Chapter Summary: Chapter 11
Environmental Hazards and Human Health
11-1. What major health hazards do we face?
We face a variety of health hazards; it is important to go through the processes of risk assessment and risk
management to determine actions to be taken to minimize risks to our health. CONCEPT 11-1 We face health
hazards from biological, chemical, physical, and cultural factors and from the lifestyle choices we make.
1. Define risk, probability, and risk assessment. List five general types of common hazards and give two
examples of each.
11-2. What types of biological hazards do we face?
Infectious diseases are caused by pathogens (bacteria, viruses) that infect our bodies. How easily the pathogen is
spread, how resistant it is to antibiotics or other treatment, availability of that treatment, and rate of infection all
contribute to the prevalence of a particular infectious disease in a given region. The WHO estimates that only 10%
of global medical R&D goes to preventing infectious diseases in less developed countries. CONCEPT 11-2 The
most serious biological hazards we face are infectious diseases, especially flu, AIDS, tuberculosis, diarrheal
diseases, and malaria.
2. Transmissible diseases can be spread from one person to another. List two factors that contribute to the
spread of infectious diseases.
3. Tuberculosis is a significant infectious disease problem. List several reasons that fighting TB
infections is especially difficult.
4. The global HIV/AIDS pandemic has caused significant death around the world, especially in SubSaharan Africa. List three impacts of the AIDS epidemic on communities in Sub-Saharan Africa.
5. List three approaches to preventing malaria.
11-3. What types of chemical hazards do we face?
Typically, 10-40 years may elapse between initial exposure to a carcinogen and the appearance of detectable
symptoms. CONCEPT 11-3 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.
6. Define mutagen, teratogen, and carcinogen. Summarize current research implying chemical effects on
the immune, nervous, and endocrine systems.
11-4. How can we evaluate chemical hazards?
There are many variables involved in estimating the effects of human exposure to chemicals. Most commercially
used chemicals have not been screened for toxicity. Because we know so little and it is nearly impossible to
thoroughly test all chemicals in use, many health officials recommend pollution prevention as the best measure.
CONCEPT 11-4A Scientists use live laboratory animals, case reports of poisonings, and epidemiological studies to
estimate the toxicity of chemicals, but these methods have limitations. CONCEPT 11-4B Many health scientists
call for much greater emphasis on pollution prevention to reduce our exposure to potentially harmful chemicals.
7. Chemical hazards, for example, are defined by their toxicity, the person’s acute and chronic reactions
to it, and its pervasiveness in the environment.
8. Toxicity estimates are based on case reports and epidemiological studies; animal testing can also be
used to estimate toxicity.
9. Define dose and response. Distinguish among acute, chronic, and subchronic exposures. Distinguish
among acute and chronic effects. Summarize three methods used to enhance our understanding of
toxicity of chemicals.
10. Define a dose-response curve. Distinguish between a linear dose-response model and a threshold doseresponse model. Describe the difficulty in deciding which model applies best when low doses are
involved. Assess the limits of toxicological research.
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11-5. How do we perceive risks and how can we avoid the worst of them?
The greatest risks for premature death are poverty, gender, and lifestyle choices. Comparative risk analysis is critical
for understanding relative risk from ecological and health problems. CONCEPT 11-5 We can reduce the major
risks we face by becoming informed, thinking critically about risks, and making careful choices.
11. Summarize key questions to be answered in risk-benefit analysis, risk assessment, and risk
management. What are the useful applications and limits of these analyses?
12. List five factors that can cause people to perceive that a technology or product has a greater risk than
the risk estimated by experts.