Food Safety Hazards – Types of Food Contamination

Food Safety Hazards – Types of Food Contamination

Understanding Hazard Analysis and Critical Control Points Part 2

The key part of developing a Hazard Analysis and Critical Control Point based food safety system is the Hazard Analysis part. This is where you go through your business step by step, and investigate all of your processes and procedures to see where there may be risks to food safety and your customers.

In this article, we will look through the main type of food safety hazard, that of food contamination. We will look at what types of food contamination exist and how you and your business can help prevent any issues in the future.

How Contamination Applies to HACCP

HACCP or Hazard Analysis and Critical Control Points is a food safety system, in which Hazards are addressed by implementing specific measures to control the production of food related products. All businesses that deals with food, such as restaurants, must have a food safety system based on HACCP. Which will help prevent cross-contamination and could potentially save someone's life.

If food contamination is not carefully controlled then customers are at risk of falling ill as a result of consuming your food products. This can cause serious and costly problems for your business.

A hazard is anything that can be dangerous in the food production line. A food hazard is something that could make food unsafe or unfit for human consumption. It is vital that you can identify stages that risks, such as contamination can be introduced into your food business, and also how the hazards could be removed or if they can't be removed then how they can be reduced to safe levels.

There are three primary types of food safety hazards, and they are:

  • Biological Contamination – involving things, such as viruses and bacteria
  • Chemical Contamination - involving chemicals in food production
  • Physical Contamination - involving physical objects in food, such as finding a plaster in food

HACCP is designed to protect the end user from illness. Contamination usually happens when foreign objects get into the raw materials, or through poorly maintained facilities and equipment, improper production procedures or poor employee practices.

Without a thorough understanding of food safety hazards, it is impossible to establish effective controls and create a successful HACCP System.

Physical contamination

Physical contamination occurs when any physical object or foreign matter gets into food; this can happen at any stage, from ingredient production right through to presenting the product to the customer.

These foreign object could be anything, but are not limited to:

  • Hair
  • Bone
  • Metal fragments
  • Stones
  • Glass
  • Wood fragments
  • Insects or other filth
  • Personal items
  • Other ingredients

This list is endless, anything that drops into the food production line, that could cause illness in others, this is a physical food hazard.

The most common contamination the public are usually aware of is the classic, “I found a hair in my soup” however items such as plastic from production facilities and cross contamination of other ingredients from nearby processes are also common. In 2019 Tommy Tucker, the UK’s largest popcorn maker went into administration after it was forced to recall all of its products due to milk contamination.

Chemical contamination

Products that fall into the chemical category include:

  • Pesticides
  • Herbicides
  • Growth hormones and antibiotics
  • Lubricants
  • Paints
  • Cleaners and sanitizers.

Chemical hazards should be controlled at every step in the production process: when in storage, and during use (cleaning agents, sanitizers), before receipt (in ingredients and packaging materials), upon arrival of materials, during processing and before shipment of product.

You need to consider that chemical contamination can happen very early in the food production chain, the main risks from pesticides and growth hormones is that they can build up over time in crops and animals whilst they are still on the farm.

Pesticides and the like, used on a farm at the top of a hill or river can flow with the water table into fields further down, which can lead to contamination in places where there are not used, which is why there need to be regular checks in place to ensure it does not become an issue in the food chain. This scientific study found that there was a build-up of Mercury in the fruit and vegetables from fields surrounding coal power plants in China, which shows that contamination can come in forms you might not usually think off.

A common form of chemical contamination comes from the cleaning chemicals used in kitchens. If they are diluted to a stronger mix then the manufacturer specifies then they can leave residue behind that can taint food, this is often found when customers complain that food “tastes of washing up liquid”, usually a sign that too much was used when cleaning the plates. Facilities have been caught out using non-food safe stainless steel cleaners on kitchen worktops to achieve a shine and there have been reports of the mould release agent on plastic food packaging and containers tainting food. This is one of the many reasons you need to be sure that people supplying you are also doing all they can to limit the risks to health.

Biological contamination

A Biological Hazard is an organism or substances which may pose a threat to human health. Anything that can cause harm to people such as illness or death, be it animals, infectious plant material or human, it can be considered a Biological Hazard. This is the kind of contamination people most worry about when eating out as it is the cause of the variety of conditions usually called “food poisoning”.

Biological hazards can include different sorts of microorganisms, such as:

  • Bacteria
  • Viruses
  • Yeasts
  • Moulds
  • Parasites

They can also include things like:

  • Rodents
  • Plant spores
  • Flies

As these carry a number of diseases with them.

Some of these are pathogens and can produce toxins. A pathogenic microorganism also can cause diseases which can vary in the degree of severity.

Examples of these disease hazards include

  • Salmonella
  • E. coli
  • Clostridium botulinum.
  • Staphylococcus aureus
  • Listeria monocytogenes
  • Toxoplasma gondii

Prevention of Biological contamination is essential to limit food-borne diseases. The contamination can be controlled by proper cleaning and sanitization. Things like the design of equipment should be chosen carefully to avoid giving places for microorganisms to grow, all equipment should be easy to clean.

The biological hazards from pests such as rodents and flies can be effectively managed with a good pest control policy. It is usually best to work with an outside specialist pest control company to provide effective management with the specialist skill required.

Allergenic contamination

Certain people with allergic reactions to some foods will become very ill if contamination happens, in extreme case some people can die from very small amount of allergens, which is why you must ensure you have practices in place to control them as part of your HACCP plan. Poorly washed cutlery, cooking services or poor staff hygiene could lead to cross-contamination. As such allergenic contamination can be physical, chemical or biological.

In November 2019 of the 12 product recall alerts issued by the UK Food Standards Agency, 9 were for issues related to unexpected or undeclared allergens being found in foods from large companies such as Harvey Nichols, La Boulangere and Unilever.

Your policies should include clear segregation and labelling of preparation areas and allergen ingredients and cooking equipment. For example if you do not use a separate deep fat fryer to fry gluten free battered fish to items containing gluten, then you run the risk of contamination through the oil and you would need to make the decision to either label all such items as may contain gluten or get a separate fryer.


Cross-contamination is when one food of a particular type comes into contact with another food type, which can cause bacteria, chemicals and objects to pass from one food type to another. Preventing such contaminations is a multi-step process, which can be controlled using HACCP. The most common example is the transfer of bacteria between raw and cooked food.

Bacterial cross-contamination is the cause of most foodborne infections. For example, when you’re preparing raw chicken, bacteria can spread to your chopping board, knife and hands and could cause food poisoning. This is why it is so important to have procedures as part of your food safety plan to segregate not just raw and cooked foods but also the tools and work surfaces they are prepared on.

A lot of the ways we prevent cross-contamination should be standard in every kitchen, such as:

  • Preparing food hygienically 
  • Using separate clearly labelled or colour coded utensils, plates and chopping boards for raw and cooked food.
  • Ensuring you don’t wash raw meat as bacteria can travel in the splashes this produces.
  • Washing your hands after touching raw food. 
  • Covering raw food and keeping it separate from cooked and ready to eat food, in fridges and freezers.

Contamination as a Hazard

As you can see stopping contamination is vitally important to providing safe food and will be one of the core goals of your HACCP based Food Safety System. Now that you understand the types of contamination and how they spread, you should look back over your procedures to ensure you have control measures at every point contamination could happen.


You can read part 1 of this series Understanding Hazard Analysis and Critical Control Points here, You can find the UK Food Standards Agency’s guidance for allergens for food businesses here and for information about food hygiene training check out our article here.

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