Chapter 1 Introduction: The Environment at Risk Learning Objectives By the end of this chapter the reader will be able to:Describe how environmental health problems influence our livesDescribe the potential impacts of population growth upon the environmentState a definition of the term environmental healthList at least five major events in the history of environmental healthIdentify current issues in the environmental health fieldDescribe employment opportunities in the environmental health field Environmental Quality Maintaining environmental quality is a pressing task for the 21st century. Healthy People 2010 GoalsGoal Number 8, Environmental Health: “Promote health for all through a healthy environment.” Healthy People 2010 Goals (continued)Goal Number 8 Objectives include:Outdoor Air QualityWater QualityToxics and WastesHealthy Homes & Healthy CommunitiesInfrastructure and SurveillanceGlobal Environmental Health Environmental Health ThreatsTrash that fouls our beachesHazardous wastes (including radioactive wastes) leaching from disposal sites Continuing episodes of air pollution in some areasExposures to toxic chemicalsDestruction of the land through deforestation Population and Environment: The Three P’s Pollution Principal DeterminantsPopulation of Health WorldwidePoverty Pollution Combustion of fossil fuels (e.g., petroleum and coal) that disperse greenhouse gases into atmosphere may cause Global warming Change in distribution of insect vectors Population Overpopulation in developing nations is leading to the human population exceeding the carrying capacity of the planet.World population of 10-12 billion during 21st century?Related to urban crowding Infectious disease epidemics: A consequence of crowding?Avian influenza A (H5N1) virus: outbreaks on poultry farms in Asia -Health officials were concerned that the virus might mutate, enabling human-to-human transmission and a resulting pandemicSwine flu (H1N1 influenza): spread through North America to other parts of the globe. -The WHO declared a pandemic. Swine Flu (H1N1 2009 Virus)Concern that a large proportion of the population might be susceptible to infection with the virusSeasonal influenza vaccine H1N1 strain might not provide protection. During the summer and fall months of 2009, influenza activity peaked.Week ending October 24, 2009—49 of 50 states reported geographically widespread disease.Worldwide (as of 31 January 2010) more than 209 countries and overseas territories or communities reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 15174 deaths. PovertyLinked to population growthOne of the well-recognized determinants of adverse health outcomes Significance of the Environment for Human HealthExposure to potentially hazardous agents accounts for many of the forms of environmentally associated morbidity and mortality.Examples of hazardous agents are:MicrobesToxic chemicals and m ...

1. Chapter 1
Introduction:
The Environment at Risk
Learning Objectives
By the end of this chapter the reader will be able to:Describe
how environmental health problems influence our livesDescribe
the potential impacts of population growth upon the
environmentState a definition of the term environmental
healthList at least five major events in the history of
environmental healthIdentify current issues in the
environmental health fieldDescribe employment opportunities in
the environmental health field
Environmental Quality
Maintaining environmental quality is a pressing task for the
21st century.

2. Healthy People 2010 GoalsGoal Number 8, Environmental
Health: “Promote health for all through a healthy
environment.”
Healthy People 2010 Goals (continued)Goal Number 8
Objectives include:Outdoor Air QualityWater QualityToxics
and WastesHealthy Homes & Healthy
CommunitiesInfrastructure and SurveillanceGlobal
Environmental Health
Environmental Health ThreatsTrash that fouls our
beachesHazardous wastes (including radioactive wastes)
leaching from disposal sites Continuing episodes of air
pollution in some areasExposures to toxic chemicalsDestruction
of the land through deforestation
Population and Environment: The Three P’s
Pollution Principal DeterminantsPopulation of
Health WorldwidePoverty
Pollution
Combustion of fossil fuels (e.g., petroleum and coal) that
disperse greenhouse gases into atmosphere may cause
Global warming
Change in distribution of insect vectors

3. Population
Overpopulation in developing nations is leading to the human
population exceeding the carrying capacity of the planet.World
population of 10-12 billion during 21st century?Related to
urban crowding
Infectious disease epidemics: A consequence of
crowding?Avian influenza A (H5N1) virus: outbreaks on
poultry farms in Asia
-Health officials were concerned that the virus
might mutate, enabling human-to-human transmission and
a resulting pandemicSwine flu (H1N1 influenza): spread
through North America to other parts of the globe.
-The WHO declared a pandemic.
Swine Flu (H1N1 2009 Virus)Concern that a large proportion of
the population might be susceptible to infection with the
virusSeasonal influenza vaccine H1N1 strain might not provide
protection. During the summer and fall months of 2009,
influenza activity peaked.Week ending October 24, 2009—49 of
50 states reported geographically widespread disease.Worldwide
(as of 31 January 2010) more than 209 countries and overseas
territories or communities reported laboratory confirmed cases
of pandemic influenza H1N1 2009, including at least 15174
deaths.
PovertyLinked to population growthOne of the well-recognized
determinants of adverse health outcomes

