Nonessential elements are, conversely, those trace elements detected in the human body which have not been found to serve in any physiological capacity. It should be noted that in 1971 there were roughly twelve trace elements recognized as essential (1), and presently some sixteen trace elements are so classified (5). With the de•velopment of more sensitive analytical techniq~es, the number of essential trace elements is expected to increase.The body regulates the levels of the various elements, both essential and nonessential, within specific limits. Abnormalities associated with the essential trace elements may be caused by a specific deficiency (from dietary inadequacies, imbalances, or the result of other diseases) or. accumulation of innately toxic concentrations of trace elements from the environment. While disease states due to the deficiency, as opposed to the excess of an essential trace element, are more prevalent, practically all concern with nonessential trace elements is with respect to the physiological effects of accumulating excesses. Since excursions in the concentrations of trace elements outside of normal ranges are theoretically detectable by an appropriately .sensitive technique, the diagnosis and treatment of human disorders based on changes in the levels of trace elements in the body is feasible. aUnderlined elements are considered causal factors in the diseases.