This document discusses several trace elements and their functions in the body. It defines trace elements as minerals present in small amounts in living tissues, some of which are essential nutrients while others may be essential but require more evidence. It notes that while trace elements are necessary for the body, they can also be toxic if consumed in too high amounts or for too long. Specific trace elements mentioned include copper, chromium, molybdenum, fluorine, and manganese, with chromium exposure potentially occurring through various industrial occupations.