Course:FNH200/Lessons/Lesson 12/Page 12.4

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12.4 Natural Constituents and Natural Contaminants

What is the basis for distinction between Natural Constituents and Natural Contaminants?

Constituents are chemical entities that are part of the normal composition of a food material - they are not the result of some external organism or activity. Contaminants, on the other hand, are present because of the presence of moulds or bacteria, or because the plant or animal was grown in a condition which permitted the toxicant to become part of the food.

The distinction between natural and environmental toxicants is a little bit less clear cut, but may be generally determined by their origin. For example, we might be able to prevent the growth of moulds, but moulds are nevertheless naturally present in the environment. Pesticides, however, are introduced into the environment by us and while not intended to become part of the food, some do to a certain extent. Mercury and lead can enter the food supply because of heavy natural deposits in the soil, but in fact are found in food predominantly because we use these metals in a wide variety of ways.

It is difficult to be definitive about the relative importance of these different food toxicants to human health. Much of what has been written on this subject can be summarized by the information in Table 12.2.

Table 12.2 Perceptions of hazards in the food supply held by popular belief compared to regulatory agencies.

This table attempts to illustrate the perceived importance of hazards in food. It is interesting to note that what is perceived by popular opinion to be the greatest hazard is in fact considered to be the least important by regulatory agencies, and vice-versa! Regulatory agencies base their ratings on a much broader information base (including statistical or epidemiological evidence) than does the general public.

An extensive discussion of each of the toxicants identified in Table 12.1 is not possible. Several will be discussed in some detail below, followed by a brief comment on the remaining ones.