Food contamination

Food can get contaminated by the water used for washing and cooking, by the soil in which it is grown, by the containers used for storage, preparation an'd serving and by the personnel handling the food at various stages, particularly at the stage of dishing it out and serving. 

Food contaminants can be of two distinct types - chemical contaminants and microorganisms. Let us discuss these two types of contamination in a little detail 

Chemical Contaminants 

You may know that we add chemicals to food when we salt fish and meat, ferment plant and animal substances or add spices to improve the taste of our food. These are. just a few examples of the large variety of chemicals we add to foods not only to preserve them but also to improve their appearance, texture and flavor. Some are added to improve nutritional value and some to help in the processing of certain food items. But are these contaminants? No, they are in fact additives. They are added intentionally. However, in excess amounts they are harmful for human health. These quantities are prescribed by laws which-protect the interests of the consumer. A permitted chemical in quantities higher than prescribed' becomes a case of adulteration.

Now let us come back to the question of contaminants. There are many instances of chemicals that are not supposed to be present in food, but get into it by accident. These cause injury to human health. Such substances can be called contaminants. Pesticides are an example of such toxic chemicals. As time goes on more and more pesticides get accumulated in our bodies due to their presence in food. Such accumulation can cause abnormalities in the functioning  of vital organs and body systems such as the kidney, circulatory system (blood) and brain. Some pesticides have been linked to cancer. 

Besides pesticides, chemicals that may leach into food from packing material, or trace amounts of lubricants that can get into the food from processing machinery are all unintentional contaminants in our food. 

Poisons like lead and cadmium can enter the food through improperly coated utensils. These  poisons are also called industrial contaminants of food. This is because factories and industries release many of these chemicals into rivers and lakes as part of their wastes. This then gets into the soil and plants. Their hazards are described in Table

This table includes several terms you may not be familiar with. To help you along here is a Box which lists difficult terms with their meaning: 

Contamination by Microorganisms 

You are probably already familiar with the term 'microorganism'. microorganism are tiny, living cells. Bacteria and viruses are microorganisms as you studied. Certain microorganisms contaminate food and cause disease in individuals who consume this food i.e. they cause food poisoning. Food poisoning, in other words, is the term used to refer to the harmful effects of consuming food contaminated by microorganisms. Food poisoning is classified into two categories: (a) food infections; and (b) food intoxication.

Food infections generally involve microorganisms present in the food at the time it is consumed. Once inside the human being they begin to grow and cause disease. Diseases like cholera, dysentery, typhoid are examples of infectious diseases caused by eating contaminated food. A number of viral infections also may be contracted by, man through contaminated food that has not been processed or handled adequately. These are infectious hepatitis, poliomyelitis, and various respiratory and intestinal disorders. 

Food intoxication involve toxic substances produced in the food by microorganisms, before it is consumed. When such food is eaten the person becomes sick because of the toxin. Staphylococcus aureus and Clostridium botulinum cause bacterial food poisoning because of the toxins they give rise to in the food. Poisons produced by staphylococci cause severe nausea, vomiting and abdominal pain. The toxin produced by Clostridium botulinum can kill. It causes dizziness. difficulty in swallowing. speaking and breathing and finally paralyzes the neck, arm and leg muscles as well as the respiratory system. 

Certain moulds also produce toxins in the food they attack. These toxins are called mycotoxins. The ones commonly known are the aflatoxins found in peanuts and sometimes maize, wheat, rice, sorghum and soybeans as well, which have been attacked by a particular mould. They cause liver diseases among those who consume such infected foods. The ergot fungus is associated with bajra, wheat, jowar and rye. This fungus produces toxins which fesult in ergotism. The toxin causes gastrointestinal disturbances, painful cramps in the legs, gangrene in fingers and toes, depression, weakness and convulsions. Gangrene is a condition where body parts begin to get destroyed due to infection. Such parts often have to be cut off otherwise it can spread to other parts of the body. 

Appendix 3 gives some hod infections and intoxication along with the causes and the types of foods usually involved in our country. After  through this table, we hope you will realize how absolutely imperative it is to implement the strictest possible standards of cleanliness in our food-related activities. It is important to mention here that food vendors that are always present around schools and offices selling sugarcane juice, coloured sherbats, pani-puri, bhelpuri, chat or cut and sliced fruits are responsible for gastrointestinal bacterial infections as well as chemical poisoning by using non-permitted food colours.