Why is regulatory focus increasingly shifting towards the broader term PFAS instead of just PFCs?

Due to the substitution issue where banning one PFAS leads to the adoption of a closely related, unregulated alternative

Regulatory agencies are broadening their focus from the older term PFCs to the comprehensive group designation of PFAS because of the persistent problem known as chemical substitution. When specific, high-profile PFAS compounds, such as PFOA, are successfully phased out or banned in manufacturing within jurisdictions like the United States, the industry often replaces them with structurally similar PFAS compounds. These replacement chemistries, while not yet specifically regulated or fully studied, often carry the same concerning properties of persistence and bioaccumulation. Therefore, focusing only on a few banned chemicals is ineffective; risk management now targets the entire class of PFAS to prevent the cycle of immediate replacement with chemically similar, unregulated substitutes.