Inhaled cellulosic and plastic fibers found in human lung tissue
provided by Roswell Park Cancer Institute
ohn L. Pauly, PhD, and colleagues in the Department of Immunology and the Division of Pathology at Roswell Park Cancer Institute (RPCI), have published the first report of the discovery of inhaled cellulosic and plastic fibers in human lung tissue. The fibers observed in the human lung may be bioresistant and biopersistent candidate agents contributing to the risk of lung cancer.
The results are published in the May, 1998 issue of Cancer Epidemiology, Biomarkers & Prevention. The objective of the study was to determine if inhaled plant (i.e., cellulosic, e.g., cotton) and plastic (e.g., polyester) fibers are present in human lung tissue and, if so, whether inhaled fibers are also present in human lung cancers. "Because airborne fibers are recognized to be ubiquitous, we hypothesized that some of these fibers might be inhaled," according to Dr. Pauly. "Further, we theorized that some of these fibers might escape the mucociliary mechanisms of the lung, particularly fibers inhaled by habitual smokers and those whose clearance mechanisms have been impaired."
To find the answers, the researchers obtained specimens of lung cancer of different histologic types and adjacent nonneoplastic lung tissue from patients undergoing lung surgery to remove a tumor. Using laboratory safeguards to prevent contamination, the specimens were compressed between two glass microscope slides and viewed by white light, fluorescent light, polarizing light and contrast illumination. Pilot experiments were then conducted with these procedures for viewing lung tissues for inhaled fibers. Near-term fetal bovine lungs and non-lung human tumors were used as controls.
Due to opposing light refraction characteristics between all fibers (except glass) and lung tissue, the researchers focused their attention on viewing fresh human lung tissue samples with a polarizing microscope.
"In one study of 114 human lung specimens (81 nonneoplastic and 33 malignant tissues) we were able to document the discovery of inhaled cellulosic and/or plastic fibers in 99 (87 percent) of the cases," according to Pauly. Of these 99 cases, 67 (83 percent) were nonneoplastic lung specimens and 32 (97 percent) were malignant lung specimens.
The inhaled fibers discovered were heterogeneous (e.g., type, color, shape, length, diameter, optical properties and other characteristics). Significantly, notes Pauly, "Most fibers exhibited little or no deterioration, supporting our premise that inhaled cellulosic and plastic fibers were bioresistant and biopersistent." While the research team makes no claim that these observed inhaled fibers are causative agents or confounders in lung pathogenesis, they are confident that the results of this study might be the impetus for additional studies which will provide insights into the complex and diverse mechanisms underlying malignant transformation.
Dr. Pauly points out that more people die worldwide of lung cancer than of any other disease and the incidence of lung cancer among smokers and non smokers is increasing. "The high mortality of lung cancer not associated with smoking has renewed interest in the risk assessment of occupational and environmental settings."
Roswell Park Cancer Institute was founded in 1898, is the nation's first and one of its largest cancer research, treatment and education centers and is the only National Cancer Institute-designated comprehensive cancer center in Western New York.
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