Asbestos fibers contributing to the induction of human malignant mesothelioma

Our plain-English summary of Asbestos fibers contributing to the induction of human malignant mesothelioma, by Y. Suzuki, S.R. Yuen (Annals of the New York Academy of Sciences, 2002).

The study

• Authors: Y. Suzuki, S.R. Yuen
• Journal: Annals of the New York Academy of Sciences
• Published: 2002;982:160-76
• Cited by: 59 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Unlabelled: To elucidate the features of the asbestos fibers contributing to the induction of human malignant mesothelioma, we used high-resolution analytical electron microscopy to determine the type, number, and dimensions of asbestos fibers in lung and mesothelial tissues in 168 cases of mesothelioma.

Results: 1. Asbestos fibers were present in almost all of the lung and mesothelial tissues from the mesothelioma cases. 2. The most common types of asbestos fibers in lung were either an admixture of chrysotile with amphiboles, amphibole alone, and occasionally chrysotile alone. In mesothelial tissues, most asbestos fibers were chrysotile. 3. In lung, amosite fibers were greatest in number followed by chrysotile, crocidolite, tremolite/actinolite, and anthophyllite. In mesothelial tissues, chrysotile fibers were 30.3 times more common than amphiboles. 4. In some mesothelioma cases, the only asbestos fibers detected in either lung or mesothelial tissue were chrysotile fibers. 5. The average number of asbestos fibers in both lung and mesothelial tissues was two orders of magnitude greater than the number found in the general population. 6. The majority of asbestos fibers in lung and mesothelial tissues were shorter than 5 micro m in length.

Conclusions: 1) Fiber analysis of both lung and mesothelial tissues must be done to determine the types of asbestos fibers associated with the induction of human malignant mesothelioma; 2) short, thin asbestos fibers should be included in the list of fiber types contributing to the induction of human malignant mesothelioma; 3) RESULTS support the induction of human malignant mesothelioma by chrysotile.

In plain English

The authors used high-resolution analytical electron microscopy to identify the type, number and size of asbestos fibers in tissue from 168 malignant mesothelioma cases (156 pleural, 12 peritoneal). Both tissues were examined in 74 cases, lung only in 45, and mesothelial tissue only in 49. Fibers were found in 117 of 119 lung samples and 114 of 123 mesothelial samples. Amosite was the most numerous lung fiber on average. In mesothelial tissue, chrysotile was most common, present in 112 of 123 cases. Chrysotile outnumbered amphibole fibers 30.3 to 1 in the cases whose mesothelial fibers were counted (22 per the Results, 13 per the Discussion). Only chrysotile was found in both tissues in 18 of 74 cases. Counts exceeded a general-population average in 45 of 49 lungs and 18 of 22 mesothelial samples. Of 10,575 fibers measured, 89.4% were shorter than 5 micrometers; 2.3% fit Stanton's dimensions for long, thin fibers. The authors concluded that both tissues should be analyzed, that short, thin fibers should be considered carcinogenic, and that their results support chrysotile as a cause of mesothelioma.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Tissue fiber burden study (case series): asbestos fibers counted, identified and measured by high-resolution analytical (transmission) electron microscopy in lung and mesothelial tissues from mesothelioma cases
• Who was studied: 168 cases of human malignant mesothelioma (164 males, 4 females; 156 pleural, 12 peritoneal; definite or probable diagnosis). Both lung and mesothelial tissues were examined in 74 cases, lung only in 45, and mesothelial tissue only in 49. Fiber counts per gram were done in 22 cases (lung and mesothelial tissue) and in 27 more cases (lung only). The article does not state where or when the cases were collected; the authors were at Mount Sinai School of Medicine, New York.
• Exposure: Exposure was not measured directly. The authors measured asbestos fibers found in tissue: chrysotile, amosite, crocidolite, tremolite/actinolite and anthophyllite. Patients' occupations were diverse, including asbestos insulators, pipe fitters, electricians, shipyard workers, U.S. Navy servicemen, sheet metal workers, power plant workers, boiler men, brake lining mechanics, fire fighters and family members of asbestos workers.
• Main results:
  • Asbestos fibers were found in 117 of 119 lung tissues (98.3%) and in 114 of 123 mesothelial tissues (92.7%).
  • In lung (119 cases), the fibers found were a mix of chrysotile with amphiboles in 43/119 (36.1%), amphiboles alone in 43/119 (36.1%), and chrysotile alone in 31/119 (26.1%).
  • In mesothelial tissue, chrysotile (alone or with amphiboles) was found in 112 of 123 cases (91.1%). Chrysotile alone was found in 90 of 123 (73.2%).
  • Among the 74 cases where both tissues were examined, chrysotile was the only type found in both lung and mesothelial tissue in 18/74 (24.3%).
  • In mesothelial tissues, the total number of chrysotile fibers was 30.3 times the total number of amphibole fibers. This ratio comes only from the cases with fiber counts in mesothelial tissue, not from all 123 cases. The Results describe the comparison as made in 22 cases, while the Discussion says it was examined in 13 of those 22 cases.
  • In lung tissue from 49 cases, the average total was 56.4 million fibers per dry gram. Amosite was the most numerous type on average (36.9 million fibers per dry gram), followed by chrysotile (19.4 million).
  • Lung fiber counts were greater than the general population average of 0.44 million fibers per dry gram (a figure from the authors' earlier study) in 45 of 49 cases (91.8%).
  • Mesothelial tissue fiber counts were greater than the general population average of 0.41 million fibers per dry gram in 18 of 22 cases.
  • Of the chrysotile fibers measured, 34.2% (2,921/8,536) were in lung and 65.8% were in mesothelial tissues. Most amphibole fibers were in lung (for example, 93.3% of amosite fibers). The authors interpreted this as showing that chrysotile moves from lung to mesothelial tissue more readily than amphiboles.
  • Chrysotile fibers were short and thin: average (geometric mean) length was 0.42 micrometers in lung, 0.39 in hyaline plaque and 0.35 in tumor, and average width was 0.04 micrometers.
  • Of all 10,575 fibers measured, 89.4% were shorter than 5 micrometers.
  • Only 247 of the 10,575 fibers (2.3%) fit Stanton's dimensions (longer than 8 micrometers and thinner than 0.25 micrometers).
• The authors' conclusion: The authors concluded that short, thin asbestos fibers should be considered carcinogenic because they were the main fiber type found in these tissues. They also concluded that fiber analysis of both lung and mesothelial tissue is needed to determine the fiber types involved, and that their tissue burden findings further support the view that chrysotile is capable of inducing human malignant mesothelioma.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Chrysotile, Amphibole Group, Amosite, Crocidolite, Tremolite, Actinolite, Anthophyllite.

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