10.2 Free Radicals

Definition of Free Radicals

A free radical is an atom or molecule that lacks one electron, making it unstable, reactive and likely to attack other atoms or molecules.

Effects of Free Radicals on Human Health

Formation

• Oxidation is a chemical reaction that occurs when a reactant loses electrons.
• Oxidation that occurs naturally in the body produces free radicals.
• This triggers a chain reaction that produces more free radicals.

Sources

• Internal factors: Metabolism and inflammation.
• External factors: Ultraviolet rays, ionising radiation, toxic waste, cigarette smoke and air pollution.

Effects of excess free radicals

• Free radicals take electrons from molecules that form DNA and damage the DNA structure.
• This forms carcinogenic substances that may cause mutation and cancer.
• Cause cardiovascular disease and infertility.
• Damage the kidneys, liver and lungs.
• Cause premature ageing, such as wrinkled skin and grey hair.