The asbestos danger
Occupational exposure to asbestos is universally associated with several lung injuries, including respiratory diseases, asbestosis, mesothelioma, and, owing to others co-factors, lung cancer. Pleural malignant mesothelioma, in particular, is highly deadly, the 5-year survival rate being of 5% only (1 over 20). In addition, due to weathering of asbestos-reinforced cement products, asbestos contamination is also becoming of concern for the general population, in particular in urban areas. The relation between asbestos use and mesothelioma cases is known since the sixties, and it is quantitatively well depicted by the evident correlation between cumulative asbestos use and mesothelioma cases shown in Figure 1.
Figure 1. Relationship between 15-year cumulative mortality of mesothelioma (1994–2008) and cumulative use of asbestos (1920–1970) weighted by the size of national populations in 56 countries (adapted from Park et al., 2011 ).
Asbestos can enter in living organisms by inhalation and, also due to its high bio-persistence (i.e. their removal or dissolution in the host organism is unlikely), can manifest its toxicity after long (20 to 40 years). For these reason, although since the 1990s asbestos started to be banned in most countries and, with a few relevant exceptions (Russia, China, Canada, and Brazil), it is almost abolished today, asbestos remains a current major worldwide health threat. In fact, it is foreseen that the peak of mesothelioma cases in the world will be reached within 2020 [1-5]. In France, a report of the High Council of Public Health (HCSP) has recently quantified the danger of asbestos in 68,000 – 100,000 deaths by 2050. At a world scale, the US National Institute of Health (NIH) estimated that 11 million people were exposed to asbestos between 1940 and 1978.
These figures lead to the conclusion that extensive researches on asbestos interaction with host organism are essential to better understand the pathogenesis, and thus to develop more efficient medical treatments or prevention strategies. Furthermore, the results and methodologies derived from these researches can be applied to other hazardous anthropogenic nanofibers or nanoparticulate, such as carbon and metal-oxide nanotubes, or particulate matter of industrial or vehicular origin, which are becoming of increasing concern for human health.
Exposure and contamination to asbestos can originate from several diverse sources, such as asbestos products plants, steel plants, shipyards, and asbestos mines. In Italy, asbestos plants for the production of fiber-reinforced cement products (90 % cement, 10 % asbestos) have been active until 1986. Two of these plants where located in the Piedmont region (NW Italy). The workers of the asbestos plants, their relatives, and many inhabitants of the villages close to the plants were exposed to high asbestos contamination levels for up to 40 years. Thousands of them died of pleural mesothelioma (the current count exceeded 3,000 individuals in 2015), or were seriously affected by other asbestos-related respiratory diseases, such as asbestosis. Other well known sources of contamination in the Piedmont region are the asbestos mine of Balangero (one of the largest mines in Europe, now dismissed) and the steel plant Fiat Ferriere, which was active in the city of Turin.
 M L Mace et al. Scanning electron microscopic examination of human asbestos bodies., Cancer letters 9, 95–104 (1980).
 V Delgermaa et al., Global mesothelioma deaths reported to the World Health Organization between 1994 and 2008, Bulletin of the World Health Organization 89, 716–24, 724A–724C (2011).
 B Price and A Ware, Mesothelioma trends in the United States: an update based on Surveillance, Epidemiology, and Results Program data for 1973 through 2003. American Journal of Epidemiology 159, 107–12 (2004).
 R A Robinson et al. Advances in Malignant Mesothelioma, New Engl. J. Med. 353, 1591–1603 (2005).
 J T Hodgson et al. The expected burden of mesothelioma mortality in Great Britain from 2002 to 2050. British Journal of Cancer 92, 587-593 (2005).
 E-K Park et al. Global Magnitude of Reported and Unreported Mesothelioma. Environmental Health Perspectives 119, 514-518 (2011).