BaP in soil has long been a particular interest of mine and I have developed an approach using the HPA surrogate marker approach and COC Margin of Exposure (MOE) method - as far as I am aware these are under consideration by the EA as an appropriate point of depature for determining alternative HCV for mutagens such as BaP.
The approach has received agreement from a number of EHO's on sites I have worked on in 2011 and 2012 and higher GAC for BaP between 5.6 and 7.0mg kg-1 have been accepted for use on resi sites.
The assessment approach is as follows:
1. Determine what the source of BaP is likely to be (and what is isn't!) using tools such as desk study findings, soil descriptions and, most importantly, double ratio source signature plot.
2. Does the data comply with the HPA requirement for the surrogate marker approach (i.e. does it fall within the limits of the Culp et al data)?
3. Calculate possible higher GAC for the BaP marker using the COC MoE approach.
With a few more EHO's and case examples behind me I may even publish - so if anyone wants to contribute ...