The term asbestos describes a group of hydrated silicates (mainly magnesium and iron silicates) formed naturally during rock metamorphism and transformed into mineral fibres through a mechanical process. Asbestos fibres have remarkable physical properties including resistance to fire, high mechanical resistance to friction and traction, and low thermal and electrical conductivity, as well as remarkable chemical properties such as resistance to chemical damage. These properties, along with the low cost of extraction, led to widespread use of asbestos fibres in many forms and in many different fields throughout the 20th century.
There are two mineral forms of asbestos that have been processed and marketed:
- serpentine asbestos used for manufacture of chrysotile or white asbestos;
- amphibole asbestos used for anthophyllite, actinolite, tremolite and the two most widely used forms, amosite or brown asbestos, and crocidolite or blue asbestos.
These six recognised types of asbestos have different chemical compositions and dimensions.
The morphology and size of the fibres are two decisive criteria in terms of the pathogenic potential of asbestos. Other factors are also involved in the toxic properties of asbestos fibres, specifically their chemical composition and surface reactivity.
Since the primary route of entry of asbestos fibres into the body is via inhalation, health risks associated with exposure to these fibres are mainly related to respiratory system disorders.
All types of asbestos are classified as having known carcinogenic potential for humans (Category 1A) by the European Union, and as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC), bearing in mind that only the European classification is of regulatory relevance in France.
The main types of cancer associated with exposure to asbestos are lung cancer and mesothelioma which affects primarily the pleura (membrane surrounding the lungs) but also the peritoneum (membrane lining the abdominal cavity) and the pericardium (membrane surrounding the heart).
These diseases are progressive and may only manifest after a latency period of 20 to 40 years, or more.
Today, asbestos is the only proven risk factor for mesothelioma, although other factors, such as ionising radiation and certain viruses, are also thought to be involved in its development. Broncho-pulmonary cancer is the first cause of mortality in subjects exposed to asbestos and this risk is exacerbated by concomitant exposure to tobacco smoke (this is not the case for mesothelioma).
In addition, epidemiological data suggest that exposure to chrysotile fibres results in a lower incidence of cancer than exposure to amphibole asbestos, particularly concerning mesothelioma. This pattern is however contested for lung cancer.
Other non-cancer disorders
Inhalation of asbestos fibres may cause other non-cancerous pleural and pulmonary disorders.
Asbestosis, along with mesothelioma and lung cancer, are typical diseases of long-term exposure to asbestos. Asbestosis is caused by a reaction of pulmonary tissue to inhaled fibres. This reaction results in sclerosis of tissue, also known as pulmonary fibrosis, which decreases breathing capacity and may lead to respiratory insufficiency in the most serious cases. The risk and severity of asbestosis depend on the levels and duration of exposure.
Pleural plaques (lesion or fibrosis of a limited area of pleural tissue) are also characteristic of asbestos exposure.
Finally, pleurisy and diffuse pleural fibrosis (or thickening) may also occur following long-term exposure to asbestos.
Conditions of exposure
Asbestos was used intensively for nearly a century in many sectors, including building and public works (insulation, coating, etc.), the cardboard and paper industry, textiles, and in joints, friction linings for vehicles (brakes), and so on. In France, the use of asbestos reached a peak in the 1970s with an amount of about 150,000 t/year.
At that time, the main producers of asbestos were:
- Canada (Quebec) and Russia for chrysotile or white asbestos;
- South Africa for crocidolite or blue asbestos and amosite or brown asbestos.
However, deposits and outcrops of asbestos can also be found in a number of countries including the United States (California), Turkey, Bulgaria, Greece, and France (Haute-Corse and New Caledonia, in particular).
The risk is highly variable depending on the type of exposure and can lead to high concentrations of fibres. There are two major types of occupational exposure to asbestos:
- direct long or short-term exposure:
Long-term exposure is found for workers involved in extraction, processing and primary use of asbestos. In these situations, asbestos concentrations that workers are exposed to are not necessarily stable but occur over a relatively long period of time.
