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Ecological Risk Assessment (ERA) is the evaluation of
risk posed to the environment and non-human inhabitants by a given condition.
Ecological Risk is used to quantify the likelihood and severity of adverse
environmental effects for the purposes of establishing site clean-up criteria,
developing risk management plans, evaluating historic, current or potential
future environmental impacts, or seeking regulatory approvals.
There is
a fundamental difference between a Human Health Risk Assessment and an
Ecological Risk Assessment. While a Human Health Risk Assessment is concerned
with estimating the effects on individuals, an Ecological Risk Assessment is
generally concerned with estimating effects on populations, communities and
ecosystems. In some cases involving endangered species, risks to individuals
may be considered.
An Ecological Risk Assessment is commonly required
as part of a site specific risk assessment. There are generally three levels of
investigation that can be conducted:
- Screening level assessment: essentially a qualitative
assessment of potential risks to important ecological receptors;
- Preliminary quantitative risk assessment: focuses on
filling gaps identified at the screening level; and,
- Detailed quantitative risk assessment: includes more
detailed data and modelling.
Each level of the assessment follows the conventional
risk assessment paradigm which includes: problem formulation (including
receptor characterization); exposure assessment; hazard assessment; and, risk
characterization. These steps are integrated into each of the three levels
discussed above. Thus, each level in this tiered approach has the same
structure and builds upon the data, information, knowledge and decisions
generated from the preceding level. The level of the assessment is dependent on
the particular site being evaluated. All three levels may be performed at one
site, with the subsequent levels of assessment becoming more specific to
identified species and/or conditions, targeting efforts to areas of greatest
concern or uncertainty.
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