Sarah Sharpley
APES
Mr. Crowley
Period: 7
Chapter 7 Outline
Vocabulary:
Epidemiologists: scientists who investigate the ecology of disease in a population.
Hormones: chemical messengers produced by organisms in minute quantities to
regulate their growth, reproduction, and other important biological functions.
Endocrine disrupter: A chemical that mimics or interferes with the actions of the
endocrine system in humans and wildlife.
Toxicants: toxic chemicals
Toxicology: The study of toxicants.
Acute toxicity: Adverse effects that occur within a short period after exposure to a
toxicant.
Chronic toxicity: Adverse effects that occur after a long period of exposure to a
toxicant.
Dose-response curve: In toxicology, a graph that shows the effect of different doses
on a population of test organisms.
Ecotoxicology: The study of contaminants in the biosphere, including their harmful
effects on ecosystems.
Precautionary principle: The policy that no action should be taken if there is any
reason to think harm might be caused.
Ecological risk assessment: The process by which the ecological consequences of
human activities are estimated.
Human health and environmental toxicology
I.
Health issues in highly developed countries
 Improved sanitation during the 20th century reduced many diseases
 The three leading causes of death in the U.S. are cardiovascular
diseases, cancer, and chronic obstructive pulmonary diseases
 Obesity is the most important risk factor for poor health
 Healthcare professionals use the “body mass index” to determine
whether a person is overweight or obese
II.
Health Issues in Developing Nations
 Gradual improvements in sanitation and drinking water supplies
in moderately developed countries are reducing diarrheal diseases
 HIV/AIDS has reduced life expectancy in these countries

III.
Child morality is particularly serious in Africa because of
malnutrition, lower respiratory tract infections, diarrheal diseases,
and malaria.
Emerging and reemerging diseases
 Emerging diseases are diseases that were not previously found
in humans, but jump from an animal host to the human species
 AIDS is the most serious emerging disease
 Reemerging diseases are infectious diseases that existed in the
past but for a variety of reasons are increasing in incidence or
in geographical range.
 The most common reemerging disease is tuberculosis.
A. Causes for reemerging diseases
 evolution of infectious organisms
 evolution of antibiotic resistance
 Urbanization, associated with overcrowding
 Pollution, environmental degradation, and
changing weather patterns
 Growth in international travel
 poverty
Environmental pollution and disease
 Elderly and children are especially sensitive to pollution
 Toxic chemicals can persist and accumulate in the environment
and magnify their concentration in the food web
IV.
Persistence, Bioaccumulation, and Biological magnification
 pesticide DDT damaged a lot of bird species because the there
were traces of DDT found in their tissue.
 Natural decomposers such as bacteria have not yet evolved ways
to degrade most synthetic pesticides, so they accumulate in the
environmental food web.
 With every step higher on the food web, it increases the
concentration of DDT which makes it so it affects many different
species at one time
V.
Endocrine Disrupters
 Some endocrine disrupters mimic estrogen, and send false
signals to the body that interfere with the normal functioning
of the reproductive system.
 It can affect both sexes
 It appears to alter reproductive growth
A. Center for Disease control and prevention


Tested a random number of Americans in which a
sample of every chemical was found in each
participants body
provides a good baseline of exposure of the U.S.
population to these compounds
VI.
Chemical Exposure
 Even “safe” chemicals can be harmful if exposed too much
 A dose of a toxicant is the amount that enters the body of an
exposed organism
 The response is the type and amount of damage that exposure to a
particular dose causes
 One way to determine acute toxicity is to administer various doses
to populations of laboratory animals
 A dose response curve shows the effect of different doses on a
population
 Doses lower than the threshold level will not have an effect on the
organism and are safe
 Differences in these genes affect how the body metabolizes
toxicants making them more or less toxic.
A. Children & exposure
 Children are more susceptible to most chemicals than
are adults because their bodies are still developing
 Also because they weigh less
VII.
Identifying Cancer-Causing Substances
 Cancer was the principal disease evaluated in toxicology
 They test the chemicals on laboratory animals such as rats
 Testing can be inaccurate because the difference in weight
 The EPA is planning to change how toxic chemicals are evaluated
and regulated
VIII.
Chemical Mixtures
 Mixtures of chemicals interact in a variety of ways, increasing the
level of complexity in risk assessment.
 A Synergistic chemical mixture has a greater combined effect than
expected
 A antagonistic interaction in a chemical mixture results in a
smaller combined effect than expected
 Dilution paradigm means that you can discard pollution into the
environment and it would be diluted sufficiently to cause no harm
 Scientists today reject the dilution paradigm in favor of the
boomerang paradigm: what you throw away can come back and
hurt you


The scope of ecotoxicology is broad-from molecular interactions in
the cells of individual organisms to effects on populations,
communities, and ecosystems
An environmental stressor is a change that taxes the environment
IX.
The Ocean and Human Health
 The ocean is important for food and natural chemical
compounds that could benefit human health
 The ocean also absorbs many wastes from human-dominated
land areas.

A. Negative Health impacts of Marine Microorganisms
 Human activities now have an impact on the ocean
including increases in land-based nutrient runoff
and pollution and a small rise in ocean temps
 This is causing an increase in the amount of disease
causing microorganisms
 A large growth of harmful algae is called algal
blooms
 Red Tides can form as well
 These toxins make their way up the food web
 This happens because of coastal pollution
 Risk assessment helps us estimate the probability
that an event will occur and lets us set priorities and
manage risks
X.
The Precautionary Principle
 The precautionary principle is also applied to existing
technologies
 This principle has been incorporated into certain laws and
decisions in many member countries
 Some scientists think this challenges the role of science-much
controversy
XI.
Cost-Benefit Analysis of Risks
 Cost-benefit analysis is an important mechanism to help decision
makers formulate environmental legislation
 A problem with this is the risk assessments on which such
analyses are based are far from perfect
 Useful in evaluating and solving environmental problems, but
decision makers must recognize the limitations of these methods