Environmental risk assessment: An Australian perspective

Supervising Scientist Report 102
Beer T and Ziolkowski F
Supervising Scientist, 1995
ISSN 1325-1554
ISBN 0 6422 4301 8


Full report

Separate sections

Executive summary

Environmental risk

Environmental risk deals with the probability of an event causing a potentially undesirable effect. Quantitative risk assessment thus deals with statistics, because probability is the mathematical measure of risk, and with hazard assessment which determines the nature of the undesirable effect. The terms have different meanings and different definitions in different areas of study.

Over the past two decades, risk assessment has attained maturity as an engineering discipline assisted by seminal reports by the United States National Research Council and by the Royal Society in Britain. Environmental agencies, principally the US EPA, have embraced it as an objective tool to enable them to set standards, set priorities and provide assistance in decision making. It has long been applied in this way to evaluate the risks to human health arising from radionuclides and chemicals in the environment. Hazard assessment has been used to study natural hazards and assist in preparing for them. The recent application of risk assessment techniques to flora and fauna is being called ecological risk analysis.

The US has a major program using risk assessment to determine environmental priorities at national, state, regional, community and tribal level. Its use in this form is called comparative risk assessment. It involves ranking issues on the basis of their likelihood of occurrence and the magnitude of the actual or perceived consequences.

The means by which risk is managed, the means by which risk is communicated to the public and the consequences of failing to undertake adequate risk assessment or undertaking incorrect risk assessments need to be known and appreciated by environmental practitioners. These issues are seen as an integral part of a quality assured environmental management system.

Methods and results

The approach adopted to the study was based on the following elements:

  1. Reviewing the literature, plus extensive consultation to determine Australian practice, and international best practice, in the application of quantitative risk assessment.
  2. Identifying areas that are of current concern to environmental protection and choosing appropriate case studies for each area.

    Each case study deals with an apparently contentious topic and the discussion of the case study seeks to determine whether the contentious aspects of the topic could have been minimised through application of quantitative risk assessment. The areas, identified by the Executive Director of the EPA, and case studies are:

    Risk from chemicals and from contaminated sites: Case study - atrazine

    Field trials on their own fail to provide definitive answers to the behaviour of chemicals. They must be integrated with computer modelling, with the results of the field trials being used to calibrate and validate the model. The model provides a predictive tool in situations other than those of the field trial. There is a reluctance to undertake such integrated studies because no model has received official accreditation. This should be done.

    Risk to people from development: Case study - Sydney 3rd runway

    This case study identified deficiencies in the standard methods of measuring the impacts of noise.

    Risk to the natural environment from development: Case study - setting priorities to investigate uranium mining.

    The techniques of comparative risk assessment were used to propose topics for the next four environmental performance reviews to be conducted by the Office of the Supervising Scientist.

    Risks of the uncertainty of nature: Case study - climate change

    Present work on climate change is driven by the implicit risk assessment expressed in the precautionary principle. This envisages large adverse consequences as a result of inaction in the face of a possible hazard.

    Risk associated with political decision-making: Case study - Coronation Hill

    The Coronation Hill saga highlights the importance of timing. The combination of environmental issues, Aboriginal issues, the timing of elections and leadership disputes led to the failure of the proposal to mine and concern about sovereign risk as an issue in Australian environmental concerns. Time heals. Sovereign risk is no longer perceived to be a risk for miners in Australia.
  3. The search for a generic framework 'that can be used for quantitative risk assessment in Australia'.

    The final choice of generic framework is shown in Figure 1. When the formal methodology of the framework was applied to the question of release of water from the restricted release zone of the Ranger Uranium Mine, the result confirmed that long term land disposal has a 90% probability of exceeding recommended radiation dosages for Aboriginal people living traditional life-styles in the area of land disposal. More significantly, the methodology highlighted that previous research and this analysis all assumed perfect knowledge of the future behaviour of the traditional owners. The fact that this is not known indicates that the Environmental Research Institute of the Supervising Scientist (ERISS) should widen its research to include Aboriginal lifestyles and culture.


Risk assessment is a tool for informed decision making. The decision facing Australian Environmental agencies is whether to introduce a process of formalised risk assessment; and if so, how should it be done and what should be its scope. Any agency that deals with risk assessment needs to be able to deal not only with matters referred to it, but also to have the freedom to identify issues that may pose future risks. This document is the first step in this process.

The next step will be a conference on risk and uncertainty in environmental management. This conference, designated a Fenner Conference by the Academy of Science, will be held 13-16 November 1995. The final day of the conference will consist of a workshop at which it is intended to undertake a risk-benefit analysis of introducing risk assessment. It is anticipated that the costs are quantifiable, once the scope of the process has been determined.

The important benefits are expected to be:

  • transparency of process;
  • informed decision making; and
  • input to priority setting.

Thus, one purpose of a conference such as this is to decide whether the value of these benefits are likely to exceed the costs of implementation.

The generic framework provides a model for accomplishing the technical aspects of risk assessment.

Application of a quantitative risk assessment requires capabilities in four primary areas:

  1. a systems analysis capability that can be used for scenario development;
  2. technical expertise that can be used to quantify hazards;
  3. statistical skills, possibly in conjunction with computer modelling expertise, that can be applied to uncertainty analysis as, for example, in probabilistic modelling; and
  4. expertise that can be used to quantify the costs or benefits associated with assessing priorities.

In most cases, quantitative risk assessment will involve the use of computers and the need to obtain or develop appropriate software. There is probably not enough work within one section of the Department to keep risk analysts employed but there should be enough work across the whole of DEST to do so. Examples from within the EPA include chemicals, contaminated sites, EIA reviews, cumulative impacts, urban air quality and Northern Territory concerns.