Environmental Hazards and Human Health. Core Case Study: The Global HIV/AIDS Epidemic According to...

Environmental Hazards Environmental Hazards and Human Healthand Human Health

Core Case Study: The Global Core Case Study: The Global HIV/AIDS EpidemicHIV/AIDS Epidemic

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

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

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

Animation: HIV ReplicationAnimation: HIV Replication

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

Projected age structure Projected age structure of Botswana's population of Botswana's population in 2020.in 2020. Figure 18-2Figure 18-2


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

Figure 18-1Figure 18-1

RISKS AND HAZARDSRISKS AND HAZARDS

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

We can suffer from:We can suffer from: Biological hazardsBiological hazards: from more than 1,400 : from more than 1,400

pathogens.pathogens. Chemical hazardsChemical hazards: in air, water, soil, and food.: in air, water, soil, and food. Physical hazardsPhysical hazards: such as fire, earthquake, : such as fire, earthquake,

volcanic eruption…volcanic eruption… Cultural hazardsCultural hazards: such as smoking, poor diet, : such as smoking, poor diet,

unsafe sex, drugs, unsafe working conditions, unsafe sex, drugs, unsafe working conditions, and poverty.and poverty.

Video: Germs in PakistanVideo: Germs in Pakistan

From ABC News, Human Biology in the Headlines, 2006 DVD.From ABC News, Human Biology in the Headlines, 2006 DVD.

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BIOLOGICAL HAZARDS: BIOLOGICAL HAZARDS: DISEASE IN DEVELOPED AND DISEASE IN DEVELOPED AND

DEVELOPING COUNTRIESDEVELOPING COUNTRIES

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

Video: Polio ScareVideo: Polio Scare

From ABC News, Environmental Science in the Headlines, 2005 DVD.From ABC News, Environmental Science in the Headlines, 2005 DVD.

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Transmissible DiseaseTransmissible Disease

Pathway for infectious disease in humans.Pathway for infectious disease in humans.Figure 18-4Figure 18-4

Transmissible DiseaseTransmissible Disease

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


Case Study: Growing Germ Case Study: Growing Germ Resistance to AntibioticsResistance to Antibiotics

Rabidly producing infectious bacteria are Rabidly producing infectious bacteria are becoming genetically resistant to widely used becoming genetically resistant to widely used antibiotics due to:antibiotics due to: Genetic resistanceGenetic resistance: Spread of bacteria around : Spread of bacteria around

the globe by humans, overuse of pesticides the globe by humans, overuse of pesticides which produce pesticide resistant insects that which produce pesticide resistant insects that carry bacteria.carry bacteria.

Overuse of antibioticsOveruse of antibiotics: A 2000 study found that : A 2000 study found that half of the antibiotics used to treat humans were half of the antibiotics used to treat humans were prescribed unnecessarily.prescribed unnecessarily.

Video: The Problem with PorkVideo: The Problem with Pork


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Case Study: Case Study: The Growing Global The Growing Global Threat from TuberculosisThreat from Tuberculosis

The highly infectious tuberculosis (TB) kills The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 1.7 million people per year and could kill 25 million people 2020.million people 2020.

Recent increases in TB are due to:Recent increases in TB are due to: Lack of TB screening and control programs Lack of TB screening and control programs

especially in developing countries due to especially in developing countries due to expenses.expenses.

Genetic resistance to the most effective Genetic resistance to the most effective antibiotics.antibiotics.

Viral DiseasesViral Diseases

Flu, HIV, and hepatitis B viruses infect and kill Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly many more people each year then highly publicized West Nile and SARS viruses.publicized West Nile and SARS viruses. The The influenza virus is the biggest killer virusinfluenza virus is the biggest killer virus

worldwide.worldwide.• Pigs, chickens, ducks, and geese are the major Pigs, chickens, ducks, and geese are the major

reservoirs of flu. As they move from one species to reservoirs of flu. As they move from one species to another, they can mutate and exchange genetic another, they can mutate and exchange genetic material with other viruses.material with other viruses.

Video: Bird FluVideo: Bird Flu


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Video: Mask of TechnologyVideo: Mask of Technology

From ABC News, Human Biology in the Headlines, 2006 DVD.From ABC News, Human Biology in the Headlines, 2006 DVD.

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Viral DiseasesViral Diseases HIV is the HIV is the second biggest killer virussecond biggest killer virus

worldwide. Five major priorities to slow the worldwide. Five major priorities to slow the spread of the disease are:spread of the disease are: Quickly reduce the number of new infections to Quickly reduce the number of new infections to

prevent further spread.prevent further spread. Concentrate on groups in a society that are likely Concentrate on groups in a society that are likely

to spread the disease.to spread the disease. Provide free HIV testing and pressure people to Provide free HIV testing and pressure people to

get tested.get tested. Implement educational programs.Implement educational programs. Provide free or low-cost drugs to slow disease Provide free or low-cost drugs to slow disease

progression.progression.

