| Direct answer The biggest biocompatibility ISO 10993 news of 2025 is the publication of ISO 10993-1:2025 (6th edition) in November 2025. The revision replaces the 2018 standard, introduces contact-day exposure logic, requires foreseeable misuse assessment, and splits the device evaluation matrix into four contact-type-specific tables — affecting how manufacturers document biological risk. |
Biocompatibility ISO 10993 testing remains the cornerstone of medical device safety validation in 2025 and into 2026. The November 2025 publication of ISO 10993-1:2025 (6th edition) has reshaped how manufacturers approach biological evaluation — and the changes are more structural than the 2018 version ever was. For medical-grade liquid silicone rubber (LSR) components, passing these tests isn’t just a regulatory checkbox. It’s proof that every batch will perform safely when contacting human tissue.
We noticed a sharp increase in client questions about ISO 10993 compliance starting in late 2025. The new standard’s requirements around contact-day logic and foreseeable misuse were catching teams off guard. This guide addresses those questions with current information — including the FDA’s position on adopting the 2025 revision.
What Is ISO 10993 and Why It Matters for Medical Devices
ISO 10993 is the international standard series governing biological evaluation of medical devices.[1] It provides a risk-management framework that categorises devices by body contact type (surface, external communicating, or implant) and contact duration (limited ≤24 hours, prolonged >24 hours to 30 days, or long-term >30 days). This categorisation determines which biological effects must be evaluated.
The standard matters because medical devices — from dialysis seals to respiratory masks — must demonstrate they won’t trigger adverse biological responses. According to FDA guidance, biocompatibility assessment is required for most patient-contacting devices in premarket submissions including 510(k)s [2]. The EU MDR Annex I similarly mandates that device materials minimise toxicity risks.
In our experience producing medical LSR components, early biocompatibility planning is the variable that most consistently separates smooth regulatory submissions from delayed ones. One project — case_005, a dialysis device seal that required USP Class VI material validation alongside ISO 10993-5 cytotoxicity testing. We selected Wacker LR 3003/60, a platinum-cured LSR with established biocompatibility documentation, at the design stage.
That single decision avoided the 8–12 week delay that material requalification would have caused later. Honestly, we’ve seen projects stall for months because manufacturers didn’t account for biocompatibility requirements until a premarket submission was already in review.
Biocompatibility ISO 10993 News: 2025–2026 Key Developments
ISO 10993-1:2025 — Published November 2025 (6th Edition)
The November 2025 publication of ISO 10993-1:2025 is the central development in biocompatibility ISO 10993 news this year. This 6th edition replaces the 2018 standard and is, according to ANSI and Measurlabs, the most structurally significant revision in the standard’s history. [3]
What changed, specifically:
- Stronger ISO 14971 alignment: The revision embeds ISO 14971 risk-management language throughout. Biological evaluation is now formally structured as a risk management activity — not a standalone test programme. Biological harm, biological hazard, and biological risk analysis replace older endpoint terminology [4].
- Contact-day exposure logic: Duration categories are now based on total exposure days accumulated across multiple uses of the same device — not a single-use duration. This re-categorisation matters most for reusable devices, which may now fall into prolonged or long-term exposure brackets, triggering additional genotoxicity or carcinogenicity evaluation.
- Foreseeable misuse requirement: Manufacturers must now include reasonably foreseeable misuse in their biological evaluation. As MED Institute explains, if users are likely to use a device for longer than intended — or at a different tissue site — that scenario must be evaluated with the same rigour as intended use.
- Four new device-category tables: The former Table A.1 matrix has been split into four separate tables, each covering a specific contact type. The ‘Physical and chemical information’ biological endpoint has been removed from the tables and integrated into the biological risk analysis section instead [4].
- Extended genotoxicity scope: Genotoxicity evaluation is now required for all devices with prolonged (>24 hours to 30 days) or long-term (>30 days) contact with any tissue except intact skin [3].
| FDA recognition status — important for US submissions As of early 2026, the FDA continues to reference ISO 10993-1:2018 (5th edition) in its 2023 guidance for premarket submissions. The US delegation opposed the FDIS ballot for ISO 10993-1:2025. Manufacturers targeting FDA submissions should proactively engage with their regulatory consultants to determine whether 2025 content will be accepted, as FDA recognition of the new edition has not yet been formally published [5]. |
ISO 10993-23:2021 for Irritation Testing — Now Widely Adopted
Introduced in 2021 but now embedded in most regulatory strategies, ISO 10993-23 replaced previous irritation testing guidance with modernised in-vitro methodologies. The standard covers dermal irritation for skin-contacting devices, mucosal irritation for devices contacting mucous membranes, and intracutaneous reactivity assessment.
