Even though they may not necessarily be harmful, any substances other than the intended ingredients present in food qualify as contaminants, although they may not always necessitate remedial action. Such substances fall into one of three possible categories, and are classified as being biological, chemical, or physical in nature. The threat posed by microorganisms is well known to most consumers and foodstuffs are generally subjected to intensive testing to that ensure they are free of pathogens, such as E. coli, salmonella species, and others such as Listeria, recently responsible for around 180 deaths from acute gastro-intestinal infection.

Chemicals may find their way into a product by a variety of routes. Often, their presence is unintentional, but unavoidable. Some of these chemical food contaminants may be present purely because they are among the ingredients of other products prepared in the same area. Common examples of this are nuts, shellfish, and dairy products that to most consumers are harmless and undetectable, but for those with an allergy to any of these, the consequences of ingesting them can be unpleasant and, in rare cases, might even prove fatal. Where such a risk may exist, the manufacturer is now required under current legislation to draw attention to any allergens that may be present by listing them prominently on the product label. In the case of known and acceptable ingredients, it may still be necessary to limit their concentration.

The presence of inappropriate chemicals in farm produce such as meat, vegetables, and fruits is also a risk, and pesticides, fertilisers, and veterinary drugs all feature among the chemical contaminants that find their way into both fresh and processed foods from time to time. Sometimes, however, the problem can originate closer to home when, for instance, cleaning products such as detergents and sanitisers are not sufficiently rinsed from work surfaces, allowing chemical residues to be left behind.

In practice, both of these problems can generally be prevented by simply ensuring that all of the required ingredients are only purchased from established suppliers with a reliable record of quality, and by adopting a proven effective cleaning regimen and monitoring it closely. However, in order to completely rule out the possibility that a given food product is free of contaminants, or that any which may be present are within acceptable limits, there is no substitute for a programme of appropriate qualitative and quantitative laboratory tests.

One should, of course, not overlook the possibility of physical contamination. This could refer to anything from human hair and pieces of animal bone, to wire staples and broken glass. In this area, hairnets and a policy of vigilance that ensures the close scrutiny of products during each and every stage in their manufacture will be the best defence.

Fortunately, to counter the risk of chemical and biological contaminants in food, there are far more effective options than simply keeping a close watch on the manufacturing process. The Neogen Corporation, for instance, has a range of test kits for hygiene monitoring, allergen testing, and the rapid detection of pathogens and mycotoxins, while CDR FoodLab provides kits for the rapid analysis of multiple samples, such as edible oils, dairy products, and wine. These, and other test kits, are available to companies in South Africa from IEPSA.

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