An ecological risk assessment framework for assessing risks from contaminated land in England and Wales - Ecology of Industrial Pollution - page 194

Representative assessment and measurement endpoints 1 are then decided
to plan subsequent tiers of the ERA.
10. Identify Gaps and Uncertainties. Having completed the desk study and
produced a CSM, a risk assessor needs to be mindful of, and document,
those areas where information was lacking or where uncertainties exist.
Missing or uncertain information may need further investigation or veri-
fication, but should at least be highlighted for caution when making
decisions.
The desk study and production of a CSM will have gathered all of the infor-
mation about a site, its contaminants and its ecological receptors. If the CSM
demonstrates that there is no potential pollutant linkage the risk assessor can
document this and exit the framework ( Fig. 9.2 ). However, if there is a potential
CPR linkage the risk assessor must proceed to Tier 1 which involves chemical
screening. Alternatively, the appropriate person has the option to exit the ERA
at this stage and take voluntary management action ( Fig. 9.2 ).
Tier 1
In Tier 1, a simple effects assessment is performed by comparing contaminant
concentrations in soil against Soil Screening Values (SSVs) to verify possible
pollutant linkages and determine which contaminants may be posing a risk to
receptors ( Fig. 9.3 ) (Environment Agency 2008c ).
SSVs are concentrations of chemical substances found in soils below which
there are not expected to be any adverse effects on wildlife such as birds,
Figure 9.3. Chemical assessment and SSVs (modified from Environment Agency 2008b ).
1 An assessment endpoint is an explicit expression of the environmental resource that is
being protected, whereas a measurement endpoint is a quantifiable indicator that relates
directly to the assessment endpoint (Environment Agency 2003 , 2004c ).