In this article
Food safety hazards can adversely affect the food we eat; they can cause harm such as foodborne illnesses, injuries and allergic reactions.
They are contaminants which can compromise the safety and suitability of our food. Hazards can affect food safety throughout the entire supply chain. Therefore, it is vital to understand what they are, how they can contaminate our food and the role of HACCP.
There are four different types of food safety hazard, which are:
You may come across three types of hazard, as some include allergens in the chemical category. In this article, you will look at it separately.
Biological, or microbiological, hazards occur when microorganisms contaminate our food. Microorganisms are living organisms that are so small that they are only visible through a microscope. These tiny organisms can be found all around us; in air, soil, water, animals and humans. Therefore, they can easily enter and contaminate our food throughout the entire supply chain.
- Bacteria, e.g. salmonella, listeria and campylobacter.
- Fungi, e.g. yeasts and moulds.
- Viruses, e.g. norovirus and hepatitis A virus.
- Parasites, e.g. worms and protozoa (Toxoplasma gondii and Giardia lamblia).
Not all microorganisms cause illness; some are even beneficial and are added intentionally to food and drinks, e.g. bacteria used in probiotics/dairy and yeast used in bread/alcohol production. However, there are many different microorganisms that can contaminate the food we eat which can cause foodborne illnesses. These are known as pathogens.
Biological hazards can also include pests, e.g. rodents, flies and other insects, as these can carry harmful microorganisms.
Biological hazards are responsible for many different foodborne illnesses, which is collectively known as food poisoning. It results from eating food that is contaminated with microorganisms. As they enter the body, they can rapidly multiply and can cause infection. Some can also produce toxins in larger numbers, which can result in intoxication.
Food poisoning is commonly seen where food has not been handled, stored or cooked properly. It can also be caused by poor hygiene and cross-contamination, which you will look at later in the unit.
The symptoms of food poisoning are highly unpleasant and can vary between individuals. It also depends on the microorganism present and the number ingested. Symptoms of food poisoning can occur in a matter of hours or weeks after eating contaminated food.
Again, this will depend on the microorganism involved. Common symptoms include diarrhoea, vomiting, nausea, high temperature and stomach cramps. In extreme cases, food poisoning can be life-threatening.
Some people are at a higher risk of food poisoning, e.g. those with compromised immune systems, expectant mothers, the elderly and children.
Food poisoning microorganisms
Many microorganisms are responsible for food poisoning and far too many to mention in this course.
It is usually caused by bacteria and viruses, for example:
- Salmonella – These bacteria that are found in a wide variety of foods, e.g. undercooked meat & poultry, unpasteurised milk, cheese and undercooked eggs. It can cause an infection known as salmonellosis. These bacteria are responsible for most food poisoning cases.
- Escherichia coli (E.coli) – These bacteria are found in undercooked beef, contaminated water, unpasteurised drinks, dairy and raw fruits/vegetables. E. coli O157: H7 is particularly dangerous, as it can also produce a toxin.
- Listeria monocytogenes – These bacteria are found in raw milk, salad, ready-to-eat foods, raw/undercooked meat, poultry and seafood. They can cause listeriosis, which is a serious infection.
- Norovirus – This is a virus that is also known as the winter vomiting bug. It is spread by humans to food and drinks, usually through poor hygiene practices. It is found in shellfish, leafy vegetables, fruit and ready-to-eat foods.
- Campylobacter – These bacteria are found in raw or undercooked poultry, unpasteurised dairy products and untreated water. They can cause an infection known as campylobacteriosis.
- Clostridium perfringens – These bacteria are common in the environment. They are typically found in beef, poultry, casseroles and gravies.
Some bacteria also produce spores, such as Bacillus cereus and Clostridium perfringens. These spores can survive cooking temperatures, which can increase the risk of food poisoning.
Food poisoning from parasites is much rarer than food poisoning caused by bacteria and viruses. It is more common where people travel to developing countries. However, if it does occur, it can be dangerous and potentially life-threatening. Parasites enter the body via contaminated food. Once in the body, they take nutrients from the host to grow and reproduce.
Parasites are present in the environment (water and soil), animals and humans. They can be transferred to food and are typically found in undercooked meat, poultry, fish and seafood, raw salad and vegetables contaminated with human and animal faeces. Parasite contamination is usually as a result of poor hygiene practices and contaminated ingredients.
Fungi such as yeasts and moulds are microorganisms, but they are not classed as a biological hazard in food. They are responsible for food spoilage, but generally do not make food unsafe to eat. However, some types of fungi do produce hazardous toxins, which is dangerous as it can result in intoxication. These toxins are classed as chemical hazards.
