Geomedicine
Geology
Health
& Disease
Countries with Universal Health Care
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
Trace Elements
Definition: A chemical element required in
minute quantities by an organism to
maintain proper physical functioning.
Earth’s 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.
Principal Chemical Constituents
of the Human Body*
Element Percentage of Body Weight
Oxygen 61
Carbon 23
Hydrogen 10
Nitrogen 2.6
Calcium 1.4
Phosphorus 1.1
Total 99.1
• ~85% of the human brain is water
• ~70% of babies are water
• ~60% of adult men are water
• ~55% of adult women are water
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.
Essential Trace Elements
Dose-Response Curves
• positive or negative effects of a trace
element are plotted as a function of
dosage
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)
Geology, Trace Elements & Health
• The ultimate source of the body’s
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
Trace Element Pathways to the
Human Body
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
Fluorine
• Makes apatite (mineral in teeth) harder
• Added to many municipal water supplies
Without Fluorine
With Fluorine
Zinc
• Heavy metal
• A critical trace element nutrient
• Without zinc  dwarfism, dermatitis, loss
of taste sensitivity, delay in the rate of
wounds healing
Dermatitis
Selenium
• Rare metal
• Lack of selenium causes abnormalities in
many plants and animals
• In humans  cancers, malformation of
nails and hair, depression, nervousness
Radon
• Odorless
• Invisible
• 2nd leading cause
of lung cancer in
U.S.
• Radon test kits
cost as low as
$8.99
Cases in Which Connections Are
Less Clear
• Radioactivity and Tobacco
• Regional Variations in Heart Disease
• Cardiovascular Disease in Georgia
• Other intriguing patterns
Regional Rates of Heart Disease in Europe
Further Complicating Factors
• Cause and Effect or Coincidence?
• Trace Element Interactions
• Distinguishing Risk From Risk Perceptions
• Impacts of Human Activities
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