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Chapter 14: Environmental Hazards and Human Health
Erin Brockovich
Web Resources
USGS
Site on emerging human/environmental health issues.
http://health.usgs.gov/
World Health Organization
Global AIDS statistics and information.
http://www.who.int/hiv/en/
Erin Brockovich
Information about grassroots environmental advocacy and how one person can make a difference.
Digital Integration
Correlation to Global Environment Watch
Access to Healthcare Pest Management
Consumption Poverty
Disease Precautionary Principle
Food Safety Risk
Globalization Sanitation
Green Chemistry U.S. Environmental Protection Agency
Instructor’s Manual for Environmental Science, 15th edition
Correlation to Explore More
Suggested Answers to End of Chapter Questions
Answers will vary but these represent phrases from this chapter. The following are examples of the material
that should be contained in possible student answers to the end of chapter questions. They represent only a
summary overview and serve to highlight the core concepts that are addressed in the text. It should be
anticipated that the students will provide more in-depth and detailed responses to the questions depending
on an individual instructor’s stated expectations.
Review
Core Case Study
1. Describe the toxic effects of mercury and its compounds and explain how we are exposed to these
toxins.
High levels of mercury can damage the human nervous system, kidneys, and lungs. Low levels of
mercury can also harm fetuses and cause birth defects. Natural sources account for about one-third of
Section 14-1
2. What is the key concept for this section? Define and distinguish among risk, risk assessment, and risk
management. Give an example of how scientist state probabilities. Give an example of a risk from each
of the following: biological hazards, chemical hazards, physical hazards, cultural hazards, and lifestyle
choices. What is a pathogen?
• Concept 14-1 We face health hazards from biological, chemical, physical, and cultural factors, and
from the lifestyle choices we make.
• A risk is the probability of suffering harm from a hazard that can cause injury, disease, death,
economic loss, or damage.
• Risk assessment is the process of using statistical methods to estimate how much harm a particular
hazard can cause to human health or to the environment.
Chapter 14: Environmental Hazards and Human Health
Section 14-2
3. What is the key concept for this section? Define infectious disease; define and distinguish among
bacteria, viruses and parasites and give examples of diseases that each can cause. Define and
distinguish between transmissible disease and nontransmissible disease, and give an example of each.
List four ways in which infectious organisms can enter the body. In terms of death rates, what are the
world’s four most serious infectious diseases? List five factors that have contributed to genetic
resistance to commonly used antibiotics. What is MRSA and why is it so threatening?
• Concept 14-2 The most serious biological hazards we face are infectious diseases such as flu,
AIDS, tuberculosis, diarrheal diseases, and malaria.
• An infectious disease is a disease caused by a pathogen such as a bacterium, virus, or parasite
invading the body and multiplying in its cells and tissues.
• Bacteria are singe-cell organisms that are found everywhere and that can multiply very rapidly on
their own. Some cause infectious bacterial diseases. A bacterial disease such as tuberculosis
results from an infection as the bacteria multiply and spread throughout the body.
• There are a number of pathways for infectious disease organisms to enter the human body. They
can be spread through air, water, food, and body fluids such as feces, urine, blood, and droplets
sprayed by sneezing and coughing, and by pets, livestock, wild animals and insects.
• The four most serious infectious diseases are pneumonia and flu, HIV/AIDS, diarrheal diseases,
and tuberculosis.
• Factors contributing to genetic resistance of bacteria to antibiotics: high rate of reproduction of
bacteria, rapid spread of bacteria because of travel around the globe, overuse of pesticides,
exchange of genetic material from resistant to nonresistant bacteria, and overuse of antibiotics for
colds and flu and other viruses.:
4. Describe the global threat from tuberculosis and list three factors that have helped it to spread. What is
the biggest viral killer and how does it spread? Summarize the threat from the hepatitis B virus. What
is the best way to reduce one’s chances of getting an infectious disease? What is the focus of
ecological medicine and what are some of its findings regarding the spread of diseases? Summarize the
health threats from the global HIV/AIDS pandemic.
Instructor’s Manual for Environmental Science, 15th edition
• See CASE STUDY: The Growing Global Threat from Tuberculosis (p. 262)
• The biggest viral killer is the influenza, or flu, virus, which is transmitted by the body fluids or
airborne emissions of an infected person. Easily transmitted and especially potent flu viruses could
spread around the world in a pandemic that could kill millions of people in only a few months.
