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Rank the following causes of death from highest to lowest probability
• Earthquake• Lightning• Stroke• Firearm assault• Drowning• Cancer
• Falling• Fireworks discharge• Motor vehicle accident• Hornet/wasp/bee sting• Heart disease• Hot weather
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What is a greater risk?Dying from a disease like measles, diphtheria, and whooping cough?
OR
Being harmed by the chemicals in vaccines?
http://video.pbs.org/video/2365449467/
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Visualizing Environmental Science
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Risk Analysis and Environmental Health
Hazards
Chapter 7[chapter opener image]
Chapter 4
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Pesticides and Children• More harmful to children than
adults– Greater exposure
• Playing in contaminated fields• Putting hands/objects in mouth
– Greater response• Developing bodies more sensitive
• Range of effects– Cancer, mental and/or physical
disabilities• Intelligence• Motor skills
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A Perspective on Risks• Risk
– The probability of harm (human or environmental) occurring under certain circumstances
– Inherent in our actions and our environment
– Risk management is the process of identifying, assessing, and reducing risks
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A Perspective on Risks• In order to
successfully manage risks, we must have a sense of their:– Causes– Likelihoods – Effects
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Quantitative Measures of Risk
• Probabilities – a mathematical statement about the likelihood of harm
• Can be expressed in three ways:– 1:100– 1/100– “One in one hundred”
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Quantitative Measures of Risk
• Ex: 1:6,210 - risk of dying from alcohol– (1 person in 6,210 people will die of alcohol related illness)
• The bigger the bottom number (denominator) the less the chance– Ex: chance of winning Power Ball lottery: about 1 in 80,000,000 – Ex: chance of laughing at with Mr. Strogen today: about 1 in 3
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Four Steps for Risk Assessment• Risk assessment: quantitative and qualitative
characterization of risks in order to manage1. Hazard identification
• Can exposure have adverse health effects?2. Dose-response assessment
• What is the relationship between the amount and the response?
3. Exposure assessment• How often are individuals exposed?
4. Risk characterization• Leads to risk management
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A Curious Dilemma • People are more concerned
about small risks than large risks – Large risk: complications
associated with smoking– Small risk: EPA-permitted amounts
of carcinogenic chemicals in water– Average life expectancy is reduced
by 8 years for smokers and 1/3 of smokers die from related-illness
– A smoker is 300,000 times more likely to get cancer from smoking than to get it from ingesting a low level of trichloroethylene in their water
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A Curious Dilemma • People seem to be far more
concerned about small risks than about large risks
• Why the difference in concern? – Habit and culture (vs.
analysis)– Perception of risks – Trust in institutions– Feeling that some risks
cannot be controlled
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Are more teenagers smoking cigarettes today compared to 20
years ago?
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An Example of High Risk: Lung Cancer• Data suggests that smoking is
on the decline among younger people, although the poor and some minority groups have disproportionally high smoking rates
• The graph shows the percentage of U.S. students (grades 9–12) who smoked cigarettes on at least 1 or 2 of the past 30 days
• In what year did smoking peak among males? Females?
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Risky Behavior – “Fun” Facts• The percentage of high school students who had been in a physical fight at
least once during the past year decreased from 42% in 1991 to 25% in 2013• 41% of students who had driven a car or other vehicle during the past 30
days reported texting or emailing while driving• The percentage of high school students who are currently sexually active
has declined from 38% in 1991 to 34% in 2013• From 2003−2013, the percent of high school students using a computer 3 or
more hours per day (for non-school related work) nearly doubled from 22% to 41%
• The percentage of high school students who watch 3 or more hours of TV on an average school day decreased since 1999 (from 43% to 32%)
• There was a significant decrease in drinking soda 1 or more times per day from 34% in 2007 to 27% in 2013
http://www.cdc.gov/media/releases/2014/p0612-yrbs.html
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Environmental Health Hazards
• Toxicants– Chemicals with adverse effects on health– All chemicals are toxic if exposure is high enough
• “The dose makes the poison”
• Toxicology – Studies the effects of toxicants on living organisms– Evaluates the mechanisms that cause toxicity– Develops ways to prevent or minimize adverse
effects
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© 2014 John Wiley & Sons, Inc. All rights reserved.
