The Regrettable Substitution Problem
When regulators restrict a specific PFAS compound, manufacturers often substitute a structurally similar compound that circumvents the restriction. PFOA was replaced with HFPO-DA (GenX) and other shorter-chain PFAS that turned out to have similar persistence, bioaccumulation, and toxicity concerns. PFOS was replaced with PFBS and other short-chain sulfonates. This ‘regrettable substitution’ pattern has led to the proliferation of thousands of PFAS compounds that collectively continue to contaminate environments and people.
Alternatives assessment (AA) is a systematic methodology for evaluating whether replacement chemicals or technologies are actually safer than the substances they replace. Well-conducted alternatives assessment prevents regrettable substitution by requiring evidence of safety — not merely regulatory approval — before a replacement is adopted.
Frameworks for PFAS Alternatives Assessment
The Green Chemistry Institute and academic partners have developed PFAS alternatives assessment frameworks that evaluate potential replacements across hazard, exposure, and performance dimensions. The framework requires demonstration that alternatives: have lower hazard profiles (assessed through toxicological testing); provide equivalent or better performance in the intended application; are technically and economically feasible to implement; and do not create new environmental or health problems.
EPA’s Design for the Environment (DfE) program — now called Safer Choice — provides a framework for identifying safer chemical alternatives in cleaning products and other consumer applications. Extending DfE/Safer Choice criteria to PFAS alternatives across additional product categories would provide a federal assessment framework for evaluating whether proposed PFAS replacements represent genuine improvement.
Class-Based Regulation as an Alternative Approach
Some regulatory experts argue that alternatives assessment is insufficient because individual chemical review is too slow to keep pace with the PFAS family’s 12,000+ compounds. A class-based approach — restricting all PFAS unless demonstrated safe and essential — inverts the burden of proof, requiring industry to demonstrate safety rather than requiring regulators to prove harm.
The EU’s proposed universal PFAS restriction represents the most comprehensive implementation of class-based PFAS regulation globally. The restriction’s essential use exemption framework — allowing continued use only where no alternatives exist and the use is critical — embeds alternatives assessment into the exemption process, creating pressure for alternatives development as a condition of continued PFAS use.