ABSTRACT
This chapter emphasizes the four established essential ultratrace elements As, B, Ni, Si plus molybdenum, an element found essential about 30 years ago. The 11 elements are arsenic, boron, bromine, cadmium, fluorine, lead, lithium, nickel, silicon, tin, and vanadium. Because of the reputation of arsenic as a poison or carcinogen, the arsenic content of foods has received some attention. However, except for foods of marine origin, the arsenic content of most foods is very low. The arsenic content of foods of plant origin is quite low because root uptake of arsenic generally is quite low. The biochemistry of arsenic at trophic levels higher than phytoplankton in the marine food chain is an unsettled topic. Some findings indicate that higher organisms themselves transform inorganic arsenic to organic forms, whereas other findings suggest that most organic arsenic that appears in these organisms comes from preformed sources.
