Lung cancer mortality among silicotic workers in Hong Kong--no evidence for a link.
BACKGROUND
The link between silica dust/silicosis and lung cancer is still very controversial. We examined the relationship between silica dust exposure and/or silicosis and lung cancer in a large cohort of silicotic workers in Hong Kong.


METHODS
All workers with silicosis in Hong Kong diagnosed during the period 1981-1998 were followed up till the end of 1999 to ascertain their vital status and causes of death. Standardized mortality ratio (SMR) for lung cancer and other major causes of death were calculated. Axelson's indirect method was used to adjust for smoking effect. Multiple Cox regression models were carried out to examine the exposure-response relationship between silica dust and lung cancer.


RESULTS
About 10% (86) of all 853 deaths were from lung cancer, giving a SMR of 1.69 [95% confidence interval (CI) 1.35-2.09]. Lung cancer SMR for caisson and surface construction workers were 2.39 (95% CI 1.50-3.62) and 1.61 (95% CI 1.21-2.10), respectively, which became 1.56 (95% CI 0.98-2.36) and 1.09 (95% CI 0.82-1.42) after adjusting for smoking. No consistent exposure-response relationship was detected between silica dust or severity of silicosis and lung cancer death.


CONCLUSIONS
Our cohort study did not offer positive support to a link between silica or silicosis and lung cancer.
Yu
I T S
IT
Department of Community and Family Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China. iyu@cuhk.edu.hk
Tse
L A
LA
Leung
C C
CC
Wong
T W
TW
Tam
C M
CM
Chan
A C K
AC
D000328:Adult; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000401:mortality*; D008297:Male; D009369:Neoplasms / Q000453:epidemiology; D016273:Occupational Exposure; D012189:Retrospective Studies; D012822:Silicon Dioxide / Q000633:toxicity*; D012829:Silicosis / Q000453:epidemiology* / Q000401:mortality
D012822:Silicon Dioxide