1. Environmental Health James M. Eddy Texas A&M 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 Grasses Insects Worms Birds Rabbits Rodents Buffalo Carnivores Birds

5. Simplified Ecosystem GrassesInsectsRabbitsBirds

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.