A multiplicity of etiologic factors can induce
interstitial pulmonary fibrosis. For the pathological-
anatomical diagnosis of asbestosis
I-IV, histopathological and supplementary
lung dust analyses are essential. Due to the
fact that minimal asbestos-associated fibrotic
changes in lung tissue are not detectable by
computer tomography (CT or HRCT) or chest
radiography, pathological-anatomical verification
is needed for a valid diagnosis.
The pathological-anatomical diagnosis
of asbestosis requires detection of an appropriate
pattern of interstitial fibrosis and
of asbestos bodies: both components must
be present.
Quantitative lung dust analysis is the
gold standard for the quantification of asbestos
body concentration and, in combination
with histological examination, it is an effective
tool for evaluation of asbestos-associated
lung fibrosis.
Asbestos is a commercial term used to
describe a group of natural mineral fibres
that share some physical properties. Asbestos
is often described as durable fibres that,
after inhalation, persist for many decades in
the lung and cause diseases. But asbestos itself
is not a single kind of mineral fibre. The
term asbestos covers an inhomogeneous
group of several different mineral fibres. For
an understanding of the genesis of asbestosassociated
diseases we must consider the
differences between the two mineral groups
chrysotile and amphibole asbestos. Chrysotile
is a serpentine mineral that has been
shown to differ markedly from amphibole asbestos.
Chrysotile is rapidly eliminated from
the lung whereas amphibole asbestos persists
over decades. Fibre dose, fibre dimensions
and fibre biopersistence are proposed
to be the decisive factors in fibre toxicity. The
biopersistence of synthetic mineral fibres has
been shown to be a good predictor of their
pathogenic potency.
Biopersistence studies have shown that
chrysotile is cleared rapidly from the lung and
accordingly has lower fibrogenic and carcinogenic
potential than amphibole asbestos.
There is new scientific evidence for the lack
of fibrogenic potency of chrysotile (with the
exception of overload situations) which is
neither durable nor accumulated. The likelihood
that chrysotile could exert a lasting or
chronic biological effect (with the exception
of overload situations) must be considered to
be extremely low. Because chrysotile and amphibole
asbestos often occur together at the
workplace and/or because chrysotile is often
contaminated with amphibole asbestos
(tremolite), simultaneous occupational exposure
to the two kinds of asbestos is frequent.
Because contamination of chrysotile with
amphibole asbestos cannot be excluded, a
safe use of chrysotile is not possible and a
worldwide ban is still a necessary objective.
