma deaths remains substantial. The continuing occurrence of malignant mesothelioma deaths underscores the need for maintaining measures to prevent exposure to asbestos fibers and other causative EMPs and for ongoing surveillance to monitor temporal trends.

[Possible health risks from asbestos in drinking water]

The recent finding of asbestos fibres in drinking water (up to 700.000 fibres/litres) in Tuscany (Central Italy) leads to concerns about health risks in exposed communities. Exposure to asbestos has been linked with cancer at several levels of the gastrointestinal tract, and it has been documented, in an animal model, a direct cytotoxic effect of asbestos fibres on the ileum. It has been recently described a possible link between asbestos and intrahepatic cholangiocarcinoma, and asbestos fibres have been detected in humans in histological samples from colon cancer and in gallbladder bile. Taken together, these findings suggest the possibility of an enterohepatic translocation of asbestos fibres, alternative to lymphatic translocation from lungs. In animal models, asbestos fibres ingested with drinking water act as a co-carcinogen in the presence of benzo(a) pyrene and, according to the International Agency for Research on Cancer (IARC ), there is evidence pointing to a causal effect of ingested asbestos on gastric and colorectal cancer. The risk seems to be proportional to the concentration of ingested fibres, to the extent of individual water consumption, to exposure timing, and to the possible exposure to other toxics (i.e., benzo(a)pyrene). Furthermore, the exposure to asbestos by ingestion could explain the epidemiological finding of mesothelioma in subjects certainly unexposed by inhalation. In conclusion, several findings suggest that health risks from asbestos could not exclusively derive from inhalation of fibres. Health hazards might also be present after ingestion, mainly after daily ingestion of drinking water for long periods. In Italy, a systemic assessment of the presence of asbestos fibres in drinking water is still lacking, although asbestos-coated pipelines are widely diffused and still operating. Despite the fact that the existence of a threshold level for health risks linked to the presence of asbestos in drinking water is still under debate, the precautionary principle should impose all possible efforts in order to revise health policies concerning this topic, and a systematic monitoring of drinking water to quantify the presence of asbestos is certainly needed in all regions. Further epidemiological studies aimed to the identification of exposed communities and to an adequate health risk assessment in their specific geographical areas are urgently needed.

Size- and type-specific exposure assessment of an asbestos products factory in China

This study describes fibre size and type-specific airborne asbestos exposures in an asbestos product factory. Forty-four membrane filter samples were analysed by scanning electron microscopy to determine the size distribution of asbestos fibres, by workshop. Fibre frequencies of bivariate (length by width) categories were calculated and differences between workshops were tested by analysis of variance. Data were recorded for 13,435 chrysotile and 1075 tremolite fibres. The proportions between size metrics traditionally measured and potentially biologically important size metrics were found to vary in this study from proportions reported in other cohort studies. One, common size distribution was generated for each asbestos type over the entire factory because statistically significant differences in frequency between workshops were not detected. This study provides new information on asbestos fibre size and type distributions in an asbestos factory. The extent to which biologically relevant fibre size indices were captured or overlooked between studies can potentially reconcile currently unexplained differences in asbestos-related disease (ARD) risk between cohorts. The fibre distributions presented here, when combined with similar data from other sites, will contribute to the development of quantitative models for predicting risk and our understanding of the effects of fibre characteristics in the development of ARD.

On Corporate Accountability: Lead, Asbestos, and Fossil Fuel Lawsuits

This paper examines the use of lawsuits against three industries that were eventually found to be selling products damaging to human heath and the environment: lead paint, asbestos, and fossil fuels. These industries are similar in that some companies tried to hide or distort information showing their products were harmful. Common law claims were eventually filed to hold the corporations accountable and compensate the injured. This paper considers the important role the lawsuits played in helping establish some accountability for the industries while also noting the limitations of the lawsuits. It will be argued that the lawsuits helped create pressure for government regulation of the industries' products but were less successful at securing compensation for the injured. Thus, the common law claims strengthened and supported administrative regulation and the adoption of industry alternatives more than they provided a means of legal redress.

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Abstract Exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease. However, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, and to explore possible mechanistic explanations for the difference, C57BL/6 mice were exposed intratracheally to amphibole or chrysotile asbestos, or to saline only. Serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes were evaluated 8 months after the final treatment. The percentages of lymphocyte sub-sets were determined in the spleen and lungs. The results show that amphibole, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17. Both fibers decreased IgG1, without significant changes in other immunoglobulin isotypes. Although there were no gross changes in overall percentages of T- and B-cells in the spleen or lung, there was a significant increase in the normally rare populations of suppressor B-cells (CD19(+), CD5(+), CD1d(+)) in both the spleen and lungs of chrysotile-exposed mice. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.

Do insulation products of man-made vitreous fibres still cause skin discomfort?

BACKGROUND

Man-made vitreous fibres (MMVFs) are used in products for insulation and as reinforcement in materials. Contamination of the skin may arise through direct or indirect contact, and from the deposition of airborne fibres. The scientific basis regarding the effects on skin of MMVFs dates from 1970-1980.

OBJECTIVES

To investigate whether currently used insulation MMVF products still cause skin discomfort.

METHODS

Focus group interviews and structured interviews were performed among workers engaged in insulation tasks and among do-it-yourself consumers with a recent experience of MMVF products.

RESULTS

A majority of interviewees experienced skin discomfort when handling MMVF products. Complaints caused by traditional (yellow) glass fibre products were more severe than those caused by products of rock or slag wool fibres. The wrists, forearms, neck and face were the locations where the skin was most affected. The situations causing problems varied between occupational tasks, but working with the hands over the head or in narrow spaces were described as the worst situations. Building construction apprentices performed insulation tasks more often than senior workers.

CONCLUSIONS

MMVF insulation products do still cause skin discomfort. Updated knowledge about people's experiences of work with such products should influence legislation.

Examining the association of lung cancer and highly correlated fibre size-specific asbestos exposures with a hierarchical Bayesian model

BACKGROUND

Asbestos is a known carcinogen. However, little is known about the differential effects of size-specific asbestos fibres. Previous research has examined the relationship with lung cancer of each fibre group in the absence of others. Attempts to model all fibre groups within a single regression model have failed due to high correlations across fibre size groups.

