NYC-WTC_000195164

NYC 9/11 Public Portal Document

. ASBESTOS REPROTEXT ® System Page 5 of 27

the pleural cavity or peritoneum), as well as lung cancer, laryngeal cancer, and gastrointestinal cancer (Dunn, 1989; Talcott Antman, 1988; lARC, 1998; Sittig, 1991). B. MESOTHELIOMA- 1. Although asbestos was thought to be the only cause of mesothelioma, a recent reclassification of these tumors has concluded that some cases may be spontaneous or related to nonasbestiform agents (Ilgren & Wagner, 1991). The latent period for developing mesothelioma can be as long as 68 years (Mowe et al, 1984). 2. All forms of asbestos have been linked with cancer in humans, but some forms are more potent than others in inducing cancer (ACGIH, 1991). Crocidolite seems to be the most potent form of asbestos for inducing tumors, followed by amosite, which in turn is more active than chrysotile (Stich, 1985). Ex-workers who had received exposure to crocidolite had increased risk of incidence of lung cancer, with squamous cell carcinoma being greater than adenocarcinoma (Deklerk et al, 1996). 3. Although chrysotile is 2 to 4 times less active than crocidolite in causing mesothelioma, it is of comparable potency in inducing lung cancer (Stayner et al, 1997; Landrigan et al, 1999). 4. A critical analysis of published studies has concluded that chrysotile is similar in potency to amphibole forms of asbestos for inducing malignant pleural mesothelioma (Smith Wright, 1998). Thus the "amphibole hypothesis", postulating the role of confounding exposure to amphiboles in chrysotile-linked cancers, has less experimental support. Some authors feel that chrysotile should be treated as being "virtually" as carcinogenic as the amphibole forms (Stayner et al, 1996). 5. An occupational cohort exposed exclusively to amosite had duration-related excess deaths from respiratory cancer and pleural and peritoneal mesothelioma; significant excess deaths were seen even with less than 6 months of employment. This study confirms that amosite is a hazard for these forms of cancer (Levin et al, 1998). 6. The rate of mesothelioma continues to rise, with estimated lifetime risks of 1.3 percent for persons bom in the UK between 1893 and 1948, 1.0 percent in those bom between 1943 and 1948, and 0.6 percent for those bom between 1948 and 1953. According to one model, deaths from mesothelioma will peak in approximately the year 2020, and may account for 1 percent of all deaths for men bom in the 1940s (Peto et al, 1995). 7. Mesothelioma is currently occurring in epidemic proportions in Europe. One study estimates the death rate will double by 2018, with approximately 1 in 150 men bom between 1945 and 1950 dying from it (Peto et al, 1999). C. With respect to occupations involving exposure to asbestos, British construction workers had the highest death rates from peritoneal cancer (PMR=990), and a relatively low rate (PMR=160) for pleural cancer. Other occupations had higher risks of death from pleural tumors, and no excess of peritoneal cancer. As a rule, the mortality risk for asbestosis followed that of peritoneal, rather than pleural, cancer (Coggon et al, 1995). D. Very small exposures to asbestos may be sufficient to increase the risk for cancer. Even a single, high-level acute exposure might be enough to increase the risk. IT IS NOT KNOWN IF THERE IS ANY SAFE DOSE FOR EXPOSURE TO ASBESTOS (Stich, 1985), although one survey suggests a threshold of 25-100 fibers/cc years for lung cancer (Browne, 1986). 1. A literature review concluded that a threshold for asbestos-induced mesothelioma may exist, based on a background of "spontaneous" and non-asbestos related cases

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NYC-WTC_000195168