field, "(1) the study of trace elements, especially their bioavailability and (2) a need to establish baseline, or background levels of contaminants/xenobiotics/potentially harmful but naturally occurring materials in water, soil, air, food, and animal tissue." The elements and minerals in the land affect people and animals immensely, especially when there is a close relationship between the two. Those who depend heavily on the land are faced with one of two problems. First, those who live in places such as Maputaland, South Africa are exposed to heavily impoverished soils which result in a number of diseases caused by mineral imbalances. Secondly, those in areas such as India and Bangladesh are often exposed to an excess of elements in the land, resulting in mineral toxicity. All living organisms need some naturally occurring elements; however, excessive amounts can be detrimental to health. There is a direct link between health and the earth because all humans ingest and breath in these chemicals and for the most part it is done unknowingly. Sources of chemical exposure There are many ways in which humans come into contact with the earth's elements and below are only a few ways in which we become exposed to them. Volcanoes are one of the main sources that bring all the toxicity from inside the earth to the outside. They bring out chemicals such as; arsenic, beryllium, cadmium, mercury, lead, radon, and uranium. Rocks are also one of the leading sources in exposure to these elements. "They are essentially the source of all the naturally occurring chemical elements found on the earth." Diseases Iodine deficiency One of the biggest geochemical diseases is iodine deficiency. Thirty percent of the world is at risk for it and insufficient intake is the most common cause of mental retardation and brain damage. The sea is a major source of iodine and those who are further from it are at a disadvantage. Another source of it is in soil; however, goitrogens such as humus and clay trap the iodine, making it hard for people to access it. Some cultures actually consume the earth's minerals by eating soil and clay; this is known as geophagy. It is most common in the tropics, especially among pregnant women. The Ottomac people of South America engage in this practice and none have suffered from any health problems related with mineral/ Iodine deficiency. Cardiovascular disease Cardiovascular disease has often been linked