‘Natural’ not always safe

Re: ‘ Surrounded by food,’ says lifelong forager, July 18

The author describes a number of plants that grow wild in Ontario — sumac, fiddlehead ferns, sweet grass, chicory, burdock, wild ginger and others — as being edible and healthy.

There is a widely held belief that if something is natural it is safe. This is often not the case. Wild plants may be safe to the extent that they do not immediately make you ill. However, the possibility of long-term deleterious effects is invariably unknown.

I am a retired toxicologist. During my working career I conducted many short- and long- term lifetime carcinogenic studies on many chemicals and some “natural” materials. In some cases the result of my studies and those of others are surprising. The juice of the croton flower stem and roots is highly carcinogenic; tobacco of course is a well- known carcinogen. Cedar, which is mentioned in the story as a flavouring, is carcinogenic.

Some years ago I discovered that salts of the metal, cobalt, which were used to treat anemia, under certain conditions could be fatal. The use of cobalt salts in foods or pharmaceuticals is now forbidden all over the world.

The most poisonous substance known, ricin, is derived from the seeds of the castor bean plant. An amount equivalent to two grains of salt is fatal for an adult.

Long- term studies of plant safety are costly, however, if particular wild plants were of interest their safety could be determined in short- term carcinogenicity tests.

Clifford I. Chappel, D. V. M., Ph. D., Oakville