Cross Contamination

What is it?

Cross contamination occurs when harmful foodborne bacteria, such as E.coli 0157, are transferred from contaminated food to uncontaminated food. Cross contamination can occur in two ways:

• by direct cross contamination - contact between raw food and ready-to-eat food during transport, storage or preparation
• by indirect cross contamination - spread of bacteria from raw food to ready-to-eat food via food handlers, equipment or surfaces. For example, indirect cross contamination via refrigerator door handles, knives, chopping boards, work surfaces, chef's cloths or cleaning cloths.

What are the sources of E. coli 0157?

E.coli 0157 can occur naturally in the intestines of animals and may be present on a range of raw foods. It is associated with raw meat including beef, pork, lamb, chicken, turkey and game. Other raw meat products such as sausages and burgers are also sources. Raw vegetables and fruit that have not been labelled as ready-to-eat must also be treated as potentially contaminated with E.coli 0157. This is because the soil they grow in can be contaminated with the organism. E.coli O157 has caused major outbreaks in Scotland in 1996 and Wales in 2005.  It is a particularly dangerous organism because:

• it can lead to serious untreatable illness and even death
• it is reported to have a very low infective dose (less than 100 bacteria can cause illness)
• it has the ability to survive refrigeration, freezing and environments which have a low pH or reduced water activity.

How can I control cross contamination in my business?

Separation between raw and ready to eat food and equipment

The safest and most reliable way to prevent cross contamination is to have completely separate areas, staff, equipment, utensils and cleaning materials. However, it is accepted that this may not be possible in many businesses and alternative controls may have to be put in place. These controls may include restricting raw food handling to specific times, and the identification of temporary raw areas which are thoroughly cleaned and disinfected after use.  Where it is not feasible to have a separate chill, refrigerator or freezer for raw food, controls must be put in place to ensure that cross contamination does not occur.

The dual use of any equipment for raw and ready-to-eat foods is dangerous. The only safe option is to have separate equipment and utensils for each. Complex items of equipment (e.g. vacuum and MAP packaging equipment, mincers and slicers) must never be used for both raw and ready-to-eat foods where there is a risk of E. coli O157.

Effective cleaning and disinfection

Cleaning is the process of physical removal of food debris, visible dirt and food particles. It is usually carried out using hot water and detergent. Cleaning alone will not remove all bacteria.  Disinfection is the process of killing bacteria and viruses following general cleaning. Disinfection can be carried out on a clean surface using either heat or a chemical disinfectant. Chemical disinfectants used as a cross contamination control must be of the BS EN 1276 or BS EN 13697 standard, and must be used in accordance with the manufacturer's instructions. Glasgow City Council can provide a list of suitable disinfectants as well as a list of local suppliers of these products.

Unless you are using a well-maintained dishwasher which is capable of achieving sufficiently high temperatures, you must separate raw food equipment and utensils from ready-to-eat food equipment during the cleaning and disinfection process. This means that raw food equipment must not be cleaned and disinfected in a sink at the same time as ready-to-eat equipment. Where sinks are used to clean and disinfect both raw food equipment and ready-to-eat food equipment, the sinks and taps must be disinfected between uses.

Adequate personal hygiene

People working in your business could contaminate food, or spread contamination from raw to ready-to-eat foods. These risks can be controlled via strict personal hygiene practices.

Handwashing is vital and must be carried out after handling raw food. The manner in which your hands are washed is extremely important. The hand washing operation must take place at a suitable wash hand basin.

Note: Disposable gloves should never be used as an alternative to hand washing

If staff protective clothing becomes contaminated from handling raw food, it must be changed before handling ready-to-eat food. The use of disposable plastic aprons is recommended when carrying out any activities where raw foods are being handled and where there is a risk of protective clothing being contaminated by raw food. Hand washing should take place after removing contaminated clothing and before putting on clean clothing.

Effective management controls and staff training

There should be a designated section on cross contamination included in your business' food safety management system/CookSafe system, detailing your procedures for controlling this hazard. All staff must be familiar with these controls and receive adequate training and instructions on how to carry these out.

How will cross contamination be covered during a food hygiene inspection?

During inspections by Glasgow City Council, the officer will pay particular attention to cross contamination and assess issues such as separation of raw and ready-to-eat foods, personal hygiene and cleaning and disinfection. Food safety officers will ask you to display your hand washing method and demonstrate this during an inspection. Cross contamination, especially where there is a risk of E. coli O157, is viewed as an extremely serious matter. Officers of Glasgow City Council are authorised to take formal action where the risk is particularly high or where a food business operator has failed to take the required steps. "Formal Action" may include the service of a notice requiring actions to be carried out - and may extend to a requirement that certain food activities be stopped. Additionally, officers may require that ready-to-eat foods which have been exposed to the risk of contamination be discarded.