1. Chapter 17 Human Health and Environmental Risks

2. Human Health Risk Factors
(1) Physical
Natural disasters, UV exposure, radiation
(2) Biological
Infectious diseases
(3) Chemical
Arsenic, PCB’s, synthetic chemicals & pesticides

3. Disease Infectious Diseases: Caused by Pathogens
Pathogens=vectors; viruses, bacteria, fungi, protists
Tuberculosis, Influenza, Bubonic Plague, HIV
Non-infectious Diseases: Genetic, Environmental, Dietary or a Combination
Cancer, Cardiovascular Diseases, Respiratory, and Digestive Diseases

6. Six illnesses account for 94% of all infectious-disease-related deaths
Respiratory infections (pneumonia)
Auto Immune Deficiency Syndrome (AIDS)
Diarrhea
Tuberculosis
Malaria
Childhood diseases (measles/tetanus)

9. Infectious Diseases Have Killed Large Numbers of People
Epidemic: when a pathogen causes a rapid increase in disease.
Pandemic: when an epidemic occurs over a large geographic region such as a continent.

10. Plague Bubonic plague/Black Death Bacteria carried by fleas.
Swollen glands, black spots, and extreme pain.
Estimated to have killed hundreds of millions of people; 30-50% of the European population in the 1300s.

12. Malaria
Infection caused by an infection from one of the several species of the protist Plasmodium.
One stage of the life cycle in the human, the other in the mosquito.
Causes recurrent flulike symptoms.
Sub-Sahara Africa, Asia, the Middle East, and Central and South America are hit the hardest.

16. Tuberculosis:
Highly contagious disease caused by a bacterium that infects the lungs.
Spread when a person coughs and expels the bacteria into the air.
Weakness, night sweats, and coughing up blood.
Can be infected but not develop the disease.
9 million develop the disease and 2 million die.
Treated with antibiotics.

20. Emergent Infectious Diseases
Infectious diseases that were previously not described or have not been common for at least the prior 20 years.
Many can pass from animals to humans.
Of particular concern because of the rapid movement of people and cargo.

22. Emergent Infectious Diseases
HIV/AIDS
Ebola
Mad Cow Disease
Bird Flu
West Nile Virus

23. Toxicology is the Study of Chemical Risks
Humans have developed many different chemicals.
Some are very helpful while others are often harmful by-products from industry.
Some of the chemicals we have developed seemed helpful but are found to be harmful

25. Types of Chemicals Neurotoxins Disrupt nervous system
Effect
Example
Neurotoxins
Disrupt nervous system
Insecticides, Lead, Mercury
Carcinogens
Create cancers
Asbestos, radon, formaldehyde, tobacco, cadmium, PCB’s
Teratogens
Interfere with embryo/fetus development
Thalidomide, alcohol
Allergens
Allergic reactions
Peanuts, milk, whey, penicillin
Endocrine Disruptors
Interfere with hormones
DDT, atrazine, Phthalates

26. Determining the Health Effects of Pollutants
Acute toxicity- adverse effects of a substance that result either from a single exposure or from multiple exposures in a short period of time (usually less than 24 hours).
Chronic toxicity is the development of adverse effects as the result of long term exposure to a toxicant or other stressor.

28. Synergistic interactions- when two risks come together and cause more harm that one would.
For example, the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

29. Retrospective Studies
Look backwards and examine exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study.
Done in response to an unexpected or random outcome to an event

30. In 1984, a chemical spill in Bhopal India release of methyl isocyanate gas killed and injured thousands of people. Retrospective study found the survivors had long term hearth effects.
Monitor people who have been exposed to a chemical at some point in the past

31. Agent Orange
A defoliant used to strip the trees of leaves in the jungles of Vietnam-contained Dioxin
Later proven to cause serious health issues -cancer, birth defects, severe psychological problems- among the Vietnamese people as well as returning U.S. servicemen and their families.
Caused mutations to DNA that led to neurological problems in successive generations

32. Chernobyl Nuclear Accident

34. Children and Chemical Exposure
Children more susceptible to chemicals:
Weigh less than adults
Bodies are still developing
Play on floors and lawns
Exposed to cleaning products and pesticides
Put things into their mouths

35. Factors determining Concentrations in Organisms
(1) Route of Exposure

36. (2) Solubility, Bioaccumulation, Biomagnification
Water-v-fat soluble
Oil soluble chemicals stored in fatty tissues
Ex: mercury, DDT, PCB’s
DDT in birds that eat fish is 8 million times that found in water

37. (3) Persistence

38. Assess, Accept and Manage Risk
Risk Analysis:
Assess, Accept and Manage Risk
Environmental Hazard: anything in our environment that potentially causes harm.
Examples: smoking, volcanoes, draining swamps, air pollution.

39. Risk Acceptance The level of risk that can be tolerated.
Difficult part of management.
No amount of information on the extent of the risk will overcome the conflict between those who are willing to live with some amount of risk and those who are not!

40. Risk Management
Integrates the scientific data in addition to the analysis of acceptable levels of risk with economic, social, ethical, and political issues.
Worldwide Standards of Risk

41. United States
European Union