4. Significance of the Environment for Human HealthExposure to
potentially hazardous agents accounts for many of the forms of
environmentally associated morbidity and mortality.Examples
of hazardous agents are:MicrobesToxic chemicals and
metalsPesticidesIonizing radiation
Scope of Environmental Health Problems Environmental factors
are thought to contribute significantly to many forms of chronic
disease such as cancer, including cervical cancer, prostate
cancer, and breast cancer.
Scope of Environmental Health Problems (continued)Large
proportion of the burden of disease associated with
environmental sourcesPrevalence of and mortality from asthma
in the U.S. have increased since 1980 by 58% and 78%,
respectively.High percentage of U.S. children with elevated
blood lead levelsDegrading air quality worldwide
Environmental Risk TransitionChanges in environmental risks
that happen as a consequence of economic development in the
less developed regions of the world.Before transition occurs,
poor quality of: FoodAirWater
Environmental Risk Transition (continued)After transition, a
new set of environmental problems take hold. Examples include

5. release of:Acid rain precursorsOzone-depleting
chemicalsGreenhouse gases
Population GrowthIncreasing at an exponential rateThreatens to
overwhelm available resourcesMay cause periodic food scarcity
and famine in some areas of the world.
Causes of Population GrowthIncreases in fertilityReductions in
mortalityMigration
Trends in Population GrowthAs of June 1999, 6 billion people
inhabited our planet.From 1931 to 1974 (a 43-year interval), the
earth’s population doubled and is projected to double again
during approximately the same interval (1974 to 2018).
Population DynamicsRefers to the ever-changing
interrelationships among the set of variables that influence the
demographic makeup of populations as well as the variables that
influence the growth and decline of population sizes.
FertilityA measure of fertility is the total fertility rate (TFR),
which indicates how many births a woman would have by the
end of her reproductive life. In the U.S., the fertility rate
fluctuates from around 2.0 to 2.1 births per woman; the natural
population replacement rate is estimated to be 2.1.

6. Fertility TrendsU.S., Canada, Japan, South Korea, Thailand,
China, and many European countries are at or below the
replacement rate for fertility.Many Asian, Latin American, and
African countries have a fertility rate of 4.0 births per woman.
Demographic TransitionRefers to alterations over time in a
population’s fertility, mortality, and make-up.Developed
societies have progressed through three stages that have
affected their age and sex distributions.
The Three Stages of
Demographic Transition
Stage 1: Population mostly young, and fertility and mortality
rates are high. Overall, the population remains small.
Stage 2: Mortality rates drop and fertility rates remain high.
There is a rapid increase in population, particularly among the
younger age groups.
Stage 3: Fertility rates drop and cause a more even distribution
of the population according to age and sex.
Figure 1-5 The demographic transition in three stages of age
and sex composition: stage 1 (left), stage 2 (middle), and stage
3 (right).
Source: Reprinted from US Census Bureau. International
Population Reports WP/02. Global Population Profile: 2002.
Washington, DC: US Government Printing Office; 2004:35.

7. Epidemiologic TransitionDescribes a shift in the pattern of
morbidity and mortality from causes related primarily to
infectious and communicable diseases to causes associated with
chronic, degenerative diseases.
Examples of
Epidemiologic TransitionChronic, degenerative diseases include
cardiovascular diseases, cancer, neuro-psychiatric conditions,
and injuries; these conditions are becoming the major causes of
disability and premature death in many nations.
Consequences of Population IncreasesUrbanizationOvertaxing
carrying capacityFood insecurityLoss of biodiversity
UrbanizationWorldwide, the proportion of urban residents has
increased from about 5% in 1800 to 50% in 2000 and is
expected to reach about 66% by 2030.
Factors that Lead to Urbanization
Industrialization
Food availability
Employment opportunities
Lifestyle considerations
Escape from political conflict

8. Hazards of the Urban Environment
Biological pathogens or pollutants including pathogenic agents
and their vectors (and reservoirs)
Chemical pollutants including those added to the environment
by human activities (e.g., industrial wastes) and chemical agents
present in the environment independent of human activities
More Hazards of the
Urban Environment
Reduced availability, increased cost, and lowered quality of
natural resources on which human health depends—e.g., food,
water and fuel.
Physical hazards (e.g., high risk of flooding in houses and
settlements built on floodplains or of mud slides or landslides
for houses on slopes)
More Hazards of the
Urban Environment
Aspects of the built environment with negative consequences on
physical or psychosocial health (e.g., overcrowding; inadequate
protection against noise; inadequate provision of infrastructure,
services, and common areas).
More Hazards of the