METHODS

We compare results from frequentist models for individual fibre size groups, and a hierarchical Bayesian model that included all fibre groups to estimate the relationship of size-specific asbestos fibre groups to lung cancer mortality. The hierarchical model assumes partial exchangeability of the effects of size-specific asbestos fibre groups to lung cancer, and is capable of handling the strong correlation of the exposure data.

RESULTS

When fibre groups are modelled independently with a frequentist model, there appears to be an increase in the dose-response with increasing fibre size. However, when subject to a hierarchical structure, this trend vanishes, and the effects of distinct fibre groups appear largely similar.

CONCLUSIONS

This is the first occasion where distinct asbestos fibre groups have been assessed in a single regression model; however, even the use of a hierarchical modelling structure does not appear to overcome all the statistical fluctuations arising from the high correlations across fibre groups. We believe these results should be compared with other occupational cohorts with similar fibre group information. Finally, results for the smallest fibre group may be suggestive of a carcinogenic potential for nanofibres.

[Levels of exposure to respirable fibres at worksites for abatement of compact and friable asbestos]

BACKGROUND

Starting from a project aimed at assessing the carcinogenic risk in some industrial sectors covered by Local Health Authority No.1 (LHA) in Perugia (USL Umbria1, Italian acronym), worksites for abatement of materials containing asbestos (MCA) were examined in order to estimate respirable fibres exposure levels in workers. Abatement work is, indeed, a fast developing sector, but is not free from asbestos risks in the long-term, particularly carcinogenic risks; this kind of work therefore requires maximum effort in respecting prevention standards prescribed in the relative legislation.

OBJECTIVES

The aim of the research was to define the personal levels of exposure to respirable fibres and to create a reliable database for the interpretation of possible asbestos-related cases of neoplasms that may occur in the future in workers of this important occupational sector.

METHODS

The authors took in consideration operations both on compact MCA and on friable MCA. In the case of compact MCA, exposure values measured by the LHA via their own sampling were compared to those measured by the companies involved in the project. In the case of friable MCA, however, sampling was only performed by the LHA and the assessment covered not only workers' exposure levels but also the pollution levels in the areas in the vicinity of the work site.

RESULTS

In the case of compact MCA, results showed moderate average values of personal fibre exposure, and always considerably lower than the limit values (100 fibres/litre) prescribed by law (Legislative Decree 81/08); however, the average values detected by the LHA (15,8 fibres/litre) were significantly higher (p < 0.001) than those detected by companies (4,9 fibres/litre). In the case of friable MCA, however, average personal exposure values of workers (106,8 fibres/litre) were even higher than the limit values prescribed by current regulations, while in areas near the work sites, average fibre pollution levels (1,04 fibres/litre) were always very low and lacked significant variations (p > 0.05) during the different phases of work.

CONCLUSIONS

According to the authors, the data collected show how in MCA abatement operations a carcinogenic risk in the long-term is in any case present, and this both in compact MCA work, where not all the prevention measures were accurately observed, and even more so, in friable MCA work, where average exposure levels of workers showed a heavy trend to exceed the above mentioned limit values. Considering the different evolution of the results of sampling carried out by the LHA and by the companies, the authors also highlight the need to provide mandatory technical guidelines for industrial hygiene laboratories so that sampling and analysis methods are as homogeneous as possible, thus making the results of research easily comparable.

[Pleural lymphatics and pleural diseases related to fibres]

It is now well established that some pleural diseases, pleural plaques and malignant mesothelioma are related to asbestos fibre exposure although the mechanism of action of asbestos fibres is not fully understood. The development of artificial mineral fibres and carbon nanotubes, which share some morphological characteristics similar to asbestos fibres, is a present concern in the context of pleural diseases. Pleural plaques develop only in the parietal pleura, and in the 1990s, clinical observations have shown that the early development of mesothelioma also occurred on the parietal pleura. The peculiarity of the parietal pleura in contrast to the visceral pleura is the presence of "stomas" which are communication holes between the pleural cavity and the parietal pleura lymphatics. Morphological observations by thoracoscopy and experimental studies have shown that inhaled fibres translocate to the pleural space and, in human, are present in the parietal pleura at specific anthracotic areas (blackspots). Fibres accumulate on the stomas, up to block and locally induce an inflammatory reaction with cytokines release, that can be the bed of mesothelioma. However, despite the experimental data and observations in human pathology, the mechanisms of fibre translocation into the pleura is not yet clearly established.

Iron overload as a major targetable pathogenesis of asbestos-induced mesothelial carcinogenesis

Few people expected that asbestos, a fibrous mineral, would be carcinogenic to humans. In fact, asbestos is a definite carcinogen in humans, causing a rare but aggressive cancer called malignant mesothelioma (MM). Mesothelial cells line the three somatic cavities and thus do not face the outer surface, but reduce the friction among numerous moving organs. MM has several characteristics: extremely long incubation period of 30-40 years after asbestos exposure, difficulty in clinical diagnosis at an early stage, and poor prognosis even under the current multimodal therapies. In Japan, 'Kubota shock' attracted considerable social attention in 2005 for asbestos-induced mesothelioma and, thereafter, the government enacted a law to provide the people suffering from MM a financial allowance. Several lines of recent evidence suggest that the major pathology associated with asbestos-induced MM is local iron overload, associated with asbestos exposure. Preclinical studies to prevent MM after asbestos exposure with iron reduction are in progress. In addition, novel target genes in mesothelial carcinogenesis have been discovered with recently recognized mesothelioma-prone families. Development of an effective preventive strategy is eagerly anticipated because of the long incubation period for MM.

Short, fine and WHO asbestos fibers in the lungs of quebec workers with an asbestos-related disease

BACKGROUND

The possible role of short asbestos fibers in the development of asbestos-related diseases and availability of lung fiber burden data prompted this study on the relationships between fiber characteristics and asbestos-related diseases among compensated workers.

METHODS

Data collected between 1988 and 2007 for compensation purposes were used; lung asbestos fibers content of 123 Quebec workers are described according to socio-demographic characteristics, job histories and diseases (asbestosis, mesothelioma, lung cancer).

