Food can be contaminated by physical objects, chemicals, or bacteria transferred to the food either through poor handling practices or from another food source. This is known as cross-contamination.

Physical contamination

Physical contamination is caused by foreign objects entering food during the food preparation and service process and generally results in an injury rather than an illness. Physical contamination can come from a number of sources and can include items such as:

  • Glass fragments from bar staff using a glass to scoop ice;
  • Dust from poor cleaning ;
  • Metal shavings from slicers and mincers;
  • A band-aid falling into food; and

Chemical contamination

Chemical food poisoning is caused by the presence of toxic chemicals in food. Examples of chemicals that may contaminate food include pesticides, insecticides, rat poison, cleaning agents, or chemicals resulting from a chemical reaction between food and inappropriate storage containers, eg galvanised cans.


Toxins are a poisonous chemical produced by some microorganisms.Some food poisoning bacteria produce toxin when they grow in sufficient numbers in food, while some others produce toxin in the stomach after being eaten. Certain types of fungi or mushrooms can be poisonous.Some algae also produce toxins; contamination may occur in shellfish and reef dwelling fish. Mould on food should always be treated with suspicion as moulds produce toxins known as mycotoxins many being cancer-producing. These toxins or poisons are often water-soluble and not destroyed by conventional cooking.

Biological contamination

Your food handling practices should ensure that food is not exposed to any food safety hazards. Poor handling practices can result in food being contaminated by bacteria. People, animals or pests can all cause bacterial contamination. Examples of how this could occur include:

Poor personal hygiene such as food handlers coughing or sneezing over food or not washing hands after eating or using the toilet;

  • Food not being protected during self-service, e.g. salad bars require sneeze screens;
  • Self-service such as buffet not being supervised;
  • Pest infestations;
  • Poor storage practices resulting in food being open to contamination;
  • Animals on food premises.


Cross-contamination is the transfer of micro-organisms from raw foods (usually animal foods) to cooked or ready-to-serve foods. Raw foods can contain high numbers of bacteria and care must be taken to ensure bacteria from raw foods are not transferred to cooked or prepared foods. This involves a number of stages of food handling.

Cross-contamination can occur in all functional areas of hospitality. It is particularly dangerous in the kitchen as large numbers of harmful bacteria can be transferred to food or food contact surfaces, increasing the risk of food poisoning.

Cross-contamination is also linked to standards of personal hygiene, cleanliness and sanitising. Practices to apply the food handling principles

  • Wash and sanitise all equipment including utensils, knives, chopping boards and work surfaces before and after use when preparing different foods, eg raw meat and cooked meat;
  • Wash hands between preparation tasks, in particular after you have handled raw meat, poultry or seafood;
  • Change single-use gloves after handling raw foods;
  • Use a clean utensil each time you taste food;
  • Minimise contact with food wherever possible by using utensils or single-use gloves; andDon’t store raw foods above cooked foods.

Pest infestation.

Premises can also pose a physical food hygiene risk — dust from air conditioning vents, peeling paint and chipped tiles can end up in food.

Correct use of single-use gloves

The Food Standards Code contains the legal requirement that food handlers must prevent contamination from anything on their bodies. Single-use gloves act as a barrier between the food handler and the food. They should be used to cover cuts, sores or dressings on the hands to prevent contamination of food products and when handling ready-to-serve foods. Gloves must be used properly to ensure this requirement is met.

  • WASH AND DRY hands before and after using gloves.
  • DISCARD gloves when they become soiled.
  • CHANGE gloves whenever hands would normally be washed.
  • CHANGE after picking anything up off the floor.
  • DISCARD gloves when leaving the work area for ANY reason.
  • WHEN RETURNING to the work preparation area, wash hands and use a new pair of gloves.
  • DO NOT REUSE GLOVES — throw away immediately after removing gloves.
  • DO NOT STORE GLOVES where they can be contaminated in the work area.

How can you control bacteria from growing in food?

Temperature control is the most effective practice for controlling bacterial growth in food. The growth of micro-organisms occurs most effectively when food is left in the danger zone, between 5°C and 60°C. Temperature control applies to every stage of food handling. Faulty equipment can also allow food to become exposed to the danger zone, eg poor seals on doors let hot or cold air escape.

Temperature control

The Food Safety Standards require temperature control for potentially hazardous foods throughout the production process. Temperature control is defined at Division 1 — Interpretation and application of Standard 3.2.2 Food Safety Practices and General Requirements as maintaining food at a temperature of:

5 deg Centigrade or below

if this is necessary to minimise the growth of infectious or toxigenic micro-organisms in the food. This ensures that the microbiological safety of the food will not be adversely affected for the time the food is at that temperature; or

60 deg. centigrade or above

Another temperature — as long as the food business can demonstrate that maintenance of the food at this temperature for the period of time, for which it will be so maintained, will not adversely affect the microbiological safety of the food.