1. HUMAN HEALTH & ENVIRONMENTAL RISKS
APES: Ch 17

2. Leading Causes of Death in the World

4. Categories of Human Health Risk
Risk is a measure of the likelihood that you will suffer harm from a hazard. Types of risk:
Physical: environmental factors like natural disasters.
Ex: tsunamis, UV exposure, climate change
Biological: risk associated with disease.
HIV/AIDS, malaria, TB, obesity
Chemical: risk associated with exposure to chemicals, both natural occurring to synthetic chemicals like pesticides.
DDT, PCB (synthetic) & arsenic, He, Pb (Natural occurring)
Nicotine, caffeine, and other substances that are abused or recreationally used are included in this category.

5. Biological Risk: Disease
Cause most of the human deaths.
A disease is any impaired function of the body with a characteristic set of symptoms.
Types of disease:
Infectious disease – caused by infectious agents called pathogens (living organism). Ex: pneumonia & sexually transmitted
Pathogens that cause most infectious diseases are viruses, bacteria, fungi, protists, and parasitic worms.
Top three infectious diseases:
respiratory infections (TB, Flu, pneumonia)
HIV/AIDS
Diarrheal diseases

6. Pathogens

7. Biological Risk: Disease
Non-transmissible disease:
Diseases not caused by living organisms cannot spread from one person to another
Ex. Cancer, heart disease, cystic fibrosis
~60% of deaths
Disease is also categorized as:
Chronic – slowly impair the body over time (decades)
Heart disease & cancer
Acute – rapidly impair the body (days or weeks)

8. Chronic Disease
Risk factors of chronic disease is different for developing & developed countries:
Developing country risk factors are associated with unsafe drinking water, poor sanitation, malnutrition.
Developed country risk factors are less activity, poor nutrition, availability of tobacco, and overeating.

9. Obesity and poor air quality
Malnutrition and sanitation

10. Biological Risk: Infectious Diseases
Pathogens have evolved a wide variety of pathways for infection:
Human to human (influenza, rhino virus)
Animals to human (plague, malaria)
Food to human (Botulism, mad cow)
Water to human (Cholera, giardia)
Epidemic – rapid increase in disease
Pandemic – epidemic that occurs over a large geographic area (continent)

12. Biological Risk: Infectious Disease
Plague (Black Death, Bubonic plague):
Cause – bacterium (Yersinia pestis) carried by fleas of rodents.
Transmitted by flea bite or handling of rodents
Killed hundreds of millions (one-fourth European population)
Treatment – modern antibiotics

14. Biological Risk: Infectious Disease
Malaria:
Cause – protists from the genus Plasmodium. Transmitted to humans by mosquitos.
Effect – Kills 1 million people/ year
Symptoms – re-current flu-like symptoms
Hardest hit are sub-Saharan Africa, Asia, Middle East
Treatment – spray mosquitos with insecticides like DDT (now banned globally)

16. Biological Risk: Infectious Disease
Tuberculosis:
Highly contagious!!
Cause – Bacterium (Mycobacterium tuberculosis)
Infects lungs and spreads by coughing (bacteria can live several hours)
Effect - One third of the world population is infected with TB
Each year 9 million are infected & 2 million die
Treatment – antibiotics if available.
If antibiotics are stopped before all bacterium are killed, they become drug resistant

18. Emergent Infectious Diseases
Defined as infectious that were previously not described for the prior 20 years

19. HIV/AIDS In 1970’s rare types of pneumonia and cancer began appearing.
Cause: Human Immunodeficiency Virus (HIV)
Spread through both sexual contact & sharing needles
Source found to be chimpanzees (from the eating of flesh)
Effect: 25 million died from HIV/AIDS
Treatment: antiviral drugs used maintain low levels of HIV in humans
Drug cocktails are very expensive but governments and non-profits have greatly improved distribution in developing countries.

20. Ebola Hemorrhagic Fever
Cause: Ebola virus
First discovered in the Congo
Infected humans & primates
Effect: Kills a large % of those infected (50 – 89% death rate) in two weeks.
Treatment: there are no drugs available to fight virus
Origin remains unknown

22. Mad Cow Disease
Neurological disease in which pathogen slowly destroys the hosts nervous system.
Cause: prions (proteins in the brain of cattle that mutate and act as a pathogen
Discovered disease could be passed to humans
Cow must consume nervous system of infected cow to contract disease
Effect: 180 k cattle infected & 166 people died
Treatment: outlaw the practice of feeding cows dead cow protein

24. Bird Flu 1918 Spanish flu (bird flu) killed 100 million people
Cause: H1N1 virus & H5N1 virus
H5N1 could potentially kill 150 million
Rarely deadly to wild birds
Not easily passed among people but future mutation could change that

25. West Nile Virus
Lives in hundred of species of birds and is transmitted among birds by mosquitos
First human to contract West Nile was in 1937
Causes inflammation of the brain
1999 virus appeared in New York