RESULTS

Most workers (85%) presented chrysotile fibers in their lungs, and respectively 76%, 64%, and 43% had tremolite, amosite, and crocidolite. Half of the total fibers were short, 30% were thin fibers and 20% corresponded to the World Health Organization definition of fibers (length ≥ 5 μm, diameter ≥ 0.2 and <3 μm). Chrysotile fibers were still observed in the lungs of workers 30 years or more after last exposure.

CONCLUSION

Our findings stress the relevance of considering several dimensional criteria to characterize health risks associated with asbestos inhalation.

The Diagnosis and Attribution of Asbestos-related Diseases in an Australian Context: Report of the Adelaide Workshop on Asbestos-related Diseases. October 6–7, 2000

Predictions of future cases of mesothelioma in Australia to the year 2020 are in the order of a total of 10,000 new cases. Compensation claims are testing the attribution in a particular case between occupational asbestos exposure and lung cancer. The cost of the problem necessitates clarifying and standardizing the criteria for a confident diagnosis of asbestos-related disease. The possibility of differences in criteria that determine attribution of asbestos to a disease prompted a consensus meeting of pathologists, epidemiologists, physicians, oncologists, radiologists, and others to define current thinking and to agree on an Australian document based on the scientific evidence for establishing diagnoses and attribution data of asbestos-related diseases in Australia. The participants' findings are reported.

Analysis of occupational asbestos exposure and lung cancer mortality using the g formula

We employed the parametric G formula to analyze lung cancer mortality in a cohort of textile manufacturing workers who were occupationally exposed to asbestos in South Carolina. A total of 3,002 adults with a median age of 24 years at enrollment (58% male, 81% Caucasian) were followed for 117,471 person-years between 1940 and 2001, and 195 lung cancer deaths were observed. Chrysotile asbestos exposure was measured in fiber-years per milliliter of air, and annual occupational exposures were estimated on the basis of detailed work histories. Sixteen percent of person-years involved exposure to asbestos, with a median exposure of 3.30 fiber-years/mL among those exposed. Lung cancer mortality by age 90 years under the observed asbestos exposure was 9.44%. In comparison with observed asbestos exposure, if the facility had operated under the current Occupational Safety and Health Administration asbestos exposure standard of <0.1 fibers/mL, we estimate that the cohort would have experienced 24% less lung cancer mortality by age 90 years (mortality ratio = 0.76, 95% confidence interval: 0.62, 0.94). A further reduction in asbestos exposure to a standard of <0.05 fibers/mL was estimated to have resulted in a minimal additional reduction in lung cancer mortality by age 90 years (mortality ratio = 0.75, 95% confidence interval: 0.61, 0.92).

Asbestos-related diseases in Thailand and review literature

Asbestos is a harmful substance that can cause both malignancy and non-malignancy in humans. Although it has been used in Thailand for several years, few cases of asbestos-related diseases were reported. Concerning about high consumption and long exposure of asbestos in the country, the incurable but preventable diseases caused by asbestos will be the health problem in the near future. The authors presented 2 cases with asbestos-related diseases, one diagnosed as malignant mesothelioma and the other as asbestosis.

[Mortality results in SENTIERI Project]

SENTIERI Project (Mortality study of residents in Italian polluted sites) studies mortality of residents in 44 sites of national interest for environmental remediation (Italian polluted sites, IPS). The epidemiological evidence of the causal association between causes of death and exposures was a priori classified into one of these three categories: Sufficient (S), Limited (L) and Inadequate (I). In these sites various environmental exposures are present. Asbestos (or asbestiform fibres as in Biancavilla) has been the motivation for defining six sites as IPSs (Balangero, Emarese, Casale Monferrato, Broni, Bari-Fibronit, Biancavilla). In five of these, increases in malignant neoplasm or pleura mortality are detected; in four of them, results are consistent in both genders. In six other sites (Pitelli, Massa Carrara, Aree del Litorale Vesuviano, Tito, "Aree industriali della Val Basento", Priolo), where other sources of environmental pollution in addition to asbestos are reported, mortality from malignant neoplasm of pleura is increased in both genders in Pitelli, Massa Carrara, Priolo, "Litorale vesuviano". In the time span 1995-2002, a total of 416 extra cases of malignant neoplasm of pleura are detected in the twelve asbestos-polluted sites. Asbestos and pleural neoplasm represent an unique case. Unlike mesothelioma, most causes of death analyzed in SENTIERI have multifactorial etiology; furthermore, in most IPSs multiple sources of different pollutants are present, sometimes concurrently with air pollution from urban areas: in these cases, drawing conclusions on the association between environmental exposures and specific health outcomes might be complicated. Notwithstanding these difficulties, in a number of cases an etiological role could be attributed to some environmental exposures. The attribution could be possible on the basis of increases observed in both genders and in different age classes, and the exclusion of a major role of occupational exposures was thus allowed. For example, a role of emissions from refineries and petrochemical plants was hypothesized for the observed increases in mortality from lung cancer and respiratory diseases in Gela and Porto Torres; a role of emissions from metal industries was suggested to explain increased mortality from respiratory diseases in Taranto and in Sulcis-Iglesiente-Guspinese. An etiological role of air pollution in the raise in congenital anomalies and perinatal disorders was suggested in Falconara Marittima, Massa-Carrara, Milazzo and Porto Torres. A causal role of heavy metals, PAH's and halogenated compounds was suspected for mortality from renal failure in Massa Carrara, Piombino, Orbetello, "Basso bacino del fiume Chienti" and Sulcis-Iglesiente-Guspinese. In Trento-Nord, Grado and Marano, and "Basso bacino del fiume Chienti" increases in neurological diseases, for which an etiological role of lead, mercury and organohalogenated solvents is possible, were reported. The increase for non-Hodgkin lymphomas in Brescia was associated with the widespread PCB pollution. Mortality for causes of death with a priori Sufficient or Limited evidence of association with the environmental exposure exceeds the expected figures, with a SMR of 115.8% for men (90% IC 114.4-117.2; 2 439 extra deaths) and 114.4% for women (90% CI 112.4-116.5; 1 069 extra deaths). These excesses are also observed when analysis is extended to all the causes of death (i.e. with no restriction to the ones with a priori Sufficient or Limited evidence): for a total of 403 692 deaths (both men and women), an excess of 9 969 deaths is observed, with an average of about 1 200 extra deaths per year. Most of these excesses are observed in IPSs located in Southern and Central Italy. The procedures and results of the evidence evaluation are presented in a 2010 Supplement of Epidemiology & Prevention devoted to SENTIERI.

