ENVIRONMENTAL RISK ASSESSMENT (ERA)
A. Introduction - In order to
understand what is meant by environmental risk assessment it is important to be
familiar with the concepts of hazard and risk. These terms have different
meanings and are not interchangeable. The following definitions are used here.
*
Hazard is the inherent potential
for something to cause harm. Hazards can include substances, machines, energy
forms, or the way work is carried out.
*
Risk is the likelihood that harm
will actually be done by the realisation of the hazard during the work being
carried out or by the way something is used.
Risk = Hazard × Exposure.
In general, the term environmental
covers the physical surroundings that are common to everybody including air,
water, land, plants and wildlife. Thus environmental risk assessment covers the
risk to all ecosystems, including humans, exposed via, or impacted via, these
media. The term environmental risk assessment does not normally cover the risks
to individuals or the general public at large from consumer products or from
exposure in the work place, where other specific legislation applies.
In other words, environmental risk
assessment (ERA) involves the examination of risks resulting from natural
events (flooding, extreme weather events, etc.), technology, practices,
processes, products, agents (chemical, biological, radiological, etc.) and
industrial activities that may pose threats to ecosystems, animals and people.
Environmental health risk assessment addresses human health concerns and
ecological risk assessment addresses environmental media and organisms.
ERA is predominantly a scientific
activity and involves a critical review of available data for the purpose of
identifying and possibly quantifying the risks associated with a potential
threat.
B. Rationality of ERA –
Identification of an emerging issue or priority for further action can result
in a demand for ERA to determine whether an initial indication of a problem is
valid or not. ERA provides the basis for most legislative and regulatory
programs as well as for international agreements to address identified threats.
While approaches vary significantly from one situation to another, and from one
jurisdiction to another, international organizations are making efforts to
bring some commonality to the approaches used.
If a threat to human health or the
environment is identified through ERA, risk management is performed to consider
the need to impose measures to control or manage the risk. While science
remains an important factor at this third stage, other key factors must also be
considered such as: socio-economic considerations; the availability of
alternative technology, products, practices, processes, etc.; international
comparisons and impacts; and communication and consultation with the public and
stakeholders that will be affected by proposed changes.
In fact, the concept of risk
management recognised the importance of an “effects-oriented approach” (e.g.,
environmental quality standards and effects standards) in addition to a
“source-orientated approach” (e.g., emission standards based on the best
available techniques not entailing excessive cost). The risk management policy
sets out criteria for judging risks of technological hazards based on the
following concepts:
* That a maximum acceptable level of risk can be identified which
should not be exceeded irrespective of the economic or social benefit that
could result from the activity under consideration.
* That a negligible risk level can be identified at which it not
sensible to try to reduce the risk further.
* That between these two levels the risk should be reduced to as
low as is reasonably practicable.
The risk criteria deriving from
such a policy are laid out explicitly in ‘Premises for Risk Management’ which
is part of any ‘National Environmental Plan’ of a nation.
C. Stages in carrying out an
environmental risk assessment – Environmental risk assessment can be thought of
as containing the following key stages.
1.
Hazard identification. This would
typically include identification of the property or situation that could lead
to harm. This step is sometimes also known as problem formulation.
2.
Identification of consequences if
the hazard was to occur. This step is sometimes also known as hazard
identification.
3.
Estimation of the magnitude of the
consequences. This can include consideration of the spatial and temporal scale
of the consequences and the time to onset of the consequences. When considering
chemicals, this step can sometimes be termed release assessment.
4.
Estimation of the probability of
the consequences. There are three components to this, the presence of the
hazard, the probability of the receptors being exposed to the hazard and the
probability of harm resulting from exposure to the hazard. This step can
sometimes be called exposure assessment or consequence assessment.
5.
Evaluating the significance of a
risk (often termed risk characterisation or risk estimation) is the product of
the likelihood of the hazard being realised and the severity of the
consequences.
A concept frequently used in
environmental risk assessment is that of the source – pathway – receptor. In
this model the pathway between a hazard source (for example a source of
contamination) and a receptor (for example a particular ecosystem) is
investigated. The pathway is the linkage by which the receptor could come into
contact with the source (a number of pathways often need to be considered). If
no pathway exists then no risk exists. If a pathway exists linking the source
to the receptor then the consequences of this is determined.
D. Uses of environmental risk
assessment – There are a wide range of uses of environmental risk assessment
and, although the specific methodology and the responsibility for carrying out
the assessment may vary, the core principles and the key stages of the process
are fundamentally the same in each case. ERA can be used in a number of ways:
*
Prioritization of Risks — When an
organization is faced with a number of potential environmental risks, ERA can
be used to establish their relative importance, and thus provides a basis for
prioritizing which risks should be dealt with first.
*
Site-specific Risk Evaluation —
ERA can be used to determine the risk associated with locating facilities in
specific locations or to determine the risks that affect a particular site
(e.g., environmental site assessment).
*
Comparative Risk Assessment — ERA
is used to compare the relative risks of more than one course of action (e.g.,
what are the risks posed by untreated water versus the risks posed by chemicals
used to treat water).
*
Quantification of Risks — ERA may
be taken to a level where the risks are quantified in order to establish
controls on the risks (e.g., maximum acceptable concentrations for chemicals in
ambient or drinking waters).
E. Guidelines for conducting ERA -
There are many approaches to conducting ERA. An overall framework developed by
the Canadian Standards Association for conducting ERA is shown below. This
framework highlights the importance of risk communication, in which
stakeholders are involved throughout the process, from identification and
priority setting, to ERA, to risk management, to monitoring and evaluation of
the implemented measures.
risk_management_frameworkF. ERA is
Used by followings –
*
Industry — Industry employs ERA to
satisfy regulatory requirements, to make decisions on the use of substances and
processes, and to locate facilities and operations based on the risks to human
health and the environment. The resource extraction sector (mining, oil and
gas) and the chemical manufacturing sector are regular users of ERA tools as
these provide mechanisms for assessing the risk of environmental damage and
implementing risk management or avoidance strategies.
*
Government — Government bodies use
ERA to implement, or determine the need for, legislation, regulations or other
controls to protect human health and/or the environment.
*
Finance — Financial organizations
such as banks, investment firms and insurance firms, use ERA to define the
financial risk associated with the environmental risks of potential
investments. This information is included in the decision making process for
the approval or rejection of loan and investment applications, and for setting
premiums, interest rates and projected returns. Environmental site assessment is
a common tool employed by the financial sector for assessing the environmental
management responsibilities and potential costs associated with ownership of a
given property.
*
Academia and NGOs — Universities
and NGOs conduct research on industrial and other human activities using ERA.
G. Conclusion – ERA is an
important tool for a number of reasons. For governments, it provides a method
for determining risks to the public and the environment, and the process is
communicated to the public to ensure transparency and understanding. The
concept is already incorporated into some legislation and is also applied
through policy and in developing new legislation.
ERA is also used in industry
beyond what is implemented through legislation, and it is used to make
decisions on materials, processes and facility siting. The process has several
advantages:
* identification of trade-offs when examining comparative risks;
* avoidance of liability; and,
* disclosing the financial costs associated with risks.
ERA is often made difficult by the
large degree of uncertainty that frequently accompanies the data. However, the
environmental risk assessment and management process offers a course of action
for making the best decision possible with the data that is available.
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