Transcript File

Environmental Sciences: Towards a
Sustainable Future Chapter 15
Environmental Hazards and
Human Health
Chapter Introduction
Avian Flu H5N1





1st appeared in Hong Kong in 1997.
Recently found in migratory birds.
First human case in 2003.
May 22, 2006 a 32 year old man dies
after contracting the disease from a
family member.
How can this be?
Viruses


Viral RNA may mix strands so if someone
were to contract avian flu while stricken
with another type of flu, the two strands
can mix forming a new virulent strand
which may be passed from human to
human.
38 diseases in the last 25 years have
jumped from animal to human.
Environmental Health
 The
study of the connections
between hazards in the
environment and human
disease and death.
Lesson 15.1
Links between human health and
the environment
Some Definitions


Environment: combination of physical,
chemical, and biological factors of where and
how people live.
Hazard: anything that can cause
1.
2.
3.

injury, death, disease
damage to personal/public property
or deterioration or destruction of
environmental components.
Existence of the hazard doesn’t mean that
undesirable consequences will follow.

Vulnerability: some people, especially
the poor, are more vulnerable to certain
risks than others.

Risk: probability of suffering a loss
as a result of exposure to a hazard
RISK= Hazard x Vulnerability
Example:



Presence of avian flu is the hazard.
This presents a risk to humans
contracting the disease.
People who work with poultry are
more vulnerable.
The CDC





Center for Disease Control
In the United States it is the lead federal
agency in charge of protecting the health
and safety of the public.
Agency under the Department of Health
and Human Services.
Other countries: Ministry of Health
Limitations:

Funding and information
The WHO



World Health Organization
Sub unit of the United Nations (therefore
all countries have access to their
information)
Located in Geneva (and maintaining 6
other regional offices) it was established in
1948. Their mission is to enable “all
peoples to attain the highest possible level
of health”.
The Report


Written in 2002
Entailed: Reducing risks, promoting
healthy life, presentation of major risk
factors “for which the means to reduce
them are unknown”
Universal Indicator of Health:

Human life expectancy.




1955-global life expectancy was 48
2008- global life expectancy is 67
By 2025- 73
This progress is a result of social,
medical, and economic advances in
the latter half of the 20th century.
Most lethal Hazards:

Some of the most lethal hazards are
the result of voluntary behavior.
Two fundamental ways to consider
hazards to human health:

Lack of access to necessary resources.



Water
Nutritious food
Exposure to hazards in the
environment.

Cultural, biological, physical, chemical,



Morbidity: The incidence of disease.
Mortality: The incidence of death.
Epidemiology: The study of the
presence, distribution, and control of
disease in populations.
Causes of Human Mortality
Figure 15-2 page 388
Environmental Hazards
 Cultural
 Biological
 Physical
 Chemical
Cultural Hazards
 Consequence
of choice
 Risky behavior

Thus we may: eat too much,
drive too fast, use addictive
drugs, consume alcohol,
smoke, sunbathe, etc.
Figure 15-3 page 388
Cultural Hazards
Smoking-related Diseases
Biological Hazards






Pathogenic bacteria
Fungi
Viruses
Protozoans
Worms
Table 15-1 page 389 gives a list of many
infectious diseases and the estimated
number of deaths yearly.
Infectious Diseases


More prevalent in but not exclusive to
developing countries
Contamination of food and water



Lack of resources for sanitation
Lack of education
Ideal climates for transmission of vectorborne (host carried: like the ticks from the
chapter intro) diseases like malaria
Physical Hazards
Natural disasters, e.g., tornadoes,
floods, hurricanes, and wildfires
 Avoidance of risk important in
prevention, e.g., building homes in
flood plains, and living on the
coast.
 Not all disasters can be avoided

Chemical Hazards
Result of industrialization
 Exposure through ingestion,
inhalation, absorption through skin
 May be direct use or accidental
 Many chemicals are toxic at low
levels

Chemical Hazards
188 chemicals are reasonably
anticipated to be carcinogenic
 Environmental carcinogens
initiate mutations in DNA;
several mutations lead to a
malignancy (cancer).

Lesson 15.2
Pathways of Risk
Figure 15-9 p. 395

Top 10 leading GLOBAL risk factors.


Underweight, unsafe sex, blood pressure,
tobacco use, alcohol use, unsafe
water/sanitation/hygeine, cholesterol,
indoor smoke from solid fuels, iron
deficiency, overweight.
These 10 are responsible for 1/3 of the
mortality.
Pathways to health hazards

Poverty: developed and
developing.


Lack of access to clean water,
adequate health care, nutritional
foods, healthy air, sanitation and
shelter.
The wealthier a nation becomes,
the healthier its population.
Life spans
 65%
of developed nation
citizens live to full life
expectancy and die of “old
age” vs. 33% in developing
nations.
Environmental Health
 Factors contributing to the
environmental health of a nation
include:
 Education
 Nutrition
 Commitment from government
 More equitable distribution of
wealth
Cultural Risk of Smoking
80% of smokers are in developing
world.
 Synergistic effect: smokers living
in polluted areas, higher risk.
 Jan 1993-EPA classifies
secondhand smoke as a class A
carcinogen.