[Health impact of indoor mineral particle pollution]

Mineral particle air pollution consists of both atmospheric pollution and indoor pollution. Indoor pollution comes from household products, cosmetics, combustion used to heat homes or cook food, smoking, hobbies or odd jobs. There is strong evidence that acute respiratory infections in children and chronic obstructive pulmonary disease in women are associated with indoor biomass smoke. Detailed questioning is essential to identify at risk activities and sampling of airborne particles may help with the identification of pollution risks. Particle elimination depends on the standard of ventilation of the indoor environment. Five per cent of French homes have levels of pollution greater than 180 μg/m³ for PM 10 and 2% for PM 2.5. The principal mineral particle air pollutants are probably silica, talc, asbestos and carbon, whereas tobacco smoke leads to exposure to various ultrafine particles. The toxicity of these particles could be more related to surface exchange than to density. Tissue measurements by electron microscopy and microanalysis of particle samples may identify an uptake of particles similar to those in the environmental sample.

Mesothelioma and asbestos, fifty years of evidence: Chris Wagner and the contribution of the Italian occupational medicine community

BACKGROUND

One of the first studies that "convincingly" described the relationship between pleural mesothelioma and asbestos was made by Wagner, Sleggs and Marchard in 1960. This article, published fifty years ago, contains much of what we still know to-day about malignant mesothelioma.

OBJECTIVES

The aims of this article were to analyze the historical and scientific developments that led to the publication of Wagner's paper, to critically examine its contents and to consider the contribution to the initernational debate on the carcinogenesis of asbestos fibres made by occupational medicine in Italy in that period.

METHODS

A thorough analysis ofscientific and historical literature on the relationship between asbestos exposure and tumours was conducted, with special regard to the articles by Italian authors in the 1960's.

RESULTS

The decisive role of Wagner's paper in understanding the aetiopathogenetic mechanisms of asbestos-related tumours is inconfutable. In particular, his article clearly demonstrated the existence of a typical cancer of the mesothelium, expressing three fundamental principles of the epidemiology of occupational cancer: association with the carcinogen, latency and individual susceptibility. Enrico Vigliani, then director of the "Clinica del Lavoro" in Milan, made important contributions to this debate, also through the collection of data regarding mortality among Italian asbestos workers.

CONCLUSIONS

Wagner's 1960 paper can be considered as a milestone not only in the history of occupational and environmental health, but also in the evolution of other medical disciplines such as epidemiology, pathology and oncology. A re-appraisal of the Italian contributions to the international debate on this subject should be considered.

Asbestos-related diseases in entertainment workers

OBJECTIVES

To investigate asbestos exposure in 4 patients (3 cases of malignant mesothelioma and 1 case ofpleural plagues) previously employed in the entertainment business.

METHODS

The patients were seen at the Occupational Health Unit of the "Clinica del Lavoro Luigi Devoto" in Milan (Italy). Information regarding exposure to asbestos (occupational, environmental, and familial) was collected through a standardized questionnaire administered to the patients by an occupational physician.

RESULTS AND CONCLUSION

The presence of asbestos in the building structures and its use were described by all patients. The presence of asbestos in public buildings used for entertainment such as cinemas and theatres was in fact confirmed by the Occupational Health Services of the Local Heath Unit. An occupational aetiology was recognised in all the cases mentioned above, thus leading to the identification of an atypical occupational sector at risk in the past for asbestos exposure,

Safety evaluation of rock wool after nasal inhalation in rats

Asbestos is reported to cause pulmonary fibrosis, and its use has been banned. We examined the biopersistence and histopathological effect of rock wool (RW) fibers in rat lungs by a nose-only inhalation exposure study. Twenty-four rats were exposed to RW fibers for 6 h daily for 5 consecutive days. Six rats each were sacrificed shortly and 1, 2, and 4 wk after exposure, and the fiber numbers and sizes in lungs were determined. The fiber number in the lungs 4 wk after exposure significantly decreased. The clearance half time was 28 d for fibers with L>20 μm and 50 d for World Health Organization fibers. The reasons for the decrease in number and size of fibers include: 1) discharge outside of the body by mucociliary movement, 2) dissolution by body fluid, and 3) phagocytosis and digestion by alveolar macrophages. Twelve rats were used for histopathological examination, and the pathological changes were classified by Wagner's criteria. As a result, changes up to only Grade 2 were observed. The reason for the increase in macrophage number was considered to be a transient reaction of body defense. These results suggest that RW has low biopersistence and only a limited pathological effect.

[Asbestos fibre lung burden and exposure indices in asbestos-cement workers]

BACKGROUND

In many previous studies, the asbestos fibres retained in the lung were regarded as a good index of cumulative occupational asbestos exposure. Twelve workers suffering from asbestos-related diseases and had been employed in an asbestos-cement factory operating from 1961 to 1994 underwent post mortem investigations in the course of a criminal law suit.

OBJECTIVES

Samples of lung tissues were collected for electron microscopy analysis to measure the asbestos fibre burden of the lungs in workers with high exposure, and assess the possible correlation between asbestos fibre lung burden and the estimated levels of cumulative exposure.

METHODS

Samples of lung parenchyma obtained from a consecutive series of 12 post-mortem examinations that were performed between 1994 and 2007and included 5 cases of malignant pleural mesothelioma, 4 lung cancers, 1 case of asbestosis and2 ofpleuralplagues, were collected, stored and analysed by SEM electron microscopy, according to the methods suggested by the current scientific literature. For each worker, all males, a detailed occupational history was reconstructed by means ofpersonal interviews; both the measurements of airborne asbestos fibresperformed by the factory in the 1970's and the duration of each single job in the plant were taken into account to estimate an individual cumulative exposure index.

