[Health surveillance for subjects with past occupational exposure to asbestos: the experience of Local Health Unit Messina 5 (Sicily)]

OBJECTIVE

In the framework of the World Health Organization (WHO)-Istituto superiore di sanità (ISS) joint research project «Cohort studies in areas of high environmental risk in Sicily», since 2007 a working group ISS-Local Health Unit Messina 5 (AUSL ME5) assessed the issue emerged during the course of a health monitoring program launched in 2003, dedicated to former employees of an asbestos-cement factory, and their relatives (378 subjects, 119 ex employees and 259 relatives).

METHODS

Communication about the health risks linked to previous exposure to asbestos, diagnostic tools for asbestos-related diseases, available preventive measures (stopping smoking tobacco, avoiding further exposure to respiratory irritants, prophylaxis of any intercurrent respiratory diseases) were focused. The working group discussed the whole structure of the activity in progress, and identified the difficulties emerged in previous years.

RESULTS AND CONCLUSIONS

The authors developed a health plan that could be useful in similar Sicilian contexts with public health problems due to past activities with asbestos.

[Mortality from asbestos-related causes and incidence of pleural mesothelioma among former asbestos cement workers in San Filippo del Mela (Sicily)]

OBJECTIVES

The present paper estimates the burden of asbestos-related disease among asbestos-cement production workers of the Sacelit plant that operated in San Filippo del Mela (Province of Messina) from 1958 through 1993.

SETTING AND PARTICIPANTS

The cohort was enumerated by the local committee of formerly exposed workers, with whom a collaboration was set up. The cohort includes 198 subjects with complete individual anagraphic information, out of 231 previous workers identified by the committee. A record-linkage with the Sicilian centre of the National mesothelioma registry enabled estimation of mesothelioma incidence for the years 1998-2008. Standardised proportionate mortality (SPMR) for asbestos-related causes was computed for the years 1986-2009. Sicilian Region constituted the reference population. The rationale for using SPMR rather than standardized mortality ratio (SMR) was a consequence for the lack of company files from which to obtain dates of start and termination of employment, and thus to compute person-years of observation, following the guidelines of the international scientific literature.

RESULTS

Standardised incidence ratio (SIR) for mesothelioma in the overall cohort was 251 (4 observed, 0.02 expected). Proportionate mortality analysis among male subjects showed significant increases for pneumoconiosis (SPMR 80.1, 5 observed), lung cancer (SPMR 2.81, 10 observed) and pleural neoplasms (SPMR 19.4, 2 observed).

CONCLUSIONS

Notwithstanding limitations in cohort reconstruction, for which the proportion of eligible subjects was 87.5% of those detected by the local committee, and the lack of information on duration of employment, it was possible to estimate a significant increase of the incidence of pleural mesothelioma with respect to Sicilian population. Also mortality from asbestos-related causes was in excess with respect to the regional reference population.

Environmental asbestos-related pleural plaque in southeast of Turkey

It is known that many malignant and benign pleural diseases occur due to environmental exposure to mineral fibers. Calcified pleural plaque (CPP) is an important sign of asbestos exposure on chest radiographic examination. To study the possible change in the prevalence of CPP and diffuse pleural thickening 3 decades after cessation of asbestos exposure. CPP were detected in 29.9% of the villagers; 4.7% had diffuse pleural thickening and 0.7% had asbestosis. The significant variable for CPP and diffuse pleural thickening was age. The youngest villager with CPP was 33 years of age and the prevalence of CPP increased with an increase in age. The reason for our cases with CPP being of advanced age is the discontinuation of asbestos exposure. This finding enables us to suggest that environmental asbestos-related disease will gradually decrease in future decades.

Risk assessment of lung cancer and asbestosis in workers exposed to asbestos fibers in brake shoe factory in Iran

Chrysotile asbestos fiber, imported from Russia, is used mainly for manufacturing purposes in Iran and related risks in the form of asbestosis and cancer were studied. Occupational exposure of all male workers (61 persons) to asbestos in a brake shoe factory was monitored. Cumulative exposures were determined through multiplication of typical exposure and work history. Risk assessment of exposed workers was estimated by risk criteria recommended by the American Environmental Protection Agency. Measurement of lung function parameters such as forced expiratory volume in one second (FEV(1)), forced volume capacity (FVC) and FEV(1)/FVC of exposed workers were obtained. Unadjusted correlation and adjusted correlation analysis for support of the association between cumulative exposure (fiber/ml-yr) and lung function parameters were used. Exposure of majority of exposed group was far greater than the occupational exposure limits (0.1 fiber/ml) in the range of 0.06-8.06 fiber/ml. Cumulative exposures in the range of 0.02 to 110.77 fiber/ml-yr were obtained. According to the risk criteria stated by ATSDR, risk assessment of workers in term of fibrotic changes was predicted for at least 24.6 percent of the exposed subjects. Again, according to the lung cancer risk criteria stated by EPA, 59 percent of workers will have excess risk. Negative correlation between lung function parameters (FEV(1), FEV(1)/FVC) and cumulative exposures adjusted for age and BMI were significant (p<0.05).

Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships

BACKGROUND

Since previous studies have provided conflicting results, we investigated the relationship between the risk of benign asbestos-related diseases and different aspects of asbestos exposure in previous asbestos workers who underwent low-dose computed tomography (CT).

METHODS

CT scans were carried out in 772 subjects. A questionnaire was employed to collect data on smoking habits and duration, peak and cumulative exposure, and time since first exposure to asbestos. Multiple logistic regression models with stepwise selection of variables were used to evaluate the associations.

RESULTS

Fourteen (1.8%) cases of asbestosis, 187 (24.2%) of pleural plaques (PP), and 50 (6.5%) of diffuse pleural thickening (DPT) were found. The significant risk factors were: cumulative exposure for asbestosis (P for trend = 0.004); time since first exposure (P for trend <0.001), and peak exposure (P for trend <0.001) for PP; and time since first exposure for DPT (P for trend = 0.024).

CONCLUSIONS

Parenchymal asbestosis and PP are associated with different aspects of asbestos exposure. DPT appears to be less specific for asbestos exposure.

Silica and Asbestos Exposure in ANCA-Associated Vasculitis with Pulmonary Involvement

Silica and asbestos exposure are thought to belong to the triggering factors of antineutrophil cytoplasm antibodies (ANCA)-associated vasculitis. We carried out a study to find out whether patients with pulmonary involvement attributable to ANCA-associated vasculitis (AAV) have been exposed to silicon-containing materials. Thirty-one patients (12 women, 19 men, median age 51 years) were interviewed using a structured questionnaire. Occupational exposure to silicon-containing chemicals was reported by 22.6% of the patients (12.9% to SiO2, 9.7% to asbestos), compared with 0% of control subjects (p<0.05). Our findings support the pathophysiologic role of silica in AAV.

Overview of asbestos issues in Korea

Asbestos is a carcinogen that causes diseases such as mesothelioma and lung cancer in humans. There was a sharp increase in the use of asbestos in Korea in the 1970s as Korea's economy developed rapidly, and asbestos was only recently banned from use. Despite the ban of its use, previously applied asbestos still causes many problems. A series of asbestos-related events that recently occurred in Korea have caused the general public to become concerned about asbestos. Therefore, it is necessary to take proper action to deal with asbestos-related events, such as mass outbreaks of mesothelioma among residents who lived near asbestos textile factories or asbestos mines. Although there have been no rapid increases in asbestos-related illnesses in Korea to date, such illnesses are expected to increase greatly due to the amount of asbestos used and long latency period. Decreasing the asbestos exposure level to levels as low as possible is the most important step in preventing asbestos-related illnesses in the next few decades. However, there is a lack of specialized facilities for the analysis of asbestos and experts to diagnose and treat asbestos-related illnesses in Korea; therefore, national-level concern and support are required.

[Hygienic evaluation of asbestos-containing friction goods application]

The author analyzed literature data and conducted hygienic studies on evaluating risks connected with asbestor fibers release into workplace air and ambient air of populated area, with application of asbestos-containing goods (friction goods, interlining materials) in automobile transport. Conclusion is that air pollution with fiber particles in concentrations exceeding allowable ones is possible only with intense mechanical processing of friction goods.

[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.

A simple approach for fitting linear relative rate models in SAS

The linear relative rate model has been employed in epidemiologic analyses of a variety of environmental and occupational exposures. In contrast to an exponential rate model, the linear relative rate model implies that the excess relative rate of disease changes in an additive fashion with exposure. The linear relative rate model may be fitted using EPICURE (HiroSoft International Corporation, Seattle, Washington), a specialized statistical software package widely used for such analyses. In this paper, the author presents a simple approach to fitting the linear relative rate model to epidemiologic data using PROC NLMIXED in the SAS statistical software package (SAS Institute Inc., Cary, North Carolina). This approach is illustrated via analyses of data from a study of mortality in a cohort of South Carolina asbestos textile workers (1940-2001).

A Review of the Federal Government's Health Activities in Response to Asbestos-Contaminated Ore Found in Libby, Montana

Vermiculite ore is a naturally occurring fibrous mineral widely used in various consumer products, such as attic insulation, lawn and garden products, and fireproofing material. While most vermiculite ore and products do not pose a health hazard, the vermiculite mined from Libby, MT was contaminated with naturally occurring asbestos. The federal Agency for Toxic Substances and Disease Registry (ATSDR) has documented a significant number of asbestos-related deaths among Libby residents. Additionally, as part of the ongoing investigation, ATSDR has learned that this contaminated ore was shipped to hundreds of locations around the United States for processing. While the Libby mine is now closed, studies from ATSDR and elsewhere show that people who worked in the Libby mine or vermiculite processing facilities may have been exposed to hazardous levels of asbestos while the facilities were in operation. People who lived or worked near these sites also may have been exposed to asbestos if they came into contact with contaminated vermiculite. Prolonged exposure to asbestos can cause serious and life-threatening health conditions, including asbestosis, lung cancer, and mesothelioma. In response, ATSDR has initiated 10 different activities to help evaluate the potential health effects among Libby residents and populations throughout the United States who might have been exposed to the asbestos-contaminated ore found in Montana. Some of these activities include conducting environmental exposure evaluations, health statistics reviews, community screenings, and disease-specific surveillance. This article presents the various follow-up activities that have been conducted to date by ATSDR and partnering state health departments.

