Health risk assessment

Health protection of public health lies at the heart of health risk assessment.

Human health risk assessment (HRA) is a process intended to estimate the risk to a population from exposure to a substance of concern. The process considers:

  • the type and composition of the substance
  • it's potential to harm
  • the way in which people may be exposed (such as through direct exposure, inhalation of air or food and water consumption)
  • how long people are exposed and how much they might be exposed to.

The quality of a health risk assessment is dependent on the accuracy of the information available on all these matters.

The process needs to consider all substances that people are exposed to and how they interact. A good quality HRA will also clearly identify any uncertainties, assumptions and limitations considered during the assessment process. High uncertainty is associated with more precautionary risk management.

When are health risk assessments used?

Health risk assessments are commonly used to assess impacts of various land uses and large scale work activities on existing or future planned communities. Development is going on all around us in WA. Some developments can put communities at risk and possibly cause ill health. These developments may include:

  • land use developments
  • industrial activities or
  • clean up of old commercial and industrial sites.

Purpose of health risk assessments

The Department of Health supports the use of a health risk assessment framework to help demonstrate whether a proposal or activity will adversely affect the health of the surrounding community.  It is usually based on the effect on a particular group of people rather than on individual impacts. A public health risk assessment does not consider work safety, unless specifically designed to do so, as these matters are normally considered separately based on the different exposure profile and separate legislation.

It requires a person to consider:

  • each aspect of their proposal or activity
  • the potential impact of chemical, biological, physical or social agents on a specified human population
  • to consider what could be done to ensure that the community is protected from the risks.

The Department of Health supports the health risk assessment framework endorsed by enHealth (external site) - Environmental Health Assessment: Guidelines for assessing human health risks from environmental  hazards 2012 (PDF 6.0MB).

Health risk assessment framework

The key steps include:

Hazard assessment

Examines whether a contaminant of concern has the potential to cause harm people, and if so, under what circumstances.  One or more contaminants of concern, including individual contaminants or mixtures, can be assessed in a single health risk assessment.

Exposure assessment

Examines what is known about the frequency, timing, levels and types of contact with a contaminant of concern.

Risk characterisation

Examines how well the data support the conclusions about the nature and extent of the risk from exposure to a contaminant of concern in a given population.

Risk management

A health risk assessment informs decision making for managing health risks.  Risk management may also consider other information, such as existing legislative requirements, government policy, available technologies and community and stakeholder expectations 


The following resources and models are available for use in Western Australia.


Scoping tools

Consultation guidelines

Produced by

Public Health