On asbestos and Hanna High School cancer cluster
by Wm. Robert Johnston
2 October 2000
Let's review some medical facts that apply to the situation at Hanna High School:
- Asbestos can cause asbestosis, lung cancer, and mesothelioma, all of which are diseases of the lungs. It may, in sufficient doses (like with asbestos workers) be associated with gastrointestinal cancers. These diseases don't appear until 15 to 40 years after exposure. Asbestos is not easily transported to other parts of the body, so it cannot account for most of the cancers reported at Hanna.
- Asbestos is only harmful if it is in the form of airborne dust. If it is solid or encapsulated, it is not a problem and federal regulations recognize this. My understanding is that the asbestos at Hanna is encapsulated (this is true for the asbestos materials I have seen there). This is safe unless disturbed. Removing it in the next 30 days while students are in the building would disturb it.
- In the U.S. today, 23% of all deaths are due to cancer. Given the size of Hanna's faculty, random cases of cancer will eventually produce a "cluster" of three cancer deaths in the same year.
We cannot rule out that a proper study could find some common cause other than asbestos. The Texas Department of Health is initiating such a study, and this is a reasonable response. But any common cause may not even be from Hanna. Also, a common cause that is airborne is more likely to produce similar types of cancer with a consistent trend over time.
I have been "exposed" to Hanna for six years--three years as a student and three as a teacher. I am concerned that the time and taxpayer expense of a federal investigation may distract from addressing any real problems--airborne allergens being an important example. I also hate to see the district pushed to remove the asbestos immediately, when the removal itself could create a risk where there is little or none.
(printed in The Brownsville Herald 12 October 2000)
© 2000, 2003 by Wm. Robert Johnston.
Last modified 8 March 2003.
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