Chemicals are substances that can be naturally occurring or they can be human-made. They are sometimes intentionally added to our food for taste and preservation purposes, e.g. sodium nitrates and sulphites. Some chemicals can also be unintentionally added, which can contaminate the food we eat. These can include dangerous hazardous substances, toxins and excess chemicals used in food processing.
Sometimes allergens are also classed as chemical hazards, but you will look at this as a separate group later in the unit.
Eating food that is contaminated with chemicals can result in immediate harm to the consumer or can cause long-term health effects if they are exposed to it over time.
Some examples of chemical hazards are (this list is not exhaustive):
These are naturally occurring chemical hazards that are produced by animals, plants and microorganisms.
- Mycotoxins – Produced by fungi.
- Aflatoxins – Found in peanuts, tree nuts and corn.
- Ochratoxins – Found in vine fruits such as currants, raisins and sultanas.
- Marine toxins – Found in fish and shellfish.
- Natural toxins – Produced by plants, e.g. glycoalkaloids in potatoes.
- Bacterial toxins – Produced by bacteria such as E.coil O157.
Unintentionally added chemicals
These are chemical hazards resulting from accidental contamination.
- Agricultural chemicals, e.g. pesticides, herbicides, fertilisers and fungicides.
- Veterinary drugs used to control and prevent illnesses in animals, e.g. antibiotics and growth hormones.
- Environmental pollutants, e.g. polychlorinated biphenyls (PCBs).
- Chemicals from machinery maintenance and cleaning, e.g. lubricants, oils, sanitisers, disinfectants and paints.
- Toxic metals, e.g. lead, zinc, arsenic, mercury and cyanide.
- Processing-induced chemicals that can be formed from reactions between compounds.
Intentionally added chemicals
These are chemicals that are deliberately added to food but could be a hazard if excess quantities are used.
- Preservatives, e.g. nitrates and sulphites.
- Added vitamins, e.g. vitamin A.
- Natural and artificial colourings, e.g. cochineal and tartrazine.
- Bleaching agents.
- Glazing and polishing agents.
Chemicals can also be intentionally added, as a result of food crime. There have been instances of deliberate food contamination with the intent of causing harm to the general public.
Chemical hazards can come from a variety of sources. Contamination can occur at any stage of food production and processing. It can also occur as a result of contact between surfaces, using non-food-grade chemicals, poor storage and human error.
In addition to chemical hazards, there are also physical hazards that can enter our food.
Physical hazards are foreign materials and objects that can enter the food we eat. This is also known as extraneous matter.
These types of contaminants can cause:
- Cuts to the mouth and gums.
- Damage to teeth.
- Injury to the throat, oesophagus (food pipe), stomach and intestines. Some people may require surgery to remove the offending item.
- Choking, which can be fatal.
These are naturally occurring physical hazards that can be found in food.
These physical hazards are more dangerous and should not be found in food
Some physical hazards can also be biological and chemical contaminants, e.g. rat droppings and plastic.
Unnatural physical hazards can come from a variety of sources at any stage of the production process.
Some examples are (this list is not exhaustive):
- Plastic – Utensils, packaging materials, disposable gloves and containers.
- Stones and pebbles – Incorporated with foods during harvesting.
- Glass – Jars, light bulbs, thermometers and bottles.
- Wood – Pallets used to store food ingredients and wooden structures.
- Metal – Nuts and bolts from process equipment/machinery, utensils, wire, shot, and office equipment such as staples and pins.
- Human origin – Hair and fingernails from a lack of food hygiene procedures, e.g. not wearing hairnets or gloves.
Naturally occurring physical hazards can enter food during harvest and can remain after processing. That is why you will often see a label warning consumers that it is a natural product and some physical hazards may remain, e.g. fishbones.
In addition to physical hazards, there are also allergenic hazards.
Allergenic hazards are those that are caused by allergens in the foods we eat. Allergens are proteins that can cause severe and dangerous reactions in some people. When someone eats a food that contains an allergen that they are allergic to, it produces an abnormal immune response in the body.
This response can produce mildly irritating symptoms for some people. However, in others, it can trigger anaphylaxis which can be a life-threatening reaction. Allergic reactions must not be confused with food intolerances.
Unfortunately, there have been many cases over the last few years where people have died from severe food allergies. According to the Food Standards Agency (FSA), around 10 people die every year from food-induced anaphylaxis.
Examples of cases in the UK
- 2020 – Nicholas Kelly aged 16 died from eating a takeaway. He was allergic to nuts.
- 2019 – Sam Collins aged 19 died after eating out at a Chinese restaurant. He was allergic to shellfish.
- 2018 – Shante Turay-Thomas aged 18 died after eating a hazelnut. She was allergic to nuts.
- 2017 – Owen Carey aged 18 died after eating a chicken burger that contained buttermilk. He was allergic to dairy.