Short-term exposure is found for workers whose activities involve the handling of asbestos-containing materials. This is the case specifically for employees conducting repair or maintenance work on products and materials containing asbestos;
- passive occupational exposure:
This type of exposure concerns individuals who work in close proximity with employees who work directly with asbestos.
Since the ban on use of asbestos in 1997, extraction, processing and primary application activities are no longer carried out in France. However, a large number of materials containing asbestos are still in use (in partition walls, fire-retardant doors, suspended ceilings, piping, floor tiles, etc.) and represent a wide variety of sources of exposure. In 2007, the French National Research and Safety Institute (INRS) estimated that 1 to 2 million workers were potentially exposed to asbestos during repair and maintenance operations, including 900,000 in the building sector. The main professions at risk of inhalation of asbestos dust are:
- workers in asbestos removal companies;
- building and public works employees;
- building and public works (construction sector) personnel involved in demolitions or refurbishments;
- light work building professionals, repair and maintenance staff (plumbers, electricians, heating installers, painters, etc.);
- workers in waste treatment activities;
- workers on asbestos-bearing sites.
As a general rule, concentrations measured in situations of occupational exposure are far higher than those found for the general population.
Exposure of the general population
Non-occupational exposure to asbestos is more difficult to evaluate because of the typically low concentrations of fibres detected, and the lack of data concerning the frequencies and duration of exposure, as well as the types of fibres.
There are four types of exposure of the general population:
- secondary asbestos exposure which concerns individuals exposed to fibres brought into the home by workers for instance via work clothing;
- passive environmental exposure associated with asbestos pollution within public and private buildings;
- domestic exposure through household items containing asbestos (insulating panels, ironing boards, toasters, etc.);
- environmental exposure associated with natural sources (asbestos outcrops), industrial sources (asbestos mines and processing plants), and materials in buildings and various facilities.
Given the wide range of exposure conditions, the levels of exposure in the general population are highly variable and only estimates used to characterise typical situations are available.
The extent of the asbestos-related disease
In France, 10% to 20% of cases of lung cancer and 85% of mesotheliomas are thought to be caused by asbestos. An expert appraisal conducted in 1996 by the French National Institute of Health and Medical Research (Inserm) found that asbestos caused about 2000 deaths annually: 1250 cases of lung cancer and 750 of mesothelioma. In 2003, the French Institute for Public Health Surveillance (InVS) estimated at more 2000 the number of new cases of lung cancer attributable to occupational exposure to asbestos. Moreover, according to the National monitoring programme for mesothelioma (PNSM), set up in 1998 by the InVS, the number of new cases annually varies between 800 and 1200, i.e. 0.3% of the total cases of cancer. It is estimated that 77% to 90% of case of pleural mesothelioma in men are associated with occupational exposure to asbestos. However, this proportion is only 27% to 50% in women, which appears to indicate that the role of environmental exposure to asbestos may be underestimated.
Since these disorders manifest after a latency period of up to 40 years post-exposure, the number of deaths attributable to asbestos will continue to increase and could reach 1000 deaths per year in 2020 for mesothelioma for instance.
The vast majority of asbestos-related diseases are caused by occupational exposure. According to the InVS, about 25% of men aged 55 years and more have been exposed to asbestos during their working life. Given that the use of asbestos gradually decreased from the 1970s onwards, and that it was subsequently banned, this percentage is lower in younger men and was estimated at 10% in men aged 35 to 54 years in 2003.
According to the most recent data published by the National Health Insurance Fund for Salaried Workers (CNAMTS), the number of recognised cases of asbestos-related occupational disease (pleural plaques, mesothelioma, broncho-pulmonary cancer, etc.) was about 5400 in 2007. However, occupational diseases have low recognition rates, estimated at only 20% for lung cancer, for example. About 30% of these diseases occur in workers in the building and public works sector, in which a large number of workers specialising in repair and maintenance (plumbers, electricians, bricklayers, painters, etc.) are potentially exposed to asbestos. Asbestos exposure is currently the second most common cause of occupational disease and the most common cause of work-related deaths (excluding occupational accidents).
