Chemistry-to-TRA-to-BER Workflow under ISO 10993-17

Where Teams Go Wrong

The common failure is treating TRA as a final report that sits beside the BER. A useful TRA should inform the biological evaluation. It can support a scientifically justified rationale that additional testing is unnecessary for certain endpoints, identify the need for more toxicological discussion, or expose a gap in the finished-device argument. It does not, by itself, prove device biocompatibility or replace evidence for every local, contact-mediated, physical, or biological response.

Where Part 17 Stops and Part 3 Begins

ISO 10993-17 addresses toxicological risk assessment of medical-device constituents, while ISO 10993-3:2026 addresses evaluation of genotoxicity, carcinogenicity, reproductive toxicity and developmental toxicity after the need for those evaluations has been established under ISO 10993-1. ISO's public preview says chemical characterization and TRA are an approach for these effect areas; that makes Parts 17 and 18 relevant evidence, not automatic substitutes for the Part 3 evaluation. Use the licensed final text for clause-level implementation and check the current market position. As of August 23, 2026, FDA's public recognition database still lists ISO 10993-3:2014 rather than the 2026 edition.

What the TRA Should Connect

• Chemical characterization: what was detected, how confidently it was identified, whether the test article is representative, and how analytical uncertainty was handled.
• Exposure assumptions: how the reported amount relates to clinically relevant patient exposure, contact duration, device use, and the population being assessed.
• Toxicological basis: whether the selected point of departure, uncertainty factors, exposure route, and other assumptions are applicable and adequately supported.
• Endpoint conclusions: how the assessment informs systemic toxicity or other applicable constituent-related questions. For genotoxicity, carcinogenicity, reproductive toxicity and developmental toxicity, preserve the separate evaluation required by the current controlled ISO 10993-3 text and applicable market framework.
• Residual uncertainty: whether more testing, better chemistry, or a clearer rationale is still needed.

The Chemistry-to-BER Decision Chain

The table below is a practical audit aid, not a substitute for the standard or device-specific scientific judgment. Each BER conclusion should preserve the conditions and uncertainty carried forward from the chemistry and TRA.

How to Audit the Chemistry-to-BER Chain

A useful internal audit starts with one detected constituent and follows it all the way through the file. The question is not only whether the compound appears in the chemistry report. The question is whether the file explains what the compound means for patient exposure, toxicological concern, endpoint conclusions, and residual biological risk.

• Start with the test article: confirm that the chemistry sample represents the finished device, including processing, cleaning, packaging, and sterilization where relevant.
• Check compound handling: verify how identified, tentatively identified, and unknown compounds were treated in the toxicological assessment.
• Follow the exposure logic: make sure assumptions are visible enough for a reviewer to understand the margin or rationale being used.
• Compare against endpoint decisions: look for places where TRA conclusions should support, limit, or change the BER endpoint table.

A Bounded Example: What TRA Can and Cannot Support

Hypothetical example: This fictional illustration uses no client data and is not a device-specific acceptance criterion. A finished, sterilized catheter is chemically characterized, and an identified constituent is quantified under an extraction design that can be related to the intended clinical use. If the exposure estimate is justified, the toxicological information is applicable, and the uncertainty is adequately addressed, the TRA may support a constituent-related systemic-toxicity rationale. The BER can then explain why that evidence supports its conclusion for the assessed question.

The available medical-device chemical characterization and TRA handbook expands this workflow into report-fitness review, unit and scaling traceability, unknown handling, toxicological source appraisal and four connected fictional case dossiers. Read the real 16-page preview or request the exact written offer.

That result does not automatically establish conclusions for sensitization, irritation, local tissue effects, hemocompatibility, or every other applicable endpoint. If the constituent remains unknown, the test article is not representative, the clinical exposure is understated, or the toxicological basis is unsuitable, the appropriate conclusion may be limited: obtain better chemistry, refine exposure, add targeted evidence, or retain the uncertainty as an unresolved biological-evaluation risk.

Reviewer-Ready TRA Checklist

The reviewer should not need to reconstruct the toxicological logic from disconnected appendices. A strong file makes the path clear: device configuration, extraction design, chemistry findings, exposure estimate, toxicological interpretation, endpoint conclusion, and final biological evaluation position. Use this checklist to keep that path visible.

• Representative article: the assessed sample and extraction design are linked to the finished device, manufacturing, cleaning, packaging, and sterilization as applicable.
• Constituent handling: identified, tentatively identified, and unknown findings are distinguished, including any constituents excluded from the quantitative assessment and the basis for exclusion.
• Exposure traceability: calculations show the amount, route, frequency, duration, patient population, and clinical-use assumptions used.
• Toxicological basis: sources, points of departure, uncertainty factors, threshold applicability, and data-quality limitations are documented.
• Endpoint boundary: the file states exactly which constituent-related questions the TRA informs and which endpoints still rely on other evidence.
• BER integration: the biological evaluation carries forward the TRA conclusion, its assumptions, and any residual uncertainty without broadening the claim.

What to Fix Before Ordering More Work

When a chemistry-driven file feels weak, the first question should be whether the existing evidence has been used properly. More chemistry, more testing, or a longer BER may still be needed, but those actions should come after the team understands the current break point.

• If the test article is unclear, fix device representation before expanding the toxicology discussion.
• If exposure assumptions are hidden, make them explicit before changing endpoint conclusions.
• If the TRA is sound but disconnected, rewrite the BER endpoint logic so the chemistry interpretation is visible.
• If uncertainty remains material, decide whether the answer is better identification, additional toxicological rationale, targeted testing, or a limited conclusion.

When Chemistry Should Change the BER

• When a constituent is detected at a level that needs toxicological interpretation.
• When an unknown or tentatively identified compound limits a testing rationale.
• When the chemistry and TRA support a scientifically justified conclusion that additional testing is unnecessary for an assessed question.
• When a material, supplier, process, sterilization, or packaging change affects the chemical profile.
• When a reviewer asks why chemistry data was not used in the biological evaluation conclusion.

FDA Context: Recognition Is Partial and the Chemical-Analysis Guidance Remains Draft

Source status checked August 9, 2026: FDA still identifies its September 2024 chemical-analysis guidance as draft and “Not for Implementation.” FDA's current recognition records list ISO 10993-17:2023 and ISO 10993-18:2020/Amd 1:2022 as partially recognized and identify specific exclusions or conditions. Use the live recognition records and applicable device-specific guidance; do not treat the draft as final policy or a declaration of conformity as broader than FDA's stated recognition.