RESULTS

A wide variation of total asbestos fibre concentrations in the lung (1,320-118 million) was observed; in all 12 workers, the lung amphibole fibre burden exceeded 1,000,000 fibres per g/dry tissue, The highest values were detected in the mesothelioma cases, in which the mean fibre concentrations differed statistically (t=2.29, p=0.045) from the mean calculated for the other asbestos-related diseases; in 9 subjects only amphibole fibres were detected. There was a good correlation between total asbestos fibre concentration and cumulative exposure index (r=0.91, p<0.0001).

CONCLUSION

This study, which was numerically the biggest ever performed in Italy for this category of workers, confirms a wide range of total asbestos fibre burden in heavily occupationally exposed workers and showed that of the asbestos-related diseases, the highest lung concentrations of asbestos fibres were reached in cases of mesothelioma. It was also observed that almost the entire lung burden consists of only amphibole fibres, all exceeding 1 million per gramme of dry tissue. This study tested a synthetic cumulative occupational exposure index, which appears to be well correlated to the level of exposure established by biological analysis.

[Size distribution of amphibole fibres from lung and pleural tissues sampled from mesothelioma cases due to environmental exposure]

BACKGROUND

It has been suggested that malignant mesothelioma might be mainly or only connected with the action of short and ultrathin fibres. On the basis of this hypothesis fibres less than 5 microm long and 0.2-0.1 microm thick would enter the pulmonary-pleura barrier and reach the parietal pleura thus inducing mesothelioma. The hypothesis raised a stimulating scientific discussion.

OBJECTIVES

The aim of this communication is to report the initial results obtained comparing the size of amphibole fibres from healthy lung tissue with those from pleural tissue sampled from subjects whose death cause of death was mesothelioma.

METHODS

Four mesothelioma cases due to environmental exposure were studied; the fibres were categorized by scanning electron microscopy; for every fibre, length and diameter were measured and the mineral type was defined by its chemical composition determined by X-ray microanalysis.

RESULTS

The most important characteristics of the detected fibres were: the average length offibres from the lung and pleural tissues taken from the same subject did not difer, in all cases, by more than 10-12%; 95% offibres found in the lung tissues of all subjects had a length greater than 5 microm; 98% of fibres found in the pleural tissues had a length greater than 5 microm; the average diameter of the fibres found in the pleural tissues was 70% of the diameter of the fibres from the lung tissues.

CONCLUSIONS

The experimental data obtained in this study confirm the correlation between malignant mesothelioma and the presence in the lung and pleural tissues of fibres with a length greater, even much greater, than 4-5 microm; thus the hypothesis that the chief factors inducing mesothelioma are the "ultrashort" and "ultrathin" fibres appears rather weak.

Presence of airborne fibers in tungsten refining and manufacturing processes: preliminary characterization

In tungsten refining and manufacturing processes, a series of tungsten oxides (WO(X)) are typically formed as intermediates in the production of tungsten powder. Studies in the Swedish tungsten refining and manufacturing industry have shown that intermediate tungsten refining processes can create WO(X) fibers. The purpose of the present study was to identify and provide a preliminary characterization of airborne tungsten-containing fiber dimensions, elemental composition, and concentrations in the U.S. tungsten refining and manufacturing industry. To provide the preliminary characterization, 10 static air samples were collected during the course of normal employee work activities and analyzed using standard fiber sampling and counting methods. Results from transmission electron microscopy analyses conducted indicate that airborne fibers with length > 0.5 microm, diameter > 0.01 microm, and aspect ratio > or = 3:1, with a geometric mean (GM) length of approximately 2.0 microm and GM diameter of approximately 0.25 microm, were present on 9 of the 10 air samples collected. Energy dispersive X-ray spectrometry results indicate that airborne fibers prior to the carburization process consisted primarily of tungsten and oxygen, with other elements being detected in trace quantities. Results from an air sample collected at the carburization process indicated the presence of fibers composed primarily of tungsten with oxygen and carbon, and traces of other elements. Based on National Institute for Occupational Safety and Health standard fiber counting rules, airborne fiber concentrations ranged from below the limit of detection to 0.14 f/cm(3). The calcining process was associated with the highest airborne fiber concentrations. More than 99% (574/578) of the airborne fibers identified had an aerodynamic diameter <or =10 microm, indicating that they were capable of reaching the thoracic regions. Until more is known about the durability and potential health effects associated with airborne tungsten-containing fibers, it would be prudent to take steps to limit or eliminate occupational exposures.

South African experience with asbestos related environmental mesothelioma: is asbestos fiber type important?

South Africa (SA), a country in which all three commercially important asbestos minerals have been mined and milled, has retained proven cases of mesothelioma linked with environmental exposure to asbestos. This study illustrates the importance of fiber type in the occurrence of environmental mesothelioma. Four studies have reviewed the source of occupational or environmental asbestos exposure in 504 histologically proven cases of mesothelioma in South Africa. One hundred and eighteen cases (23%) were thought to be related to environmental exposure to asbestos. In the vast majority of these cases, exposure was linked to crocidolite mining activities in the Northern Cape Province. Two cases were thought to have occurred in relation to amosite and Transvaal crocidolite exposure in the Limpopo Province. In the balance of cases there was some uncertainty. No cases were reported with exposure to South African chrysotile. Consequently, in the vast majority of cases of mesothelioma, environmental exposure to asbestos occurred in the Northern Cape Province, in proximity to mines, mills and dumps where crocidolite was processed. Crocidolite appears to be far more mesotheliomagenic than amosite, and chrysotile has not been implicated in the disease. This is true for both occupationally and environmentally exposed individuals.

[Histopathological diagnosis of pneumoconiosis]

Asbestos-related diseases constitute a major health problem due to the great number of workers exposed to asbestos over the past 50 years. Personal injury lawsuits against industries that deal with asbestos number in the hundreds, and new cases continue to be filed. The scientific issues related to asbestos are complex, and, although the broad outlines of asbestos-related diseases have been well-established, many significant aspects (such as the pathology involved) are poorly understood. In Brazil, asbestos has been mined commercially since 1940, with production levels recently approaching 200,000 tons/year, resulting in the asbestos exposure of approximately 10,000 workers in the mining activity, and an unknown number of workers in asbestos-cement industry, primarily roofers and concrete rooftop water tank installers. One study, using appropriate methods of scientific investigation to evaluate the effects of such exposure on the health of asbestos mine workers in Brazil was conducted as part of a multicenter study and entitled "Morbidity and Mortality Among Workers Exposed to Asbestos in Mining Activities, 1940-1996". Drawing upon the experience acquired during the course of that study, the objective of the current report was to give an overview of asbestos-related diseases, with a special focus on the difficulties involved in establishing the histopathological diagnosis.

