Preventing regrettable substitution through regulatory frameworks: using REACH regulation and Stockholm Convention as case studies

Abstract Background Regrettable substitution, which involves the replacement of a hazardous chemical with an alternative that later proves equally harmful or introduces new risks, remains an ongoing significant challenge for chemical regulation. As regulatory frameworks such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) and the Stockholm Convention increasingly drive transitions away from the use of hazardous substances, the need to prevent regrettable substitution has become central to effective chemicals management. Methods This study examines how regrettable substitution can be prevented through deliberate regulatory design and implementation. Using REACH and the Stockholm Convention as case studies, we performed a qualitative study involving interviews and document analysis. Results Reflexive thematic analysis generated interconnected themes that collectively identify how regulatory frameworks can potentially prevent regrettable substitution. These include improving the reliability, completeness, and transparency of regulatory data to support informed substitution; using incentives and structured regulatory support to promote innovation in safe(r) alternatives; establishing coherent and coordinated regulatory approaches that reduce fragmentation; strengthening partnerships among regulators, industry, and scientific actors to enhance information flow; adopting proactive and precautionary regulatory strategies, including early screening; and reinforcing compliance through enhanced monitoring and enforcement. Conclusions The findings demonstrate that regrettable substitution is not merely a scientific or technical failure but a systemic and operational regulatory issue arising from late hazard identification, incomplete exposure and performance information, siloed regulatory structures, and uneven innovation incentives. The study concludes that preventing regrettable substitution requires regulatory frameworks that are anticipatory, integrated, transparent, and adaptive that can actively steer the substitution process toward genuinely safe(r) and sustainable chemical solutions.