Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:5:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 5 (pt 2/5)
Character Range: 1193863–1196861

important to reconsider the objectives that were used for the Preliminary ERA, taking into account the results of the Preliminary ERA. If appropriate, new objectives should be identified.
The main objectives for a Definitive ERA should be to:
    * identify contaminants of concern (including mixtures and contaminant form, such as metal valency state, e.g. As3+)
    * produce clearly defined quantitative predictions regarding the current and future risks to site-specific ecological values due to contaminants at the site
    * determine site-specific EILs that take into account the ecological values at the site.
The objectives of this stage may need to be revised from time to time and should always be informed by the outcomes of the preliminary ERA.

5.2              Receptor identification
In a Definitive ERA, a biological survey of the site and surrounding areas that may be affected by off-site migration of the contaminants of concern (and/or public consultation on both areas) may be conducted. The objective of this is to identify the key ecosystems, processes and species that may be adversely affected by the contamination. Assumptions made linking site ecological values to receptors should be documented in the ERA report. If any ecological values that were identified are not to be protected then the basis of this decision should also be reported.

5.3              Exposure assessment
Advanced models may be used to describe present and future transport, transformation and environmental partitioning of the contaminants of concern. These models will need to be refined and calibrated using actual field data to enhance the level of assurance of the model predictions. Such fate and transport models should examine the partitioning of the contaminants of concern between the environmental compartments (for example, water, soil, sediment, biota and air) that are relevant for the site and areas that may receive off-site migration.

In addition to transport models, specific information regarding food, soil, water, ingestion rates and inhalation rates may be estimated from site-specific field data, providing a specific exposure assessment for each biota.

The sampling and analysis of other environmental media for contamination such as food, air and water supplies may also provide specific exposure information.

Other techniques of exposure assessment may include biopsy analysis of tissues, body fluids or excreta of biota from the site.

Detailed analysis of the uncertainty of the exposure assessment should also be conducted to define the boundaries of the risk posed by the uncertainty levels in the exposure assessment. Various statistical techniques are available to determine the level of uncertainty and also to identify the most sensitive exposure assessment parameters.

This may guide further studies and field activities to reduce the uncertainty.

5.4              Toxicity assessment
As part of the Definitive ERA, it may be useful to review the currency