Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 1/9)
Character Range: 920408–923463

3                   Data collection and data evaluation

3.1              Data collection
Data collection entails the acquisition and analysis of information about contaminants at a site that may affect human health and which will be the focus of the risk assessment. The purpose of data collection is to gather data that will improve the CSM and hence enable a more site-specific assessment of risk to be made. Data will relate to not only contaminants (that is, the source) but the physical environment in which they are present (that is, the pathways of exposure). In some instances, it may also be appropriate to gather additional information about the potential exposed populations.

It is recommended that a systematic planning process is used for defining the objectives of a site risk assessment and to develop a sampling plan for the collection and evaluation of representative data to achieve those objectives. The elements of the data collection stage are described in more detail in Schedule B2, including the data quality objective process and the preparation of a sampling and analysis quality plan. The general requirements for data collection in site investigation apply equally to data collected for the purpose of risk assessment. There are a number of issues in data collection that are specific to health risk assessment, which are discussed below.

3.2              Source variables
There are a number of variables commonly required for health risk modelling, which can be measured on a site-specific basis. Site-specific data is preferable to the use of literature or model default values, because environmental variables may have large ranges. Choosing a worst-case value to account for uncertainty adds conservatism to the risk assessment. Consistent selection of worst-case values results in compounding of the conservatism and can result in unrealistic modelled outcomes. Getting site-specific data permits use of realistic values and provides more confidence in the risk assessment outcome.

    3.2.1          Organic speciation
Several organic compounds are commonly analysed as groups of substances, for example, petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and phenols. Such tests may be useful for providing cost-effective estimates of the quantity of contaminant present, but are problematic in risk assessment because toxicity data is generally only available for specific substances. For certain complex mixtures commonly found on contaminated sites (e.g. petroleum hydrocarbons (as discussed in Section 4.8.3), PAHs and PCBs as discussed in Schedule B7, Appendix A2) there are established ways of mitigating this problem, which provide the preferred way of assessing these mixtures. On sites where the contamination can be fully defined by reference to individual specific substances (for which toxicity data is available), it is preferable to assess these specific substances.

Chemical analyses providing detailed breakdowns for groups of organic compounds into individual substances (e.g. PAH), or