Some Healthy, Some Lethal
Both books are concerned with the long-term influences on human health and disease of several dozen chemical elements classified as metals or metalloids, as they are present in our environment, notably in air, drinking water, and food. Both were designed for laymen, but scientists even in biomedical disciplines are certain to find in them much novel and fascinating information. (Unhappily for serious scholars, the references to scientific literature are sketchy.) The volumes cover essentially the same ground from about the same points of view. In style as well as content, both are highly readable, informative, provocative, and occasionally dogmatic. Both are well indexed.The vocabulary is non-technical, and the texts contain delightful anecdotes. This stylistic casualness, however, does not obscure the very serious purpose of the author or the deep biological and social significance of his message.
Dr. Schroeder, recently deceased, classifies trace metals into three categories: those that are essential for good health and should therefore be present in the diet in minute quantities (chromium, cobalt, copper, iron, manganese, molybdenum, selenium, vanadium, zinc, and perhaps nickel and strontium); those that may compromise health and longevity when present in amounts that might enter the body over long periods of time (especially antimony, arsenic, beryllium, cadmium, lead, and mercury); and those inert in amounts likely to be encountered in any non-occupational chronic exposure (aluminum, tin, titanium, zirconium, etc.). Much of the evidence for these distinctions during the past 12 to 14 years comes from the researches of the author and his colleagues at the Trace Element Laboratory in Brattleboro, Vermont, an affiliate of the Department of Physiology of the Dartmouth Medical School. Hypertension in rats chronically fed cadmium and the protective effect of zinc are among Dr. Schroeder's many well-known discoveries in the field of trace metals. The roles of cadmium in human hypertension and of chromium deficiency in human arteriosclerosis receive much attention.
On the subject of environmental pollution, the author is neither alarmist nor complacent. He demonstrates how unlikely it is that industry now or in the foreseeable future will pollute significantly the open oceans. (There is no mention of radioactive contamination, however.) He considers the swordfish ban part of a world-wide mercury scare due to an inexcusable misinterpretation of data about natural mercury levels in the environment. But as a dedicated physician he is deeply concerned about the adverse health effects of local environmental pollution, particularly by cadmium, lead, and beryllium. He castigates the lead, petroleum, and food-processing industries for several of their practices and challenges the objectivity of their scientific staffs. He is scarcely less tolerant of some federal regulatory agencies - notably the Food and Nutrition Board of the National Research Council - for its failure to acknowledge human dietary requirements for chromium, cobalt, manganese, molybdenum, and selenium.
In both books Dr. Schroeder makes an impassioned plea for society to correct promptly the metal excesses and deficiencies that he believes to be firmly demonstrated. Almost every textual assertion about these dislocations is expressed in numerical terms. For example, "Methyl mercury is 50 times as toxic as mercury and it stays in fat ... fourteen times as long." Or again, "... nearly 94 per cent of the fatal diseases in this country involve trace metals in one way or another ... and 70.7 per cent are directly involved with them." As a scientist, the author fully understood that such statements involve statistical and methodological uncertainties. As an educator, however, he recognized that numbers impress almost everyone and that quantification adds authenticity to any declaration. Dr. Schroeder was both an excellent scientist and a superb polemicist. We all are in his debt on both accounts.
THE TRACE ELEMENTS ANDMAN (Devin-Adair, 1973. 178 pp.$7.95) and THE POISONSAROUND US (Indiana, 1974. 144pp. $6.95). By Henry A. Schroeder,M.D., late Professor of Physiology.
Dr. Gosselin is Irene Heinz Given Professor ofPharmacology at the Dartmouth MedicalSchool.
