Examples of Health Studies
18 years of age and older were eligible for
x-ray testing. At least two of three experts who
Medical Testing of Individuals
reviewed the x-rays found that 994 of those
Potentially Exposed to Asbestoform
5,590 participants (18%) had pleural abnormali-
Minerals Associated with
ties (thickening or scarring of the pleural lining
of the lungs). The risk of pleural abnormalities
Vermiculite in Libby, Montana
increased with age and length of residence in
ATSDR conducted a medical screening program
the Libby area. Forty-eight percent (159 of 328)
in Libby to evaluate the health of residents and
of former vermiculite facility employees had
former residents who were exposed to asbestos-
pleural abnormalities. Five percent (6 of 122)
contaminated vermiculite, a mineral mined and
of those participants who reported no apparent
processed in Libby for many years. From July to
exposure had pleural abnormalities. Factors
November 2000, there were 6,149 participants
most strongly related to having pleural abnor-
in the asbestos medical testing sponsored by
malities were (1) having been a vermiculite
ATSDR. When testing was offered again from
facility worker, (2) having household contact
with a worker, and (3) being a male. The risk of
In fiscal year 2001, ATSDR
having a pleural abnormality was almost 8 times
greater for former vermiculite facility workers
provided funds to seven states
when compared to people of the same age who
to conduct asbestos-related
had not worked in the vermiculite facility. The
risk of finding a pleural abnormality was 3.3
health activities for
times greater for females who have household
communities that received
contact with vermiculite facility workers when
compared to women who have no household
contaminated Libby ore.
contacts with these workers. The risk of having
a pleural abnormality was 5 times greater for
July to September 2001, an additional 1,158
men than for women.
participants were screened in Libby. Those eli-
gible for testing included former W.R. Grace
tion tests were offered to all study participants.
workers from Libby and people who lived,
Being a current smoker was the strongest
worked, or played in Libby for at least 6 months
risk factor for restricted breathing. Moder-
before December 31, 1990, when the vermiculite
ate-to-severe restriction in breathing capacity
mine and facilities closed. W.R. Grace owned
was found in 5.7% of former W.R. Grace work-
and operated the vermiculite mining and pro-
ers. Moderate-to-severe restriction in breathing
cessing operations in Libby for a number of
capacity was found in 2.2% of men who were
years.
over 18 years of age and 1.6% of women who
were over 18. In those under 18 years of age
The testing included an interview to obtain
who were tested, no one had moderate to severe
information needed to better analyze the health
restricted lung function. Other factors affecting
information; a three-view chest x-ray; and a
restricted breathing included (1) being a non-
worker (that is, not working in a vermiculite
the testing that was conducted from July to
facility) who was exposed to vermiculite,
November 2000 include the following:
(2) having had chest surgery, and (3) being
overweight.
44 chapter 3
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