Monitoring for heavy metals

There appears to be no clear chemical definition of the term, heavy metal, but in the broadest sense the term seems to be restricted to metals of greater atomic number than calcium. Thus, nutritionally essential trace elements such as copper, zinc and manganese are heavy metals along with others which are not regarded as serving any useful function in the body such as lead and mercury. It is not certain how many metals are naturally present in food and clearly this will depend on factors such as the source and type of food but it is probable that many metals which occur in nature will also occur in minute traces in food. In practice most of these present no problem and from the point of view of food contamination only a few of the heavy metals, in particular lead, mercury and cadmium, at the present time are of real interest. It is worth noting that some of the essential trace metals may act as contaminants if certain levels are exceeded.