Beyond molecular structure: Comparing Australian and European regulatory approaches to nano-identification and classification

Across regulation and toxicology, nanomaterials challenge foundational assumptions about substance identity and risk assessment. Through comparing substance identification requirements across Australian and European industrial chemical regulation - the Australian Industrial Chemicals Introduction Scheme (AICIS) and the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) respectively - this article explores how legal actors have incorporated the evolving science of nanotoxicology into the identification frameworks that establish regulatory approaches. These frameworks are important as they structure how regulators delineate between 'new' substances requiring novel risk assessment and regulatory approval, and 'existing' substances that have already been assessed. The findings reveal REACH and AICIS have created contrasting approaches to nano-identification. REACH employs a comprehensive multifactorial method aligned with emerging nanotoxicological principles, while AICIS relies on broader structure-based CAS identifiers. These frameworks differ in both factors used and the specificity of material identification. Such regulatory data discrepancies could impact nano-risk regulation, creating potential scientific and legal vulnerabilities for managing distinct nanoforms with variable risk identities in Australia's regulatory environment. This analysis shows that the effective regulation of complex materials depends not just on accurate material characterisation, but on the structural design of legal information systems that mediate between scientific knowledge and regulatory action.