Period 5 element dimethyl telluride, (CH)Te, a gas with a garlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure. Iodine is the heaviest essential element utilized widely by life in biological functions (only tungsten, employed in enzymes by a few species of bacteria, is heavier). Iodine's rarity in many soils, due to initial low abundance as a crust-element, and also leaching of soluble iodide by rainwater, has led to many deficiency problems in land animals and inland human populations. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. Iodine is
Trace metal vegetables are sources. Taken in excessive amounts, trace elements can cause problems. For example fluorine is required for the formation of bones and enamel on teeth. However, when taken in an excessive amount can cause a disease called "Fluorosis', in which bone deformations and yellowing of teeth are seen. Fluorine can occur naturally in some areas in ground water. Trace metals include iron that can help to prevent anemia, and zinc that is a cofactor in over 100 enzyme reactions. Trace metal Trace metals are the metals subset of trace elements; that is, metals normally present in small but measurable