Development of quantitative exposure data for a pooled exposure-response analysis of 10 silica cohorts.
BACKGROUND
Comprehensive quantitative silica exposure estimates over time, measured in the same units across a number of cohorts, would make possible a pooled exposure-response analysis for lung cancer. Such an analysis would help clarify the continuing controversy regarding whether silica causes lung cancer.


METHODS
Existing quantitative exposure data for 10 silica-exposed cohorts were retrieved from the original investigators. Occupation- and time-specific exposure estimates were either adopted/adapted or developed for each cohort, and converted to milligram per cubic meter (mg/m(3)) respirable crystalline silica.


RESULTS
Quantitative exposure assignments were typically based on a large number (thousands) of raw measurements, or otherwise consisted of exposure estimates by experts (for two cohorts). Median exposure level of the cohorts ranged between 0.04 and 0.59 mg/m(3) respirable crystalline silica. Exposure estimates were partially validated via their successful prediction of silicosis in these cohorts.


CONCLUSIONS
Existing data were successfully adopted or modified to create comparable quantitative exposure estimates over time for 10 silica-exposed cohorts, permitting a pooled exposure-response analysis. The difficulties encountered in deriving common exposure estimates across cohorts are discussed.
Unit of Environmental Cancer Epidemiology, International Agency for Research on Cancer, Lyon, France.
Andrea 't
A'
Mannetje
Kyle
K
Steenland
Harvey
H
Checkoway
Riitta-Sisko
RS
Koskela
Matti
M
Koponen
Michael
M
Attfield
Jingqiong
J
Chen
Eva
E
Hnizdo
Nicholas
N
DeKlerk
Mustafa
M
Dosemeci
D015331:Cohort Studies; D004391:Dust; D019652:Extraction and Processing Industry; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D012822:Silicon Dioxide / Q000009:adverse effects / Q000032:analysis*; D013997:Time Factors
D004391:Dust; D012822:Silicon Dioxide