ISO 10993-7:2026: What the new revision means for ethylene oxide sterilization residuals

What is ISO 10993-7:2026?

ISO 10993-7:2026 is the revised standard for residual ethylene oxide and ethylene chlorohydrin in EO-sterilized medical devices. It specifies allowable limits for EO and ECH, procedures for measuring those residuals, and methods for determining conformity so that EO-sterilized products can be released. The standard also includes additional background guidance and a flowchart in Annexes A to K.

In practical terms, ISO 10993-7:2026 helps manufacturers answer three critical questions:

1.      How much residual EO and ECH may remain on or in the finished device?

2.      How should residuals be measured and interpreted?

3.      How can product release be justified with evidence that is clinically and toxicologically relevant?

What has changed in the 2026 revision?

ISO states that the third edition replaces ISO 10993-7:2008 and incorporates the 2019 amendment and the 2009 corrigendum. The main changes include allowable limits and extraction conditions derived from patient population and duration of use, permission to use risk assessment to establish allowable limits, additional guidance on product release, and further guidance on determining residuals and factors that influence residual levels.

The most important practical shift is a stronger move from “testing against a number” toward exposure-based and risk-based justification. Manufacturers should expect to explain why the residual limits, extraction conditions, release criteria and data interpretation are appropriate for the actual device and its intended clinical use.

A simplified way to understand the revision is this:

Why EO residuals require careful control

EO is effective because it can penetrate complex device configurations and packaging systems, but that same capability means residuals can be retained in certain materials or product designs. ISO’s introduction to the revised standard notes that EO has biological effects and that ECH can form when EO comes into contact with free chloride ions; ethylene glycol (EG) is described as a hydrolytic reaction product of EO and water.

The 2026 edition focuses on residual EO and ECH. ISO’s abstract also clarifies that ISO 10993-7:2026 does not specify device limits for EG, because the risk assessment in Annex F indicates that calculated allowable EG levels are higher than those likely to occur in a medical device.

For regulatory and quality teams, this distinction matters. EO residual control is not only a question of analytical chemistry. It connects the sterilization process, material selection, packaging, aeration, toxicological risk assessment and biological evaluation of the final device.

Which products are in scope?

ISO 10993-7:2026 applies to EO-sterilized medical devices where residual EO or ECH may create patient or user exposure. ISO also clarifies important exclusions: EO-sterilized devices or components with neither direct nor indirect body or user contact, such as certain in vitro diagnostic devices, are outside the scope. The standard also does not apply to devices demonstrated not to absorb or retain EO or ECH, such as medical devices made exclusively of metal alloys and glass.

This means manufacturers should not apply the standard mechanically. The first step is to define the device configuration, materials, contact type, user or patient exposure, and whether EO/ECH can realistically be absorbed, retained and released under the conditions of use.

A more risk-based approach to allowable limits

One of the most technically important developments in ISO 10993-7:2026 is the way allowable limits are linked to toxicological exposure assumptions. ISO describes the use of an uncertainty-factor approach to derive exposure-duration-specific tolerable intake values for EO and ECH, and the conversion of those values into subpopulation-specific cumulative exposure allowable limits expressed per device.

In more accessible language: the standard asks manufacturers to think about how much residual exposure a patient or user may receive from the device in real use, not only what a test result shows in isolation.

This creates a stronger link between ISO 10993-7 and the broader biological evaluation process. ISO 10993-1:2025 defines requirements and principles for evaluating biological safety within a risk management process, aligned with ISO 14971. For EO-sterilized devices, ISO 10993-7:2026 is therefore one important part of the overall biological safety file, not a standalone document.

What manufacturers should review now: a prioritized approach

For manufacturers using ethylene oxide sterilization, the transition to ISO 10993-7:2026 should not start with a long checklist. It should start with the questions that determine the entire residual evaluation strategy: Who is exposed? For how long? Through which route? And what residual exposure can be justified for the finished device?

A structured review can be divided into three levels: foundational decisions, supporting evidence and lifecycle controls.

Practical review sequence

For an efficient gap assessment, manufacturers can use the following sequence:

This prioritization helps manufacturers focus first on the decisions that have the greatest regulatory and toxicological impact. The objective is not simply to add more documents to the technical file, but to create a clear and defensible chain of evidence: from intended use and patient exposure to residual limits, test strategy, product release and lifecycle control.

Relationship with EU MDR technical documentation

For manufacturers placing medical devices on the EU market, ISO 10993-7:2026 should be considered in the context of Regulation (EU) 2017/745 and the manufacturer’s technical documentation. In Europe, harmonised standards provide presumption of conformity only when their references are published in the Official Journal of the European Union; the European Commission explains that voluntary use of such standards confers presumption of conformity with the requirements they aim to cover once published in the OJEU.

This means manufacturers should always check the current harmonisation status, applicable transition arrangements and the specific MDR requirements being addressed. Even when a standard is not yet harmonised, a new ISO revision may still represent relevant state of the art and may influence expectations for scientific justification, risk management and technical documentation.

Why this revision matters for Notified Body assessments

From a Notified Body perspective, ISO 10993-7:2026 increases the importance of clear, traceable and scientifically justified evidence. A technical file should not simply contain a residual test report. It should demonstrate how residual limits were selected, how extraction and testing were performed, how release criteria were established, and how results support the biological safety of the finished EO-sterilized device.

Common documentation weaknesses include unclear device categorization, missing links between test conditions and clinical use, insufficient justification for allowable limits, incomplete method validation evidence, or change control records that do not evaluate EO/ECH impact. These gaps can lead to questions during conformity assessment and may delay review.

ISO 10993-7:2026 should therefore be treated as an opportunity. By reviewing EO residual strategies now, manufacturers can improve product release robustness, reduce regulatory uncertainty and demonstrate that biological safety is managed with current scientific and regulatory expectations in mind.