Background values PFAS in Flanders

Since the focus of the study was to derive background values for PFAS, the 50 sampling locations were selected on the absence of PFAS sources in the immediate vicinity.

Background values of PFAS in Flanders could be determined.  In addition to PFOS and PFOA, PFBA was frequently determined above the quantification limit (in all 50 soil samples). For these 3 substances a background value was derived, corresponding to the 90-percentile of observations (resp. 1.5 µg/kg dm, 0,96 µg/kg dm and 1.25 µg/kg dm for PFOS, PFOA and PFBA).

Interesting insights in background levels of a wide range of emerging contaminants

An exploratory soil campaign was performed to evaluate the presence (background values) of PFAS and 52 other emerging contaminants in Flemish unsuspected soils. A number of these substances may be widely distributed in the environment. These include (chemical) pesticides, several of which are no longer allowed to be used, but which may still be present in soil, sediment and groundwater.

For some substances, values above the quantification limit are regularly found. This is the case for the flame retardant BDE-209, bisphenol A and F, DDT and a number of its metabolites, the fungicides boscalid and hexachlorobenzene and the herbicide glyphosate and its degradation product AMPA. For diflufenican only sporadic values above the quantification limit were found. For the remaining substances, only very sporadic or no values above the quantification limit were found.

Policy recommendations

This exploratory study gives interesting insights that next to PFAS, other contaminants of concern should be part of policy recommendations. 

Different analytical methods were used for the determination of PFAS and other selected substances of concern in soil samples. The analytical methods however remain a challenge to determine background levels and to reach relevant quantification limits.

The study was performed by VITO under the commission of OVAM. More info on the detailed results (in Dutch) can be found on the OVAM-website. The study consists of three parts: (1) analyses, (2) deriving background values for perfluorinated compounds and (3) policy recommendations. The study was presented on the ENSOr3 webinar.