free radical

Free radical” — an atom or a molecule with an unpaired electron. Because they have a free electron, such molecules are highly reactive with nearby molecules. By interacting with cellular components, free radicals may cause cellular and genetic damage, and their involvement has been implicated in several diseases. Free radicals are generated by smoking, environmental pollutants, exposure to UV radiation, and also occur naturally in the body as a result of metabolic processes. Free radical damage may be countered with antioxidants.