Environmental Risk Assessment

Uses of ERA

ERA is needed in case of risk identification of an emerging issue or prioritization of further action. It has provided the basis for most legislative and regulatory programs as [Page 236]well as for international agreements and policy implications to address the associated threats. It is performed on a spectrum of environmental issues, such as hazardous waste clean-ups, permitting activities for water and air discharges, for land and water management, forests, watersheds, estuaries, and for establishing environmental quality standards and guidelines.

This technique is used in a wide range of professions such as industry sectors, finance sectors, private sectors, government bodies, nongovernmental organizations (NGOs), and academia to examine risks of very different natures. 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; it 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.
• Comparative Risk Assessment: ERA is used to compare the relative risks of more than one course of action, for example, 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, for example, maximum acceptable concentrations of chemicals in ambient or drinking waters.
• Qualitative Risk Assessment: ERA can be used to explain the risk qualitatively within any facility.
• Transportation Risk Assessment: ERA tools can be used to assess the risks associated with hazardous substances carried by various modes of transportation.

Overview of ERA Methods

ERA in general contexts consists of four integrated processes: (1) identifying underlying sources of risk; (2) determining the pathways by which such risks can materialize; (3) estimating the potential consequences of these risks under various scenarios; and (4) providing the means for mitigating and coping with these consequences.

Several procedures and a host of tools, software, and databases have been developed for ERA over the past half a century. The tools of mapping material and energy flows are essential diagnostic tools to indicate likely sources and magnitudes of emissions and wastes in key processes. The accepted conceptual structure for conducting ERA includes the following

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