Identification
Rust --- that red, brittle, flaky stuff --- is pretty hard to miss. When you wax your car, look at the wax application pad. It is the color of your car. Wipe your fingers over aluminium siding, and the color comes off on your fingers as a powdery dust. Remove the shudders from your house and find that the house color has faded. All of these are examples of oxidation.
Oxidation-Reduction Potential
This is the complete title of the oxidation process. All oxidation reactions involve the loss of electrons from one atom and the gaining of electrons by another, all with oxygen in the process. As an atom loses electrons, it is reduced from its whole. All body cells get their energy because of oxidation of the foods we eat. Oxidation converts what we eat to chemical energy, and what is left is eliminated as waste. Without oxidation, the cells would die. All food and beverages have a varying degree of this potential.
Toxicity
Oxidation also occurs to our food before we consume it. Food spoilage begins with oxidation of the fatty acids or color pigments contained in them. A banana peel turns brown because of oxidation. Because oxidation is essentially a breakdown of a substance, it can also have a negative effect on our environment. It is the effects of oxidation that cause hardening of the arteries. The steel rods used to re-enforce concrete are also responsible for that concrete chipping, cracking and breaking.
Summary
Oxidation is a natural occurring chemical process that works at the atomic level. The process breaks down a substance by requiring atoms to give up electrons. Oxidation is both beneficial and toxic. In biochemistry, oxidation is essential to cellular function and thus our body's function. In nature, the toxic effects would include food spoilage and rust. All this takes place on organic, or carbon-based, substances.