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Short asbestos fibres

On 3 March 2004, the Conseil d'Etat (French Council of State) acknowledged the responsibility of the state in its wrongful failure to take steps to prevent risks associated with occupational exposure to asbestos dust. This failure is particularly characterised by an absence of studies and lack of regulations.

This decision, concerning one of the most important health crises in France in recent years, formed a key guidance element for measures to reinforce expertise ability and global monitoring of occupational risks which feature in the French Occupational Health Plan (PST) 2005-2009.

The hazardous nature of asbestos was identified at the turn of the 20th century, but prevention and protection measures were taken much too late. In France, asbestos was not recognised as a source of occupational illness (asbestosis) until 1945. Its use was only regulated in 1977 after all forms of asbestos had been classified as carcinogenic by the IARC (although this had been proven in the mid 1950s by Doll and then Wagner). An outright ban on all uses of asbestos was not put in place until 1997 in France and confirmed at European level by Directive 99/77/EC prohibiting any extraction, manufacture or processing of asbestos fibres by 1 January 2005 at the latest.

Regulatory provisions on the protection of the general and occupational population against risks associated with asbestos dust inhalation stipulated measures concerning the accumulation of asbestos fibre dust. However, following an international consensus adopted in the late 1960s, only fibres defined as being the most hazardous, measuring over 5 microns long and less than 3 microns wide and whose length/width ratio exceeds 3, were taken into account.

Dodson et al. (2003) question the scientific community on the possible pathogenicity of short asbestos fibres in a publication entitled "Asbestos fiber length as related to potential pathogenicity: a critical review" which appeared in the "American journal of industrial medicine".



On 7 February 2005, Afsset received a solicited request from its funding ministries (Health, Environment and Employment) to conduct an assessment of the risks associated with short asbestos fibres, i.e. fibres defined as being shorter than 5 microns. As a first step to carry out this solicited request, an expert assessment had to be conducted on the contents and potential impact of the publication behind this request as a first step.

Once the publication had been analysed, the requested expert assessment focused mainly on the following issues:

 Assessment of fibres less than 5 microns long, particularly with regard to publications post 1996;
 Characterisation of the granulometric distribution of asbestos fibres depending on the exposed population (general or occupational) and the type of asbestos;
 Assessment of the health risks associated with exposure to short asbestos fibres on the basis of the granulometric distribution previously established.

Moreover, this assessment should enable an appraisal of the relevance of regulatory provisions in force, particularly on current thresholds and the absence of measures concerning dust accumulation for short asbestos fibres.

Working method:

The Agency formed a restricted panel of experts attached to the Committee of Specialised Experts "Air" in order to conduct an expert assessment of the contents and impact of the publication by Dodson et al. (2003).

The Agency appointed the Research Laboratory on Inhaled Particules (LEPI) to carry out an overview and second analysis of the granulometric distribution of asbestos fibres depending on their type (chrysotile, amphiboles) and the circumstances in which the general population is exposed (indoor or outdoor environment, type of materials present, etc.).

The Agency asked the French National Institute of Health and Medical Research (Inserm) to draw up a bibliographical report of current data on the pathogenicity of "short" asbestos fibres. The work analysed touched on epidemiology, experimental studies, biometrology and air sampling analyses. Accordingly, a review will be carried out of data on the presence of short asbestos fibres in the atmosphere, their biological effects and the significance of their presence in biological samples.

Lastly, the Agency finalised the creation of an ad hoc working group to carry out this solicited request.

The health risk assessment also addressed the issue of occupational health.




On 9 January 2006, the Agency sent its funding ministries the results and conclusions of the critical review of the article by Dodson et al. (2003). The experts thereby considered this article admissible, even if it only presented partial data on "short" fibres, and pointed out that this type of fibre can present toxic effects. The expert group deemed the currently available data sufficient to consider that a risk of zero to humans has not been demonstrated. It is not sufficient enough, however, to characterise this risk, including in metrological terms, and to provide a satifactory solution for managing this risk. The group therefore recommends that the further investigations planned by Afsset be carried out.

 

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Nanotechnologies cover a large number of technological fields all of which concern nanometrically sized structures (a nanometre = 10-9 m). Electronics and information and communication technologies are examples of such fields.
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