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Skip to 0 minutes and 1 second Broadly speaking, natural toxins, pesticides residues, drug residues, and heavy metals are all in the range of food contaminants. There are a range of potential sources of contamination.

Skip to 0 minutes and 15 seconds Contamination can include pollution at source through the air, soil, or water in which crops are grown.

Skip to 0 minutes and 24 seconds It can also occur through pest or animal contamination of the crop, or through the use of fertilisers, insecticides, or natural toxins that may be part of the plant or fungi mixed with the crops, such as mycotoxins produced by fungi. Once harvested, contaminants may be introduced during methods of transport, storage, packaging, food processing, and food handling. Food handlers or consumers may also contaminate the food, especially with bacteria. Therefore, food can be contaminated at various points along the stages of food production. Food growing, food handling, or food processing.

The source of food contaminants

Food contaminants are chemical substances that have not been intentionally added to food. These chemicals may have an adverse effect on animal and human health.

Contaminants can be introduced to food during any of the following stages:

production manufacture
processing preparation
treatment packing
packaging transport
storage cooking

Types of food contaminants include:

  1. Naturally-occurring contaminants
  2. Process contaminants
  3. Man-made pollutants

More information about each of these is included below:

1. Naturally-occurring Contaminants

Examples of naturally-occurring contaminants include Mycotoxins and Alkaloids.

Alkaloids are chemical compounds containing nitrogen, which can have a physiological effect on humans.

Mycotoxins are toxins produced by fungi that contaminate food, such as maize or peanuts. Mycotoxins can contaminate crops while it is growing or can cause contamination at later stages such as during storage. They are known to be toxic to humans and animals, causing various negative health effects.

At high levels of contamination, mycotoxins may be acutely poisonous, causing immediate illness or even death, but chronic exposure – small amounts over a long period – can cause other health effects such as cancer, that develop later.

2. Process contaminants

Process contaminants are introduced during various stages of food processing, such as cooking. Examples include acrylamide and heterocyclic amines (HCAs).

HCAs are an example of a type of chemical carcinogen – a cancer causing agent - that are produced during cooking. Meat contains proteins that when heated at high temperatures can combine to form HCAs. HCAs are known to have carcinogenic potential for humans and this may be why there is an association between regular consumption of well cooked meat and colon cancer.

Acrylamide is a toxin formed by the reaction between reducing sugar and the amino acid asparagine during cooking. It is typically produced during the baking or frying of foods containing starch. Acrylamide is found in food products such as crisps, biscuits and chips.

Like heterocyclic amines, it is thought that chronic exposure to acrylamide may increase the risk of cancer development.

3. Man-made pollutants

Man-made pollutants include Melamine and Dioxins. These toxins are produced through manufacturing processes.

Melamine is sometimes deliberately – and illegally – added to milk powder in order to boost the apparent protein content of the product. Melamine shows up in tests for protein content determination as if it were a protein.

This is very dangerous as melamine is poisonous, and this form of food contamination has led to infant deaths in recent cases of contamination within China.

Dioxins are a by-product of some manufacturing processes, such as the production of herbicides, and are known to be toxic to humans. Dioxins are chemicals that can build up in the environment and become taken up by some crops.

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This video is from the free online course:

Tackling Global Food Safety

Queen's University Belfast