5. What is malaria and how does it spread? How much of the human population is subject to this threat?
Explain how deforestation can promote the spread of malaria. List six major ways to reduce the global
threat from infectious diseases.
• See CASE STUDY: Malaria—Death by Parasite-Carrying Mosquitoes.
• About 47% of the world’s population lives in areas in which malaria is prevalent. Malaria kills at
least 1 million people a year or about 2 people every minute. More than 80% of these victims live
in sub-Saharan Africa and most of them are children younger than age 5.
• Ways to reduce the threat of malaria.
o Develop new antimalarial drugs and vaccines, as well as biological controls for
Anopheles mosquitoes.
• Clearing and developing tropical forests leads to the spread of malaria among workers and the
settlers who follow them. A 5% loss of tree cover in one part of Brazil’s Amazon forest led to a
50% increase in malaria in that study area. A possible explanation is that deforestation creates
partially sunlit pools of water that make ideal breeding ponds for malaria-carrying mosquitoes
• Figure 14-8. Ways to prevent or reduce the incidence of infectious diseases, especially in
developing countries.
o Increase research on tropical diseases and vaccines
o Reduce poverty and malnutrition
o Improve drinking water quality
o Reduce unnecessary use of antibiotics
Chapter 14: Environmental Hazards and Human Health
Section 14-3
6. What is the key concept for this section? What is a toxic chemical? Define and distinguish among
carcinogens, mutagens, and teratogens, and give an example of each. Describe the human immune, nervous,
and endocrine systems and for each of these systems, give an example of a chemical that can threaten it.
What is a neurotoxin and why is methylmercury (Core Case Study) an especially dangerous one? What are
six ways to prevent or control environmental inputs of mercury? What are hormonally active agents (HAAs),
what risks do they pose, and how can we reduce those risks? Summarize health scientists’ concerns about
exposure to bisphenol A (BPA) and the controversy over what to do about exposure to this chemical.
Summarize the concerns over exposure to phthalates. List six ways to reduce your exposure to HAAs.
• Concept 14-3 There is growing concern about chemicals in the environment that can cause cancers
and birth defects, and disrupt the human immune, nervous, and endocrine systems.
• A toxic chemical is one that can cause temporary or permanent harm or death to humans and
animals.
• The human immune system consists of specialized cells and tissues that protect the body against
disease and harmful substances by forming antibodies that render invading agents harmless. Some
chemicals such as arsenic, methylmercury, and dioxins can weaken the human immune system
and leave the body vulnerable to attacks by allergens and infectious bacteria, viruses, and
protozoa.
• The endocrine system is a complex network of glands that releases tiny amounts of hormones into
the bloodstreams of humans and other vertebrate animals. Low levels of these chemical
messengers turn on and turn off bodily systems that control sexual reproduction, growth,
development, learning ability, and behavior. This system can be disrupted by molecules of certain
pesticides and other synthetic chemicals, including aluminum, Atrazine™ and several other
herbicides, DDT, PCBs, mercury, phthalates, and BPA
Instructor’s Manual for Environmental Science, 15th edition
• Some scientists believe that, as a precaution, governments and individual consumers should act to
sharply reduce the use of potentially harmful hormone disrupters, especially in products used
widely by pregnant women, infants, and young children. They also call for manufacturers to
search for less harmful substitutes for such chemicals.
• Bisphenol A (BPA) is an estrogen mimic that is widely used in certain plastics. In males, excess
estrogen can cause feminization, smaller penises, diminished sex drive and sperm counts, and the
presence of both male and female sex organs. In females, several studies have found that higher
levels of BPA are associated with infertility, recurrent miscarriages, and breast cancer.
Section 14-4
7. What are the two key concepts for this section? Define toxicology, toxicity, dose, and response. What
are three factors that affect the level of harm caused by a chemical? Give three reasons why children
are especially vulnerable to harm from toxic chemicals. Describe how the toxicity of a substance can
be estimated by testing laboratory animals, and discuss the limitations of this approach. What is a dose-
response curve? Explain how toxicities are estimated through use of case reports and epidemiological
studies, and discuss the limitations of these approaches.
