Risk assessment of chemicals: assessment of exposure from all sources
Last update 17 August 2017
The prime aim of the Industrial Chemicals (Notification and Assessment) Act 1989 is to provide a national system of notification and assessment of industrial chemicals to protect the Australian people and the environment by establishing the risks that could be associated with importing, manufacturing or using industrial chemicals.
We assess the risks to occupational health and safety, public health and the environment from industrial chemicals by using well established, internationally accepted methodology (International Programme on Chemical Safety, 1999; European Commission, 2003).
Department of Health officers carry out occupational health and safety and public health assessments. Department of the Environment officers conduct environmental assessments for NICNAS under a service agreement.
The type and degree of risk assessment varies depending on the type of new chemical notification (that is, certificate or permit) or existing chemical assessment product. Most assessments cover some or all of these elements:
- hazard identification
- hazard assessment, incorporating the dose-response relationship
- exposure assessment
- risk characterisation, where hazard and exposure assessments are integrated.
For some chemicals declared as Priority Existing Chemicals (PECs), because of specific concerns about their potential effects on health and environment, assessments may be limited to a hazard and/or exposure assessment.
Assessments are conducted case-by-case and are based on a weight-of-evidence approach, taking into account scientific judgement, knowledge of the mechanism of action of effects, and recognition of the inherent uncertainty in extrapolating animal data to humans.
With risk assessments, recommendations are formulated to manage risk, taking into account existing risk management strategies.
Hazard assessment establishes the toxicity of a chemical and identifies the set of inherent properties that makes it capable of causing adverse effects. It identifies the types of hazards that might occur in acute or repeated exposure situations through different exposure routes.
A major variable in risk characterisation is estimating exposure—identifying the extent of exposure to a particular chemical, and determining the frequency and duration of that exposure and all the routes by which exposure occurs over the chemical's lifecycle.
For most chemicals, establishing exposure is probably the most variable aspect of risk assessment. It reflects various contributing factors such as differing and/or unique exposure and use patterns of chemicals across a range of industrial uses, the unique nature of ecosystems, fauna and flora, and differing methodologies for exposure assessment.
The exposure assessment is a critical element of the risk assessment and can comprise direct exposure (for example, workers carrying out manufacture or consumer use of household products), and indirect exposure through the environment (for example, through drinking water).
The assessment of direct and indirect exposures to a chemical is important for determining risk, particularly for public health and environmental aspects where exposure may arise from several sources—the raw chemical itself, a preparation or mixture, finished goods containing the chemical (such as treated fabrics and carpet) or contamination of the environment (for example, by lead and other chemicals in household dust and air).
Where exposure of the population to a chemical is likely or suspected (through biomonitoring data or known chemical properties such as leaching) the risk assessment is extended to include all sources of exposure.
The release of chemicals into the environment (for example, from leaching, exudation and/or surface abrasion) may occur at any time in the article's lifecycle, including through using, handling, disposing or storing.
Hence, NICNAS's risk assessment, while concentrating on regulating chemical use, may also consider the use of a chemical in the production of and release from a finished article.
Information about the possible release of a chemical from an article may therefore be required so we can fully assess risk.
Risk characterisation involves integrating hazard identification, hazard characterisation and exposure assessments.
Interpreting and integrating the information on hazard and exposure to estimate risk is complex and can involve determining what risk is acceptable and how risk should be managed.