Introduction
The use of chemicals as food additives is an ancient practice, sodium chloride being the first to be used. Food additives are currently a part of our way of eating especially in the industrialized world.
According to one estimate, as many as 10,000 compounds or combinations of compounds may find thier way into foods during processing, packaging or storage. These include unintentional additions also, e.g. residues of pesticides used to treat crops, minute amount of drug fed to animals (hormones, antibiotics) and chemicals that seep out of plastics and other packaging materials.

Why chemicals are added in food
Additives are generally used for solving complex problems of storing, cleaning, handling, heating and packaging commercially prepared foods. Some additives are merely used to preserve the natural colour of the foods e.g. addition of nitrate to meat to preserve the pink colour. In brief, these additives serve one or more of the following functions listed below in the foods:
1. Preservatives
2. Buffers
3. Emulsifiers
4. Neutralising agents
5. Sequestering agents (or chelating agents)
6. Stabiliser
7. Anticaking agents
8. Flavouring and colouring agents.

In addition, some additives are used as nutritional supplements to increase the nutritive value of foods such as potassium iodide and vitamins. Before these chemicals are cleared for use, they are tested on experimental animals, one at a time

Side effects of chemical additives
Humans injest dozen of chemicals daily during the course of thier life time. No one can say the overall effect these chemicals can have on the body ; which chemicals are poisonous or carcinogenic by interacting with others; which are dissipated in the body and which are cumulative. For example, we have seen how the nitrates added to meat could transform into carcinogenic nitrosamines by reacting with amino acids in the stomach. While most of these additives have been cleared as safe by the food administrations of various countries, some continue to be controversial. Some examples are:
1. BHA (Butylated Hydroxy Anisole) and BHT (Butylated Hydroxy Toluene) are used as antioxidants
2. Carboxymethyl cellulose as a stabiliser
3. Aspartame and Sucralose as well as Saccharine as artificial sweeteners
4. Monosodium glutamate (MSG), also called Chinese salt is the best known flavour enhancer commercially used in oriental restaurants and in prepared foods. Earlier, it was used in baby foods but it is now discontinued after studies revealed that large amounts destroys the brain cells in young mice. Now MSG has been found to be responsible for the so called Chinese restaurant syndrome which produces headaches, tightness in the chest and forearms accompanied by weakness and palpitations.

Common Chemical Additives and the foods they are used for preservation
1. Acidulant are used to preserve soft drinks, fruit juices, jams, soft drink powders etc.
2. Anticaking compounds are used in producing table salts, preserving baking powder and malted milk powder to prevent moisture absorption
3. Antioxidants are used in cooking oils and fats and dehydrated foods to prevent rancidity
4. Artificial sweeteners flare added to soft drinks and low calorie foods to improve sweet taste
5. Bleaching and maturing agents for preserving flour for proper bleaching and ageing
6. Colours are added in butter, cheese soft drinks, confectionery, jellies, etc for pleasing appearance
7. Emulsifiers added in ice creams, confectionery coatings, cakes, soft drinks, etc to disperse one liquid in another
8. Flavours added in all processed foods to provide flavour for the food.
In as much as these additives may improve the taste and appearance of foods, it is worthy to note that one must be very careful in consumption of these processed foods as some of them when consumed in excess can be carcinogenic.