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Environmental Hazards and
Human Health
Chapter 17
Some Definitions
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Environment: combination of physical, chemical,
biological, cultural, and personal choice factors
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Hazard: anything that can cause injury, death,
disease, damage to personal/public property, or
deterioration or destruction of environmental
components
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Risk: probability of suffering a loss as a result of
exposure to a hazard
The Picture of Health: Some Terms
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Morbidity: incidence of disease in a
population
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Mortality: incidence of death in a
population
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Epidemiology: study of presence,
distribution, and control of disease in a
population
Causes of Human Mortality
Loss of Life Expectancy from Various Risks
Environmental Hazards
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Physical
Biological
Chemical
Cultural
Personal Choices
Physical Hazards
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Natural disasters, e.g., tornadoes, floods,
hurricanes, and wildfires
Avoidance of risk important in prevention,
e.g., building homes in floodplains, and
living on the coast
Climate change: consequences of
elevated greenhouse gases
Biological Hazards
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Pathogenic bacteria
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Cholera, Tuberculosis, Streptococcus, Anthrax, Bubonic
Plague
Developing genetic resistance (Staphylococcus aureus)
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Fungi
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Influenza, HIV/AIDS, Malaria, Smallpox, Typhoid, Ebola
Protozoans
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black mold, cryptococcus
Viruses
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Rapid reproduction, easily spread
Overuse of Antibiotics and Antibacterial products
Overuse of Pesticides
Giardia, Ameoba
Worms
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Hook worms, tape worms, Guinea worms
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Infectious Diseases
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Major Health Threat
Spread through Air,
Water, Food & Bodily
Fluids
Epidemics & Pandemics
Resistant bacteria &
insects
Since 1950
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Death from infectious
diseases have declined
Better Health Care
Antibiotics
Vaccines
The Most Deadly Viral Diseases
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Influenza
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#1 Killer
Rapid Transmission
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Airborne
Contact
Global Efforts
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Vaccines
Tracking the virus
Education
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HIV/AIDS
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#2 Killer
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Sexually transmitted
Slow to develop symptoms
Global Efforts
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Antiviral drugs (Free/low
cost)
Reduce new infections
Concentrate on those most
likely to spread HIV
Free Testing
Education
Research
Global Map of
Tuberculosis, 2001
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Why is tuberculosis on the rise?
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Not enough screening and control programs
Genetic resistance to a majority of effective
antibiotics
Person-to-person contact has increased
AIDS individuals are very susceptible to TB
Infectious Diseases
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More prevalent in, but not exclusive to,
developing countries
Contamination of food and water
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Lack of resources for sanitation
Lack of education
Ideal climates for transmission of
vector-borne diseases like malaria
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Malaria on the rise
since 1970
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Drug Resistant
Plasmodium
Insecticide
Resistance
Mosquitoes
Warmer Global
temperatures
AIDS individuals
very vulnerable
Malarial Parasite
Life Cycle
Worldwide Distribution of Malaria
Other Prevalent & Well-Know Viral
Diseases
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Hepatitis B (HBV)
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Transmission
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West Nile, Lyme, HIV, Flu & SARS
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Blood to Blood
Sexual Contact
Viruses that move from animals to
humans
Prevention
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WASH YOUR HANDS!!!
Vaccinations
Education
Knowing the history of one’s partners
Risk and Infectious Diseases
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One major pathway of risk is
contamination of food and water
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Inadequate hygiene
Inferior sewage treatment
Control of Infectious Disease
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Genome sequencing
of the Anopheles
mosquito
Bed nets
Change in land use
practices: wetland
development
New effective
antimalarial drugs
Chemical Hazards
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Toxic Chemicals
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Carcinogens – Cause Cancer
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74 chemicals are known to be carcinogenic
Environmental carcinogens initiate mutations in DNA;
several mutations lead to a malignancy
Mutagens – Cause Mutations
Teratogens – Cause Birth Defects
Chemical Hazards
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Result of industrialization
Exposure through ingestion, inhalation,
absorption through skin
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May be direct use or accidental
Many chemicals are toxic at low levels
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PCBs
Mercury
Bisphenol A
PCBs
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Class of chlorine-containing
compounds
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Very stable
Nonflammable
Break down slowly in the
environment
Travel long distances in the air
Fat soluble
Biomagnification
Food chains and webs
Banned, but found everywhere
Mercury & Minamata Disease
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Hg: teratogen and potent neurotoxin
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How are humans exposed?
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Once airborne, persistent and not degradable
1/3 from natural sources
2/3 from human activities
Enters the food chain: biomagnification
Inhalation: vaporized Hg or particulates of inorganic salts
Eating fish with high levels of methylmercury (Minamata Disease)
Effects of Hg on humans
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Neuroligical
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ataxia, numbness, weakness, vision, hearing, speech
Insanity, paralysis, coma, death
Who is most at risk?
