TABLE 2.

Lung Fiber Burdens in Malignant Mesothelioma Patients

Fiber type	Percent of patients with fibers	Percent of controls with fibers
Chrysotile	80	67
Tremolite	20	11
Crocidolite	59	16
Amosite	81	40
Other:
Mullite	98	98
Iron	88	65
Rutile	83	79
Muscovite	61	65
Silica	55	65

Note. In a study of young persons (age 50 yr or less at the time of diagnosis), the lungs of 69 patients who had died with malignant pleural mesothelioma and 57 controls selected from the national work-related disease surveillance system in the United Kingdom were analyzed by electron microscopy for fiber distribution. Increased odds ratios for mesothelioma were found for crocidolite, amosite, and tremolite; the contribution of chrysotile was less clear due to low biopersistence. Nonasbestos fibers probably made no contribution to mesothelioma in this study (McDonald et al., 2001).