A low level asbestos exposure case-control epidemiology study
Abstract
The potential for low levels of airborne asbestos exposure in public schools and in public and commercial buildings in the United States has generated concern due to the large population at risk and the definite human carcinogenicity of asbestos at high levels. To assist in the clarification of the risk associated with low level asbestos exposure and in the decision-making in asbestos management in schools and in other buildings, a case-control study was conducted to estimate the risk relationship between low levels of asbestos exposure and pulmonary cancer among Indiana public school teachers. This population at risk was chosen due to its relative stability and the availability of mortality records, as well as the controversy surrounding the entire issue of asbestos management in schools. A total of 236 lung cancer cases and 154 controls to be used in this case-control study were identified from a previous proportionate mortality rate study which had examined over 8,000 teachers' death certificates. The controls were selected from teachers who died of chronic bronchitis, emphysema or a chronic obstructive pulmonary disease. These diseases were selected because they are associated to smoking with a similar risk ratio as lung cancer (RR = 6-10). This was an important factor in selecting the controls because of the lack of smoking information in this study and smoking's known synergistic effects with asbestos. The teachers' work history and their potential for asbestos exposure, as well as the reliability of the information obtained on the presence or absence of asbestos, was determined to calculate the odds ratio. Odds ratios were calculated for different potential exposure scenarios, to estimate the association between the potential for low level asbestos exposure and pulmonary cancer. The scenarios were selected based on different degrees of potential exposure and reliability of the information on the presence or absence of asbestos in schools. Overall, the calculated odds ratios were not statistically significantly different from one even with an 80% confidence interval, and thus the null hypothesis, that the potential for low level asbestos exposure in schools does not increase the risk of developing lung cancer, was not rejected.
Degree
Ph.D.
Advisors
Zimmerman, Purdue University.
Subject Area
Public health
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