Progression of pneumoconiosis in coal miners after cessation of dust exposure: a longitudinal study based on periodic chest X-ray examinations in Hokkaido, Japan.
BACKGROUND
The progression rate of pneumoconiosis in retired coal miners over ten years has not been studied in Japan.


METHODS
A retrospective longitudinal study was undertaken using chest X-rays of 1091 pneumoconiosis subjects in Hokkaido, Japan between 1985 and 2005.


RESULTS
The final numbers of subjects were 207 (19% of the entry) after 1 decade and 85 (8%) after 2 decades. Sixty-two percent of 207 subjects after 1 decade and 29% of 85 showed progression in 2 decades. Thirty-one percent of ILO category 1 and 55% of category 2 subjects showed progression to complicated pneumoconiosis after 1 decade, and 6% (4 of 64) of category 1 and 6% (5 of 77) of category 2 subjects progressed to complicated pneumoconiosis during 2 decades.


CONCLUSIONS
The progression of pneumoconiosis was observed after the cessation of dust exposure, especially during the first 10 years.
Kimura
Kiyonobu
K
Clinical Research Center for Pneumoconiosis, Hokkaido Chuo Rosai Hospital (Workmen's Accident Compensation Hospital), Japan Labor Health and Welfare Organization, Iwamizawa. ranrankk@cello.ocn.jp
Ohtsuka
Yoshinori
Y
Kaji
Hiroshi
H
Nakano
Ikuo
I
Sakai
Ichiro
I
Itabashi
Koichi
K
Igarashi
Takeshi
T
Okamoto
Kenzo
K
D000368:Aged; D003032:Coal Mining / Q000639:trends*; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008400:Mass Chest X-Ray / Q000639:trends*; D008875:Middle Aged; D011009:Pneumoconiosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology*; D012189:Retrospective Studies; D013997:Time Factors