Environmental Health Hazards• Epidemiology
– The study of how toxicants, biological agents (disease), and physical agents (accidents, radiation) affect the health of human populations
– Studies large groups of people and investigates range of causes and types of disease and injuries
– Toxicant exposure can be acute or chronic
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© 2014 John Wiley & Sons, Inc. All rights reserved.
Environmental Health Hazards•Acute toxicity
Immediate effects after a single short period, high-level exposure Symptoms include dizziness, nausea, death
•Chronic toxicityProlonged effects to long-term, low-level exposureSymptoms can mimic other chronic diseaseWe know much less about chronic toxicity
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Toxicology Studies
• Retrospective studies– “Looking back” – Monitoring people who have already been exposed to a chemical to determine the effects
• Prospective studies– “Looking forward”– Monitoring people who might become exposed to a chemical to determine the effects
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Biological Risks
• Infectious diseases: those caused by disease-causing infectious organisms, known as pathogens– Ex: pneumonia and
venereal diseases
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Pathogens• Bacteria:
– Cholera– Tuberculosis– Syphilis
• Virus:– HIV/AIDS– Hepatitis– Ebola
• Protozoa:– Malaria
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What causes disease?• Infectious agents (pathogens) that are spread by:
– Air– Water– Food– Body fluids– Vectors (nonhuman carriers, like mosquitoes)
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Pathways of Transmitting Pathogens
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Disease-Causing Agents in the Environment
• Sewage-contaminated water– Environmental threat to public health– Drinking water is periodically tested for
fecal coliform bacteria (such as E. coli)• 1993, U.S. outbreak of Cryptosporidium
– https://www.youtube.com/watch?v=mu_EZJ3vFSg
• 2000, waterborne E. coli outbreak in Canada
• 2009, cholera outbreak in Zimbabwe• 2010, cholera outbreak in Haiti
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Fecal Coliform Bacteria
Fecal coliform bacteria – group of bacteria found in the intestines and feces of vertebrate animals
Escherichia coli (E. coli) is usually the bacteria tested for – its presence indicates a risk of other wastewater pathogens
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(<1 bacterium per 100 mL of water)
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Water Facts Every 20 seconds, a child dies from a water-related
illness in the world More than 3 times as many people lack access to
clean water than live in the United States More people have cell phones worldwide than have
access to a toilet Half of the hospital beds in the world are occupied by
patients suffering from diseases associated with lack of access to safe drinking water, inadequate sanitation, and poor hygiene
Courtesy of water.org
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Water Facts Diarrhea is the second leading cause of death among
children under five in the world; it kills more children than malaria, AIDS, and measles combined
Of the 60 million people added to the world's towns and cities every year, most move to informal settlements (i.e. slums) with no sanitation facilities
An American taking a five-minute shower uses more water than the average person in a developing country slum uses for an entire day
1.1 billion people still practice open defecation In 3 days, the amount of untreated fecal matter in the world
would fill up the SuperdomeCourtesy of water.org
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Common Diseases from Human Wastewater Cholera is a bacterial disease (Vibrio cholerae) often
transmitted by drinking contaminated water Symptoms include: severe diarrhea, vomiting, and leg
cramps 100,000-120,000 deaths every year from cholera
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Common Diseases from Human Wastewater
Typhoid fever is a bacterial disease (Salmonella typhi) often transmitted by drinking contaminated water
Symptoms include: high fever, malaise, headache, constipation or diarrhea
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Common Diseases from Human Wastewater Hepatitis A and E are infections of the liver by
viruses, spread through water or food Symptoms include: fever, fatigue, nausea,
vomiting, abdominal pain
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Some Human Diseases Transmitted by Polluted Water
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• Thinking Skill: Explicitly assess information and draw conclusions
• Objective: Describe the effect of toxins that are transported throughout the environment
11-19-15
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What effect will climate change have on the spread of diseases?