Non-occupational malignant pleural mesothelioma due to asbestos and non-asbestos fibres

BACKGROUND AND AIM

The occurrence of malignant pleural mesothelioma (MPM) has been reported among population groups with no documented professional exposure to asbestos fibres living in different geographic areas. This paper reviews existing data related to non occupational MPM including its occurrence in the province of Catania (Sicily, Italy).

METHODS

An electronic search of literature related to non occupational MPM was performed including the year 2005.

RESULTS

Non occupational MPM in subjects living in areas contaminated by a variety of asbestos and non asbestos fibres has been well documented through a number of epidemiologic studies including cases series, case-control studies, and a cohort study. In addition, the observation of familial clustering of MPM, suggests that genetic factors may play a role in the pathogenesis of this malignancy. The epidemiological evidence also suggests that MPM may occur as a result of the interaction between environmental carcinogens, genetic factors, and virus infection.

CONCLUSION

It is likely that genetic predisposition and non-occupational exposure to low doses of asbestos and asbestos-like fibres may concur to the development of malignant mesothelioma. However, additional epidemiological and laboratory studies are needed to further understand the relationship between environmental exposure and individual susceptibility to this malignancy.

Changes in workplace concentrations of airborne respirable fibres in the European ceramic fibre industry 1987 1996

As part of a wider epidemiological research programme, an occupational hygiene study was carried out during 1995-1996 to assess workers' current exposures to airborne materials in six European refractory ceramic fibre (RCF) plants. These plants had also participated in a cross-sectional occupational hygiene survey in 1987. The sampling strategy focussed principally on personal shift-average exposures of workers, by occupation, to respirable fibres. Monitoring was undertaken in two integrated phases: a 1-week cross-sectional survey followed by a prospective, and ongoing, programme by the RCF industry. Statistical (analysis of variance) analyses to identify patterns of variability by plant, occupational group (OG) and occupations within group were based on 464 individual shift samples, the greatest amount of data being available for production occupations. Concentrations of respirable fibres showed marked differences between plants and between OGs. Average respirable fibre concentrations among Primary and Secondary Production and Ancillary workers ranged from <0.1 f ml(-1) to up to 0.4 f ml(-1), depending on OG and plant. Individual shift-average measurements were almost invariably <1 f ml(-1). Within Secondary Conversion and Finishing, plant-specific averages ranged from 0.3 f ml(-1) to 1.25 f ml(-1). Respirable fibre concentrations were, in some plants, less than half those found in 1987. In other plants, mainly those where concentrations had been relatively low in 1987, the dust exposure had remained essentially unchanged or increased slightly. An ongoing programme of sampling is being carried out by the participating companies, generating additional information that could assist research in the long term and in improving control.

[Mesothelioma incidence decreases parallel to asbestos exposure decrement or interruption: a confirmation of a dose-response relationship, with implications in public health]

On the basis of the available evidence, several groups of experts and investigators identified a dose-response relationship between exposure to commercial types of asbestos fibres and mesothelioma risk. The first mathematical model was proposed by Peto et al. It was derived from a conceptualisation of the multistage theory of cancer and provides an interpretation of the risk for the occurrence of mesothelioma in cohorts of exposed workers. In the study described in this paper, the author reviewed the data suggesting a decrease in mesotheliomas rate follosing reduction or interruption of exposure. Descriptive analyses and the few available long-term cohort studies indicate a decrease in risk. This is supported also by the fact that even the most biopersistent asbestos fibres are eliminated from the lungs. Indeed, a slow but effective reduction of risk has been demonstrated in the cohort of Wittenoom workers in Australia, previously exposed to crocidolite.

[Mortality from pleural and peritoneal cancer in a cohort of asbestos workers, many years after start of the exposure: possible role of fibers clearance]

The multistage theory of carcinogenesis assumes rates of mesothelioma increasing monotonically as a function of time since first exposure (TSFE) to asbestos. However, some authors have suggested that the increase in mesothelioma rate with TSFE might be attenuated by clearance of asbestos from the lungs. We estimated mortality time trends from pleural and peritoneal cancer in a cohort of 3443 asbestos-cement workers. The role of asbestos clearance was explored using the traditional mesothelioma multistage model, generalized to include a term representing elimination over time. We observed 139 deaths from pleural and 56 from peritoneal cancer during the period 1950-2003. The rate of pleural cancer increased during the first 40 years of TSFE and reached a plateau thereafter. In contrast, the rate of peritoneal cancer increased monotonically with TSFE. The model allowing for asbestos elimination fitted the data better than the traditional model for pleural (p = 0.02) but not for peritoneal cancer (p = 0.22). The risk for pleural cancer, rather than showing an indefinite increase, might reach a plateau when a sufficiently long time has elapsed since exposure. The different trends for pleural and peritoneal cancer might be related to clearance of the asbestos from the workers' lungs.

[Malignant mesothelioma of the pleura in a truck driver]

BACKGROUND

Among the responsibilities of the health operators in the occupational health and safety services of the local health units in Lombardy (Italy) is the administration of standardized questionnaires for the investigation of possible occupational exposure to asbestos fibres in subjects diagnosed with malignant mesothelioma.

OBJECTIVES

To describe a case of malignant mesothelioma in a truck driver suspected of being occupationally exposed to asbestos during the course of administration of the questionnaire.

METHODS

Analysis of the literature regarding asbestos contamination of truck cabs. Some years ago Italian authors described a case of asbestosis in a truck-driver and findings of pollution by asbestos fibres in the cabs of some models of trucks.

RESULTS

The subject had worked for more than 30 years as a truck driver operating on long distances on truck models described in literature as contaminated by asbestos fibres. He had not transported materials made of asbestos, and had not carried out maintenance on the trucks, nor had he any non-occupational sources of exposure to asbestos. Thus the mesothelioma was related to occupational exposure and procedures were initiated for reporting a suspected occupational disease.

