Geomedicine

GeologyHealth

& 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.

Oxygen 61Carbon 23

Hydrogen 10Nitrogen 2.6Calcium 1.4

Phosphorus 1.1Total 99.1

Principal Chemical Constituents of the Human Body*

Element Percentage of Body Weight

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.

• ~85% of the human brain is water• ~70% of babies are water • ~60% of adult men are water• ~55% of adult women are water

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 kitscost 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