Chapter 11 Risk Toxicology, and Human Health. APES 1/24/11 Stamp on NB for 12 Notes on Chapter 11 Work on Population ? And FRQ Tomorrow Test Prep!

Chapter 11

Risk Toxicology, and Human Health

APES 1/24/11

Stamp on NB for 12 Notes on Chapter 11 Work on Population ?

And FRQ

Tomorrow Test Prep! Final on Wed.. Scantron bring a

number 2 pencil!

Think of an activity you do:

What are the risks? Are there other

activities you do that are less risky?

Chance of DYING

1 in a 1,000,000 chance 1 in a 100,000 chance 1 in a 10,000 chance 1 in a 1,000 chance 1 in a 100 chance 1 in a 10 chance

RISKS AND HAZARDS

Risk is a measure of the likelihood that you will suffer harm from a hazard.

We can suffer from: 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.

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Becoming Better at Risk Analysis

We can carefully evaluate or tune out of the barrage of bad news covered in the media, compare risks, and concentrate on reducing personal risks over which we have some control.

Figure 18-3

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 body’s detoxification

systems. One’s genetic makeup.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

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

Figure 18-10

BIOACCUMULATION

Bioaccumulation is the lifetime accumulation of a toxic substance in an individual organism’s body. Some toxic substances such as mercury or DTT (pesticide) do not easily leave the body once they have been absorbed and therefore accumulate over time.

Biomagnification

Biomagnification, also known as bioamplification, or biological magnification is the increase in concentration of a toxic substance, such as the pesticide DDT or the heavy metal Mercury, as it moves upward through a food chain.

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

Long-term exposure to some chemicals at low doses may disrupt the body’s: Immune system: specialized cells and tissues

that protect the body against disease and harmful substances.

Nervous system: brain, spinal cord, and peripheral nerves.

Endocrine system: complex network of glands that release minute amounts of hormones into the bloodstream.

CHEMICAL HAZARDS

A hazardous chemical can harm humans or other animals because it: Is flammable Is explosive An irritant Interferes with oxygen uptake Induce allergic reactions.

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.

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

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TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Estimating human exposure to chemicals and their effects is very difficult because of the many and often poorly understood variables involved.

Figure 18-11

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Children are more susceptible to the effects of toxic substances because: Children breathe more air, drink more water, and

eat more food per unit of body weight than adults.

They are exposed to toxins when they put their fingers or other objects in their mouths.

Children usually have less well-developed immune systems and detoxification processes than adults.

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.

Protecting Children from Toxic Chemicals

The U.S. Environmental Protection Agency proposed that regulators should assume children have 10 times the exposure risk of adults to cancer-causing chemicals.

Some health scientists contend that regulators should assume a risk 100 times that of adults.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Some scientists and health officials say that preliminary but not conclusive evidence that a chemical causes significant harm should spur preventive action (precautionary principle).

Manufacturers contend that wide-spread application of the precautionary principle would make it too expensive to introduce new chemicals and technologies.

Pathogens-

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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)

Transmissible Disease

Pathway for infectious disease in humans.Figure 18-4

Transmissible Disease

WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries.

Figure 18-5

Case Study: Growing Germ Resistance to Antibiotics

Rabidly producing 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.

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.

The viral life cycle · must have a

host cell Treating Viral

Disease · vaccines · why are

vaccines not always effective ?

Viral Disease·

Examples of Viral Disease

Influenza (flu) World Influenza Pandemic (1918-19) ·1. global epidemic (pandemic) killed 20 million people, 500 000 in the U.S. alone ·2. airborne and direct contact ·3. no vaccine ·4.particularly virulent strain

Human Immunodeficiency Virus (HIV) 1. virus responsible for AIDS (acquired immunodeficiency

syndrome) 2. sexually transmitted disease, also blood borne…

infected needles in IV drug users 3. attacks the immune system and allows for secondary

infections most people do not die from AIDS, but from the resulting

secondary infections (pneumonia or TB) 4. no vaccine available 5. some antiviral drugs show effectiveness and prolong

the lives of those who are HIV positive

· Internet article on HIV.. what’s working to halt the spread ?

Viral Diseases

Flu, HIV, and hepatitis B viruses infect and kill many more people each year then 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.

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.

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 Kaposi’s sarcoma (above).

Figure 18-1

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

How Would You Vote?

Should developed and developing nations mount an urgent global campaign to reduce the spread of HIV and to help countries afflicted by the disease? a. No. A global AIDS campaign could divert attention

and resources from efforts to combat other serious threats.

b. Yes. The disease is decimating the populations and destroying the economies of many developing countries.

Avian Bird Flu Spread among birds · Most cases of avian influenza infection in humans

have resulted from contact with infected poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces contaminated with secretion/excretions from infected birds.

