Only study participants 18 years of age and
Moderate to severe restriction in breath-
older were eligible for x-rays. Three B-readers
ing capacity was found in 1.8% of all those
(experts in reading chest x-rays for asbestos-
tested.
related lung abnormalities) found that 18% of
Moderate to severe restriction in breathing
those x-rayed had abnormalities in the lining of
capacity was found in 5.5% of former W.R.
their lungs (pleural abnormalities). The risk of
Grace workers.
pleural abnormalities increased with increasing
In those under 18 years of age who were
age and increasing length of residence in the
tested, no one had moderately to severely
Libby area. The rate of pleural abnormalities
restricted lung function.
found in groups within the United States that
Other factors associated with restrictive
have no known asbestos exposures ranges from
abnormalities included being a non-W.R.
0.2% to 2.3%. Interstitial abnormalities (abnor-
Grace/Zonolite worker exposed to vermicu-
malities of the lung tissue itself) were found in
lite, having had chest surgery, and being
0.8% of the persons undergoing chest x-rays.
overweight.
An x-ray was considered abnormal if two of
three B-readers found an abnormality consistent
Preliminary Findings of
with asbestos exposure.
Computed Tomography
Factors most strongly related to having pleu-
Study in Libby, Montana
ral abnormalities were (1) having been a W.R.
ATSDR initiated a study in response to the
Grace/Zonolite worker, (2) having household
Libby community's interest in the use of com-
contact with a W.R. Grace/Zonolite worker, and
puted tomography testing. The overall goal was
(3) being a male. The odds of finding a pleu-
to determine if computed tomography is useful
ral abnormality were 1.7 to 4.4 times greater
as a screening tool for detecting asbestos-related
(depending on age) for former W.R. Grace
lung abnormalities in persons who had indeter-
workers as compared to nonworkers. The odds
minate chest x-rays in Libby, Montana.
of finding a pleural abnormality were 3.3 times
greater for females who had household con-
The 353 participants of the 2000 Medical
tact with W.R. Grace workers as compared to
Testing Program who were participants in the
women who had no household contacts with
computed tomography study were in one or
these workers. In non-household contacts, the
more of the following categories:
odds of finding a pleural abnormality were five
times greater for men than for women. Other
18 years of age and older
factors associated with significantly increased
indeterminate chest x-ray--(Only one of
odds of pleural abnormalities included smok-
the three B-readers reported an abnormality
ing, playing in vermiculite piles, duration of
along the lining of the lungs or chest wall
residence in Libby, asbestos exposure in the
(pleural abnormalities) on participant's chest
military, and increased body mass index.
x-ray)
former vermiculite mine and mill work-
Lung function tests (spirometry) were offered to
ers--55 participated
their household contacts--99 participated
are as follows:
persons with exposure to vermiculite as a
Being a current smoker was the strongest risk
result of past direct recreational behaviors--
factor for restrictive abnormalities.
199 participated
44 chapter 3
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