Pleuroparenchymal lung disease secondary to nonoccupational exposure to vermiculite

An unusual case of pleuroparenchymal lung disease caused by the inhalation of vermiculite dust, presumably containing asbestos fibers is described. The uniqueness of the case lies in the very indirect nature of exposure -- the wife of a factory owner, rather than a worker exposed to asbestos, whose factory manufactured vermiculite. The present case illustrates the importance of taking careful occupational histories of all household members when presented with a patient whose chest radiograph exhibits features consistent with asbestos exposure.

Behavior of rock wool in rat lungs after exposure by nasal inhalation

To evaluate the safety of rock wool (RW) fibers, we examined the biopersistence of RW fibers in the lungs of rats, based on the changes of fiber number and fiber size in the length and width, in a nose-only inhalation exposure study. Twenty male Fischer 344 rats (6 to 10 wk old) were exposed to RW fibers at a fiber concentration of 70.6 (20.4) fiber/m(3) and a dispersion density of 30.4 (6.6) mg/m(3) [arithmetic mean (SD)] continuously for 3 h daily for 5 consecutive days. Five rats each were sacrificed shortly after exposure ended (baseline group) and at 1, 2, and 4 wk after exposure, and their lung tissues were ashed by a low temperature plasma-asher. The numbers and sizes of fibers in the ash samples were determined using a phase contrast microscope and a computed image analyzer. The fiber numbers in the lungs at 4 wk after exposure had significantly decreased from the baseline value, i. e. shortly after exposure (p<0.05). The half-lives of RW fibers calculated using the one-compartment model were 32 d for total fibers and 10 d for fibers longer than 20 microm in length. Fiber number was 53.6% of the baseline at 4 wk after exposure (baseline group=100%). Likewise, fiber sizes had significantly decreased at 4 wk after exposure (p<0.05), probably because fibers had been dissolved in body fluid, phagocytosed by alveolar macrophages or discharged from the body by mucociliary movement. In future studies, it will be necessary to examine the carcinogenicity of RW fibers through long-term inhalation studies.

Beyond foreign-body-induced carcinogenesis: Impact of reactive oxygen species derived from inflammatory cells in tumorigenic conversion and tumor progression

Foreign-body-induced carcinogenesis is a traditional, maybe old, way of understanding cancer development. A number of novel approaches are available today to elucidate cancer development. However, there are things we learn from the old, and thus I bring out some examples of various clinical cases and experimental models of foreign-body-induced tumorigenesis. What is notable is that the foreign bodies themselves are unrelated to each other, whereas commonly underlying in them is to induce inflammatory reaction, especially stromal proliferation, where those exogenous materials are incorporated and undigested. Such foreign-body-induced carcinogenesis is also recognized in the step of tumor progression, the final step of carcinogenesis that tumor cells acquire malignant phenotypes including metastatic properties. And the phenomenon is universally observed in several cell lines of different origins. In this review I would like to show the evidence that tumor development and progression are accelerated inevitably by inflammation caused from foreign bodies, and that reactive oxygen species derived from inflammatory cells are one of the most important genotoxic mediators to accelerate the process.

[Asbestos fibre dimensions and mesothelioma]

The critical considerations formulated by Tomatis et al. did not take into account all the experimental works and all the research on human pleura that from the Seventies on has unanimously indicated that asbestos fibre mesothelioma is caused by the ultrafine fibres class. These fibres that are so fine are not visible with light microscopy are mostly ultrashort, but they also include, in varying percentages, elements that are >5 microm long. The conclusions of Tomatis et al, which attribute mesothelioma to fibres of all lengths and diameters, are not confirmed in the literature. Today, mesothelioma prevention must consist of identifying and cutting down airborne ultrafine fibres, above all in urban environments. The techniques for doing so now exist and can be applied. The ultrafine class of asbestos, forgotten for decades, must be the principal target for prevention programs and must be widely monitored in work and daily life settings.

Mechanism of fiber carcinogenesis: from reactive radical species to silencing of the beta igH3 gene

Although the U.S. Environmental Protection Agency has restricted the industrial use of regulated forms of asbestos in the United States since the early 1970s, environmental exposure to asbestos remains a health concern in the United States and is a significant health issue among developing countries. Exposure to asbestos is associated with chronic pulmonary diseases and cancer of the lung, pleura, and peritoneum. The mechanism of fiber carcinogenesis is far from clear and is likely to be complex, depending on fiber dimensions, surface properties, and physical durability. The induction of reactive oxygen and nitrogen species upon phagocytosis of fibers plays an important role in fiber genotoxicity. The beta igH3, a secreted protein induced by the transforming growth factor-beta and essential for cell adhesion, is downregulated in asbestos-induced tumorigenic human bronchial epithelial cells. Ectopic expression of the beta igH3 gene abrogates the tumorigenic phenotype and suggests that the gene plays a causal role in fiber carcinogenesis. A better understanding of the carcinogenic mechanism of asbestos and other mineral fibers will provide useful information on interventional and preventive measures for asbestos-mediated diseases such as human pleural and peritoneal mesotheliomas.

Health consequences of the September 11 World Trade Center attacks: a review

In the aftermath of the September 11 World Trade Center (WTC) attack, a large number of people sustained potential exposures to smoke, dust, particulate matter, and a variety of toxins, including asbestos, pulverized concrete, glass fibers, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated furans and dioxins. Additionally, many had exposure to psychological traumatogens. The most common effects seen to date are respiratory and mental health consequences. The long-term consequences of exposures are not yet known, and there remains concern about the potential for late-emerging diseases such as cancers. This article reviews WTC-related health effects, the spectrum of exposures and how they were documented, and discusses future preventive efforts.

[Asbestosis and microfiber role]

Based on the predominant content of thin and short asbestos fibres in lung and mesothelioma tissues, it was recently stated (2005) that such fibres "appear to contribute to the causation of human malignant mesothelioma". In another study of the same year it was stated that fibres in the order of few microm length and 0.2 microm diameter are the sole able to induce mesothelioma. This scientific conclusions entail some implications from practical point of view. The enormous amount of information gained on asbestos in the last decades is based on the definition of a fibre as an alongated particle with an aspect-ratio of at least 3:1, a diameter < or = 3 microm and a length > or = 5 microm. These parameters were used up today to define occupational and in some case non-occupational limits. In which way can "reference" values be established if all lengths or only fibres shorter than 5 microm are considered? Nowadays we have no answer. Secondly, assuming a prevalent role of such fibres especially in mesothelioma cases, how can reliable estimates of past exposure obtained in a medico-legal context, since they have never been counted? Morever, how might he the employer responsibility assessed since short fibres were not measured by definition pathogenic, and this not measured, nor were there appropriate filtering systems up to the middle of the '80?

