Geology, trace elements and health.
Both animal and vegetable life depend for their existence on appropriate amounts of various trace elements, albeit in very small amounts. This paper lists some of these trace elements and the ailments in which they play an important role. The elements discussed are gold, platinum, copper, lead, zinc, aluminium, silica, mercury, cadmium, selenium, arsenic, and iodine. The diseases involved range from multiple sclerosis, various cancers, arthritis, goitre, Down's Syndrome, and mental retardation. Less well known are Keshan, Alzheimer's, Itai-Itai, and Minamata diseases. Of particular interest in the latter part of the twentieth century is the discovery that serious deficiencies of either copper or zinc in the diet of animals may break down their immune defence mechanisms. The ability of certain plants selectively to concentrate particular heavy metals in their tissues and pollen is discussed.