Using Science to Address
Environmental Problems
Chapter 2
Problem: Outbreak of Disease
Actions that can contribute to outbreaks of
infectious diseases are:
 Global travel
 Social factors
 Disruption of Natural Environments
 Overcrowded conditions in cities
Epidemiologists (people who study the ecology of
a disease in a population) are establishing links
between human health and human activities
Remote Sensing: A means of acquiring information using
airborne equipment and techniques to determine the
characteristics of an area. Aerial photographs from aircraft
and satellite are the most common form of remote sensing.
See pages 22 – 23 in text.
Read how epidemiologists used remote sensing to help with malaria problem.
Scientific Method
• Define problem: Establish question to be
investigated and research the problem
• Form a hypothesis
• Test the hypothesis: set up and perform an
experiment.
• Analyze and interpret data collected to
form a conclusion
• Communicate your results.
Reasoning
Scientists use reasoning to discover general
principles. Two types:
*Inductive reasoning – seeks unifying
explanation for the data. Goes from
specific to general.
*Deductive reasoning – makes
relationships among data more apparent.
Goes from general to specific.
Kudzu: Read the handout
Theory
• Can be used to predict the existence of
as-yet unobserved things or phenomena.
• An integrated explanation of numerous
hypotheses
• Example: Cell Theory
Risk
• The probability of injury, disease, death, or
environmental damage under a given set o
circumstances.
• Risk = 0, no risk
Risk = 1, high risk
• In 2002, the population of the US was
approximately 283 million. If the American
Cancer Society concluded that 170,000 people
who smoked died of lung cancer, what is the
probability of a US citizen dying of lung cancer?
0.006
Risk Assessment
Includes the following:
 Identification of the
hazard
 Dose-response
assessment
 Assessment of the
exposure
 Characterization of the
risk
Toxicity
• Acute: produces an effect within a short period
of a single exposure. Effects range from
dizziness and nausea to death and can occur
immediately or within several days
• Chronic: generally produces damage to vital
organs, such as kidneys or liver, following longterm, low-level exposure to the chemical.
Insecticides used
by Saginaw Co.,
Minnesota
Lethal Dose
• LD50:What dose is lethal to 50% of a population
of test organisms
• The smaller the LD50, the more lethal the
substance
• The LD50 values are lower for children than
adults.
Chemical
LD50(mg/kg) administered orally to rats
Cocaine
17.5
Caffeine
200.0
How much caffeine would it take to kill 50% of people
weighing 68 kg (150 lbs.)?
• By means of comparison, a 7 oz cup of coffee has the
following caffeine (mg) amounts:
• Drip 115-175
• Espresso 100mg of caffeine 1 serving (1.5-2oz)
• Brewed 80-135 Instant 65-100
• Decaf, brewed 3-4
• Decaf, instant 2-3
• Tea, iced (12 ozs.) 70
• Tea, brewed, imported 60
• Tea, brewed, U.S. 40
• Tea, instant 30
Approximately 90 cups of Drip coffee.
Dose Response Curve
Shows the effect of
different does on a
population of test
organisms.
Threshold level: the
maximum dose that has
no measurable effect on
the organisms.
ED50/LD50 – Effective
dose 50/Lethal dose 50 =
the dose that causes 50%
of a population to exhibit
whatever response is
under study
Carcinogens: Any substance
known to cause cancer
• Cancer was traditionally the only disease
evaluated in the chemical risk assessment of
environmental contaminants
• Rats and mice often respond differently to the
same toxicant
• It is assumed that one can extrapolate from doses
and cancer rates in rates to determine human
cancer rates.
• The body often handles very small doses of
carcinogens differently than very large doses.
• These are usually studied in very large doses.
Risk Assessment of Chemical
Mixtures
Chemical mixtures can interact by:
 Additivity – the effect is exactly what one
would expect
 Synergistic – has a greater combined
effect than would be expected
 Antagonistic – has a smaller combined
effect than would be expected
Precautionary Principle
• When a technology or chemical product is
suspected of threatening human health or
the environment, precautionary measures
should be taken even if there is scientific
uncertainty about the scope of danger.
• See text, page 30, right side, Christine
Todd Whitman quote.
Ecological Risk Assessment