[The role of asbestos fibre dimensions in the pathogenesis and prevention of mesothelioma]

The particular point of view, recently published by Gerolamo Chiappino, on the pathogenetic role of asbestos fibres size in the origin of mesothelioma and on the possibility of mesothelioma prevention until the middle of the '80s needs to be critically clarified. The suggestion of an exclusive role of ultrashort and ultrathin fibres in the origin of mesothelioma is based on a biased interpretation of the literature. A review of the epidemiological, experimental, and molecular literature suggests that Chiappino's statements on the role of dose, dose-response effect, and genetic susceptibility are scientifically unsound Chiappino states that, in the past, in the workplaces where use and exposure to asbestos were not stopped, any reduction in the intensity of exposure by means of dust control measures or personal protective equipment would not have contributed to reduce the frequency of mesothelioma. In the authors' opinion the underlying assumptions are invalid.

[Mortality and hospital discharges in the population of Biancavilla (Sicily) contaminated by natural fibres]

OBJECTIVE

The volcanic area of Biancavilla (Sicily Italy) has been included by the Italian national law among the areas of "environmental reclamation" due to the presence of amphibole fluoro-edenitic fibres in the environment. The aim of the study was to evaluate the health of residents in the area, through the analysis of the mortality registry and the hospital discharge records.

DESIGN

Age, cause and gender specific indirect standardized mortality ratios SMR (1995-2000) and morbidity ratios SHR (2001-2003) were computed with 95% confidence intervals, using the population of surrounding municipalities as reference.

RESULTS

statistically significant increases in mortality and morbidity were observed, both in men and women, for malignant pleural neoplasms (mortality: men SMR= 700, 6 observed; women SMR= 840, 3 observed; hospital admissions: women SHR= 1210, 5 observed), cardiovascular diseases (mortality: men SMR= 115, 267 observed, women SMR= 115, 278 observed; hospital admissions: men SHR= 109, 631 observed; women SHR= 114, 528 observed) and respiratory diseases (mortality: men SMR= 164, 68 observed; women: SMR= 215, 44 observed; hospital admissions: men SHR= 139, 558 observed, women SHR= 125, 374 observed).

CONCLUSIONS

the excesses observed in this study are consistent with previous findings and suggest the need for further investigations aimed at improving the knowledge of the mineralogical aspects of the fibres, the assessment of human exposure and at estimating the prevalence of pleural plaques and lung fibrosis.

Fluoro-edenitic fibres in the sputum of subjects from Biancavilla (Sicily): a pilot study

BACKGROUND

An excess of mortality for malignant neoplasms of the pleura in Biancavilla, promoted an investigation for pleural mesothelioma, disclosing 17 cases. As the absence of known sources of asbestos exposure, a local stone quarry, located near the inhabited area, used for the extraction of building materials, was investigated. Amphibolic fibres were found in the quarry and identified as fluoro-edenite "new end-member of the edenite / fluoro-edenite series" and recognized as the fluoro-edenite holotype by International Mineralogical Association--Commission on New Minerals and Mineral Names. A pilot study was performed to verify the feasibility of using spontaneous sputum as an exposure indicator for these fibres, in a context in which the use of aerosol-induced sputum technique would not be easily accepted.

METHODS

Hypothesizing a behaviour of the new fibre analogous to that of asbestos, the determination of the free fibres and the ferruginous bodies in spontaneous sputum was carried out. Phase Contrast Optical Microscope and an Environmental Scanning Electron Microscope fitted with X-ray energy dispersive analysis system (micro-analysis) were used to examine the samples. The criteria for inclusion in the study were: 1) subjects hospitalized for exacerbation of chronic obstructive pulmonary disease symptoms, 2) age > or = 45 years, 3) residence in Biancavilla for at least 30 years.

RESULTS

The preliminary findings are related to 12 subjects (7 females and 5 males). Uncoated fibres (with length > 5 microm, diameter < 3 microm, aspect ratio 3.1) and ferruginous bodies were searched. Six out of twelve subjects (4 females, 2 males) had at least one of the three samples positive for the presence of fluoro-edenite, confirmed by micro-analysis. The fibre concentration found in the sputum ranged from 0.04 to 10 fibres/g; the length from 20 to 40 microm, the diameter was < 0.5 microm. No ferruginous bodies were found in any of the samples. The four women with a positive sample were housewives. Of the two men with a positive sample, one was a farmer and the other a mason. Therefore, it may be assumed that the exposure to fluoro-edenitic fibres was mainly environmental.

CONCLUSION

The occurrence of the pleural mesothelioma cases and the presence of fluoro-edenitic fibres in spontaneous sputum, evidence the need to study the biological activity of fluoro-edenitic fibres and the implementation of epidemiological monitoring systems.

Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats

In an attempt to examine the interaction of man-made mineral fibres with benzo[a]pyrene (B[a]P), homozygous X-lacI transgenic F344 rats were intratracheally treated with rock (stone) wool RWI and glass wool MMVF 10 fibres together with B[a]P. To analyze the induction of gene mutations by fibres and B[a]P in lung, single doses of 1 and 2 mg fibres/animal or multiple doses of 2 mg fibres/animal were administered weekly on 4 consecutive weeks (total dose 8 mg/animal). B[a]P (10 mg/animal) was administered either simultaneously with fibres (for single dose treatment with fibres) or together with the last fiber treatment (for multiple dose treatment with fibres). Animals were scarified 4 weeks after the last treatment. Benzo[a]pyrene administered simultaneously with RW1 fibres exhibited a strong synergistic effect on mutagenicity, the observed mutant frequency (MF) being more than three-fold higher than the net sum of the MF induced after separate administration of both agents. Our data suggest that DNA adducts induced by simultaneous B[a]P and fiber treatment lead to a strong increase in mutatant frequencies.