Environmental Hazards and Human Health

1
Chapter 18

• Environmental Hazards and Human Health

2
Core Case Study The Global HIV/AIDS Epidemic

• AIDS has reduced the life expectancy of
  sub-Saharan Africa from 62 to 47 years 40 years
  in the seven countries most severely affected by
  AIDS.

Projected age structure of Botswana's population
in 2020.
Figure 18-2
3
Core Case Study The Global HIV/AIDS Epidemic

• The virus itself is not deadly, but it cripples
  the immune system, leaving the body susceptible
  to infections such as Kaposis sarcoma (above).

Figure 18-1
4
What is a(n)

• Epidemic disease in a small area, i.e. Georgia,
  Midwest, United States
• Pandemic disease that is spreading through many
  continents around the world

5
RISKS AND HAZARDS

• RISKS POSSIBILITY OF SUFFERING HARM FROM A
  HAZARD THAT CAN CAUSE ILLNESS, INJURY, DISEASE
  DEATH, ECONOMIC LOSS OR ENVIRONMENTAL DAMAGE.
• RISK ASSESSMENT SCIENTIFIC PROCESS OF
  ESTIMATING HOW MUCH HARM A PARTICULAR HAZARD CAN
  CAUSE TO HUMAN HEALTH OR THE ENVIRONMENT.

6
RISKS AND HAZARDS

• Biological hazards from more than 1,400
  pathogens.
• Chemical hazards in air, water, soil, and food.
• Physical hazards such as fire, earthquake,
  volcanic eruption.
• Cultural hazards such as smoking, poor diet,
  unsafe sex, drugs, unsafe working conditions, and
  poverty.

7
BIOLOGICAL HAZARDS DISEASE IN DEVELOPED AND
DEVELOPING COUNTRIES

• Diseases not caused by living organisms cannot
  spread from one person to another
  (nontransmissible disease), while those caused by
  living organisms such as bacteria and viruses can
  spread from person to person (transmissible or
  infectious)

8
Transmissible Disease

• Pathway for infectious disease in humans.

Figure 18-4
9
Transmissible Disease

• WHO estimates that each year the worlds seven
  deadliest infections kill 13.6 million people
  most of them the poor in developing countries.

Figure 18-5
10
Case Study Growing Germ Resistance to Antibiotics

• Infectious bacteria are becoming genetically
  resistant to widely used antibiotics due to
• Genetic resistance Spread of bacteria around the
  globe by humans, overuse of pesticides which
  produce pesticide resistant insects that carry
  bacteria.
• Overuse of antibiotics A 2000 study found that
  half of the antibiotics used to treat humans were
  prescribed unnecessarily.

11
Case Study The Growing Global Threat from
Tuberculosis

• The highly infectious tuberculosis (TB) kills 1.7
  million people per year and could kill 25 million
  people 2020.
• Recent increases in TB are due to
• Lack of TB screening and control programs
  especially in developing countries due to
  expenses.
• Genetic resistance to the most effective
  antibiotics.

12
Solutions to Tuberculosis

• Early identification treatment with active TB
• Treatment with 4 inexpensive drugs cure up to 90
  of individuals with active TB
• Must be taken everyday for 6-8 months
• Symptoms disappear after a few weeks, people stop
  taking the drugs allowing the
• Disease to recur in drug-resistant forms and
• Spread

13
Viral Diseases

• Flu, HIV, and hepatitis B viruses infect and kill
  many more people each year than highly publicized
  West Nile and SARS viruses.
• The influenza virus is the biggest killer virus
  worldwide.
• Pigs, chickens, ducks, and geese are the major
  reservoirs of flu. As they move from one species
  to another, they can mutate and exchange genetic
  material with other viruses.

14
Viral Diseases

• HIV is the second biggest killer virus worldwide.
  Five major priorities to slow the spread of the
  disease are
• Quickly reduce the number of new infections to
  prevent further spread.
• Concentrate on groups in a society that are
  likely to spread the disease.
• Provide free HIV testing and pressure people to
  get tested.
• Implement educational programs.
• Provide free or low-cost drugs to slow disease
  progress.

15
Case Study Malaria Death by Mosquito

• Malaria kills about 2 million people per year and
  has probably killed more than all of the wars
  ever fought.

Figure 18-7
16
Case Study Malaria Death by Mosquito

• Economists estimate that spending 2-3 billion on
  malaria treatment may save more than 1 million
  lives per year.

Figure 18-6
17
Case Study Malaria Death by Mosquito

• Spraying insides of homes with low concentrations
  of the pesticide DDT greatly reduces the number
  of malaria cases.
• Under international treaty enacted in 2002, DDT
  is being phased out in developing countries.