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Environmental Changes and Emerging Diseases
• 25% of injury and disease worldwide is related to human-caused environmental changes
• Climate change gives disease-causing agents the opportunity to thrive
• Cutting forests, building dams and agriculture may bring us into contact with disease-causing agents and increasing populations of disease-carrying organisms such as mosquitoes
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Social Factors Contribute to Disease Epidemics
• Drainage ditches on each side of this road clearing in the Amazon rain forest are a breeding ground for mosquito larvae
• Global travel has contributed to the rapid spread of disease over great distances
• Highly concentrated urban populations promote rapid spread of disease among large numbers of people
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Social Factors Contribute to Disease Epidemics
• Diseases carried by animals– Malaria and West Nile
Virus spread by mosquitoes– Lyme disease spread by
deer ticks– Bubonic plague spread by
rats and fleas
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Emergent Diseases
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Environmental Health Hazards• Pandemic
– Disease reaches nearly all parts of the world• Influenza (flu)• Avian influenza affects birds and then infects humans
– Hard to transmit to humans, but once infected, human mortality is high
• H1N1 (Swine) Flu - https://www.youtube.com/watch?v=lFl3FRNpU4E – Late Spring 2009, Mexico– Pandemic by early Summer
– Understanding and controlling pandemics requires:• Understanding of the environment and conditions that allow
the virus to survive and travel• Cooperation among many governments and individuals
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People and Livestock in Close Proximity• Avian influenza difficult to
transfer from human to human, more common bird to human
• Swine flu transferred from pigs, 2009 Mexico outbreak
• Children in rural China live and play near livestock– Pigs and chickens share
enough genetic similarities to facilitate disease transfer
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Movement and Fate of Toxicants• Some toxicants are
particularly dangerous– Resist degradation– Travel quickly in the
environment• DDT
– A pesticide banned in the U.S. in 1972
– Causes birds to lay eggs with thin shells
– Very persistent and can bioaccumulate in organisms © 2014 John Wiley & Sons, Inc. All rights reserved.
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Environmental InSight• Persistence: how long a chemical remains in
the environment until it breaks down
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Environmental InSight• Bioaccumulation
– Chemical stored in organisms with higher concentrations found at the top of the food chain
• Biological magnification– Increased concentration as toxicant
passes through levels of the food chain
– Note how the level of DDT increased in the tissues of various organisms as DDT moved through the food chain
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Biomagnification
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Mobility of Pesticides in the Environment
• Toxicants can move through soil, water, air• Agricultural pesticides runoff into rivers and streams,
harming aquatic life– Adverse effects on aquatic
plants and animals, like bone degeneration in fish
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© 2014 John Wiley & Sons, Inc. All rights reserved.
Environmental Working Group
• This watch-dog organization analyzed five common herbicides found in drinking water
• 3.5 million people in the Midwest have elevated cancer risk due to exposure to herbicides
• EPA has mandated a reduction in the use of those herbicides
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• Stockholm Convention on Persistent Organic Pollutants, 2001– UN treaty to protect human
health from the 12 most toxic persistent organic pollutants (POPs)
– Requires countries to develop plans to eliminate the production and use of intentionally produced POPs
• Exception: DDT
Global Ban of Persistent Organic Pollutants
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Determining Health Effects of Pollutants• Toxicity determined by the
dose that produced adverse effects
• Dose– The amount of a toxicant
that enters the body• Response
– Type and amount of damage to a particular dose
– Lethal dose: causes death – Sub-lethal dose: causes harm
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Toxicology
• Dose: the amount of a substance that a person has in their body– Can be:
• Ingested• Inhaled• Injected • Absorbed
• “The dose makes the poison”
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• Different doses of chemical administered to populations of laboratory animals
• Data findings used to predict effects on humans
• The dose that is lethal to 50% of a population of test animals is called the LD50
• The smaller the LD50 , the more toxic the chemical
Determining Health Effects of Pollutants
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Dose-Response Curve• Dose-response curve
– A graph that shows the effects of different doses on a population of test organisms
– Evidence suggests that there is not a safe dose for certain toxicants
The figure on the left shows the response increases as the dose increases and harmful response is above threshold; on right, A has a lower ED50 than B, however B more toxic than A at lower doses
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Dose-Response StudiesDose (hypothetical units) Percent Mortality
1 0%2 0%3 4%4 10%5 40%6 60%7 90%8 96%9 100%
10 100%
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Do The Math• If the LD50 of a pesticide is 20 mg/kg for a
mouse, what amount would be considered safe to ingest for a human?
