The findings in this report are subject to at least five limitations.
First, occupation and industry codes that meet NCHS quality criteria are available
only for certain states and for certain years. Thus, PMRs only reflect the
industrial and occupational profiles of those states in those years. Second,
these codes represent only the usual industry and occupation as entered on
each death certificate, which is not always the industry and occupation in
which the decedent's causative exposure occurred. Third, the state of residence
at death is not always the state in which the decedent's causative exposure
occurred, especially given the typically long latency and chronic course of
the pneumoconioses. Fourth, slight differences exist in the ICD coding for
asbestosis between the 9th and 10th revisions. In the 10th revision, the rubric
for code J61 is "pneumoconiosis due to asbestos and other mineral fibers,"
whereas the rubric for the 8th and 9th revisions was simply "asbestosis."
The overall effect of this change is unclear but might have resulted in an
increase in the number of cases between the 9th and 10th revisions (i.e.,
between 1998 and 1999). Because occupational fiber exposures were predominantly
to asbestos, the net effect of this change probably is small; the trend of
increasing asbestosis deaths indicates no evidence of any substantial change
during 1998-1999. Finally, as with any data based solely on death certificate
information, cause of death information is subject to potential errors associated
with disease diagnosis, recording, and coding. For example, this information
can be impacted by temporal changes in public and medical awareness and practice.
In the years after the Farmington, West Virginia, mine disaster in 1968, the
nation's attention focused on hardships suffered by coal miners, with a possible
attendant rise in recording of CWP on death certificates. More recently, focus
on asbestosis has increased, with a marked increase in asbestos-related litigation.8 This trend also has raised awareness of asbestosis,
likely leading to its more frequent diagnosis and recording on death certificates.
In addition, new technologies such as computed tomography are used increasingly,
resulting in increased diagnostic sensitivity for pneumoconiotic diseases.