Raw foods of animal original are the most likely candidates for contamination and cause of food poisoning (or "foodborne illness"). These foods include:

• Raw meat
• Poultry
• Eggs
• Shellfish, and
• Unpasteurized milk.

Foods that mingle the products of many individual animals are particularly hazardous because a pathogen present in one animal may contaminate the whole batch. For instance, a single hamburger may contain meat from hundreds of animals, or a single restaurant omelet may contain eggs from hundreds of chickens.

While washing raw fruits and vegetables decreases contamination, it does not eliminate it. Recent food poisoning outbreaks have shown that the quality of the water used for washing and chilling produce after it is harvested is critical. Unclean water for washing, fresh manure for fertilization, as well as the consumption of some uncooked vegetables and unpasteurized fruit juices pose higher risks.

Toxins, such as pesticides inadvertently added to food or naturally poisonous substances used to prepare meals, can also cause foodborne illness. For example, every year, people become ill after mistaking poisonous mushrooms for the safe species, or after eating poisonous reef fishes.