In 2005, the French Ministry of Health estimated the financial impact of compensation for victims to be between 1.3 and 1.9 billion euros per year. According to the same report, the cumulative cost over 20 years of care for victims of asbestos is thought to be between 26.8 and 37.2 billion euros.
Asbestos has been known to be hazardous since the beginning of the 20th century. Its use was however not regulated in France until 1977. A complete ban on asbestos was adopted in France in 1997. At the European level, all extraction, manufacturing, and processing of asbestos fibres was prohibited in 1999 by Directive 99/77/EC (with effective implementation at the latest on 1 January 2005).
Protection of the general population
French regulations intended to protect the general population from the risks of exposure to asbestos provide for detection and monitoring of materials containing asbestos and for information to occupants of buildings containing asbestos.
Flocked asbestos surfaces, insulation and suspended ceilings containing asbestos must be identified and monitored on a regular basis. An initial assessment of the state of repair of these materials must be carried out by a technical inspector using an evaluation chart that covers the apparent wear of the materials, their physical protection, exposure to shocks and vibrations, and air circulation. On the basis of the results of this assessment (score 1, 2 or 3), the owner of the building must:
- either conduct a periodic control on the state of repair within three years if the result is 1;
- monitor the level of dust accumulation if the result is 2;
- carry out suitable maintenance within 12 months if the result is 3.
An identification programme for other materials containing asbestos such as floor tiles, coatings, and asbestos-cement products, has also been in place since 2001.
Furthermore, regardless of the type of materials in place, the level of dust accumulation measured inside the buildings must not exceed the regulatory threshold of 5 fibres per litre (f/l).
For all buildings that were granted a building permit before 1 July 1997, i.e. the date on which asbestos use was banned in France, the results of this identification must be reported in an asbestos technical file (DTA). This file is the responsibility of the owner and must be updated at each intervention (removal, monitoring, maintenance, etc.) on asbestos-containing materials located in the building.
The main reference texts can be consulted on the website of the Ministry of Health.
Protection of workers
Specific regulatory provisions apply to the protection of workers concerning the risks of exposure to asbestos, in addition to general prevention measures in the work environment. In order to limit risks for workers, French regulations require that employers implement:
- common prevention measures for all activities with a risk of exposure to asbestos;
- specific prevention measures for removal and encapsulation of asbestos or items containing asbestos, and for operations on materials, equipment, or articles that may cause release of asbestos fibres;
Common prevention measures applicable to all activities involving contact with asbestos include:
- initial risk assessment;
- information and training of staff
- control of dust accumulation levels for asbestos fibres by analytical transmission electron microscopy (TEM) in order to guarantee compliance with limit values;
- measures concerning organisation of activities, monitoring of exposure, treatment of waste, and protection of the worksite environment;
- worker protection measures focused specifically on containment, operating techniques and methods that limit release as much as possible, implementation of collective protection measures and personal protection equipment suitable for each operation.
Depending on the dust accumulation levels and the processes implemented, Ministerial Orders adopted by the Ministry of Labour stipulate the technical rules to be followed by companies, collective protection measures and personal protection equipment, measures for the protection of worksite environments, and applicable provisions on completion of works.
Encapsulation activities and removal operations for asbestos and asbestos-containing materials are carried out by certified companies. Regulations recently abandoned the notion of friable versus non-friable asbestos for the implementation of protection measures.
Generally, young workers and temporary staff are prohibited from carrying out activities that may result in release of asbestos fibres.
The mean concentration of asbestos fibres, over eight hours of work, must not exceed 10 fibres per litre, as of 1 July 2015 (Article R.4412-100 of the French Labour Code, as set out in Ministerial Order 2012-639 dated 4 May 2012).
The main reference texts can be consulted on the website of the Ministry of Health.
 Decree No. 96-1133 dated 24 December 1996