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

to EMPs, with periodic summary reporting of
findings. Representative EMP exposure data
could help identify worker populations or particular
types of EMPs warranting further study
(i.e., more in-depth exposure assessment; medical
surveillance; epidemiologic studies of particular
types of EMPs, processes, job tasks, occupations,
or industries; and toxicity studies of
particular EMPs). Occupational exposure data
should be collected and stored in a comprehensive
database. Information similar to that
described by Marchant et al. [2002] should be
incorporated into the database to support these
efforts. This could be accomplished in parallel
with efforts to develop an occupational exposure
database for nanotechnology [Miller et al. 2007]
or efforts to develop a national occupational exposure
database [Middendorf et al. 2007].
3.5.2 Collect and Analyze Available
Information on Health
Outcomes Associated with
Exposures to Asbestos Fibers
and Other EMPs
The body of knowledge concerning human
health effects from exposure to EMPs consists
primarily of findings from epidemiological
studies of workers exposed to asbestos fibers.
There is general agreement that workers exposed
to fibers from any asbestiform amphibole
mineral would be at risk of serious adverse
health outcomes of the type caused by
exposure to fibers from the six commercially
exploited asbestos minerals. NIOSH commented
on the most recently proposed MSHA
rule on asbestos (subsequently promulgated as
a final rule), stating that “NIOSH remains concerned
that the regulatory definition of asbestos
should include asbestiform mineral fibers
such as winchite and richterite, which were
of major importance as contaminants in the
NIOSH CIB 62 • Asbestos
Libby, MT, vermiculite” [NIOSH 2005]. To ensure
a clear science base that might support a
formal recommendation for control of occupational
exposures to all asbestiform amphibole
fibers, it would be reasonable to thoroughly
review, assess, and summarize the available
information on asbestiform amphiboles such
as winchite, richterite, and fluoro-edenite that
have not been commercially exploited.
It will also be important to quantitatively determine
the health risks posed by EMPs from
nonasbestiform amphiboles and to compare
them to the risks posed by fibers from asbestiform
amphiboles. If nonasbestiform amphibole
EMPs are, in fact, associated with some risk, a
quantitative risk assessment would be needed
to understand the risks relative to those associated
with exposures to asbestos fibers. If new
epidemiological and other evidence is sufficient
to support such a risk estimate, that could lead
to the development of risk management policies
for nonasbestiform amphibole EMPs distinct
from risk management policies for asbestos fibers.
Risk management policies that differ for
asbestiform and nonasbestiform amphiboles
would motivate the development and routine
use of new analytical methods that differentiate
asbestiform from nonasbestiform particles.
In addition to collecting and analyzing information
on health outcomes associated with exposures
to asbestiform EMPs and EMPs from
nonasbestiform amphiboles, similar information
related to other EMPs (e.g., erionite, wollastonite,
attapulgite, and fibrous talc) should be collected
for systematic analysis. Additional relevant information
may be gleaned from epidemiological
studies conducted on some SVFs (e.g., glass and
mineral wool fibers, ceramic fibers).
Surveillance and epidemiological studies generally
have been circumscribed by the long latency
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