Free Radical

**Semantic type:** Inorganic Chemical

**Definition:** Molecules or atoms with at least one unpaired or 'free' electron in the outermost electron shell. Chemically unstable, free radicals stabilize themselves by appropriating an electron from a nearby molecule, thereby damaging that molecule by altering the electron number in its outermost electron shell. By-products of both normal cell processes and environmental toxin exposure, oxygen free-radicals in high concentrations may damage DNA, proteins, and lipids, thereby increasing the risk for various diseases including cancer. (NCI04)

**Synonyms:** - Free Radicals - free radical