About GIS
Exposure
Cancer and other diseases can be triggered by exposure to toxic agents. The presence and concentrations of such agents may vary geographically. Toxic agents that can increase cancer risk include:
- Chemicals in the air, water, and/or food supply, such as asbestos (air) and arsenic (water).
- Radiation. This includes both naturally occurring ultraviolet (UV) radiation from the sun and man-made radiation from nuclear accidents.
- Bacteria and viruses, such as H. pylori, human papillomavirus (HPV), hepatitis, and HIV.
Because many cancers develop over a long period of time, knowing the spatial context throughout a person's life is important to understand his or her total exposure to toxic agents. Recently, scientists have discovered that some cancers are caused by a combination of an underlying genetic abnormality coupled with environmental exposure. Such "gene-environment" interactions further emphasize the importance of spatial context.
