Naturally Dangerous. (Book Reviews).

Collman JP, University Science Books, Sausalito, 2001, 270 pages, $49.95, ISBN 1-891389-09-2

The author is a professor of chemistry at Stanford University. The subtitle of the book is 'Surprising Facts about Food, Health and Environment'. It is written for non-scientists, engineers, physicians and scientists alike. It is full of surprising anecdotes, curious facts and historical oddities: current observations from our everyday lives to the scientific principles that can explain them. Two main themes underly all the examples--both natural and artificial chemicals can be dangerous, and the safety and/or effectiveness of any particular substance depends on its concentration and the part of the body exposed to it.

The first chapter is about chemicals lurking in our grocery store. The other chapters are about the pharmacy; Is 'health food store' an oxymoron?'; Infectious agents: are all microorganisms bad?; Cancer and the environment; interesting points in a selection of 27 of the chemical elements; Natural and unnatural molecules in the environment; Is the sky falling??; Dust, magnets and scuba diving, and We are all radioactive!

The section on global warming is the best I have ever read on the subject. It is much more complex than presented in the media. The major greenhouse gas is water vapour in clouds. Their variability complicates the calculations. And there are many interesting and different topics throughout the book. I liked his section on irradiation of foods, which he calls 'cold pasteurisation'. The pubic tends to be afraid of this method of food processing because many people believe that gamma rays are asubstance that stays in the food.

There are many fascinating subjects here, perhaps too many to digest by reading from beginning to end. But you can start anywhere as the chapters each stand alone. Scientific terms are defined in the Glossary and there is a list of selected references in an appendix. The book is a cheerful contribution to bridging the gap between the two cultures, scientific and non-scientific.

Despite the subtitle, only a quarter of the main part of the book is about foods or nutrients and here I found a few factual errors, e.g. 'lysine is not found in sorghum (page 9); 'beer is nearly a complete food (page 39); 'calcitriol may become available in the future as a drug (page 74); '400 IU of vitamin E can raise blood pressure (page 73); 'zinc supplements of 25 mg are recommended for thin, pregnant women, who are typically zinc deficient (page 128). There are other statements that are a little uncritical e.g. 'other epidemiologic evidence implicates trans fatty acids in a higher incidence of breast cancer (page 20); 'studies have shown that folic acid deficiency may be responsible for 15-20% of heart attacks in men' (page 73) and 'if you go above 500 mg vitamin C twice daily you are just making expensive urine (page 72). Collman lists some 20 people who read and advised on sections of the book. If Naturally Dangerous goes to a second edition, an evidence-based nutritionist should be able to prune weak nesses from the draft of an otherwise fresh and enjoyable book.