Evaluation of Deposition and Clearance of Asbestos (Detected by SEM-EDS) in Lungs of Deceased Subjects Environmentally and/or Occupationally Exposed in Broni (Pavia, Northern Italy)

Biodurability is one of the main determinants of asbestos hazardousness for human health. Very little is known about the actual persistence of asbestos in lungs and its clearance, nor about differences in this regard between the different mineralogical types of asbestos. The aim of the present study was to evaluate the amount, the dimensional characteristics and the mineralogic kinds of asbestos in lungs (measured using SEM-EDS) of a series of 72 deceased subjects who were certainly exposed to asbestos (mainly crocidolite and chrysotile) during their life. Moreover, we investigated possible correlations between the lung burden of asbestos (in general and considering each asbestos type), as well as their dimension (length, width, and l/w ratio) and the duration of exposure, the latency- in case of malignant mesothelioma (MM), the survival and the time since the end of exposure. In 62.5% of subjects, asbestos burden in lungs was lower that the threshold considered demonstrative for occupational exposure. In 29.1% of cases no asbestos was found. Chrysotile was practically not detected. The mean length of asbestos fibers and the length to width ratio were significantly related to the duration of exposure to asbestos. No other statistically significant correlations were found between the amount and dimensional characteristics of asbestos (nor with the relative amount of each asbestos type) and the other chronological variables considered. In conclusion, it was pointed out that chrysotile can be completely removed from human lungs in <8 years and, instead, amphiboles persist much more time. The present results suggest, as well, that the finding of no asbestos in lungs cannot rule out the attribution of MM to asbestos (in particular, chrysotile) inhaled in an occupational setting. This point is of crucial importance from a legal point of view.

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

Increased mortality due to malignant mesothelioma has been demonstrated by several epidemiologic studies in the area around Broni (a small town in Lombardy, northern Italy), where a factory producing asbestos cement was active between 1932 and 1993. Until now, the inorganic fiber burden in lungs has not been investigated in this population. The aim of this study is to assess the lung fiber burden in 72 individuals with previous occupational and/or anthropogenic environmental exposure to asbestos during the activity of an important asbestos cement factory. Inorganic fiber lung burden was assessed in autoptic samples taken from individuals deceased from asbestos-related diseases using a scanning electron microscope equipped with an energy-dispersive spectrometer. Significant differences in the detected amount of asbestos were pointed out among the three types of exposure. In most lung samples taken from patients who died of mesothelioma, very little asbestos (or, in some cases, no fibers) was found. Such subjects showed a significantly lower median amount of asbestos as compared to asbestosis. Almost no chrysotile was detected in the examined samples. Overall, crocidolite was the most represented asbestos, followed by amosite, tremolite/actinolite asbestos, and anthophyllite asbestos. There were significant differences in the amount of crocidolite and amosite fibers according to the kind of exposure. Overall, these findings provide novel insights into the link between asbestos exposure and mesothelioma, as well as the different impacts of the various types of asbestos on human health in relation to their different biopersistences in the lung microenvironment.

Lung carcinogenicity of inhaled multi-walled carbon nanotube in rats

BACKGROUND

Multi-walled carbon nanotubes (MWCNTs) constitute one of the most promising types of nanomaterials in industry today. With their increasing use, the potential toxicity and carcinogenicity of MWCNT needs to be evaluated in bioassay studies using rodents. Since humans are mainly exposed to MWCNT by inhalation, we performed a 104-week carcinogenicity study using whole-body inhalation exposure chambers with a fibrous straight type of MWCNT at concentrations of 0, 0.02, 0.2, and 2 mg/m3 using male and female F344 rats.

RESULTS

Lung carcinomas, mainly bronchiolo-alveolar carcinoma, and combined carcinomas and adenomas were significantly increased in males exposed to 0.2 and 2 mg/m3 MWNT-7 and in females exposed to 2 mg/m3 MWNT-7 compared to the clean air control group. However, no development of pleural mesothelioma was observed. Concentration-dependent toxic effects in the lung such as epithelial hyperplasia, granulomatous change, localized fibrosis, and alteration in BALF parameters were found in MWNT-7 treatment groups of both sexes. There were no MWNT-7-specific macroscopic findings in the other organs, including the pleura and peritoneum. Absolute and relative lung weights were significantly elevated in male rats exposed to 0.2 and 2 mg/m3 MWNT-7 and in all exposed female groups. The lung burdens of MWNT-7 were clearly increased in a concentration-dependent as well as a duration-dependent manner.

CONCLUSION

There is clear evidence that MWNT-7 is carcinogenic to the lungs of male and female F344 rats, however no plural mesothelioma was observed.

Prevention of Asbestos-Related Disease in Countries Currently Using Asbestos

More than 40 years of evaluation have consistently confirmed the carcinogenicity of asbestos in all of its forms. This notwithstanding, according to recent figures, the annual world production of asbestos is approximatively 2,000,000 tons. Currently, about 90% of world asbestos comes from four countries: Russia, China, Brazil and Kazakhstan; and the wide use of asbestos worldwide represents a global threat. The purpose of this paper is to present a review of the asbestos health impact and to discuss the role of epidemiological investigations in countries where asbestos is still used. In these contexts, new, "local" studies can stimulate awareness of the size of the problem by public opinion and other stakeholders and provide important information on the circumstances of exposure, as well as local asbestos-related health impacts. This paper suggests an agenda for an international cooperation framework dedicated to foster a public health response to asbestos, including: new epidemiological studies for assessing the health impact of asbestos in specific contexts; socio-cultural and economic analyses for contributing to identifying stakeholders and to address both the local and global implications of asbestos diffusion; public awareness on the health and socio-economic impact of asbestos use and banning.

