Dose-response meta-analysis of silica and lung cancer.
OBJECTIVE
To examine the association between occupational exposure to silica and lung cancer from a systematic review (and meta-analysis) of the epidemiologic literature, with special reference to the methodological quality of observational studies.


METHODS
We searched Medline, Toxline, BIOSIS, and Embase (1966-December 2007) for original articles published in any language. Observational studies (cohort and case-control studies) were selected if they reported the result of dose-response analyses relating lung cancer to occupational exposure to silica after appropriate adjustment for smoking.


RESULTS
Ten studies (4 cohort studies and 6 case-control studies) met the inclusion criteria of the meta-analysis, nine of which contributing to the main analysis (dose-response analysis, no lag time). We found increasing risk of lung cancer with increasing cumulative exposure to silica, with heterogeneity across studies however. Posthoc analyses identified a set of seven more homogeneous studies. Their meta-analysis resulted in a dose-response curve that was not different from that obtained in the main analysis.


CONCLUSIONS
Silica is a lung carcinogen. This increased risk is particularly apparent when the cumulative exposure to silica is well beyond that resulting from exposure to the recommended limit concentration for a prolonged period of time.
Lacasse
Yves
Y
Centre de recherche, Centre de Pneumologie, Hôpital Laval, Institut universitaire de cardiologie et de pneumologie de l'Université Laval, 2725 Chemin Ste-Foy, Quebec, P. Quebec G1V 4G5, Canada. Yves.Lacasse@med.ulaval.ca
Martin
Sylvie
S
Gagné
Dominique
D
Lakhal
Lajmi
L
D002273:Carcinogens / Q000633:toxicity*; D016022:Case-Control Studies; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D016021:Epidemiologic Studies; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D012822:Silicon Dioxide / Q000633:toxicity*; D012829:Silicosis / Q000150:complications; D012907:Smoking / Q000009:adverse effects*
D002273:Carcinogens; D012822:Silicon Dioxide