Chapter 18 Environmental Hazards and Human Health

Chapter 18Chapter 18

Environmental Hazards Environmental Hazards and Human Healthand Human Health

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

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

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

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

What is a(n)What is a(n)

Epidemic – disease in a small area, i.e. Epidemic – disease in a small area, i.e. Georgia, Midwest, United StatesGeorgia, Midwest, United States

Pandemic – disease that is spreading Pandemic – disease that is spreading through many continents around the world;through many continents around the world;

RISKS AND HAZARDSRISKS AND HAZARDS

RISKSRISKS – POSSIBILITY OF SUFFERING HARM – POSSIBILITY OF SUFFERING HARM FROM A HAZARD THAT CAN CAUSE ILLNESS, FROM A HAZARD THAT CAN CAUSE ILLNESS, INJURY, DISEASE DEATH, ECONOMIC LOSS OR INJURY, DISEASE DEATH, ECONOMIC LOSS OR ENVIRONMENTAL DAMAGE.ENVIRONMENTAL DAMAGE.

RISK ASSESSMENT RISK ASSESSMENT – SCIENTIFIC PROCESS OF – SCIENTIFIC PROCESS OF ESTIMATING HOW MUCH HARM A PARTICULAR ESTIMATING HOW MUCH HARM A PARTICULAR HAZARD CAN CAUSE TO HUMAN HEALTH OR HAZARD CAN CAUSE TO HUMAN HEALTH OR THE ENVIRONMENT.THE ENVIRONMENT.

RISKS AND HAZARDSRISKS AND HAZARDS

Biological hazardsBiological hazards: from more than : from more than 1,400 pathogens.1,400 pathogens.

Chemical hazardsChemical hazards: in air, water, soil, : in air, water, soil, and food.and food.

Physical hazardsPhysical hazards: such as fire, : such as fire, earthquake, volcanic eruption.earthquake, volcanic eruption.

Cultural hazardsCultural hazards: such as smoking, : such as smoking, poor diet, unsafe sex, drugs, unsafe poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.working conditions, and poverty.

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))

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

Infectious bacteria are becoming genetically Infectious bacteria are becoming genetically resistant to widely used antibiotics due to:resistant to widely used 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.

Case Study: The Growing Global Case Study: 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.

Solutions to TuberculosisSolutions to Tuberculosis

Early identification & treatment with active TBEarly identification & treatment with active TB Treatment with 4 inexpensive drugs cure up Treatment with 4 inexpensive drugs cure up

to 90% of individuals with active TBto 90% of individuals with active TB Must be taken everyday for 6-8 monthsMust be taken everyday for 6-8 months Symptoms disappear after a few weeks, Symptoms disappear after a few weeks,

people stop taking the drugs allowing thepeople stop taking the drugs allowing the Disease to recur in drug-resistant forms and Disease to recur in drug-resistant forms and SpreadSpread

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 than highly many more people each year than highly publicized West Nile and SARS viruses.publicized West Nile and SARS viruses. The influenza virus is the biggest killer virus The influenza 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.

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

progress.progress.

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

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



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, DDT Under international treaty enacted in 2002, DDT

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


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.

TOXICOLOGYTOXICOLOGY

Bioaccumulation – molecules stored in the Bioaccumulation – molecules stored in the bodybody

Biomagnification – moves up through food Biomagnification – moves up through food chains & increases concentrationchains & increases concentration

Acute effects – suddenAcute effects – sudden

Chronic effects – long-termChronic effects – long-term

Synergism – 1 + 1 = 3Synergism – 1 + 1 = 3

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

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


TOXICOLOGY: ASSESSING TOXICOLOGY: 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 person who is exposed.The person who is exposed. The effectiveness of the body’s detoxification The effectiveness of the body’s detoxification

systems.systems. One’s genetic makeup.One’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.



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.


Precautionary principlePrecautionary principle – 1– 1stst do no harm do no harm PoisonPoison – any substance with an LD-50 of 50 – any substance with an LD-50 of 50

mg or less /kg of body weightmg or less /kg of body weight LD50LD50 – amount of a chemical received in 1 – amount of a chemical received in 1

dose that kills 50% of the animals in a test dose that kills 50% of the animals in a test population within 14-day periodpopulation within 14-day period

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

Dose-Response CurvesDose-Response Curves

Show effects of various dosages of a toxic Show effects of various dosages of a toxic agentagent

Threshold doseThreshold dose – takes minimum amount – takes minimum amount before damage is seenbefore damage is seen

Non-threshold dose Non-threshold dose – any dosage causes – any dosage causes harm that increases with dosageharm that increases with dosage

PCB’sPCB’s

Most widespread toxin – stableMost widespread toxin – stable Used as cooling liquid in transformers, Used as cooling liquid in transformers,

capacitors, hydraulic fluids, adhesives, capacitors, hydraulic fluids, adhesives, paints, dirt road surfacespaints, dirt road surfaces

Causes liver problems, miscarriages, low Causes liver problems, miscarriages, low birth weight, cancer, endocrine disruptionbirth weight, cancer, endocrine disruption

Often in fatty parts of fish (fat-soluble)Often in fatty parts of fish (fat-soluble)

DioxinsDioxins

Formed as by-product of herbicides, germ-Formed as by-product of herbicides, germ-killer (hexachlorophene), burning compounds killer (hexachlorophene), burning compounds with chlorine, Agent Orangewith chlorine, Agent Orange

Source for humans = meat, eggsSource for humans = meat, eggs Interferes with immunity; is a carcinogen; Interferes with immunity; is a carcinogen;

causes hormonal disruption (thyroid), causes hormonal disruption (thyroid), nervous system, nervous system,

Causes muscle aches and painsCauses muscle aches and pains

AsbestosAsbestos

From brake linings, fire-retardants, siding, From brake linings, fire-retardants, siding, floorsfloors

Causes:Causes: asbestosis, asbestosis, mesothelioma, mesothelioma, GI cancerGI cancer

LeadLead

From paints, metals, solderingFrom paints, metals, soldering Interferes with blood cell formation,Interferes with blood cell formation, Causes kidney damage, sterility, Causes kidney damage, sterility,

miscarriages, birth defects, and CNS damagemiscarriages, birth defects, and CNS damage

MercuryMercury

Sources:Sources: Elemental (naturally occurring)Elemental (naturally occurring) Coal burning power plantsCoal burning power plants Mercury using industries Mercury using industries

Problems with speech, swallowing, walking, Problems with speech, swallowing, walking, deafness, vision, destroys cells, convulsionsdeafness, vision, destroys cells, convulsions

RISK ANALYSISRISK ANALYSIS

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 multiplicative:Reliability of a system is multiplicative: 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.


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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Chapter 18 Environmental Hazards and Human Health