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Environmental Hazard and Risk
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
I. Into to Environmental Hazards
A. Environmental health = assesses environmental factors
that influence human health and quality of life
- Natural and human-caused factors are both considered
B. There are 4 types of environmental hazards –
physical hazards, chemical hazards, cultural hazards,
and biological hazards
- We can reduce risk by better environmental choices
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
I. Into to Environmental Hazards
C. Physical hazards = occur naturally in our environment
1. Earthquakes, volcanoes, fires, floods, droughts,
exposure to UV radiation
2. We can’t prevent them, but we can prepare for them
3. We increase our vulnerability by deforesting slopes
(landslides), channelizing rivers (flooding), etc.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
I. Into to Environmental Hazards
D. Chemical Hazards = synthetic chemicals such as
pesticides, disinfectants, pharmaceuticals
1. Harmful natural chemicals also exist
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
I. Into to Environmental Hazards
E. Biological Hazards = result from ecological interactions
1. Viruses, bacteria, and other pathogens
2. Infectious (communicable, or transmissible) disease
= other species parasitize humans, fulfilling their
ecological roles
- We can’t avoid risk, but we can reduce the likelihood
of infection
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
I. Into to Environmental Hazards
F. Cultural Environmental Hazards= result from the
place we live, our socioeconomic status, our occupation,
our behavioral choices
- Smoking, drug use, diet and nutrition, crime, mode of
transportation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Smoking = Bad
2009 – 20% of Americans smoke
1965 – 42% of Americans smoke
It is the leading cause of preventable death in America,
killing 443,000 Americans each year.
No Don,
No! Don’t
light it!
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
II. Biological Hazards
A. Disease is a major focus of
environmental health
B. Despite our technology, disease
kills most of us
C. Disease has a genetic and
environmental basis
1. Cancer, heart disease,
respiratory disorders
2. Poverty and poor hygiene can
foster illnesses
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
II. Biological Hazards
D. Infectious diseases kill 15
million people per year
1. Half of all deaths in
developing countries
2. Developed countries
have better hygiene,
access to medicine, and
money
E. Vector = an organism that
transfers pathogens to a
host
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Leading Causes of Death World-Wide
1. Cardiovascular disease (29%)
2. Infectious disease (26%)
3. Cancer (13%)
Leading Causes of Death in U.S.A.
1. Cardiovascular disease (25.4%)
2. Cancer (23%)
3. Stroke (5.6%) / Chronic Lower Resp. Disease (5.3%)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
II. Biological Hazards
F. Many diseases are increasing, such
as tuberculosis, acquired
immunodeficiency syndrome
(AIDS), and the West Nile virus
G. Our mobility spreads diseases
H. Diseases are evolving resistance to
antibiotics
I. Climate change will expand the
range of diseases
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
III. Chemical Hazards
A. Toxicology = the study of the effects of poisonous
substances on humans and other organisms
B. Toxicity = the degree of harm a toxicant can cause
1. “The dose makes the poison” = toxicity depends on
the combined effect of the chemical and its quantity
2. Analogous to pathogenicity or virulence = the degree
of harm of biological hazards that spread disease
C. Toxicant = any toxic agent
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
III. Chemical Hazards
D. Environmental Toxicology - Deals with toxic substances
that come from or are discharged into the environment
E. Studies the health effects on humans, other animals, and
ecosystems
1. Focus mainly on humans, using other animals as test
subjects
2. Can serve as indicators of health threats
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
III. Chemical Hazards
F. The environment contains
countless natural chemicals that
may pose health risks
G. But, synthetic chemicals are also
in our environment
- Every human carries traces of
industrial chemicals
80% of U.S. streams contain at least trace amounts of 83
wastewater contaminants
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
III. Chemical Hazards
H. Very few chemicals have been thoroughly tested
I. 100,000 chemicals are on the market today
- 72,000 industrial
- 8,700 food additives
- 2,000 new chemicals introduced per year
J. We don’t know the effects, if any, most have
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
K. Rachel Carson published Silent Spring in 1962, which began
public debate over chemicals
1. Brought together studies to show DDT risks to people,
wildlife, and ecosystems
2. In the 1960s, pesticides were mostly untested and were
sprayed over public areas, assuming they would do no
harm
3. The book generated significant social change
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
A. Toxins may concentrate in water
1. Runoff carries toxins from large land areas to small
volumes of surface water
2. Chemicals can leach into the soil
3. Chemicals enter organisms through drinking or
absorption
- Aquatic organisms are effective pollution indicators
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
B. Airborne toxicants travel
widely - Because chemicals
can travel by air, their effects
can occur far from the site of
chemical use
C. Pesticide drift = airborne
transport of pesticides
D. Synthetic chemical
contaminants are found
globally
- They appear in arctic polar
bears, Antarctic penguins,
and people living in
Greenland
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
E. Toxins can degrade quickly and become harmless, or
they may remain unaltered and persist for decades
1. Rates of degradation depends on temperature,
moisture, and sun exposure
F. Persistent chemicals have the greatest potential for harm
G. Breakdown products = toxicants degrade into simpler
products
1. May be more or less harmful than the original
substance
2. DDT degrades into DDE, which is also highly
persistent
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
H. Some toxicants can be
excreted or metabolized
- Fat-soluble toxicants are
stored in fatty tissues
• 1. Bioaccumulation =
toxicants build up in animal
tissues
• 2. Biomagnification =
toxicants concentrate in top
predators
- Near extinction of peregrine
falcons and brown pelicans
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
IV. Routes of chemical transport
I. Chemical toxicants also exist naturally and in our food
- Don’t assume natural chemicals are all healthy and
synthetic ones are all harmful
J. Some scientists feel that natural toxicants dwarf our
intake of synthetic chemicals
1. Natural defenses against toxins are effective against
synthetic ones, too
2. Critics say natural toxins are more readily metabolized
and excreted, and synthetic chemicals persist and
accumulate
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
A. Environmental Risk Assessment involves understanding
the potential for harm to people, organisms, and the
greater environment posed by different hazards.