Class A = known human carcinogen
In response to being classified “Class A”…
Substantial fallout: smoke free
zones in malls, work places, bars
restaurants, etc.
 2% decrease in second hand smoke
= in terms of human exposure to
harmful particulates of eliminating
all coal-fired power plants in the
country.

Infectious disease
 Reasons in developing countries:




Contaminated food
Contaminated water
Inadequate hygiene
Lack of adequate sewage
 Back

to lack of education, wealth, nutrition!
Developed causes:

Factory like production of food
 Inadequate
surveillance.
Indoor Air Pollution

Three factors in
the developed
world



*Humans breath 30lb of air in each day!
Hazardous fumes
from home
products
Well-insulated
buildings
Long exposure to
indoor air (90%
time spent
indoors)

Indoor Air Pollution
Developing countries:
 Results from burning biofuels
(wood, dung) inside homes
Acute respiratory infections in
children
Chronic lung diseases
Lung cancer
Birth-related problems
Three categories of impact on human
health:



Chronic: gradual deterioration over a
period of time.
Acute: life-threatening reactions
within a matter of hours or days.
Carcinogenic: pollutants initiate
changes in cells that lead to
uncontrolled growth and division
(cancer).
Disaster Risk Reduction:
The publication of Living with Risk: A Global
Review of Disaster Reduction Initiatives (2004)
by the Inter-agency Secretariat of the
International Strategy for Disaster Reduction
The UN World Conference on Disaster
Reduction (January 2005) by 168 country
delegates who met in Kobe, Japan.
1.
2.

Created the Hyogo Framework for Action
Hyogo Framework for Action
1.
2.
3.
4.
5.
Make disaster risk reduction a
priority.
Know the risks and take action.
Build understanding and awareness.
Reduce risk.
Be prepared and ready to act.
Lesson 15.3
Risk Assessment
Governmental Stewards

If governments are to be stewards of
the health of their people, they need
the kind of information a thorough
evaluation of health risk can bring
them.
Risk Assessment

The process of evaluating the
risks associated with a
particular hazard before taking
some action in which the
particular hazard is present.
The Truth

Most people do not make choices
based upon risk assessment.


They make them based upon
familiarity, control, etc.
Risk assessment is an important
process in the development of public
policy

Major way of applying sound science to
the problems of environmental
regulation according to the WHO.
Risk assessment


Began in the mid-1970’s by the EPA
as a way of addressing the cancer risks
associated with pesticides and toxic
chemicals.
There are four steps associated with
the process (updated in 2005).
Risk Analysis
 4 steps to EPA’s risk analysis.




Hazard assessment (Linking hazard to its
effects)
Dose-response assessment (how much,
how severe)
Exposure assessment (how long)
Risk characterization (putting it all
together to decide the risk and its
accompanying uncertainties)
Risk Management

Usually involves:
 Cost-benefit analysis
 Risk-benefit analysis
 Public preferences
Risk Perception: Hazard vs. Outrage


Hazard expresses primarily a concern
for fatalities while outrage expresses a
number of additional concerns.
Outrage includes:







Lack of familiarity
Extent to which the risk if voluntary
Media attention
Lack of trust in scientists and industry
Morality
Control
Fairness
Hazard Assessment


Process of examining evidence linking
a potential hazard to its harmful
effects.
Sometimes the link is not so clear.


Time delay between the incident and its
effect.
In the end hazards assessment tells us
we may have a problem.
Animal Testing:

Several hundred animals (usually mice). Takes 3
years. Costs $250,000.


If a significant number of animals develop tumors,
then the substance is listed as a possible human
carcinogen.
Objections:



Rodents and humans may have very different responses.
The dose difference in the animals vs. the human.
Ethics.
Dose-response and exposure


Dose-response: the concentration of
the chemical with respect to the
severity of the response. At this point
vulnerability may then be introduced.
Exposure: Identifying humans already
exposed to the chemical, how they
became exposed and calculating the
dose and length of time.
Risk characterization:


Pulls together the first three steps (risk
assessment, hazard assessment, and
dose-response exposure assessment)
in order to determine the risk and its
accompanying uncertainty.
The limit: analysts must work with the
available information, which never
seems sufficient.
World Health Report


WHO, 2002.
Looked at the following criteria with
respect to risk assessment:




Potential global impact.
High likelihood of casualty.
Modifiability.
Availability of data.
DALY



Data must be assessed with a common
“currency”.
Disability adjust life year
Represents the loss of one healthy
year of a person’s life.
Risk Assessment/Management
 Some suggest we use distributive
justice in making decisions about
risk
 Ethical process of making
certain that everyone receives
proper consideration
 Should reduce environmental
racism/injustice
Risk Assessment/Management
Not a perfect system
 Precautionary principle
 Lack of certainty should not
be used as a reason for
preventing environmental
degradation/hazards
