College papers academic writing service


Asbestos and colon cancer lack of association in a large case-control study

Case-Control Studies The case-control studies retained for thorough evaluation after exclusion of studies that did not assess exposure to asbestos or did not meet other exclusion criteria are listed in Table 6.

  • Occupation-related risks for colorectal cancer;
  • Inhalation Toxicology 11 9;
  • Abstract Previous studies linking exposure to asbestos with human colon cancer have used mortality rather than incidence as their endpoint and have neither assessed nor controlled for confounding by diet, genetic factors, or other risk factors for colon cancer.

The details of the design aspects of those studies are presented in Table C. Page 221 Share Cite Suggested Citation: The National Academies Press. Of the 11 citations, one Dumas et al. Separate results for colon and rectal cancers could not be readily merged into a colorectal grouping as was done for the cohorts, but the results have been considered together in this review.

The findings of all 11 studies are summarized in Table 11.

IN ADDITION TO READING ONLINE, THIS TITLE IS AVAILABLE IN THESE FORMATS:

Thirteen results for any exposure were reviewed; eight point estimates exceeded 1. When they were combined, the average estimate of association was 1.

We next considered separately high-quality and lower-quality studies Figure 11. The case-control studies evaluating gradients of exposure Figure 11.

That is, among groups with colorectal cancer those with high exposure did not, in aggregate, have a greater risk of cancer than those with simply any exposure. Page 224 Share Cite Suggested Citation: Findings related to the response to asbestos by tissues in the colon and rectum were evaluated from several well conducted chronic rodent studies, four with inhalation exposure and six with dietary administration.

Supplemental Content

Page 225 Share Cite Suggested Citation: In contrast, the case-control studies lacked consistency: Strength of Associations For the case-control studies, the summary estimate of association was close to null and not statistically significant. Moreover, evidence of a dose-response relationship in the case-control studies was lacking. The overall observed risk estimate from cohort studies was modestly above 1.

Coherence Colorectal tumors are most commonly adenocarcinomas that arise in polyps. Multiple risk factors are associated with colon cancer, including age, familial predisposition, obesity, physical inactivity, and inflammatory bowel disease. The potential role of asbestos fibers as a cofactor has not been investigated in epidemiologic or experimental studies. Asbestos bodies and asbestos fibers have been identified in the colon.

In patients with inflammatory bowel disease and colon tumors, it is uncertain whether fibers accumulate secondarily at sites of mucosal injury or ulceration associated with inflammation or in an expanding tumor. As is the case for finding asbestos bodies at other sites, contamination during collection or processing of tissue samples is a possibility, as discussed in Chapter 4.

Looking for other ways to read this?

One animal study Amacher et al. One HHS 1985 of six lifetime, high-dose asbestos feeding studies in rodents HHS 1983, 1985, 1988, 1990a,b,c did, however, produced benign adenomatous colon polyps in rats after chrysotile exposure.

  • Mortality of asbestos cement workers using almost exclusively chrysotile fibre;
  • International Archives of Occupational and Environmental Health 59 5;
  • American Journal of Industrial Medicine 39 6;
  • Moreover, evidence of a dose-response relationship in the case-control studies was lacking;
  • This study suggests not only that occupational exposure to asbestos is not a risk factor for colon cancer in the general population of Los Angeles, but also that observed associations between asbestos and colon cancer should not be interpreted as causal unless confounding by nonoccupational factors has been evaluated and controlled;
  • Of the 11 citations, one Dumas et al.

Benign adematous colon polyps are a precursor of the most common type of colon cancer in humans. No polyps were produced by chronic asbestos feeding in hamsters. Conclusion The committee judged that some aspects of the evidence were supportive of a causal association: The overall lack of consistency or of the suggestion of an association among the case-control studies even those of the highest quality and the absence of convincing dose-response relationships in either type of study design, however, weigh against causality.