• Concept 14-4A Scientists use live laboratory animals, case reports of poisonings, and
epidemiological studies to estimate the toxicity of chemicals, but these methods have limitations.
• Concept 14-4B Many health scientists call for much greater emphasis on pollution prevention to
reduce our exposure to potentially harmful chemicals.
• Toxicology is the study of the harmful effects of chemicals on humans and other organisms. In
effect, it is a study of poisons.
• Scientists usually use mathematical models to extrapolate, or estimate, the effects of low-dose
exposures based on the measured results of high-dose exposures. Then they extrapolate these
results from test organisms to humans to estimate LD50 values for acute toxicity. Some scientists
challenge the validity of extrapolating data from test animals to humans, because human
physiology and metabolism often differ from those of the test animals. Scientists estimate the
toxicity of a chemical by determining the effects of various doses of a chemical on test organisms
and plotting the results in a dose-response curve. One approach is to determine the lethal dose—
the dose that will kill an animal. A chemical’s median lethal dose (LD50) is the dose that can kill
50% of the animals (usually rats and mice) in a test population within an 18-day period.
Chapter 14: Environmental Hazards and Human Health
8. Summarize the controversy over the effects of trace levels of chemicals. Why do we know so little about the
harmful effects of chemicals? What is the precautionary principle? Explain why the use of pollution
prevention based on the precautionary principle to deal with health threats from chemicals is controversial.
Describe some efforts to apply this principle on national and international levels. What is the U.N. Minamata
Convention for reducing mercury pollution? How did pollution prevention pay off for the 3M Company?
• Some scientists view exposures to trace amounts of synthetic chemicals with alarm, especially
because of their potential long-term effects on the human immune, nervous, and endocrine
systems. Others scientists view the threats from such exposures as minor. They point out that
average life expectancy has been increasing in most countries, especially more-developed
countries, for decades. Some scientists contend that the concentrations of such chemicals are so
low that they are harmless. All agree that there is a need for much more research on the effects of
Instructor’s Manual for Environmental Science, 15th edition
Section 14.5
9. What is the key concept for this section? What is risk analysis? In terms of premature deaths, what are
the three greatest threats that people face? What are six ways in which poverty can threaten one’s
health? Describe the health threats from smoking and how we can reduce these threats. Summarize our
knowledge of the health effects of using e-cigarettes. How can we reduce the threats resulting from the
use of various technologies? What are five factors that can cause people to misjudge risks? List four
guidelines for evaluating and reducing risk.
• Concept 14-5 We can reduce the major risks we face by becoming informed, thinking critically
about risks, and making careful choices.
• See CASE STUDY: Cigarettes and E-Cigarettes
• The more complex a technological system, and the more people needed to design and run it, the
more difficult it is to estimate the risks of using the system. The overall reliability of such a
system—the probability (expressed as a percentage) that the system will complete a task without
• failing—is the product of two factors: System reliability (%) = Technology reliability (%) ×
Human reliability (%).
• Five factors can cause people to see a technology or a product as being more or less risky than
experts judge it to be: fear, degree of control we have, whether a risk is catastrophic (not chronic),
some people suffer from optimism bias, and instant gratification.
• Some guidelines for evaluating and reducing risk:
o Compare risks. Is there a risk of getting cancer by eating a charcoal-broiled steak once or
twice a week for a lifetime? Yes, because almost any chemical can harm you if the dose is
large enough. The question is whether this danger is great enough for you to worry about. In
evaluating a risk, the key question is not “Is it safe?” but rather “How risky is it compared to
other risks?”
10. What are this chapter’s three big ideas? Explain how we can lessen the threats of harm from mercury
in the environment by applying the three scientific principles of sustainability?
This chapter’s big ideas:
• We face significant hazards from infectious diseases such as flu, AIDS, diarrheal diseases,
malaria, and tuberculosis, and from exposure to chemicals that can cause cancers and birth
defects, and disrupt the human immune, nervous, and endocrine systems.
• Because of the difficulty in evaluating the harm caused by exposure to chemicals, many
health scientists call for much greater emphasis on pollution prevention.
Chapter 14: Environmental Hazards and Human Health
Critical Thinking
1. Assume that you are a national official with the power to set policy for controlling environmental
mercury pollution from human sources (Core Case Study). List the goals of your policy and outline a
plan for accomplishing those goals. List three or more possible problems that could result from
implementing your policy.
Answers will vary.
The precautionary principal would advocate applying the three scientific principles of sustainability.
2. What are three actions you would take to reduce the global threats to human health and life from: (a)
tuberculosis, (b) HIV/AIDS, and (c) malaria?
(a) Tuberculosis (TB): 1. Provide faster and cheaper diagnosis for TB in more hospitals. 2. Inform the
public about symptoms in the early stages, since they usually go unnoticed. 3. Stress the importance of
3. Explain why you agree or disagree with each of the following statements: (a) We should not worry
much about exposure to toxic chemicals because almost any chemical, at a large enough dosage, can
cause some harm. (b) We should not worry much about exposure to toxic chemicals because, through
genetic adaptation, we can develop immunity to such chemicals. (c) We should not worry much about
Instructor’s Manual for Environmental Science, 15th edition
exposure to toxic chemicals because we can use genetic engineering to reduce our susceptibility to
their effects. (d) We should not worry about exposure to a chemical such as bisphenol A (BPA)
because it has not been absolutely proven scientifically that BPA has killed anyone.
4. Should we ban the use of hormone mimics such as BPA in making products to be used by children
younger than age 5? Should such a ban be extended to all products? Explain.
Latest research into the harmful effects of BPA has again linked BPS with abnormal male and female
reproductive organ development in animals and sperm development in humans. In addition to male
5. Workers in a number of industries are exposed to higher levels of various toxic substances than the
general public is. Should we reduce the workplace levels allowed for such chemicals? What economic
effects might this have?
It is a business’ responsibility to have a safe environment for their workers to work in. In principle,
there should not be any more pollutants in their workplace than anywhere else, but in practice, if this is
6. Do you think there should be a ban on smoking indoors in all public places? Explain. Do you think that
electronic cigarettes should be taxed and regulated like conventional cigarettes? Explain.
I believe there should be a ban on smoking indoors. It is the smoker’s choice to smoke, but not
7. What are the three major risks you face from each of the following: (a) your lifestyle, (b) where you live, and
(c) what you do for a living? Which of these risks are voluntary and which are involuntary? List three steps
you could take to reduce each of these risks. Which of these steps do you already take or plan to take?
Chapter 14: Environmental Hazards and Human Health
Answers will vary depending upon where students live. Acceptable answers will include living in cities,
8. In deciding what to do about risks from chemicals in the area where you live, would you support
legislation that requires the use of pollution prevention based on the precautionary principle and on the
assumption that chemicals are potentially harmful until shown otherwise? Explain.
I would support this type of legislation. My observations are that it is generally much cheaper to
Global Environment Watch Exercise
Search for mercury pollution and research the latest developments in studies of the harmful health
effects of mercury (Core Case Study). Find an example of an effort to prevent or control mercury
pollution and write a short report summarizing your findings. Try to find reports of two studies that
reach different conclusions about how mercury should be regulated. Summarize the arguments for
these conclusions on both sides. Based on what you have found, do you think that mercury pollution
should be regulated more strictly in the state or country where you live? Explain your reasoning.
People in the U.S. are mainly exposed to methylmercury, an organic compound, when they eat fish and
shellfish that contain methylmercury. Whether an exposure to the various forms of mercury will harm
a person's health depends on a number of factors (below). Almost all people have at least trace
• the chemical form of mercury;
• the dose;
The European Union (EU) adopted, in 2005, a strategy to reduce the release of mercury into the
environment, reduce production and demand and ensure protection against exposure, in particular to
methylmercury in fish and other seafood. This strategy was followed by adoption of Regulation EC
Instructor’s Manual for Environmental Science, 15th edition
Data Analysis
1. a. By what percentage did life expectancy in Botswana increase between 1950 and 1995?
b. By what percentage is life expectancy in Botswana projected to decrease between 1995 and 2015?
(a) Life expectancy increased by about 41% between 1950 and 1995.
1. a. By what percentage is life expectancy in Botswana projected to increase between 2015 and 2050?
b. By what percentage is life expectancy in Botswana projected to decrease between 1995 and 2050?
(a) Life expectancy is projected to increase by 33% between 2015 and 2050.
