The Stockholm Convention’s PFAS Journey
The Stockholm Convention on Persistent Organic Pollutants—adopted in 2001 and entered into force in 2004—provides the primary international legal framework for global elimination of persistent, bioaccumulative, and toxic chemicals. The Convention’s listing mechanism has placed three PFAS compounds on its global elimination lists over the past 15 years: PFOS (Annex B, restricted use, 2009); PFOA (Annex A, elimination, 2019); and PFHxS (Annex A, elimination, 2022). Each listing represents a global commitment by the Convention’s 184 parties to eliminate production and use of listed compounds, with exceptions for essential uses that require specific national exemption registrations. Understanding the Stockholm Convention’s PFAS trajectory—and its limitations—is essential for international policy on PFAS management.
The Listing Mechanism: From Proposal to Global Elimination
The Stockholm Convention listing process begins with a proposal from any party supported by a risk profile meeting the Convention’s Annex D screening criteria (persistence, bioaccumulation, toxicity, and evidence of long-range transport). The Persistent Organic Pollutants Review Committee (POPRC)—a subsidiary scientific body of 31 experts—evaluates proposals through a multi-stage process: screening (Annex D); risk profile (Annex E); risk management evaluation (Annex F); and recommendation for listing with draft text covering production, use, trade, releases, and wastes provisions. The Conference of the Parties (COP) then considers the POPRC recommendation and adopts listing amendments by consensus (though parties may opt out). The full process from proposal to COP adoption typically takes 4–8 years. PFAS proposals under consideration beyond PFHxS include: long-chain perfluorocarboxylic acids (LC-PFCAs, C9–C21); chlorinated paraffins (which interact with fluorochemical markets); and potentially PFBS and PFBS-related short-chain PFAS in future cycles.
Implementation Challenges: The Annex B Problem
PFOS’s Annex B (restricted use) listing—rather than Annex A (elimination)—reflects the political reality of 2009 when firefighting and certain industrial uses of PFOS were considered technically essential. Parties that registered specific use exemptions (China for chrome plating, some countries for AFFF) have continued PFOS production and use under those exemptions for over a decade. China’s PFOS production under registered exemptions has been significantly above initially reported levels, according to UNEP monitoring. The gap between Stockholm Convention listing and actual global phase-out reveals that voluntary compliance by major producers is insufficient—and that a future Annex A listing for PFOS (transitioning from restricted to eliminated status) is needed to close the production loophole. The 2023 COP11 meeting advanced discussions on upgrading PFOS to Annex A and on the LC-PFCAs listing—steps that would further restrict global PFAS production.
The Class-Based PFAS Approach: A Convention Innovation
One of the most significant innovations in PFAS governance discussions at the Stockholm Convention level is the proposal for class-based PFAS listing—listing all PFAS (or all fluorinated substances above a certain chain length) under a single Annex rather than pursuing compound-by-compound listing. POPRC has developed methodological frameworks for group assessments of chemically related substances, applicable to PFAS. A class-based Stockholm Convention listing would eliminate the regulatory treadmill of listing one PFAS while industry shifts to unlisted alternatives—the “regrettable substitution” cycle that has characterized PFAS regulation globally. Environmental NGOs (IPEN, Pesticide Action Network) and scientific advocacy organizations have been the primary proponents of class-based listing; the outcome depends on the consensus of parties including major producing nations (China, US-non-party, Russia).
The Stockholm Convention’s PFAS trajectory—from PFOS restriction to PFOA elimination to emerging class-based approaches—represents 15 years of progressive but incomplete global PFAS governance, with the most important advances still to come in the next COP cycle.