Changes

However, some trace elements such as As, Cd, Pb, Hg and Rn have no/limited biological functions and are generally toxic to humans; they are called non-essential trace elements.<ref name=Setal2013 />

However, some trace elements such as As, Cd, Pb, Hg and Rn have no/limited biological functions and are generally toxic to humans; they are called non-essential trace elements.<ref name=Setal2013 />

From the above biological classification of elements, it can be seen why medical geology sets its eyes on the trace elements: they are the causes of most health problems sourced from geologic materials. They emanate from igneous, sedimentary or metamorphic rocks, as well as industrial minerals. They contaminate groundwater through boreholes or through springs/streams. In addition, they can be released during volcanic eruptions.

From the above biological classification of elements, it can be seen why medical geology sets its eyes on the trace elements: they are the causes of most health problems sourced from geologic materials. They emanate from [[igneous]], sedimentary or metamorphic rocks, as well as industrial minerals. They contaminate groundwater through boreholes or through springs/streams. In addition, they can be released during volcanic eruptions.

===Geochemobiological Pathways===

===Geochemobiological Pathways===