New ISO standards bring clarity to chain of custody

Sustainability claims are everywhere. From recycled plastics and responsibly sourced fibres to renewable fuels and low-carbon materials, companies increasingly promise products with specific environmental or social characteristics.

But in complex global supply chains, proving those claims is not always straightforward. Materials move through multiple processing steps, are mixed, transformed and traded across borders. Without robust systems to track and verify what happens along the way, the credibility of sustainability claims can quickly come into question.

That is where chain-of-custody (CoC) systems play a critical role.

The framework behind the claims

Chain of custody provides the mechanisms that allow organizations to trace, account for and communicate the characteristics of materials as they move through supply chains. Yet these systems have often been applied differently across industries, sometimes without a common reference point.

To address this challenge, ISO has published two International Standards - ISO 22095-2 and ISO 22095-3 - strengthening the global framework for CoC systems. They introduce internationally harmonized requirements for two widely used CoC models: mass balance and book and claim. Designed to work across sectors, the new parts serve as umbrella references that support certification bodies and policymakers while facilitating cross-border trade.

Developed by technical committee ISO/TC 308, Chain of custody, the standards build on ISO 22095:2020, which established the common terminology and models used across industries. While that first standard laid the conceptual foundations, the new parts move one step further: they provide practical operational requirements for two of the most widely used CoC models.

What the new parts cover

ISO 22095-2 focuses on the mass balance model, widely used in sectors such as chemicals, plastics, agriculture and textiles. In mass balance systems, materials with and without specified characteristics - such as recycled or renewable content - can be mixed with conventional materials during processing.

What matters is not physical segregation, but accurate accounting of the quantities entering and leaving the system. The standard defines clear requirements for how these models should operate, including system boundaries, attribution rules, conversion factors and communication principles.

ISO 22095-3, meanwhile, addresses another widely used model: book and claim. Here, sustainability characteristics are transferred through administrative instruments rather than physical material flows. These instruments - known as Transferable Instruments with Entitlement to Claim (TIECs) - allow organizations to support sustainable production even when physical traceability is impractical.

The new standard establishes a globally aligned methodology for how these instruments are created, transferred and retired, helping prevent double counting and strengthening transparency. It also provides a trusted foundation for mechanisms such as Environmental Attribute Certificates (EACs) used in energy and environmental markets.

"With the publication of these two new parts, the chain of custody toolbox is further completed, giving the user communities two essential new instruments," says Jack Steijn, Chair of ISO/TC 308. "They reduce the risk of misinterpretation and double counting, strengthen the integrity of sustainability claims and establish core principles that will guide future standardization efforts across industries."

ISO/TC 308 can now be followed on LinkedIn .