Food Safety Hazards and Contamination
This domain tests whether you can identify the main hazard types in a food business and explain how they reach food. You must distinguish a hazard (something that can cause harm) from contamination (the presence of a hazard in food) and from food poisoning (illness after eating contaminated food).
Hazard types
- Biological: bacteria, viruses, moulds and parasites. Common examples include Salmonella, Campylobacter, E. coli O157, Listeria monocytogenes, Staphylococcus aureus, Clostridium perfringens and Bacillus cereus.
- Chemical: cleaning chemicals, pesticides, allergens, veterinary residues and toxic metals.
- Physical: glass, metal, plastic, stones, hair and packaging.
- Allergenic: a hazard for susceptible people; even a trace can trigger a severe reaction.
How contamination happens
Contamination can be primary (from the raw ingredient), direct (raw food touching ready-to-eat food), indirect (hands, cloths, boards, knives), from pests, from the environment (dirt, water, air) or from people (hands, coughing, wounds). High-risk foods are usually moist, protein-rich and ready to eat: cooked meat, dairy, eggs, seafood, cooked rice and prepared salads.
Worked example
A worker portions raw chicken on a board, wipes the board with a cloth, then uses the same board and cloth to slice cooked ham for a sandwich. The ham is not cooked again. Reasoning: chicken juices can carry Campylobacter or Salmonella; the cloth spreads the juice; the ham is ready-to-eat and receives no kill step; the consumer is exposed. The correct action is to use separate boards or clean and disinfect the board and discard the cloth before touching the ham.
Traps
- Smell, taste and appearance do not prove food is safe.
- Allergens are a hazard even when the food looks normal.
- “Food poisoning from the last meal” is an unsafe assumption; incubation periods vary.