- 2016 – Natasha Ednan-Laperouse aged 15 died after eating a baguette containing sesame. She was allergic to sesame.
A person who is allergic to certain ingredients does not have to eat vast amounts for them to suffer a life-threatening reaction. Some people can get extremely ill from the smallest quantities. Therefore, food businesses must ensure that allergens are identified and strictly controlled.
There are 14 allergens recognised by EU law as being the most prevalent and more likely to cause a reaction. These are listed in Annex II of the EU Food Information for Consumers Regulation No.1169/2011. By law, food businesses must inform consumers if any of the 14 allergens are used in their food and drink products.
These allergens are used in an array of different foods. They are standalone foods but are also ingredients in manufactured, restaurant and takeaway foods.
|Allergen||Examples of where it is commonly found|
|Eggs||In cakes, sauces, mayonnaises, quiches and glazes.|
|Fish||In salad dressings, pizzas and sauces.|
|Milk||In butter, cheese, cream, powders, yoghurt and glazes.|
|Peanuts (groundnuts)||In sauces, cakes, curries, flours, desserts and biscuits.|
|Celery (all of the plant, including the root celeriac)||In celery salt, salads, soups, sauces and stock cubes.|
|Mustard (liquid, powder and seeds)||In bread, curries, marinades, salads, soups, sauces and meat products.|
|Tree nuts (almonds, hazelnuts, walnuts etc.)||In bread, curries, biscuits, crackers, powders, desserts, sauces, oils, stir-fry meals, ice-cream and marzipan.|
|Sesame (seeds)||In bread, curries, sauces, humous, oils and salads.|
|Lupin (flower and seeds)||In flour, bread, pasta and pastries.|
|Soybeans||In tofu, soy protein, miso, edamame, flour, sauces, soya milk, desserts, yoghurt and ice-cream.|
|Cereals (gluten) (oats, rye and barley)||In flour, batter, baking powder, bread, cakes, pasta, sauces, pastry, meat products, couscous, breadcrumbs and soups.|
|Molluscs (oysters, snails and mussels)||In stews or sauces.|
|Sulphur dioxide and sulphites||In alcoholic drinks such as wine, dried fruits, soft drinks, meat products and vegetables.|
|Crustaceans (crab, prawns and lobster)||In sauces and pastes. Used widely as ingredients in Thai foods.|
Allergens are likely to enter food as a result of cross-contact, which is very similar to cross-contamination.
The hazards you have looked at earlier in the unit can also enter our foods as a result of cross-contamination. It is caused by the unintentional transfer of contaminants from various sources to the foods we eat.
There are three main ways cross-contamination can occur:
Cross-contamination usually refers to biological hazards, for example:
- The transfer of microorganisms from raw meat, poultry, fish and seafood to other foods, surfaces, hands and equipment, for example:
– Using the same utensils, knives, surfaces, chopping boards for raw and cooked foods or not washing/sanitising them properly.
– Touching raw foods and not washing hands before touching other foods.
– Storing raw foods incorrectly with cooked and ready-to-eat foods, e.g. raw poultry dripping on cooked food.
– Washing raw meat, which could contaminate surfaces with splashes containing bacteria.
- Microorganisms from people handling food, e.g. from unwashed hands, sneezing, coughing, clothing and hair.
- Poor waste disposal, which also encourages pests that carry biological hazards.
Cross-contamination can also occur with chemical and physical hazards.
Like biological hazards, chemical contaminants can also be transferred to food, for example:
- Preparing food where there are chemical residues on equipment, surfaces and hands.
- Spraying chemicals in the air, which can land on food, surfaces and equipment.
- Chemicals in packaging that can migrate into the food, e.g. coatings in tins and plastic containers.
Cross-contamination is also possible with physical hazards, where objects can pass to food from other foods, equipment and people. It is less likely than the other contaminants, but it is still a risk.
Products containing allergens are often unintentionally transferred to allergen-free ones, which is known as cross-contact. As you have seen earlier in the unit, this could result in fatalities if someone has a severe allergic reaction.
It can occur as a result of:
- Poor hygiene practices, e.g. not sufficiently washing hands, surfaces and equipment.
- Using the same equipment for processing and storing allergen and non-allergen products, e.g. storing gluten-free flour in a jar that has had gluten-containing flour.
- Allergen products being used, processed and stored where non-allergen products are.
- Putting an allergen on a non-allergen meal and then removing it.
- Allergen products being accidentally used due to poor labelling, a lack of training and human error.
Allergen cross-contact is not affected by cooking. Therefore, it does not reduce the risks of an allergic reaction. Also, someone could have a severe reaction to the smallest (trace) amounts of allergen. Therefore, extreme care must be taken to ensure that cross-contact does not happen. HACCP aims to control food safety hazards, cross-contamination and cross-contact.