Page 145 - Materials Chemistry, Second Edition

L1644_C04.fm Page 120 Tuesday, October 21, 2003 3:13 PM

because these do not normally connote a lethal injury and their severity seems to
be within an individual’s control. Death and injury from attack by strangers is widely
feared as a high risk because of the apparent frequency of such occurrences as
reported by the news media. Risk implies not only some adverse result, but also
uncertainty. Risk changes as information becomes more specific — a golfer has
greater risk of death by lightning than the population as a whole, whether this is
perceived as likely or not. The risk from an injury at home or being struck by
lightning can be calculated because these events actually happen. In contrast, assess-
ment of risk attributable to low levels of environmental contaminants is an uncer-
tainty exercise.
People use the term risk in everyday language to mean “chance of disaster.”
When used in the process of risk assessment it has specific definitions; the most
commonly accepted is “the combination of the probability, or frequency, of occur-
rence of a defined hazard and the magnitude of the consequence of the occurrence”
(Royal Society, 1992). On the other hand, hazard can be defined as “the potential
to cause harm” and also as “a property or situation that in particular circumstances
could lead to harm” (Royal Society, 1992).
The risk assessment is applied in a wide range of professions and academic
subjects. Engineers “risk assess” bridges to determine the probability and effect of
failure of components; social welfare workers “risk assess” their clients to evaluate
the likelihood of the recurrence of antisocial behavior. Risk assessment has become
a commonly used approach in examining environmental problems. It is used to
examine risks of very different natures.
Environmental contamination problems are complex issues with worldwide
implications. Risks to human and ecological health as a result of toxic materials or
their introduction into the environment are a matter of great interest to modern
society. The effective management of environmental contamination problems has
therefore become an important environmental aim that will remain a growing social
issue for the next years.
The foundations for risk assessment methodologies have traditionally been based
on the examination of effects to human health, but much more emphasis is now
placed on all types of environmental damage. In comparison to human health risk
assessment, which is a relatively new field, risk assessment for ecological effects is
very much in its infancy and the field is constantly developing.
ERA consists of evaluating the probability that adverse effects on the environ-
ment or human health occur or may occur as a consequence of exposure to physical,
chemical or biological agents. Evaluation of environmental risk requires knowledge
of adverse effects that might be caused by exposure to chemical substances or
materials, as well as of the intensity and duration necessary to produce adverse
effects on the environment, including the population.
Risk assessment is a tool used to organize, structure and compile scientific
information in order to help identify existing hazardous situations, anticipate
potential problems, establish priorities and provide a basis for regulatory controls
and/or corrective actions. It can also be used to determine and measure the
effectiveness of corrective measures or remedial actions. A key underlying prin-
ciple of risk assessment is that some risks are tolerable — a reasonable and even

© 2004 CRC Press LLC