Mesothelioma from asbestos exposures: Epidemiologic patterns and impact in the United States

Mesothelioma, a rare tumor, is highly correlated with asbestos exposure. Mesothelioma, similar to all asbestos-related diseases, is dose/intensity dependent to some degree, and studies showed the risk of mesothelioma rises with cumulative exposures. Multiple processes occur in an individual before mesothelioma occurs. The impact of mesothelioma in the United States has been continuous over the last half century, claiming between 2,000 and 3,000 lives each year. Mesothelioma is a preventable tumor that is more frequently reported as associated with asbestos exposure among men than women. However, the rate of asbestos-associated mesothelioma is on the rise among women due to better investigation into their histories of asbestos exposure. It is of interest that investigators detected asbestos-associated cases of mesothelioma in women from nonoccupational sources-that is, bystander, incidental, or take-home exposures. It is postulated that asbestos-associated mesotheliomas, in both men and women, are likely underreported. However, with the implementation of the most recent ICD-10 coding system, the correlation of mesothelioma with asbestos exposure is expected to rise to approximately 80% in the United States. This study examined the demographic and etiological nature of asbestos-related mesothelioma.

Mesothelioma and analysis of tissue fiber content

The strong relationship between mesothelioma and asbestos exposure is well established. The analysis of lung asbestos burden by light and electron microscopy assisted to understand the increased incidence of mesothelioma in asbestos mining and consuming nations.The data on the occupational exposure to asbestos are important information for the purpose of compensation of occupational disease No. 4105 (asbestos-associated mesothelioma) in Germany.However, in many cases the patients have forgotten conditions of asbestos exposure or had no knowledge about the used materials with components of asbestos. Mineral fiber analysis can provide valuable information for the research of asbestos-associated diseases and for the assessment of exposure. Because of the variability of asbestos exposure and long latency periods, the analysis of asbestos lung content is a relevant method for identification of asbestos-associated diseases. Also, sources of secondary exposure, so called "bystander exposition" or environmental exposure can be examined by mineral fiber analysis.Household contacts to asbestos are known for ten patients (1987-2009) in the German mesothelioma register; these patients lived together with family members working in the asbestos manufacturing industry.Analysis of lung tissue for asbestos burden offers information on the past exposure. The predominant fiber-type identified by electron microscopy in patients with mesothelioma is amphibole asbestos (crocidolite or amosite). Latency times (mean 42.5 years) and mean age at the time of diagnose in patients with mesothelioma are increasing (65.5 years). The decrease of median asbestos burden of the lung in mesothelioma patients results in disease manifestation at a higher age.Lung dust analyses are a relevant method for the determination of causation in mesothelioma. Analysis of asbestos burden of the lung and of fiber type provides insights into the pathogenesis of malignant mesothelioma. The most important causal factor for the development of mesothelioma is still asbestos exposure.

The case for a global ban on asbestos

BACKGROUND

All forms of asbestos are now banned in 52 countries. Safer products have replaced many materials that once were made with it. Nonetheless, many countries still use, import, and export asbestos and asbestos-containing products, and in those that have banned other forms of asbestos, the so-called "controlled use" of chrysotile asbestos is often exempted from the ban. In fact, chrysotile has accounted for > 95% of all the asbestos used globally.

OBJECTIVE

We examined and evaluated the literature used to support the exemption of chrysotile asbestos from the ban and how its exemption reflects the political and economic influence of the asbestos mining and manufacturing industry.

DISCUSSION

All forms of asbestos, including chrysotile, are proven human carcinogens. All forms cause malignant mesothelioma and lung and laryngeal cancers, and may cause ovarian, gastrointestinal, and other cancers. No exposure to asbestos is without risk. Illnesses and deaths from asbestos exposure are entirely preventable.

CONCLUSIONS

All countries of the world have an obligation to their citizens to join in the international endeavor to ban the mining, manufacture, and use of all forms of asbestos. An international ban is urgently needed. There is no medical or scientific basis to exempt chrysotile from the worldwide ban of asbestos.

Asbestos is still with us: repeat call for a universal ban

All forms of asbestos are proven human carcinogens. All forms of asbestos cause malignant mesothelioma, lung, laryngeal, and ovarian cancers, and may cause gastrointestinal and other cancers. No exposure to asbestos is without risk. Asbestos cancer victims die painful lingering deaths. These deaths are almost entirely preventable. When evidence of the carcinogenicity of asbestos became incontrovertible, concerned parties, including the Collegium Ramazzini, called for a universal ban on the mining, manufacture, and use of asbestos in all countries around the world (J Occup Environ Med. 1999;41:830-832). Asbestos is now banned in 52 countries, and safer products have replaced many materials that once were made with asbestos. Nonetheless, a large number of countries still use, import, and export asbestos and asbestos-containing products. And in many countries that have banned other forms of asbestos, the so-called "controlled use" of chrysotile asbestos is exempted from the ban, an exemption that has no basis in medical science but rather reflects the political and economic influence of the asbestos mining and manufacturing industry. All countries of the world have an obligation to their citizens to join in the international endeavor to ban all forms of asbestos. An international ban on asbestos is urgently needed.