Food contamination

Food contamination

    • Food contamination refers to the presence of harmful chemicals and microorganisms in food which can cause consumer illness. A separate issue is genetically modified food, or the presence in foods of ingredients from genetically modified organisms, also referred to as a form of food contamination.


    • The impact of chemical contaminants on consumer health and well-being is often apparent only after many years of prolonged exposure at low levels (e.g. cancer). Chemical contaminants present in foods are often unaffected by thermal processing (unlike most microbiological agents). Chemical contaminants can be classified according to the source of contamination and the mechanism by which they enter the food product.


    • Agrochemicals are used in agricultural practices and animal husbandry with the intention to increase productivity. Such agents include pesticides (e.g. insecticides, herbicides, rodenticides), plant growth regulators, veterinary drugs (e.g. nitrofuran, fluoroquinolones, malachite green, chloramphenicol), and bovine somatotropin (rBST).

    Environmental contaminants

    • Environmental contaminants are chemicals that are present in the environment in which the food is grown, harvested, transported, stored, packaged, processed, and consumed. The physical contact of the food with its environment results in its contamination. Possible sources of contamination are:
    • Air: radionuclides (137Caesium, 90Strontium), polycyclic aromatic hydrocarbons (PAH).
    • Water: arsenic, mercury.
    • Soil: cadmium, nitrates, perchlorates.
    • Polychlorinated biphenyls (PCB) , dioxins, and polybrominated diphenyl ethers (PBDE) are ubiquitous chemicals, which are present in air, water, soil, and the entire biosphere.

    Packaging materials:
    • Antimony, tin, lead, perfluorooctanoic acid (PFOA), semicarbazide, benzophenone, isopropylthioxanthone (ITX), bisphenol A.Processing/cooking equipment: copper, or other metal chips, lubricants, cleaning and sanitizing agents.Naturally occurring toxins: mycotoxins, phytohaemagglutinin, pyrrolizidine alkaloids, grayanotoxin, mushroom toxins, scombrotoxin (histamine), ciguatera, shellfish toxins, tetrodotoxin, among many others.

    Banned pesticides, carcinogens

    There are many cases of banned pesticides or carcinogens found in foods.
    • Greenpeace exposed in 2006 in China that 25% of surveyed supermarkets agricultural products contained banned pesticides. Over 70% of tomatoes that tested were found to have the banned pesticide Lindane, and almost 40% of the samples had a mix of three or more types of pesticides.Fruits were also tested in this investigation. Tangerines, strawberries and Kyofung grapes samples were found contaminated by banned pesticides, including the highly toxic Methamidophos. These fruits can also be found in Hong Kong market. Greenpeace says there exists no comprehensive monitoring on fruit produce in the Hong Kong as of 2006.In India, soft drinks were found contaminated with high levels of pesticides and insecticides, including lindane, DDT, malathion and chlorpyrifos.

    Hair in food

    • Many people consider hair in food to be particularly unpleasant, however there are certain risks to be considered such as choking and repulsion induced vomiting. There are also considerations of contaminants on the hair itself such as waxes or other hair products that may cause problems. It is claimed sometimes that it does not usually pose any serious health risk, but in other cases it is claimed that it does pose a health risk.

    • For example, people working in the food industry are required to cover their hair. Also, when people are served food which contains hair in restaurants or cafes, people may complain to the manager. Despite this, it is not valid ground to sue the restaurant in the United States but in the United Kingdom it breaks the regulations of the UK Food Safety Act 1990 and is known to cause food poisoning and people can sue for this. In one case a supermarket considered banning a man with a beard working there. In such cases there exists protection for food workers who have facial hair, which is called 'snood'. The cause of people's disgust with hair in food could be that hair is not easily digestible and is the wrong shape for being processed in the body. Hair in food was often a common cause of complaint from people eating food, before the introduction of complete capture hairnets.

    Processing contaminants

    • Processing contaminants are generated during the processing of foods (e.g. heating, fermentation). They are absent in the raw materials, and are formed by chemical reactions between natural and/or added food constituents during processing. The presence of these contaminants in processed foods can not be entirely avoided. However, technological processes can be adjusted and/or optimized in order to reduce the levels of formation of processing contaminants. Examples are: nitrosamines, polycyclic aromatic hydrocarbons (PAH), heterocyclic amines, histamine, acrylamide, furan, benzene, trans fat, monochloropropanediol (MCPD), semicarbazide, 4-hydroxynonenal (4-HNE), and ethyl carbamate. There is also the possibility of metal chips from the processing equipment that requires metal detection. In many conveyor lines, the line will be stopped, or when weighing the product with a Check weigher, the item can be rejected for over- or underweight as well as detection of very small pieces of metals.

    Emerging food contaminants

    • While many food contaminants have been known for decades, the formation and presence of certain chemicals in foods has been discovered relatively recently. These are the so-called emerging food contaminants, e.g. acrylamide, furan, benzene, perchlorate, perfluorooctanoic acid (PFOA), monochloropropanediol (MCPD), 4-hydroxynonenal and (4-HNE).

Last modified: Wednesday, 29 February 2012, 7:13 PM