[Recycle of jute bags; asbestos in agriculture, exposure and pathology ]

During the last four years, a deeper examination of malignant mesothelioma (MM) cases occurred within non asbestos textile industry highlighted asbestos past exposure in several textile industrial divisions. In spite of that, poor information about recycled textile bags previously containing asbestos fibres is available to the National Mesothelioma Registry, although holding a remarkable data bank on more than 3500 work histories and sources of asbestos exposures. Besides the analysis of the exposure circumstances and the registered health effects of the past exposure within the recycling activity, the aim of this research was to relate the possible involvement of the agricultural sector, where the use of recycled jute bags was very diffused. The MM cases were collected from the Mesothelioma Registry of Brescia, asbestosis, pleural plaques and lung cancer cases were collected from the Occupational Diseases Archive of the Local Public Occupational Health Service of the Province of Brescia. During the 1977-2006 period, 8 cases of MM, 4 cases of pulmonary asbestosis, 4 of isolated bilateral pleural plaques and I of lung cancer in pulmonary asbestosis, were observed among workers employed in bags recycling activity in 4 small companies, one of them still operating, employing about 50 workers. Even more, among the 65 MM cases classified by the Registry with "unknown asbestos exposure" (UAE), the most relevant frequency of working histories concerned the agriculture sector. Confirming a past signalling, the investigations underlined the cross linkage between this working activity and the diffusion of recycled bags in the agriculture sector. In the Province of Brescia, the activities of these small jute bags recycling plants were linked, even geographically, to the asbestos cement manufacture plant using a huge number of bags, roughly until mid seventies. Therefore, a large number of these recycled bags, previously containing asbestos, were generally used for harvesting and trading agricultural typical products of northern Italy. According to the 2003 National Mesothelioma Registry Guide Lines, MM in agricultural workers are still classified as UAE due to poor information available. In the light of these new findings, it looks reasonable to review the UAE within agriculturalists attributing a new classification of "possible" occupational asbestos exposure, although other exposure circumstances might have occurred in the past.

[Evaluation of rounded atelectasis induced by exposure to asbestos]

We encountered 19 patients of rounded atelectasis induced by exposure to asbestos from 2000 to 2007. All patients were men whose ages arranged from 60 to 89 years with a mean of 74.2 years. Twenty rounded atelectasis were present in the right lung and 5 in the left lung. Five patients had 2 rounded atelectasis. In 21 rounded atelectasis were found in Segment 10 and while other 2 found in S1 and each in S5 and 9. Eleven patients were diagnosed with no symptoms through medical examinations. Other 8 patients complained of dyspnea, chest pain and cough. Thirteen patients complicated with benign asbestos pleurisy and only 3 patients accompanied asbestosis. Eighteen patients (95%) displayed pleural plaques and 15 patients with calcified plaques. Ten patients had been exposed to asbestos in the shipyards and 4 in construction works and other 5 patients had also exposed by occupational exposure to asbestos. The mean period of exposure to asbestos was 26.6 years and the mean latency periods from the first asbestos exposure to the diagnosis of rounded atelectasis were 51.6 years. An autopsied patient had 18,100 asbestos bodies per 1 g of dry lung tissue which meant the heavy asbestos exposure. High incidence of pleural plaques and long period of latency from the first exposure to the appearance of rounded atelectasis in this study suggested that rounded atelectasis might appear less high-dose exposure to asbestos than former patients who were reported 6 years ago.

Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study

Carbon nanotubes have distinctive characteristics, but their needle-like fibre shape has been compared to asbestos, raising concerns that widespread use of carbon nanotubes may lead to mesothelioma, cancer of the lining of the lungs caused by exposure to asbestos. Here we show that exposing the mesothelial lining of the body cavity of mice, as a surrogate for the mesothelial lining of the chest cavity, to long multiwalled carbon nanotubes results in asbestos-like, length-dependent, pathogenic behaviour. This includes inflammation and the formation of lesions known as granulomas. This is of considerable importance, because research and business communities continue to invest heavily in carbon nanotubes for a wide range of products under the assumption that they are no more hazardous than graphite. Our results suggest the need for further research and great caution before introducing such products into the market if long-term harm is to be avoided.