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
Fluorine deficiency Fluorine deficiency Fluoride or fluorine deficiency is a disorder which may cause increased dental caries (or tooth decay, is the breakdown of dental tissues by the acidic products released by the "bacterial fermentation of dietary carbohydrates.") and possibly osteoporosis (a bone disorder which leads to a decrease in bone mass, and an increase in bone fragility), due to a lack of fluoride in the diet. In terms of dietary sources, fish and tea are considered natural sources of fluoride, as well as tap water that has been fluoridated. The extent to which the condition truly exists, and its relationship to