· You cannot contract bird flu by eating poultry · The strain that has spread to humans (H5N1) has a

mortality rate of 50% · There have been a few cases of human to human

transmission, but these are rare and unsustained · Some antiviral drugs have shown some effectiveness · Vaccines could be produced but stockpiles and ability

to ramp up production in a pandemic are inadequate http://www.cdc.gov/flu/avian/gen-info/facts.htm

Bacterial Disease Treating Bacterial Infections · Antibiotics · Why do antibiotics lose their

effectiveness ?

Tuberculosis (the silent global epidemic)

Kills 1.6 million and infects 8 million · Respiratory infection spreads airborne droplets containing the bacterium · 1 in 3 people globally infected with TB · About 10% will develop active TB infections and then spread the disease to about 10-15 others · Treatment

o There are drugs that are effective but they must be taken for about 6-8 weeks

o Strains resistant to commonly used antibiotics have arisen o Screening a population is very effective in identifying infected

individuals · AIDS make infected individuals less able to fight the disease · Population growth and urbanization makes spreading the disease more likely

Cholera · A water borne infection that is spread by unclean

water supplies · Clean water video · http://www.globalwater.org/video-dyingofthirst.html · NPR cleaning water ·http://www.npr.org/templates/story/story.php?

storyId=5043050 · Information on cholera ·

http://www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_g.htm#What%20is%20cholera

Diseases Caused by Protozoans

Malaria · Caused by the protozoan Plasmodium · Vector for the disease is the female

Anopheles mosquito ·

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

· Symptoms include fever, chills, anemia, enlarged spleen, abdominal pain, headaches, weakness, greater susceptibility to other disease. Liver and kidney damage in

some cases · These symptoms come about when the

organism reproduces in red blood cells and causes these cells to rupture

· There are drugs that are effective at killing the parasites in infected humans Resistant strains are developing Development of a vaccine is a major research

Malaria - efforts to eradicate

Local efforts funded by Gates Foundation 1. Controlling the vector (mosquito) will slow

the spread of the disease 2. Remove sources of standing water…

habitat needed by the mosquito to reproduce 3. Use DDT to kill mosquitoes

Resistant mosquito strains are emerging

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

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.

Case Study: Malaria – Death by Mosquito

Fig. 18-8, p. 424

Solutions

Infectious Diseases

Increase research on tropical diseases and vaccines

Reduce poverty

Decrease malnutrition

Improve drinking water quality

Reduce unnecessary use of antibiotics

Educate people to take all of an antibiotic prescription

Reduce antibiotic use to promote livestock growth

Careful hand washing by all medical personnel

Immunize children against major viral diseases

Oral rehydration for diarrhea victims

Global campaign to reduce HIV/AIDS

Ecological Medicine and Infectious Diseases

Mostly because of human activities, infectious diseases are moving at increasing rates from one animal species to another (including humans).

Ecological (or conservation) medicine is devoted to tracking down these connections between wildlife and humans to determine ways to slow and prevent disease spread.

Case Study: A Black Day in Bhopal, India

The world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India. An explosion at Union Carbide pesticide plant in

an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas.

15,000-22,000 people died Indian officials claim that simple upgrades could

have prevented the tragedy.

How Would You Vote?

Should we rely more on the precautionary principle as a way to reduce the risks from chemicals and technologies?

a. No. Assuming that every chemical or technology is a serious health or environmental threat will lead to wasteful over-regulation, high costs and hinder the development of critically needed pesticides, plastics, and other commercial products.

b. Yes. Preventing the commercialization of harmful chemicals and technologies is better than dealing with the high costs of medical treatments and environmental damage.

RISK ANALYSIS

Scientists have developed ways to evaluate and compare risks, decide how much risk is acceptable, and find affordable ways to reduce it.

Figure 18-12

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%.

RISK ANALYSIS

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

Figure 18-A

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

Perceiving Risk

Most individuals evaluate the relative risk they face based on: Degree of control. Fear of unknown. Whether we voluntarily take the risk. Whether risk is catastrophic. Unfair distribution of risk.

Sometimes misleading information, denial, and irrational fears can cloud judgment.

RISK ANALYSIS

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

Figure 18-14

The Global HIV/AIDS Epidemic

According to the World Health Organization (WHO), in 2005 about 42 million people worldwide (1.1 million in the U.S.) were infected with HIV.

There is no vaccine for HIV – if you get AIDS, you will eventually die from it.

Drugs help some infected people live longer, but only a tiny fraction can afford them.

WHO’s World’s 7 Deadliest Diseases

1. acute respiratory infections (pneumonia and flu) 3.9 million 2. acquired immune deficiency syndrome (HIV) 3.0 million 3. diarrheal diseases (bacteria, viruses, protists) 2.1 million 4. tuberculosis (bacterial) 1.6 million 5. malaria (protozoan) 1.1 million 6. hepatitis B (viral) 1 million 7. measles (viral) 800 000

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