Asbestos Fibers and Other Elongate Mineral Particles: State of the ...

to enable toxicity testing. Another approach has
used a fiber size classifier [Deye et al. 1999], but
this has not provided large enough quantities of
EMPs for long-term inhalational exposure studies
in animals. NIOSH researchers are currently
evaluating the possibility of developing a fiber
size classifier with increased output to generate
much larger quantities of particles in restricted
size ranges for toxicological testing.
An outcome of the proposed research programs
should be an understanding of the relationships
between and among the results of human observational
studies and in vitro, short-term in vivo,
and long-term in vivo experimental studies.
Any research undertaken should be designed
to ensure that results can be interpreted and
applied within the context of other studies. For
example, EMPs used in long-term animal inhalation
studies should also be tested in in vitro/in
vivo assay systems so that findings can be compared.
The results of such experiments can help
to develop and standardize in vitro/in vivo assay
systems for use in predicting the potential toxicity
of various types of EMPs.
Government agencies, other organizations,
and individual researchers have already recommended
similar research strategies for evaluating
the toxicity of mineral and synthetic fibers
[Greim 2004; ILSI 2005; Mossman et al. 2007;
Schins 2002; Vu et al. 1996]. These published
strategies should be used as a foundation for
developing a research program.
Some research and improvements in sampling
and analytical methods used to routinely assess
exposures to EMPs can be done in the short
term, and because the results of the toxicological
studies provide a clearer understanding of EMP
characteristics that determine toxicity, it will be
necessary to ensure that the measurement techniques
used in evaluating workplace exposures
NIOSH CIB 62 • Asbestos
incorporate the exposure metrics used in determining
the dose-response effect found in animal
studies. The development of such exposure measurement
techniques should (1) reduce the subjectivity
inherent in current methods of particle
identification and counting, (2) closely quantify
EMPs on the basis of characteristics that are important
to toxicity, and (3) reduce cost and shorten
turnaround times in comparison with current
EM methods.
Toxicological, exposure assessment, and epidemiological
research should be conducted with
the overarching goal of developing information
necessary for risk assessments. Although
a framework for mineralogical research is not
provided in this Roadmap, research providing
a better understanding of mineralogical
physicochemical properties will help inform the
risk assessment process. Improved risk assessments
and analytical methodology are needed
to inform the development of new and revised
occupational exposure limits for control of exposures
associated with the production of EMPcaused
disease.
For those individuals who have an asbestosrelated
disease or are at high risk of developing
an asbestos-related disease, research is needed
to improve methods and clinical guidance for
screening, diagnosis, secondary prevention, and
treatment of EMP-caused diseases. The development
and validation of biomarkers of disease
and improved lung-imaging technologies can
lead to earlier diagnosis of asbestos-related disease.
It will also be important to advance knowledge
on how to effectively treat EMP-caused
diseases, especially malignant mesothelioma,
which is fatal in most cases. Accomplishing the
goals of early diagnosis and development of
treatment options can improve the quality and
quantity of life for those who develop asbestosrelated
disease.
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