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Clean-up work on a building containing
an excessive amount of asbestos. |
Is it possible to determine with certainty the links between
various pulmonary pathologies and the patient's exposure to asbestos
in the past? Up to now it has been difficult to compare the results
obtained by various laboratories carrying out lung tissue sample analyses.
Thanks to a European research project - the first of its kind in the
world - considerable advances on this sensitive public health issue
are guaranteed. The accumulation of several thousand reference samples
will provide the metrological tools needed to determine the origin
of these pathologies.
Our knowledge of the serious lung symptoms
attributable to asbestos fibres goes back some time and, while increasingly
strict preventive measures banning this material have now been adopted,
it has nevertheless continued to be used for too long and without
proper precautions in the construction industry and other industrial
applications. Essentially, the damage caused by the inhalation of
asbestos fibres can be classified under four types of pathology. Asbestosis,
a generalised lung fibrosis, which was very widespread in the past
as a result of major cumulative exposure to asbestos, is now becoming
rarer - at least in its advanced form - thanks to the obligatory precautions
now taken in the industries handling this material. Mesothelioma,
a tumour of the pleura or the peritoneum caused specifically by asbestos
may become apparent only decades after the original exposure. Diffuse
or localised fibrosis (pleural plaques) of the pleura, less serious
than the preceding pathology, is also a disease closely linked to
the inhalation of asbestos. Finally, bronchial cancer may be induced
by the inhalation of asbestos - but may also result from many other
causes - the commonest of which is smoking.
Lung tissue samples, dried and homogenised,
used as certified reference materials (seen under a scanning
electron microscopy) |
Objective presence?
Nowadays, these diseases are recognised as occupational diseases,
and the victims are joining forces to claim compensation for the
damage they have suffered. But how are the merits of their claims
to be backed up? "Apart from carrying out an occupational case study,
from which it is often difficult to produce tangible evidence, the
only way of actually assessing the existence and magnitude of exposure
to asbestos - and, where appropriate, establishing a link with pathologies
currently present - consists in finding objective evidence of the
presence of fibres in pulmonary samples taken from the patients
concerned," explains Pascal Dumortier, of the Erasmus Hospital (Brussels),
one of the partners in the European project that has set about tackling
this problem.
In Europe, some 30 or so specialised laboratories are carrying out
such biometrological analyses. "The problem," adds Dr Dumortier, "is
that their work is based on totally non-standardised procedures, thereby
ruling out valid comparisons and any semblance of a common approach."
The need for reference
materials As a direct result of this deficiency, a research project
was launched in 1995 under the Standards, Measurements and Testing
programme with the aim of producing a range of "certified reference
materials" (CRMs), - biological or physico-chemical samples(1)
with a defined composition serving as a standard for validating
analyses. In the case in point, the CRMs are in fact lung tissue
samples which were taken during autopsies on patients who had suffered
exposure to asbestos and which were duly calibrated according to
their fibre content. "In the case of asbestos pathologies," continues
Dr Dumortier, "it is essential, for the purposes of expert medical
and legal reports and other scientific work, that we are able to
compare the results obtained on lung tissue samples in terms of
fibre concentration and granulometry." From now on the CRMs will
serve as standards to be supplied to laboratories, enabling them
to adopt a common language when reporting on, and interpreting,
analytical results.
From feasibility to
practice During the initial phase, five European laboratories, with
the Finnish Institute of Occupational Health (Helsinki) acting as
coordinator, conducted a feasibility study on the production of
a CRM for the analysis of asbestos in lung tissue. This study has
shown that it is possible to produce high-precision measurements
based on lung tissue samples that are sufficiently dry and homogeneous.
The second phase of the project brings eight EU laboratories together
with the task of producing a range of operational CRMs which will
be used to supply all the European centres involved in these analyses.
The development of these CRMs - several thousand reference samples
will be distributed - will provide the metrological tools needed
to diagnose whether or not a pathology is attributable to exposure
to asbestos, according to harmonised European standards.
The result of this research is of interest not merely to the analysis
laboratories. Instrument manufacturers also require CRMs to check
the precision of their equipment, notably in the electron microscopy
sector. Furthermore, the international distribution of these standardised
samples - which have no equivalent in other parts of the world,
especially the United States - represents a genuine scientific and
economic endeavour.
(1) There are some 400 certified reference
materials in Europe in a wide variety of areas (biomedical, environment,
water and food microbiology, agriculture and physico-chemical properties
of industrial materials).
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For
more information on this project,
