Trading Standards Institute Advice

Chemical contamination of food

This leaflet is for all food businesses, including those involved in catering, food production, food preparation, retail premises, restaurants, pubs, cafes, and fast-food shops.

What is chemical contamination?
Chemicals have a range of important uses in food businesses. Some chemicals are naturally occurring in our food - however these and other chemicals may present a hazard if food handlers don't know that chemicals may be present, or if the chemicals are present in high concentrations. Food may be contaminated through ignorance or carelessness.

How can chemicals get into food rooms?
The following examples show how and where your food could become contaminated and give instances of which chemicals have contaminated food


  • poisons may be found naturally in some raw food materials
  • some foods, such as toadstools, some wild mushrooms, red kidney beans, green potatoes and daffodil bulbs are poisonous to people - sometimes, as with kidney beans, we can make them safe by thorough cooking, but in other cases cooking may not make any difference


  • unless organic supplies are chosen, foods may be treated with chemicals, such as pesticides and fungicides that are used on a farm - additives to animal feeds and veterinary residues may also be present in animal and poultry meat


  • food may become contaminated if cleaning chemicals are not used properly or if the wrong chemicals are used, and it is important to remember that not all cleaning chemicals are safe to use in areas where food is prepared - for example, chemicals such as bleach are too strong for use in food rooms


  • petrol and diesel from vehicle fumes can contaminate food
  • you should never use a vehicle to move chemicals and then use the same vehicle to move food as this can create a serious risk to food safety


  • you may need to oil or grease catering equipment with moving parts such as mixers or slicers - you must use 'food safe' oil or grease on items which come into contact with food
  • read the manufacturer's labelling carefully

Chemicals from metals can also contaminate food. Some metals such as cadmium (which may have been used in kitchen equipment such as fridges and cookers) and zinc (which is used for galvanising), are harmful and must not come into contact with food.

Tin cans can also be a hazard as they are made of iron, coated with tin plate. Sometimes acidic foods such as fruit can react with the tin plate, which may break down and be absorbed by the food. This food is harmful and must not be eaten. Once you have opened a can you must transfer the remaining food to a suitable lidded food container.

What happens when food is contaminated?
Some forms of chemical contamination may only taint food, which means that only the taste will be affected.

However other chemicals, for example bleach, are extremely harmful and can cause severe vomiting very quickly. Some chemicals cause long-term conditions such as organ damage or cancer, and can even kill.

Your food safety management system
You must do everything you can to stop your food being contaminated.

As part of your food safety management system, you need to consider every part of how you produce and prepare food. You need to identify how your food could be contaminated and put controls in place to reduce the risk of contamination.

Reducing the risk of contamination
The following are some controls you can put in place to reduce the risk of this happening to your customers and consumers and to protect your business:

You should always store cleaning chemicals away from food - this will reduce the risk of spills or contamination of food products.

Never store chemicals in food containers.

Never use food containers for cleaning jobs - for example, mixing bowls rather than buckets.

Train your staff to use cleaning materials in line with manufacturers' instructions. If you use too much cleaner it can be difficult to rinse away and any traces left behind could contaminate food.

Never clean near open food, and make sure you cover all food properly and put it away safely before you use chemicals.

Choose cleaning products that are suitable for a food environment and that are described as 'food safe'. This means that they are non-toxic, non-tainting, usually non-perfumed and non-corrosive so that they will not chemically react with materials used for food equipment.

Never use spray pesticides such as fly spray - droplets can fall on to food and food surfaces. You should control flying insects by using an electronic fly killer, or better still by using a fly screen to prevent flying insects getting into the food room in the first place. The use of other kinds of spray (for cockroaches) or baits (rat poison), which could contaminate food, should only be used by a pest control specialist.

It's a good idea to use a professional pest controller. If a pest controller uses a spray, you must clean all food-preparation surfaces to remove any traces left behind that may contaminate food.

You should remember that some foods may have been sprayed as crops in the field - for example fruits and salads. These foods are often eaten raw and must be thoroughly and carefully washed in running water. Once you have cleaned these you should treat them as ready-to-eat foods and protect them from further contamination.

Anything that smells strong can taint food. You should avoid highly perfumed cleaning products such as 'lemon fresh' or pine disinfectant.

Tell food-handling staff that they should not wear strong perfume or aftershave, or other toiletries and cosmetics. This is especially important for anything used on hands that may come into contact with food, such as heavily perfumed soaps or hand creams.

Wash hand basins used by food handlers should be supplied with unperfumed soap.

You must train food handlers how to store food safely.

You should check packaging to make sure that there is no damage or risk of chemical contamination.

You should get rid of any damaged goods, packaging or blown cans.

You should keep equipment and utensils in a good condition, and regularly clean and maintain them. Get advice from manufacturers and service engineers to make sure that you use the correct food safe oils and grease for maintaining equipment.

More information
You will find further guidance in our other leaflets on this website. Information can also be found on the Food Standards Agency website.

Alternatively, contact your local environmental health service for advice.

Please note
This leaflet is not an authoritative interpretation of the law and is intended only for guidance.

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