Foodborne Hazards and Risk Assessment
What to know
Candidates must classify hazards into biological, chemical, physical, and allergenic categories and explain how each causes harm. Biological hazards dominate: bacteria (Salmonella, Listeria monocytogenes, E. coli O157:H7, Clostridium botulinum, Staphylococcus aureus), viruses (norovirus, hepatitis A), and parasites. Understand growth conditions - the temperature danger zone (5–63 °C), moisture (aw), pH, and oxygen - and the difference between infection (ingestion of live pathogens) and intoxication (pre-formed toxin, e.g. S. aureus, B. cereus).
Chemical hazards include cleaning residues, pesticides, mycotoxins, and unapproved additives. Physical hazards are foreign objects (glass, metal, bone). Allergens are treated as a distinct hazard requiring declaration and cross-contact control.
Risk assessment concepts
Know hazard vs. risk: a hazard is a potential source of harm; risk is the likelihood and severity of harm. Risk assessment follows hazard identification, hazard characterisation, exposure assessment, and risk characterisation. Risk-based inspection prioritises high-risk businesses.
Traps
- Confusing intoxication with infection (toxin is heat-stable; reheating does not make it safe).
- Treating allergens as a quality issue rather than a safety hazard.
- Forgetting that Listeria grows at refrigeration temperatures.
Rule of thumb
Match the organism to its control: temperature control for most bacteria, rapid cooling for spore-formers, strict hygiene for viruses (which do not multiply in food).
Worked example
Rice left at room temperature: Bacillus cereus spores germinate and produce toxin. Reheating kills cells but not the heat-stable toxin - the food is still unsafe.