Foodborne Illness and Food Safety Hazards
What you must understand
Foodborne illness happens when contaminated food causes infection or intoxication. Learn the three hazard families and their controls. Biological hazards (bacteria, viruses, parasites, molds) cause most illnesses. Chemical hazards include cleaners, sanitizer residue, pesticides, and allergens. Physical hazards are foreign objects such as glass, metal, bone, or hair.
Know the big bacterial pathogens by their source and control. Salmonella travels with poultry and eggs and is controlled by thorough cooking. E. coli O157:H7 comes from undercooked ground beef and contaminated produce and water. Listeria survives refrigeration, grows in cold, moist foods like deli meats and soft cheese, and threatens pregnant people and older adults. Clostridium perfringens grows in cooked foods held warm too long. Staphylococcus aureus is carried on skin and passed by hands and coughing. Bacillus cereus is linked to cooked rice left at room temperature. Norovirus spreads from infected hands and vomit, and hepatitis A spreads from an infected food handler.
Distinguish infection (pathogen grows in the body) from intoxication (a toxin already in the food causes illness). The FAT TOM conditions for bacterial growth are Food, Acidity, Temperature, Time, Oxygen, and Moisture. Remove any one and growth slows.
Traps to watch
Do not blame food color, smell, or taste as proof of safety; pathogens do not change appearance. Do not confuse a food allergy with a food intolerance or with a foodborne infection. Do not assume freezing kills bacteria; it only pauses growth. Do not say viruses grow in food; they need a living host.
Rule of thumb
If a question asks the single most likely cause of a bacterial outbreak, look for time and temperature abuse of a cooked food. If it asks about a food handler spreading illness, look for bare-hand contact and poor handwashing.