Thus, the committee determined that the evidence is suggestive but not sufficient to infer a causal relationship between asbestos exposure and colorectal cancer. Cancer in a factory using amosite asbestos. International Journal of Epidemiology 13 1: Mortality and cancer morbidity in cohorts of asbestos cement workers and referents.

British Journal of Industrial Medicine 47 9: Evidence for excess colorectal cancer incidence among asbestos-exposed men in the Beta-Carotene and Retinol Efficacy Trial. American Journal of Epidemiology 162 9: Effects of ingested chrysotile on DNA synthesis in the gastrointestinal tract and liver of the rat. Environmental Health Perspectives 9: Mortality in miners and millers of crocidolite in Western Australia. British Journal of Industrial Medicine 45 1: Presence of asbestos bodies in organs other than the lung.

Mortality due to asbestos-related causes among railway carriage construction and repair workers. Occupation Medicine London 49 8: Page 227 Share Cite Suggested Citation: Mortality from all cancers of asbestos factory workers in east London 1933-80. Occupational and Environmental Medicine 57 11: Mortality from respiratory and digestive cancers among asbestos cement workers in Italy.

Cancer Detection and Prevention 15 6: Construction occupations, asbestos exposure, and cancer of the colon and rectum. Journal of Occupational Medicine 36 9: Rectal cancer and occupational risk factors: A hypothesis-generating, exposure-based case-control study.

Asbestos and colon cancer: lack of association in a large case-control study.

International Journal of Cancer 87 6: Carcinoma of the colon in asbestos-exposed workers: Analysis of asbestos content in colon tissue. American Journal of Industrial Medicine 19 5: A cohort followed up to death. British Journal of Industrial Medicine 44 6: A cohort study of mortality among Ontario pipe trades workers.

Occupational and Environmental Medicine 61 9: Colon cancer, physical activity, and occupational exposures: Asbestos and colon cancer: Lack of association in a large case-control study.

American Journal of Epidemiology 135 8: Mortality of asbestos cement workers using almost exclusively chrysotile fibre.

Journal of the Society of Occupational Medicine 36 4: Occupational exposures and cancer of the colon and rectum. American Journal of Industrial Medicine 22 3: Cohort mortality study of women compensated for asbestosis in Italy. American Journal of Industrial Medicine 36 1: A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents.

American Journal of Industrial Medicine 39 6: Relation of soft-tissue sarcoma, malignant lymphoma and colon cancer to phenoxy acids, chlorophenols and other agents. Scandinavian Journal of Work, Environment and Health 7 2: Chronic inhalation toxicity of size-separated glass fibers in Fischer 344 rats.

  • The findings of all 11 studies are summarized in Table 11;
  • Thirteen results for any exposure were reviewed; eight point estimates exceeded 1;
  • Selikoff IJ, Seidman H;
  • Occupation Medicine London 49 8:

Fundamental and Applied Toxicology 20 4: Relationship between lung biopersistence and biological effects of man-made vitreous fibers after chronic inhalation in rats. Environmental Health Perspectives 102 Supplement 5: Research Triangle Park, NC: Page 228 Share Cite Suggested Citation: Research Triangle Park, North Carolina: Gastrointestinal carcinoma and occurrence of pleural plaques on pulmonary X-ray.

Journal of Occupational Medicine 22 12: Hodgson J, Jones R. Mortality of asbestos workers in England and Wales 1971-1981. British Journal of Industrial Medicine 43 3: Mortality of workers employed in two asbestos cement manufacturing plants.

British Journal of Industrial Medicine 44 3: Asbestos, cement, and cancer in the right part of the colon. Occupational and Environmental Medicine 51 2: A Cancer Journal for Clinicians 56: Incidence of cancer among Finnish patients with asbestos-related pulmonary or pleural fibrosis.

Cancer Causes and Control 10 1: A quantitative study on the distribution of asbestos bodies in extrapulmonary organs. Mortality experience in a cohort exposed to amosite.

Occupational and Environmental Medicine 55 3: Inhalation Toxicology 6 6: