These are the chemicals released in a process called oxidation. Oxidation is when molecules in cells split and become unstable. This unstable activity causes a chain reaction in the surrounding molecules. The resulting free radicals can harm important molecules in the cells, including genes. Free radicals can work both for us and against us; increased free radical activity might combine with other factors to cause some cancers. On the other hand, radiation therapy works in part by creating free radicals.
Read more about free radicals and your immune system.
Audio contributed by: Erin Brockovich