9. Urban Environment
Natural resource degradation (e.g., of soil and water quality)
National/global environmental degradation with more indirect
but long-term influences on human health
Carrying CapacityThe population that an area will support
without undergoing environmental deteriorationThe carrying
capacity of an environment tends to limit population size. Food
availability, reproductive behavior, and infectious diseases tend
to keep animal populations in check.
Population CrashesIf components of the human life support
system are disrupted by overpopulation of the planet, the
species Homo sapiens could suffer a population crash.
Key Terms and DefinitionsEnvironmentEcological
modelEcological system (ecosystem)Environmental health
EnvironmentRefers to “. . . the complex of physical, chemical,
and biotic factors (as climate, soil, and living things) that act
upon an organism or an ecological community and ultimately
determine its form and survival.”
The Ecological ModelProposes that the determinants of health
(environmental, biological, and behavioral) interact and are
interlinked over the life course of individuals.

10. Figure 1-8 The ecological model of population health.
Source: Adapted and reprinted with permission from Who Will
Keep the Public Healthy? Educating Public Health Professionals
for the 21st Century, © 2003 by the National Academy of
Sciences, courtesy of the National Academies Press,
Washington, D.C., p. 33; and from Dahlgren G, Whitehead M.
Policies and Strategies to Promote Social Equity in Health.
Stockholm, Sweden: Institute for Futures Studies; 1991.
Ecosystem“An ecosystem is a dynamic complex of plant,
animal, and microorganism communities and the nonliving
environment interacting as a functional unit.”Millennium
Ecosystem Assessment, 2003
Environmental Health“…addresses all the physical, chemical,
and biological factors external to the person, and all the related
factors impacting behaviours.” Encompasses control of
environmental factorsAims to prevent diseaseSource: World
Health Organization
Historical BackgroundAncient historyGreeks
(Hippocrates)RomansOccupational health contributionsPost
1800 periodCurrent “hot topics”

11. HippocratesHippocrates, a Greek philosopher who lived
between 460 and 370 BC, often is referred to as “the father of
medicine.” He emphasized the role of the environment as an
influence on people’s health and health status in his work titled
On Airs, Waters, and Places (ca. 400 BC).
Hippocrates (continued)Proposed that environmental and
climatic factors such as the weather, seasons, and prevailing
winds; the quality of air, water, and food; and one’s geographic
location were influential in causing changes in human health.
Current Hot TopicsEnvironmental justiceGlobal climate
changeNuclear powerPesticides and herbicidesWar and
terrorism
Careers in Environmental HealthIndustrial Hygienist:
Responsible for control of hazards that may affect workers as
well as hazards that may impact the community.
More Careers in
Environmental HealthToxicologist:The field of environmental
toxicology specializes in the effects of toxic chemicals upon the
environment and living creatures such as human beings and
wildlife. Occupational and industrial toxicologists investigate
the effects of chemicals found in the workplace upon the health
of workers.

12. More Careers in
Environmental Health Environmental Health
Inspector:Responsible for monitoring and enforcing government
regulations for environmental quality.
More Careers in
Environmental HealthOccupational Health
Physician/Occupational Health Nurse:Involved with the
prevention and treatment of occupationally related illnesses and
injuries Investigate hazards in the work environment Develop
procedures for abatement of hazards Conduct health education
programs
Chapter 2
Environmental Epidemiology
Learning Objectives
By the end of this chapter the reader will be able to:Define the
term environmental epidemiologyDescribe three major

13. historical events in environmental epidemiologyProvide
examples of epidemiologic tools used in environmental
healthIdentify types of associations found between
environmental hazards and health outcomesList study designs
used in environmental epidemiology
What is Environmental Epidemiology?The study of diseases and
health conditions (occurring in the population) that are linked to
environmental factors.These exposures usually are involuntary.
Epidemiology’s Contributions to Environmental Health
Concern with populationsUse of observational dataMethodology
for study designsDescriptive and analytic studies
Concern with PopulationsEnvironmental epidemiology studies a
population in relation to morbidity and mortality.Example: Is
lung cancer mortality higher in areas with higher concentrations
of “smokestack” industries?
Use of Observational DataEpidemiology is primarily an
observational science that takes advantage of naturally
occurring situations in order to study the occurrence of disease.
Methodology for
Study DesignsCharacteristic study designs used frequently in