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Children
Pregnant women and fetuses
Chemical Hazards
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Other Chemicals
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Suppress the Immune System
Interfere with the Nervous System
Interrupt the Endocrine System – Hormonally
Active Agents (phthalates)
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Gender Benders
Thyroid Disrupters
Cancer
Obesity
Bisphenol A (BpA)
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Estrogen mimic
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Found in many common products made of plastic
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Laboratory findings indicate heated plastic releases
compounds into food and water
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Effects on human health
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Females – excessive hair, early menstruation & menopause,
cancer
Males – breasts, shrunken testes, cancer
OBESITY
Should it be banned?
Environmental Health
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Factors contributing to the environmental
health of a nation include:
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Education
Nutrition
Commitment from government
More equitable distribution of wealth
Toxic Risk Pathways
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Categories of impact of pollutants
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Chronic: effect takes place over a period of
years
Acute: life-threatening reaction within a period
of hours or days
Carcinogenic: pollutants initiate cellular
change leading to cancer
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The risk of being
poor
The cultural risk
of tobacco use
Risk and
infectious
diseases
Toxic risk
pathways
Pathways of Risk
The Risk of Being Poor
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One major pathway for hazards is poverty
No money for health insurance
Higher probability of exposure to
environmental hazards
The 10 Leading Global Risk Factors
Fig. 15-9 here
Example: Indoor Air Pollution
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Developed Countries
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Hazardous fumes from
home products
Well-insulated
buildings
Long exposure to
indoor air
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Developing Countries
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Results from burning
biofuels (wood, dung)
inside homes
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Acute respiratory
infections in children
Chronic lung diseases
Lung cancer
Birth-related problems
Cultural Hazards
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Consequence of choice
Risky behavior
To what cultural hazards do students
commonly subject themselves?
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Driving
Drugs, Alcohol, and Tobacco
Poor food Choices
Deaths from Various Cultural Hazards
The Cultural Risk of Tobacco Use
Risk Assessment
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Environmental risk assessment by the
EPA
Public-health risk assessment
Risk management
Risk perception
Definition of Risk
Assessment
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The process of
evaluating the risks
associated with a
particular hazard
before taking some
action in which the
particular hazard is
present
Environmental Risk Assessment by the EPA
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Toxicology
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Hazard assessment (What chemicals cause
cancer?)
Dose-response assessment (How much?)
Exposure assessment (Who? How long?)
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Age
Genetics
Solubility & Persistence of Chemicals
Biomagnification
Multiple Chemical Sensitivity (MCS)
Risk characterization (How many will die?)
Kids and Chemicals – Analysis of
umbilical cord blood
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Infants and children more susceptible to
the toxic effects of chemicals than adults
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Eat, drink water, and breathe more per unit of
body weight than adults
Put their fingers in their mouths
Less well-developed immune systems and
body detoxification processes
Estimating Toxicity –
Use of Animals and Nonanimals
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Dose-response curve: median lethal dose
(LD50)
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Non-threshold dose-response model
Threshold dose-response model
Can the data be extrapolated to humans?
Are there more humane methods?
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Computer simulations
Tissue cultures
Chicken egg membranes
The Results of Toxicological Studies Regulation of Smoking
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Warning labels
Smoke-free zones in public places
FDA regulations
Lawsuits against the tobacco industry
Taxes
Education
Public-Health Risk Assessment
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Potential
global
impact
High
likelihood of
causality
Modifiability
Availability
of data
Risk Management
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Usually involves:
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Cost–benefit analysis
Risk–benefit analysis
Public preferences
Risk Perception: Hazard vs. Outrage
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Hazard: expresses primarily a concern
for fatalities only
Risk Perception: Hazard vs. Outrage
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Outrage includes:
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Lack of familiarity
with technology
Extent to which the
risk is voluntary
Public impressions
of hazards
Overselling safety
Morality
Control
Fairness
Risk
Assessment/Mana
gement
 Some suggest we
use distributive
justice in making
decisions about risk
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Ethical process of
making certain that
everyone receives
proper consideration
Should reduce
environmental
racism/injustice
Risk Assessment/Management
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Not a perfect system
Precautionary principle
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Lack of certainty should not be used as a reason
for preventing environmental degradation/hazards
Those introducing a new chemical or new
technology would have to follow new strategies
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A new product is considered harmful until it can be proved to
be safe
Existing chemicals and technologies that appear to cause
significant harm must be removed
2000: global treaty to ban or phase out the
dirty dozen (POPs)