Environmental Health

1
Environmental Health
James M. Eddy Texas AM University
2
Biological Determinants of Environmental Health

• Biological factors are the basis of many
  environmental health problems
• History tells us a lot about the role of
  biological determinants
• Solutions to environmental health problems are
  often biological

3
Ecosystems

• Definition of Ecosystem
• Plants, animals, microorganisms, taken together
  with the non-living physical environment make up
  an ecosystem.

4
Complex Ecosystem
Prairie Ecosystem 1830
Rodents
Grasses
Buffalo
Rabbits
Carnivores
Birds
Worms
Birds
Insects
5
Simplified Ecosystem
Grasses
Insects
Rabbits
Birds
6
Ecosystem Food Chains

• The more complex the ecosystem, the more stable
  it becomes.
• The ecosystem modification is difficult to predict

7
Historical Examples of Ecosystem Modification

• DDT in Borneo
• Building Dams (Schistosomiasis)
• Elimination of species/Introduction of species
  (alligators, sea lamprey, mongoose)

8
Ecosystems The Food Chain Trophic Levels

• Plants or producers
• Herbivores or primary consumers
• Small carnivores or secondary consumers
• Top carnivores or tertiary consumers

9
Law of Thermodynamics

• Energy may be converted from one form to another
  but can never be created or destroyed.
• No conversion of energy from one form to another
  is 100 efficient.

10
Food Chain Example 1
1 man
600 trout
180,000 frogs
540,000 grasshoppers
2,000 tons grass
11
Food Chain Example 2
30 people
180,000 frogs
54,000,000 grasshoppers
2,000 tons grass
12
Food Chain Example 3
900 people
54,000,000 grasshoppers
2,000 tons grass
13
Food Chain Example 4
2,000 people
2,000 ton grass
14
Food Chain Example 5
1 man
600 trout
180,000 frogs
540,000 grasshoppers
2,000 tons grass
15
Closing Thoughts

• Biology plays a major role in many environmental
  health problems. In order to successfully deal
  with environmental problems, in the long term, we
  must approach these problems using sound
  scientific methods.