Asbestos: What is it?
Asbestos is a substance belonging to the fiber category. They are elongated bodies in which the length prevails with respect to diameter and width. We have two distinct types of fibers, natural ones, that is, that are found in nature ( asbestos, zeolites, sepiolites ) and artificial ones ( slag wool, rock wool, ceramic fibers ), which are mineral fibers, produced by man through of technological procedures, and which today have almost completely replaced it.
Why is it dangerous?
Asbestos does not only cause asbestosis, but also other diseases, some very serious.
Its manipulation determines the release of the fibers, which can disperse in the air and - once they come into contact with humans - penetrate and progress along the airways.
Asbestos, therefore, given the size of its fibers, is an easily inhalable substance. These fibers are also bioresistant, that is, before being destroyed by the organism with which they came into contact, they need a lot of time, so they can cause damage.
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Asbestos was widely used, especially years ago, because it is fire-resistant, is an excellent sound-absorbent, and is also a dielectric. Its properties of resistance to acids, micro-organisms and wear, its flexibility and the possibility of being "woven" in very ductile structures, make it very used on an industrial level. For example, we can find it in railway carriages, ships, asbestos cement and in the textile industry.
Types of asbestos
There are different types of asbestos, which cause different types of diseases. Its fibers, for simplicity, can be divided into two large groups:
• Serpentine group : it is represented by chrysotile (white or gray asbestos), and it is much more used than other types of asbestos. In fact, it corresponds to about 93% of world production, and this is good because it is less harmful than the second group. It is produced mainly in South Africa, the Russian Federation, Canada, Yugoslavia, Europe (Corsica and, more than half of it only in Italy, especially near Turin).
• Amphibole group:
Crocidolite or blue asbestos = iron silicate. The most dangerous of all. It is of Australian origin, and was used in England for the construction of gas masks for military use.
Brown amosite or asbestos = iron and magnesium silicate. Dangerous, but less than crocidolite. Workers in the shipbuilding industry were found in the USA and Canada.
Anthophyllite = magnesium silicate
Tremolite = magnesium silicate and calcium. Used in Turkey as a material for building houses.
Actinolite = calcium, magnesium and iron silicate.
Types of exposure
Exposure to asbestos was recorded in around 3, 000 types of activity. The main ones are:
- Extraction of asbestos fibers from mines and quarries;
- Paint mixtures;
- Reinforced concrete industry;
- Paper industry (asbestos cardboards): paper, stove coverings, radiators, booths, film production;
- Textile industry: fireproof clothing and fabrics, such as theater curtains;
- Industry of friction materials (rolling stock, railway, ships) and the production of brakes and clutches (especially lifts);
- Chemical industry: production of filters;
- Thermal and acoustic insulation industry;
- Asbestos cement pipes for pipelines and construction industry (roofs, chimneys, pipes).
It should be noted that there are innumerable types of exposure to asbestos, which are not as frequent as those mentioned above and which are therefore called " unusual". Non-working sources of contamination can be due to the proximity of production sites, the use of asbestos structures in old houses and laboratories, fibers taken home by miners or industrial workers, and environmental contamination.
Legislation
There has been a wealth of legislation on asbestos for many years. Since 1992 a very strict law has been in force which, throughout the national territory, prohibits the extraction, import and export, marketing and production of asbestos or products containing it. Exposure to this substance is today limited only to workers employed in the activities of removing it from places still contaminated, and in reclamation. For these activities, specific workers' protection regulations are envisaged, concerning in particular information, the use of personal protective equipment and limited access to work areas. The personal protection devices against asbestos relate to clothing (self-contained breathing apparatus, hood, gloves, overshoes), double-filter masks (for ultrafine powders) and disposable masks for asbestos dust.
However, even if the 1992 law prohibits its use, today it still makes sense to talk about asbestos pathologies, both because there are still exposed subjects, who are the same people in charge of removal and reclamation (although in reality it is possible, adopting the appropriate precautions, obtain the zeroing of the risk during these maneuvers) but above all, a real medical problem is given by the considerable latency period between the exposure and the appearance of the pathology (which occurs in the ex-exposed). For example, knowing that asbestos lung cancer has a latency period of about 20-25 years and that of the pleura (mesothelioma) of about 30, assuming that a person started working in places at risk in the 1980s, yes will be able to see asbestos pathologies until 2010-2015.
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