Residential proximity to naturally occurring asbestos and mesothelioma risk in California.
BACKGROUND
Little is known about environmental exposure to low levels of naturally occurring asbestos (NOA) and malignant mesothelioma (MM) risk.


OBJECTIVE
To conduct a cancer registry-based case control study of residential proximity to NOA with MM in California.


METHODS
Incident MM cases (n = 2,908) aged 35 yr or more, diagnosed between 1988 and 1997, were selected from the California Cancer Registry and frequency matched to control subjects with pancreatic cancer (n = 2,908) by 5-yr age group and sex. Control subjects were selected by stratified random sampling from 28,123 incident pancreatic cancers in the same time period. We located 93.7% of subjects at the house or street level at initial diagnosis. Individual occupational exposure to asbestos was derived from the longest held occupation, available for 74% of MM cases and 63% of pancreatic cancers. Occupational exposure to asbestos was determined by a priori classification and confirmed by association with mesothelioma.


RESULTS
The adjusted odds ratios and 95% confidence interval for low, medium, and high probabilities of occupational exposures to asbestos were 1.71 (1.32-2.21), 2.51 (1.91-3.30), and 14.94 (8.37-26.67), respectively. Logistic regression analysis from a subset of 1,133 mesothelioma cases and 890 control subjects with pancreatic cancer showed that the odds of mesothelioma decreased approximately 6.3% for every 10 km farther from the nearest asbestos source, an odds ratio of 0.937 (95% confidence interval = 0.895-0.982), adjusted for age, sex, and occupational exposure to asbestos.


CONCLUSIONS
These data support the hypothesis that residential proximity to NOA is significantly associated with increased risk of MM in California.
Department of Public Health Sciences, University of California at Davis, Davis, CA 95616-8638, USA.
Xue-lei
XL
Pan
Howard W
HW
Day
Wei
W
Wang
Laurel A
LA
Beckett
Marc B
MB
Schenker
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001194:Asbestos / Q000009:adverse effects*; D002140:California / Q000453:epidemiology; D002273:Carcinogens; D016022:Case-Control Studies; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D005843:Geography; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008654:Mesothelioma / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D008875:Middle Aged; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis; D010190:Pancreatic Neoplasms / Q000453:epidemiology / Q000209:etiology; D010997:Pleural Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D012042:Registries; D012111:Residence Characteristics; D012307:Risk Factors; D017678:Sex Distribution
D002273:Carcinogens; D001194:Asbestos