Environmental Engineering Reference
In-Depth Information
The dose makes the poison.
P
ARACELSUS
, 1540
Risk Assessment
Hazard identification
What is the hazard?
Risk Management
Comparative risk analysis
How does it compare
with other risks?
In this chapter you will learn the risks of harm from
disease and chemicals, how such risks are determined,
and how well we perceive risks. It addresses the fol-
lowing questions:
Risk reduction
How much should
it be reduced?
Probability of risk
How likely is the
event?
What types of hazards do people face?
■
Risk reduction strategy
How will the risk
be reduced?
What types of disease (biological hazards)
threaten people in developing countries and devel-
oped countries?
■
What chemical hazards do people face, and how
can they be measured?
Consequences of risk
What is the likely
damage?
Financial commitment
How much money
should be spent?
■
How can risks be estimated and perceived?
■
Figure 14-2
Science
:
Risk assessment
and
risk management.
KEY IDEAS
■
Rapidly producing infectious bacteria can undergo
natural selection and become genetically resistant to
widely used antibiotics.
■
In terms of deaths caused, the three most serious
hazards are poverty/malnutrition, smoking, and
pneumonia/flu and the three most serious infectious
diseases are AIDS, malaria, and diarrhea.
■
It is difficult and costly to determine the risk of harm
from chemicals.
■
Most of us have a distorted view of the risks we
face.
Risk assessment
is the scientific process of esti-
mating how much harm a particular hazard can cause
to human health.
Risk management
involves deciding
whether or how to reduce a particular risk to a certain
level and at what cost. Figure 14-2 summarizes how
risks are assessed and managed.
Science: Types of Hazards
We can suffer harm from cultural hazards,
biological hazards, chemical hazards, and physical
hazards, but determining the risks involved is
difficult.
We can suffer harm from four major types of hazards:
■
Cultural hazards
such as smoking, unsafe working
conditions, poor diet, drugs, drinking, driving, crimi-
nal assault, unsafe sex, and poverty
■
Biological hazards
from pathogens (bacteria, viruses,
and parasites) that cause infectious disease
■
Chemical hazards
from harmful chemicals in the air,
water, soil, and food
■
Physical hazards
such as a fire, earthquake, volcanic
eruption, flood, tornado, and hurricane
14-1
RISKS AND HAZARDS
Science: Risk and Risk Assessment
Risk is a measure of the likelihood that you will suffer
harm from a hazard.
Risk
is the
possibility
of suffering harm from a hazard
that can cause injury, disease, death, economic loss, or
environmental damage. It is usually expressed in
terms of
probability:
a mathematical statement about
how likely it is to suffer harm from a hazard. Scientists
often state probability in terms such as “The lifetime
probability of developing lung cancer from smoking a
pack of cigarettes per day is 1 in 250.” This means that
1 of every 250 people who smoke a pack of cigarettes
per day will develop lung cancer over a typical life-
time (usually considered 70 years).
It is important to distinguish between
possibility
and
probability.
When we say that it is
possible
that a
smoker can get lung cancer, we are saying that this
event could happen.
Probability
gives us an estimate of
the likelihood of such an event.
14-2 BIOLOGICAL HAZARDS: DISEASE
IN DEVELOPED AND DEVELOPING
COUNTRIES
Science: Nontransmissible
and Transmissible Diseases
Diseases not caused by living organisms do not
spread from one person to another, while those
caused by living organisms such as bacteria and
viruses can spread from person to person.
