Naturally Occurring Mutagens

Summary

There are a number of mutagens in our environment and they can be classified into two major groups: those of biological origin and those of non-biological origin. The latter group includes metals, such as mercury and cadmium, and cooked foods such as the charred surface of fish or hamburger, etc. The cooked foods are related to or produced by human activity and will not be dealt with here. Naturally occurring mutagens are those originating from microbes, plants and animals. Among them the most important and those causing the greatest concern are the products of fungi that are collectively called mycotoxins. They contaminate human foodstuffs from several sources, and some are known to have strong mutagenicity. A second group which concerns Us consists of several endogenous substances produced by green plants such as pyrrolizidine alkaloids, allyl isothiocyanate, cycasin, etc. Many of these have been discovered either from a sudden outbreak of toxicosis in livestock and poultry, or from the frequent occurrence of hepatomas or cancers among inhabitants of certain districts. Surprisingly, potent mutagenicity has been discovered for flavinoids that commonly exist in the leaf constituents of green plants. Mutagens of animal origin exhibit somewhat different characteristics from mycotoxins and those occurring in plants. They are produced in the animal’s body and may be mutagenic to the animal itself. A good example is dimethylnitrosamine, which is produced in an animal’s stomach when it ingests foodstuffs containing nitrous acid or nitrite (ham or sausage) together with secondary amines (fish, meat, etc.).

After reviewing those naturally occuring mutagens, special attention will be focused on the epidemiologiacl significance of mycotoxins in the human population and on the adaptation of herbivorous insects.