B. Hazard, Exposure, and Risk are three terms used
frequently, and these terms mean different, noninterchangeable things
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
C. Hazard = is the inherent potential for something to cause
harm. Hazards range from minimal to deadly in terms
of human injury, or from minimal to catastrophic
damage to the environment, or a specific component of
the environment (water, air, etc.)
D. When thinking about overall risk, determining the
severity of the hazard is important.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
E. Exposure = What is the probability of being exposed to
the risk? Can be based on occurrence (I only fly twice a
year vs. drive times a day) or number of individuals (only
100 people of a city of 1 million live within a mile of the
chemical plant)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
F. Risk = The likelihood that the hazard will actually
happen and cause harm. How probable is it that the
hazard will actually happen?
Risk = hazard x exposure
(so how dangerous something is times the likelihood of
actually being exposed to it, or the level or time of
exposure)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
G. Evaluating Environmental Risk by regulatory agencies or
companies involves three steps:
1. Risk Assessment – What are the hazards? What is the
toxicity and extent of exposure?
2. Risk Acceptance – What is the acceptable level of risk
(based on social/economic/political considerations)
3. Risk Management – Determine policy with input from
citizens, industry, and interest groups.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
H. Risk Assessment
1. Risk assessment seeks to identify a potential hazard and
determine the magnitude of the potential harm.
2. MANY companies, organizations do risk assessment
3. Developed nations have federal agencies to manage risk
- The U.S. has the Centers for Disease Control (CDC),
the EPA, and the Food and Drug Administration
(FDA)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
Question 1: Which is riskier, driving 25 miles a day or
flying 1,000 miles per year?
Risks: 1.3 deaths per 100,000,000 miles for driving
1.9 deaths per 100,000,000 miles for flying
Question 2: Use the Risk Assessment Matrix, and
determine the level of risk for the following 2 scenarios:
1. Students getting injured using 12 M HCl
2. Students getting injured using 1 M HCl
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
V. Risk analysis
I. We try to minimize risk, but
we often misperceive it
- Flying versus driving
J. We feel more at risk when we
cannot control a situation
- We fear nuclear power
and toxic waste, but not
smoking or overeating
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
K. Risk Acceptance
1. Most difficult in the risk- analysis process
2. EPA lists a 1 in 1 million risk as acceptable for most
environmental hazards.
3. Scientific assessments are considered with economic,
social, and political needs and values
4. Comparing costs and benefits is hard
a. Benefits are economic and easy to calculate
b. Health risks (costs) are hard-to-measure
probabilities of a few people being affected
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
L. Risk Management
1. Risk management is the policy put in place that is
determined from the research as well as economic
factors.
2. All levels of pollutant contaminants (air, water,
toxins) that are set nationally and internationally are a
result of implementing risk management.
3. Most companies have risk management plans in place.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
M. Federal Risk Management
M. Federal agencies apportion responsibility for tracking and
regulating synthetic chemicals
1. FDA: food, food additives, cosmetics, drugs, and medical
devices
2. EPA: pesticides
3. Occupational Safety and Health Administration (OSHA):
workplace hazards
O. Many public health and environmental advocates fear it isn’t
enough
1. Many synthetic chemicals are not actually tested
2. Only 10% have been tested for toxicity
3. Fewer than 1% are government regulated
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
N. One approach to determining safety
1. Innocent until proven guilty approach: generally
assumes products/chemicals are safe unless
demonstrated negative event occurs
- Benefits: not slowing down technological
innovation and economic advancement
- Disadvantage: putting into wide use some
substances that may later on turn out to be
dangerous, big recalls
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
O. Precautionary principle approach: General
assumption that chemicals/products are inherently
dangerous, must prove safe before released on the
market
1. Far fewer recalls
2. Identifies troublesome toxicants before they are
released
3. But, this may impede the pace of technology and
economic advance
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
P. Philosophy affects policy
Different nations use different policies; most use a mix
between the “innocent until proven guilty” principle
and the precautionary principle
- Europe is shifting more towards the precautionary
principle
- Industries like the “innocent until proven guilty”
approach because it allows them to produce more
and make more money
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Two approaches for determining safety
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings