trace elements

Chromium, cobalt, copper, iron, manganese, magnesium, molybdenum, selenium, zinc, and other elements that occur in very small amounts (usually less than 1 to 10 parts per million) as constituents of living organisms, and are necessary for their growth, development, and health. Whereas the shortage of trace elements in the body may result in stunted growth or even death, their presence in higher amounts is also harmful. Also called trace metals.