new insights, new guidelines
About half a year ago, OVAM published the first version of its “Guideline PFAS”. With this guideline, OVAM aimed to provide guidance on whether PFAS should be considered as a “suspect substance” and, if so, how an appropriate investigation strategy can be drawn up. In addition to this guideline, VITO, on behalf of OVAM, developed a proposal for remediation treshold values for PFOS and PFOA in soil and groundwater. These treshold values are preferably used when performing a site-specific risk assessment of PFOS/PFOA contaminated sites. Apart from this, the new document ("Assessment values for PFAS in soil and groundwater") also contains treshold values for free use of soil (in the context of soil excavation) or target values, and a summary of the physicochemical and toxicological data. As scientific research on perfluorinated compounds is still evolving, the derived values are provisional values.
Remediation treshold values for PFOS and PFOA
PFAS toxicity data are dominated by PFOS and PFOA because of the widespread occurrence of these components in the environment. Much less information is available from the other PFAS. The TDI is the starting point for the regulations derived in the different countries. In recent years there has been a downward trend in the TDIs that have been derived.
VITO developed a proposal for remediation values for PFOS and PFOA in both soil and groundwater. These values can be used as reference values when assessing soil contamination. The proposed values, the rationale and derivation, as well as the methodology used can be found in this document: Proposal for soil remediation values for PFOS and PFOA.
Background values for PFAS in top soil
VITO carried out a study for OVAM on the derivation of background values for perfluorinated compounds (Touchant et al., 2020).
On 50 unsuspicious (non-contaminated) samples from the top layer (0-20 cm) of Flemish soils, 28 perfluorinated compounds (PFAS) were analyzed. For Vlarebo-standardized parameters, the background are based on the 90-percentile values.
In addition, VITO derived target values (= treshold values for free use of soil), taking into account the background values and the proposed soil remediation treshold values.
The updated Guideline PFAS and the report “Assessment values for PFAS in soil and groundwater” (both in Dutch) can be found on the OVAM website. The document “Proposal for soil remediation values for PFOS and PFOA” can be found on the S-Risk website.