Geomedicine

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Geomedicine

• Geology and Disease

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Objectives

• Understand the basic principles of geomedicine
• Understand the connections between trace
  elements, geology, and health
• Understand cases in which connections are less
  clear
• Understand further complicating factors

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Trace Elements

• Definition A chemical element required in minute
  quantities by an organism to maintain proper
  physical functioning.
• Earths crust is composed of only a few major
  elements so, too, are organisms.
• More than 99 of the human body is made of six
  elements.

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Principal Chemical Constituents of the Human
BodyElement Percentage of Body Weight
Oxygen 61 Carbon 23 Hydrogen 10 Nitrogen
2.6 Calcium 1.4 Phosphorus 1.1 Total 99.1
Source R.M. Parr, .Trace Elements in Human
Milk,. International Atomic Energy Agency
Bulletin 25, 2 (1983) 8. All other
elements.led by sulfur, potassium, sodium, and
chlorine.make up the other 0.9 percent of the
body.
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Essential Trace Elements
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Dose-Response Curves

• positive or negative effects of a trace element
  are plotted as a function of dosage

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Dose-Reponse (cont.)

• Some elements have no effect in low
  concentrations, but can be toxic or fatal at high
  concentrations (i.e. lead, mercury)
• Other elements may be needed to avoid deficiency,
  but benefits only increase up to a point (i.e.
  calcium hard to OD on!)
• Perhaps the most common scenario is when small
  amounts of an element are necessary for optimal
  health, but large amounts are toxic or fatal
  (i.e. copper, molybdenum)

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Geology, Trace Elements Health

• The ultimate source of the bodys trace elements
  is the earth rocks minerals
• Concentrations vary by rock type and rock
  location
• Concentrations are modified by natural processes
  as well as deliberate and accidental human
  activities

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Trace Element Pathways to the Human Body
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Iodine

• Necessary for proper functioning of the thyroid
  glad
• All cells in the body need iodine for proper
  functioning
• All glands (thyroid, adrenal, etc.) especially
  need iodine for the production of hormones
• Lack of iodine leads to goiter

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Fluorine

• Makes apatite (mineral in teeth) harder
• Added to many municipal water supplies

Without Fluorine With Fluorine
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Zinc

• Heavy metal
• A critical trace element nutrient
• Without zinc ? dwarfism, dermatitis, loss of
  taste sensitivity, delay in the rate of wounds
  healing

Dermatitis
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Selenium

• Rare metal
• Lack of selenium causes abnormalities in many
  plants and animals
• In humans ? cancers, malformation of nails and
  hair, depression, nervousness

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Radon

• Odorless
• Invisible
• 2nd leading cause of lung cancer in U.S.

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Cases in Which Connections Are Less Clear

• Radioactivity and Tobacco
• Regional Variations in Heart Disease
• Cardiovascular Disease in Georgia
• Other intriguing patterns

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Further Complicating Factors

• Cause and Effect or Coincidence?
• Trace Element Interactions
• Distinguishing Risk From Risk Perceptions
• Impacts of Human Activities

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Summary

• Geology bears on Human Health
• Geology bears on health of animals and plants
• Many effects are independent of human activities
• Geographic variation is often how some diseases
  are recognized
• Better understanding of the medical importance of
  naturally occurring trace elements could lead to
  the elimination of many instances of regionally
  chronic diseases