Michael Harbut, M.D., the co-director of the Barbara Ann Karmanos Cancer Institute's National Center for Vermiculite and Asbestos-Related Cancers (NCVAC) and chief of the Center for Occupational and Environmental Medicine, reported the findings after studying a patient who was exposed to taconite dust as a child.
The patient, studied since 2004 and currently 55 years of age, was exposed as a child to taconite dust unknowingly by her father, a taconite miner from 1962-1969, who carried the taconite dust on his work clothes. Taconite is used in the production of steel and road-patching material. It has been mined in Michigan and Minnesota.
The patient has experienced increasing pain on her right side for the past 31 years, a persistent cough and wheezing. As the pain increased so did her medication. Using a new imaging approach, Harbut was able to show the progression of the patient's pleural plaque over a three year period, from 2005-2008. The patient's pleuritic pain, as well as the findings of her pulmonary function, physical exam and symptomology are consistent with those diagnosed with asbestosis and pleural plaques, as established by the American Thoracic Society.
These findings also support earlier human and animal reports that dusts produced by taconite mining can evoke the same biological responses as do other fibers already defined as asbestos or asbestiform materials.
A New Approach
Using a new radiography approach developed by Carmen Endress, M.D., FACR, associate professor of Radiology, Wayne State University School of Medicine and radiologist at the NCVAC, there was a documented increase in pleural plaques, causing erosion on the interior wall of the ribs.
"This action of the pleural plaque against the covering of the bone and the bone itself is a biologically plausible and an anatomically logical explanation of the unrelenting pain which some patients experience," said Harbut.
This new imaging approach involves enhancing images obtained on the 64-slice high resolution CT scan using the Vitrea imaging software program. By using this imaging approach, Harbut was able to demonstrate that:
- Evidence based on the CT findings, the physical examination, pulmonary function studies, epidemiology and history of the patient's intractable pleural pain meets the criteria for diagnosis of asbestosis. Combined with the known science of taconite dust, a link between the mine where the patient's father worked and the patient's disease was established.
- Due to the clarity and definition of this new imaging approach, it is more likely to detect asbestos-related diseases and cancer at an earlier stage.
- Earlier detection will allow the possibility for additional treatment options to manage the pain caused by pleural plaque beyond the narcotics often prescribed for patients with advanced stages of asbestos disease. This includes exploring other forms of traditional and nontraditional methods to control pain.
"Patients often require a lifetime of narcotics to allow functioning, but we are hopeful that with this new imaging technology, more selective pain management approaches with fewer side effects can be instituted resulting in a better quality of life,” Harbut said.
Redefining Asbestos
Finally, the report supports the identification of taconite, which has not yet been categorized as asbestos but causes a disease consistent with asbestosis, and recommends a reevaluation of the definition of asbestos. This is especially important within the context of legislative efforts to prohibit the use of asbestos.
These findings were featured in the July 20, 2009 edition of the International Journal of Occupational and Environmental Health.
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