Food Hazards

Food hazards have the potential to harm consumers' health, and they arise when food is exposed to hazardous agents, resulting in food contamination. They are subdivided into four primary categories: biological, chemical, physical and allergenic hazards.

Hazards		Examples
Physical hazards	They are associated with the presence of foreign objects.	Foreign objects such as wood, glass or metal chips from damaged tools or utensils Accessories worn by food handlers, hair or plasters
Chemical hazards	They occur when chemicals are present in food at levels that can be hazardous to humans.	Natural toxins (from food plants and animals), mycotoxins (from mould) and pesticide residues Detergents, sanitising agents, bleaching agents, and insecticides
Biological hazards	They are mainly microorganisms that cause illness.	Bacteria, yeasts, moulds, viruses and parasites
Hazards from food allergens	Food allergy refers to the immune system's reaction to certain substances or ingredients in foods.	Some students or staff may be allergic to specific foods or food ingredients. Please see here for more details.

Food Contamination

There are three ways on how food contamination could happen: primary, direct and cross-contamination.

Primary Contamination	Occurs in primary food production processes such as harvest, slaughter, collecting, milking and fishing.	The contamination of eggs by a hen's faeces
Direct Contamination	The contaminants (hazards) affect the food when the person handles it with direct contact. This is the most common type of contamination.	Sneezing over food Touching food with unclean or wounded hands
Cross-contamination	The contamination is caused by the transference of a hazard present in a food to another food via the surfaces of utensils that have contact with both without requisite cleaning and disinfection.	Handling food with the same pair of gloves after handling garbage and using the phone Wiping kitchen utensils with the same cloth after using it to wipe tables without disinfection Using the same knife and cutting board for both raw meat and cooked food

Food Poisoning

Food poisoning, also known as foodborne diseases, is usually caused by the consumption of contaminated food or water containing bacteria (e.g. Salmonella), viruses (e.g. norovirus), parasites or toxins (e.g. ciguatoxin). Depending on the causative agent involved, patients may fall ill within hours or days after the consumption of contaminated food. Common symptoms of food poisoning include nausea, abdominal pain, diarrhoea, vomiting and fever.

Bacteria and viruses are the most common causative agents of foodborne diseases related to food premises and food businesses in Hong Kong. The top causes of food poisoning are:

• lnadequate cooking

• Cross-contamination of cooked or ready-to-eat food by raw food

• Improper holding temperature (e.g. storage at room temperature for too long or inadequate chilling temperature)

• Poor personal and environmental hygiene

Temperature Danger Zone

Storing food at the Temperature Danger Zone (i.e. between 4°C and 60°C) can allow various types of bacteria to grow rapidly. Therefore, proper temperature control to keep food away from the Temperature Danger Zone at all stages of food preparation is important to prevent bacterial food poisoning. While chilling will inhibit bacterial growth (but cannot kill them), high temperature treatment can destroy bacteria effectively.

2-hour / 4-hour Rule

The 2-hour / 4-hour rule is a good way to keep food safe even if it has been out of refrigeration or placed at ambient temperature after cooking. The rule has been scientifically proven and is based on how fast microorganisms grow in food at the Temperature Danger Zone between 4°C and 60°C.

The table below outlines the 2-hour / 4-hour rule. ✓means "yes" and ✘ means "no".

Food held at 4°C-60°C for	For refrigeration to use later	For immediate use and consumption
<2 hours	✓	✓
2-4 hours	✘	✓
>4 hours	✘	✘

Prepared foods held at temperatures between 4°C and 60°C for 4 hours or more must be thrown away.

Five Keys to Food Safety and Good Hygiene Practices

To prevent food poisoning, food handlers and other staff should follow the "Five Keys to Food Safety".

Good Hygiene Practices (GHPs) are an extension of the "Five Keys to Food Safety" to cover personal hygiene, environmental hygiene and food hygiene. Apart from preventing contaminants during food production and maintaining of well-equipped establishments, operation monitoring, product information, food delivery and on-going training are equally important. GHPs are fundamental to ensuring food safety in food premises.

Training of Food Handlers

Any staff member who prepares or handles food (including catering contractors) in a school or childcare facility should be supervised, instructed, and trained in food hygiene matters before reporting duty to ensure that they are familiarised with the working environment and adhere to safe food preparation practices. Food handlers should be trained according to their responsibilities, working environment and tasks. Refresher training is also essential, whereas the frequency will vary depending on the type of facility, its risks, the foods/drinks given and the competence of the staff. It is recommended to provide retraining courses to food handlers every two years.