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Risk Characterisation |
Tier 2 - Risk CharacterisationAt this tier, Risk Characterisation should involve at least some quantification of the potential risk to receptors from the contaminant/s of concern. You should relate the on-site contaminant concentrations to the modified criteria and decide on the likelihood of an adverse effect occurring. Depending on the level of data collection you have undertaken for the preceding tasks, it may be appropriate to determine population-level responses by sensitive species. Quotient or continuous exposure-response methods may be used to achieve this and a discussion of the use of these and other methods are provided in the resources.
As with Tier 1, the same questions are asked regarding the concentration of contaminants compared with the modified criteria established. Also, you should critically assess the quality and limitations of the supporting data and the appropriateness of the modified criteria. Tier 3 - Risk CharacterisationA Tier 3 Risk Characterisation should involve modelling of contaminants, exposure and toxicity to quantify and simulate current and future risks to populations, communities and/or ecosystems from contaminants. This may also include estimates of effects associated with a range of control options from no mitigation (i.e. no action) to maximum control (e.g. complete clean up). A discussion of the use of these and other methods are provided in the resources.
You may choose to relate the on-site contaminant levels to the criteria modified from the Tier 2 RA and decide on the likelihood of an adverse effect being generated, while taking into account the assumptions on which the criteria were derived and the background concentrations of contaminants. Again, a full assessment of the assumptions used in modelling exposure and developing modified acceptance criteria should be undertaken.
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