A carcinogen is a substance known or believed to cause cancer in humans. Better understand a number of specific known and possible carcinogens and how they might affect your risk for cancer.. | | Learn how certain viruses, bacteria, and parasites are recognized risk factors for several types of cancer in humans. | | Read about the connection between different kinds of air pollution and your risk for cancer. | | Understand more about the cancer risk associated with such medical treatments as hormone replacement therapy and others. | | | | Find out how radiation from cellular phones, sunlight and UV radiation, and other sources affect your risk for cancer. | | Exposure to some chemicals can affect your risk of getting cancer. Learn more here. | | Are the products you use everyday linked to cancer? Find out what current research says. | | |