Sporozoites penetrate liverand develop into merozoites

Female mosquito bites infected human,ingesting blood that contains Plasmodiumgametocytes

Merozoites enter blood-stream and develop into gametocytes causing malaria and makinginfected person a new reservoir

Female mosquito injects Plasmodium sporozoites into human host

Plasmodiumdevelops inmosquito

Fig. 18-7, p. 423

Stepped Art

Malaria – Death by Mosquito

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

Case Study: Case Study: Malaria – Death by MosquitoMalaria – Death by Mosquito

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


Spraying insides of homes with low Spraying insides of homes with low concentrations of the pesticide DDT greatly concentrations of the pesticide DDT greatly reduces the number of malaria cases.reduces the number of malaria cases. Under international treaty enacted in 2002, Under international treaty enacted in 2002,

DDT is being phased out in developing DDT is being phased out in developing countries.countries.

Case Study: Case Study: Malaria – Death by MosquitoMalaria – Death by Mosquito

Animation: Life Cycle of PlasmodiumAnimation: Life Cycle of Plasmodium

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Ecological Medicine and Ecological Medicine and Infectious DiseasesInfectious Diseases

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

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

CHEMICAL HAZARDSCHEMICAL HAZARDS

A toxic chemical can cause temporary or A toxic chemical can cause temporary or permanent harm or death.permanent harm or death. MutagensMutagens are chemicals or forms of radiation are chemicals or forms of radiation

that cause or increase the frequency of mutations that cause or increase the frequency of mutations in DNA.in DNA.

TeratogensTeratogens are chemicals that cause harm or are chemicals that cause harm or birth defects to a fetus or embryo.birth defects to a fetus or embryo.

CarcinogensCarcinogens are chemicals or types of radiation are chemicals or types of radiation that can cause or promote cancer.that can cause or promote cancer.

CHEMICAL HAZARDSCHEMICAL HAZARDS

A hazardous chemical can harm humans or A hazardous chemical can harm humans or other animals because it:other animals because it:

• Is flammableIs flammable

• Is explosiveIs explosive

• An irritantAn irritant

• Interferes with oxygen uptakeInterferes with oxygen uptake

• Induce allergic reactions.Induce allergic reactions.

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

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

that protect the body against disease and harmful that protect the body against disease and harmful substances.substances.

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

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

Case Study: Case Study: A Black Day in Bhopal, IndiaA Black Day in Bhopal, India

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

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

15,000-22,000 people died15,000-22,000 people died Indian officials claim that simple upgrades could Indian officials claim that simple upgrades could

have prevented the tragedy.have prevented the tragedy.

TOXICOLOGYTOXICOLOGY: ASSESSING : ASSESSING CHEMICAL HAZARDSCHEMICAL HAZARDS

Factors determining the harm caused by Factors determining the harm caused by exposure to a chemical include:exposure to a chemical include: The amount of exposure (dose). The amount of exposure (dose). The frequency of exposure.The frequency of exposure. The individual person who is exposed.The individual person who is exposed. The effectiveness of the body’s detoxification The effectiveness of the body’s detoxification

systems.systems. The person’s genetic makeup.The person’s genetic makeup.


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



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



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

eat more food per unit of body weight than eat more food per unit of body weight than adults.adults.

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

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


Under existing laws, most chemicals are Under existing laws, most chemicals are considered considered innocent until proven guiltyinnocent until proven guilty, , and estimating their toxicity is difficult, and estimating their toxicity is difficult, uncertain, and expensive.uncertain, and expensive. Federal and state governments do not regulate Federal and state governments do not regulate

about 99.5% of the commercially used chemicals about 99.5% of the commercially used chemicals in the U.S.in the U.S.

RISK ANALYSISRISK ANALYSIS

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



Estimating risks from using many Estimating risks from using many technologies is difficult due to unpredictability technologies is difficult due to unpredictability of human behavior, chance, and sabotage.of human behavior, chance, and sabotage.

Reliability of a system is Reliability of a system is multiplicativemultiplicative:: If a nuclear power plant is 95% reliable and If a nuclear power plant is 95% reliable and

human reliability is 75%, then the overall human reliability is 75%, then the overall reliability is (0.95 X 0.75 = 0.71) 71%.reliability is (0.95 X 0.75 = 0.71) 71%.


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

Figure 18-AFigure 18-A


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


Perceiving RiskPerceiving Risk

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

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

RISK RISK ANALYSISANALYSIS

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


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