18
CHEMICAL HAZARDS

• A toxic chemical can cause temporary or permanent
  harm or death.
• Mutagens are chemicals or forms of radiation that
  cause or increase the frequency of mutations in
  DNA.
• Teratogens are chemicals that cause harm or birth
  defects to a fetus or embryo.
• Carcinogens are chemicals or types of radiation
  that can cause or promote cancer.

19
TOXICOLOGY

• Bioaccumulation molecules stored in the body
• Biomagnification moves up through food chains
  increases concentration
• Acute effects sudden
• Chronic effects long-term
• Synergism 1 1 3

20
Effects of Chemicals on the Immune, Nervous, and
Endocrine Systems

• Molecules of certain synthetic chemicals have
  shapes similar to those of natural hormones and
  can adversely affect the endocrine system.

Figure 18-9
21
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Factors determining the harm caused by exposure
  to a chemical include
• The amount of exposure (dose).
• The frequency of exposure.
• The person who is exposed.
• The effectiveness of the bodys detoxification
  systems.
• Ones genetic makeup.

22
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Typical variations in sensitivity to a toxic
  chemical within a population, mostly because of
  genetic variation.

Figure 18-10
23
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Under existing laws, most chemicals are
  considered innocent until proven guilty, and
  estimating their toxicity is difficult,
  uncertain, and expensive.
• Federal and state governments do not regulate
  about 99.5 of the commercially used chemicals in
  the U.S.

24
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Precautionary principle 1st do no harm
• Poison any substance with an LD-50 of 50 mg or
  less /kg of body weight
• LD50 amount of a chemical received in 1 dose
  that kills 50 of the animals in a test
  population within 14-day period

25
Toxicity Rating LD50 (mg per kg of body weight) Average Lethal Dose Examples
Supertoxic Less than 0.01 Less than 1 drop Nerve gases, botulism, mushroom toxins, dioxin
Extremely Toxic Less than 5 Less than 7 drops K cyanide, heroin, atropine, parathion, nicotine
Very Toxic 5 50 7 drops to 1 teaspoon Mercury salts, morphine, codeine
Toxic 50 500 1 teaspoon to 1 ounce Lead salts, DDT, NaOH, H2SO4, caffeine, CCl4
Moderately Toxic 500 5,000 1 ounce to 1 pint Methyl alcohol, ether, amphetamines
Slightly toxic 5000 15,000 1 pint to 1 quart Ethanol, lysol, soaps
26
Dose-Response Curves

• Show effects of various dosages of a toxic agent
• Threshold dose takes minimum amount before
  damage is seen
• Non-threshold dose any dosage causes harm that
  increases with dosage

27
PCBs

• Most widespread toxin stable
• Used as cooling liquid in transformers,
  capacitors, hydraulic fluids, adhesives, paints,
  dirt road surfaces
• Causes liver problems, miscarriages, low birth
  weight, cancer, endocrine disruption
• Often in fatty parts of fish (fat-soluble)

28
Dioxins

• Formed as by-product of herbicides, germ-killer
  (hexachlorophene), burning compounds with
  chlorine, Agent Orange
• Source for humans meat, eggs
• Interferes with immunity is a carcinogen causes
  hormonal disruption (thyroid), nervous system,
• Causes muscle aches and pains

29
Asbestos

• From brake linings, fire-retardants, siding,
  floors
• Causes
• asbestosis,
• mesothelioma,
• GI cancer

30
Lead

• From paints, metals, soldering
• Interferes with blood cell formation,
• Causes kidney damage, sterility, miscarriages,
  birth defects, and CNS damage

31
Mercury

• Sources
• Elemental (naturally occurring)
• Coal burning power plants
• Mercury using industries
• Problems with speech, swallowing, walking,
  deafness, vision, destroys cells, convulsions

32
RISK ANALYSIS

• Estimating risks from using many technologies is
  difficult due to unpredictability of human
  behavior, chance, and sabotage.
• Reliability of a system is multiplicative
• If a nuclear power plant is 95 reliable and
  human reliability is 75, then the overall
  reliability is (0.95 X 0.75 0.71) 71.

33
RISK ANALYSIS

• Annual deaths in the U.S. from tobacco use and
  other causes in 2003.

Figure 18-A
34
RISK ANALYSIS

• Number of deaths per year in the world from
  various causes. Parentheses show deaths in terms
  of the number of fully loaded 400-passenger jumbo
  jets crashing every day of the year with no
  survivors.

Figure 18-13
35
RISK ANALYSIS

• Comparisons of risks people face expressed in
  terms of shorter average life span.

Figure 18-14