Is There a Link Between Asbestos and Colon Cancer?

Both the National Institute of Health and the Agency for Toxic Substances and Disease Registry agree that, as yet, there is no strong evidence for a positive connection between colon cancer and exposure to asbestos. Numerous studies have linked the inhalation of asbestos to lung cancer, but no such widespread studies have proven that inhaling or ingesting asbestos causes gastrointestinal cancers, like stomach or colon cancer. Small, retrospective studies where asbestos workers had an increased probability of dying from colon cancer only provides a beginning to explore the connection between the popular building material and cancerous growths.

The main studies cited to raise people's concern over asbestos exposure looked at employees who are regularly exposed to asbestos, such as installers of insulation and manufacturers of asbestos acoustic ceiling tiles. Two different studies, accounting for nearly 20,000 employees, showed them 1.5 times more likely than a nonemployee to die of colecteral or gastrointestinal cancer. However, these studies are still relatively small and do not establish a causal connection between the asbestos and those cases of cancer. Other small studies that looked at people's exposure through drinking water showed statistically insignificant danger that could be better accounted for by established cancer risks like smoking.

Another reason to doubt a connection between colon cancer and asbestos is that increased exposure does not seem to increase risk. For instance, with lung cancer, the longer a person is exposed to asbestos, the more likely they are to develop lung cancer. This relationship is not true for colon or other gastrointestinal cancer. Furthermore, scientists have studied the oral ingestion of asbestos in animals. In these experiments, they found no biological methods by which asbestos encouraged cancerous growth. As with many environmental factors in incurable diseases like cancer, additional evidence from prospective studies of the general population is needed to establish a link between colon cancer and asbestos.