14. environmental epidemiology:Cross-sectionalEcologicCase-
ControlCohort
Two Classes of
Epidemiologic StudiesDescriptiveDepiction of the occurrence of
disease in populations according to classification by person,
place, and time variables.AnalyticExamines causal (etiologic)
hypotheses regarding the association between exposures and
health conditions.
Measures of Disease FrequencyPrevalencePoint
prevalenceIncidenceIncidence rateCase fatality rate
Prevalence
Refers to the number of existing cases of a disease, health
condition, or deaths in a population at some designated time
Point PrevalenceRefers to all cases of a disease, health
condition, or deaths that exist at a particular point in time
relative to a specific population from which the cases are
derived.
Formula for Point Prevalence
Number of persons ill

15. Point Prevalence = at a point in
Total number in the group time
IncidenceThe occurrence of new disease or mortality within a
defined period of observation (e.g., week, month, year, or other
time period) in a specific population.
Formula for Incidence Rate
Incidence Number of new cases over a time
Rate = period x multiplier
Total population at risk (e.g., 100,000)
Case Fatality Rate (CFR)
Provides a measure of the lethality of a disease.
Case Fatality Rate (CFR)
(continued)
Number of deaths due to disease “X”
CFR (%) = x 100 during a
Number of cases of disease “X” time period

16. Major Historical Figure:
Sir Percival Pott (1714-1788)A London surgeon thought to be
the first individual to describe an environmental cause of
cancer.Chimney sweeps had high incidence of scrotal cancer
due to contact with soot.
Major Historical Figure:
John SnowAn English anesthesiologist who linked a cholera
outbreak in London to contaminated water from the Thames
River in the mid-1800s.Snow employed a “natural experiment,”
a methodology used currently in studies of environmental health
problems.
Study Designs Used in Environmental
EpidemiologyExperimental Case SeriesCross-SectionalEcologic
Case-ControlCohort
Odds Ratio (OR)A measure of association for case- control
studies.Exposure-odds ratio:Refers to “… the ratio of odds in
favor of exposure among the cases [A/C] to the odds in favor of
exposure among the non-cases [the controls, B/D].”

17. Odds Ratio Table
Odds Ratio Equation
Note that an OR >1 (when statistically significant) suggests a
positive association between exposure and disease or health
outcome.
Relative Risk (RR)The ratio of the incidence rate of a disease or
health outcome in an exposed group to the incidence rate of the
disease or condition in a non-exposed group.
Relative Risk (RR) Table
RR Equation
A
A + B
RR =
C
C + D
Notes:
When an association is statistically significant:
RR >1 indicates that the risk of disease is greater in the
exposed group than in the nonexposed group.
RR<1 indicates possible protective effect.

18. Study EndpointsSelf-reported symptom ratesPhysiologic or
clinical examinationsMortality
Figure 2-5 The epidemiologic triangle.
Source: Reprinted with permission from RH Friis, TA Sellers.
Epidemiology for Public Health Practice. 4th ed. Sudbury, MA:
Jones and Bartlett Publishers; 2009:439.
What is the
Epidemiologic Triangle?Used for describing the causality of
infectious diseasesProvides a framework for organizing the
causality of other types of environmental problems
Environment in the “Triangle”The term environment is defined
as the domain in which disease-causing agents may exist,
survive, or originate; it consists of “All that which is external to
the individual human host.”
Host in the “Triangle”A host is “a person or other living animal,
including birds and arthropods, that affords subsistence or
lodgment to an infectious agent under natural conditions.”
Agent in the “Triangle”Agent refers to “A factor, such as a

19. microorganism, chemical substance, or form of radiation, whose
presence, excessive presence, or (in deficiency diseases)
relative absence is essential for the occurrence of a disease.”
CausalityCertain criteria need to be taken into account in the
assessment of a causal association between an agent factor (A)
and a disease (B).
Hill’s Criteria of
CausalityStrengthConsistencySpecificityTemporalityBiological
gradientPlausibilityCoherence
Bias in Environmental Epidemiologic StudiesDefinition of
biasThe healthy worker effectConfounding
Definition of Bias“Systematic deviation of results or inferences
from the truth. Processes leading to such deviation. An error in
the conception and design of a study—or in the collection,
analysis, interpretation, reporting, publication, or review of
data—leading to results or conclusions that are systematically
(as opposed to randomly) different from the truth.”Porta M. A
Dictionary of Epidemiology. 5th ed. New York, NY: Oxford
University Press; 2008.
Healthy Worker EffectRefers to the observation that employed
populations tend to have a lower mortality experience than the

20. general population.The healthy worker effect could introduce
selection bias into occupational mortality studies.
ConfoundingDenotes “… the distortion of a measure of the
effect of an exposure on an outcome due to the association of
the exposure with other factors that influence the occurrence of
the outcome.”Porta M. A Dictionary of Epidemiology. 5th ed.
New York, NY: Oxford University Press; 2008.
Limitations of Epidemiologic StudiesLong latency periodsLow
incidence and prevalenceDifficulties in exposure
assessmentNonspecific effects