Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 2/6)
Character Range: 2901416–2904329

necessarily imply acceptability or that a health risk is not likely to be present, particularly if more sensitive populations[1] are present or the assumptions for land use scenarios are not appropriate.

The HILs are designed to be used to define the contaminants that require a more detailed (Tier 2) risk assessment. The tiered process of health risk assessment into which the HILs fit is described in detail in Schedule B4.

The HILs have been designed to be protective of the health of most people who could potentially be exposed to soil contaminants under four broad land use categories. For people within sensitive populations; for example, the immunosuppressed, those with pre-existing illness, or those with pica behaviour, the HILs may not be sufficiently protective of health. These issues would need to be addressed in a site-specific assessment.

The HILs have been developed under four broad land use categories (discussed in detail in Section 3). To estimate potential human exposure to soil contaminants within each of these land use categories, generic assumptions have been made about the environment, human behaviour, the physicochemical characteristics of contaminants, and the fate and transport of contaminants in soil (refer to Sections 3 and 4). The HILs have been derived by comparing estimated exposures with toxicity criteria using a quantitative modelling process. The toxicity criteria for all of the contaminants addressed in this guidance are outlined in the toxicity profiles included in Appendix A.

As indicated above, the HILs are not intended to be used as clean-up levels for contaminated sites. The decision on whether clean-up is required and, if so, to what extent, should be based on site-specific assessment and risk management options. Health risk assessment is one aspect of making the decision, with other considerations such as practicality, timescale, effectiveness and cost also being important.

1.3              Interpretation and use of the HILs

    1.3.1         Limitations on the use of the HILs
The information in this Schedule is designed to assist risk assessors in the application of HILs to assess the potential risks posed to human health by soil contaminants, in a preliminary site assessment. Critical to this judgement is whether the conceptual site model (CSM) used to describe any of the generic land use categories is representative of the site in question.

The CSM for some sites may identify other potential risks from site contamination that are not covered by the HILs, including:
    * additional sources of contamination, for example, in groundwater or surface water
    * short-term acute health risks, such as explosive or asphyxiation risks associated with the build-up of gases in a confined space, or the skin irritation risk associated with direct dermal contact with some soil contaminants
    * leaching of soil contamination into