• (Calculate the “safe” amount by taking the LD50 and dividing it by 1,000)
20 mg/kg ÷ 1000 = 0.02 mg/kg• Calculate the maximum amount that a 80 kg
man could ingest and still be considered “safe”80 kg × 0.02 mg/kg = 1.6 mg
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Poisons• Poisons: materials that kill at a
very small dose (50 milligrams or less per kilogram of weight)
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• The dose at which 50% of a population will exhibit the response under study (ED50)
• Threshold level– The maximum dose at
which the toxicant has no measurable effect
– Doses lower than threshold level are considered safe
• This scientist is measuring a toxicant in human blood serum
Determining the Health Effects of Pollutants
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Cancer-Causing Substances• Carcinogens are any substance that causes cancer• Most common method of determining cancer-causing agent is to
expose groups of laboratory animals to various doses and count how many animals develop cancer
– Indirect and uncertain– Humans and laboratory animals may respond differently to chemical
exposure– Laboratory animals generally exposed to massive doses relative to their
body size– Risk assessment assumes we can extrapolate from these experiments,
determining expected cancer rates in humans and the safety of some chemicals—assumptions that may over or underestimate a toxicant's danger
• EPA working with toxicologists to develop direct evidence of risk involved with exposure to low doses of cancer-causing chemicals
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Risk Assessment of Chemical Mixtures• Although humans are exposed to combinations of chemical
compounds in air, food and water, most studies are done on single chemicals– Mixtures of chemicals increase level of complexity in risk assessment – Too many chemical mixtures to evaluate– Chemical mixtures interact by one of three ways: additivity, synergy, or
antagonism
• Additivity: the additive effect of each component of the mixture– Additivity is generally used in order to asses the risk for chemical mixtures
• Synergy: the mixture has a greater combined effect than the chemicals individually
• Antagonistic: mixture has a smaller combined effect than the chemicals individually
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Interactions• Synergistic interactions: when two (or more)
risk factors have a greater effect together than each by themselves– Ex: being exposed to asbestos and smoking gives
you a 400 times greater chance of developing lung cancer than if you experienced only one of those risks
+ =
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Children and Chemical Exposure• Children are more
susceptible than adults– Weigh less than adults– Interact more with their
environment– Undergoing growth and
development – Higher metabolic rate,
requires more oxygen (increased susceptibility to air pollution)
1990 study in Los Angeles found that 80% of children who died for reasons other than respiratory disease had early stage lung disease
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EnviroDiscovery Smoking: A Significant Risk
• Single largest cause of preventable death
• Causes serious diseases– Lung cancer, emphysema, heart disease,
premature death
• Passive smoking also increases risk of cancer
• Fewer in developed nations smoke and public bans working
• Smoking is increasing in developing nations
• 2005 international treaty to ban tobacco advertising worldwide
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The Precautionary Principle• The idea that we should not
adopt a new technology, practice, or material until it is demonstrated that:– The risks are small– The benefits outweigh the
risks
• Puts the burden of proof onto the developers
• “An ounce of prevention is worth a pound of cure”
These city kids are probably exposed to lead in the soil (from leaded gasoline)
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The Precautionary Principle: Common Sense?
• There is also controversy– Scientists feel it endorses the
making of decisions without the input of science
• The EU (European Union) banned beef from U.S. and Canada because of the use of hormones to make cattle grow faster
• The EU uses precautionary principle with respect to GMOs (genetically modified organisms)
• Precautionary principle or economic protectionism?
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Case Study: Endocrine Disrupters• Many industrial and agricultural
chemicals are endocrine disrupters • Some disrupters mimic hormones • Can cause reproductive disorders,
infertility, and hormonally-related cancers
• Congress amended Food Quality Protection Act and Safe Drinking Water Act of 1996 – EPA to develop plan to establish testing for
potential endocrine disruptors
• Lake Apopka, Florida, alligators have abnormalities in their reproductive systems