RPF (Relative Potency Factor)

A weighting factor used to sum multiple PFAS compounds on a common PFOA-equivalent scale before comparing to the group EQS threshold.

Relative Potency Factor. Used for grouped substance compliance where individual members have different toxicological potency. For PFAS (No.65), concentrations of each of the 25 PFAS compounds are multiplied by their RPF (relative to PFOA = 1) and summed to give a PFOA-equivalent total. This total must not exceed 0.0044 μg/L (AA-EQS) or correspond to 0.077 μg/kg ww in fish biota. PFOS has RPF = 2 (twice as potent as PFOA); PFNA has RPF = 10; TFA has RPF = 0.002.

Legal reference

Directive (EU) 2026/805 Annex VI footnote 26