For silicone medical components, ISO 10993-23 is particularly relevant. LSR’s inert properties typically demonstrate favourable irritation profiles — provided manufacturing residues are properly controlled. We’ve never had an irritation test failure on our LSR components, and I suspect it’s because our vacuum molding process at -0.08 MPa eliminates most volatile residuals before the part is even demolded.
That said, Measurlabs notes that the FDA does not currently accept in-vitro methods for irritation as equivalent to in-vivo — so the regulatory path still requires animal testing in some jurisdictions[3].
ISO 10993-10:2021 Sensitisation Updates
The 2021 revision to ISO 10993-10 addresses skin sensitisation testing. The Local Lymph Node Assay (LLNA) is now preferred over the traditional Guinea Pig Maximisation Test (GPMT) for many applications due to reduced animal use. The stimulation index threshold commonly indicating a positive LLNA response is >3.
Key ISO 10993 Tests for Silicone Medical Components
Cytotoxicity (ISO 10993-5)
Cytotoxicity testing is universally required for patient-contacting devices. The standard evaluates whether device materials or extracts cause cell death or inhibit cell growth using mammalian cell cultures — typically L-929 fibroblasts with MTT or neutral red uptake assays.
Key parameters:
- Cell viability threshold: Below 70% (relative to negative control) indicates cytotoxic potential
- Test methods: Direct contact, indirect contact (agar barrier), or extract method
- Extraction conditions: 37°C for 24 hours at defined surface-area-to-volume ratios
In our Class 1000 cleanroom production of medical LSR components, vacuum levels at -0.08 MPa during molding eliminate trapped air and potential bubble-related contamination. That process control directly supports cytotoxicity compliance by minimising extractables from processing residuals.
Sensitisation (ISO 10993-10)
Sensitisation testing evaluates delayed-type hypersensitivity (Type IV) responses. For platinum-cured medical LSR, sensitisation risk is inherently low — the material’s stable chemistry means none of the common rubber accelerators that trigger allergic responses are present. That’s one reason silicone is preferred for long-term implants over organic rubber alternatives.
- LLNA (Local Lymph Node Assay): Stimulation index >3 commonly indicates a positive response
- GPMT (Guinea Pig Maximisation Test): Classical method with induction and challenge phases; still used in some jurisdictions
Irritation (ISO 10993-23)
Irritation testing assesses localised inflammatory responses. Unlike sensitisation, irritation is typically reversible when exposure ends. For LSR components, the material’s biologically inert nature generally yields favourable irritation profiles — which tracks with our in-house experience, though third-party confirmation is always required for regulatory submissions.
Hemocompatibility (ISO 10993-4)
For blood-contacting devices, hemocompatibility evaluation addresses hemolysis (ASTM F756), thrombogenicity, complement activation, and coagulation effects.
Medical-grade LSR’s smooth surface finish — achievable through precision mold design with surface roughness Ra ≤ 0.2 μm — supports hemocompatibility by minimising protein adhesion and platelet activation. Our mold surface treatment includes DLC (Diamond-Like Carbon) coating with hardness ≥ 2200 HV, which maintains this surface quality across 50,000+ molding cycles.
ISO 10993-5 Cytotoxicity Testing: Interlaboratory Variability
A 2023 interlaboratory study published in PMC highlighted critical variability in ISO 10993-5 testing outcomes [6]. The study found that only 58% of 52 participating laboratories correctly identified both cytotoxic and non-cytotoxic reference materials. For PVC tubing — a material with known cytotoxic potential — results ranged from 0% to 100% cell viability across labs. That spread was genuinely surprising, even for those of us who work in controlled environments daily.
Key findings affecting test reliability:
- Serum supplementation (10%) significantly increased test sensitivity
- Extended incubation periods improved detection of marginal cytotoxicity
- Extraction parameters (temperature, time, ratio) substantially impact results
This variability is why working with experienced testing partners and establishing validated in-house screening matters. In our production environment, we use the MTT cytotoxicity assay as a batch release screen, with acceptance criteria established through correlation to third-party ISO 10993-5 testing.
Common cytotoxicity failure modes in silicone components:
- Residual processing chemicals or cleaning agents
- Uncured polymer fractions
- Extractables from colorants or additives
- Sterilisation residuals (ethylene oxide, gamma radiation byproducts)
Our process controls address these risks through: platinum-cured LSR with complete cure validation (no peroxide residuals), vacuum molding at -0.08 MPa to eliminate trapped volatiles, post-cure thermal treatment at 200°C for 4 hours for complete crosslinking, and material certification from suppliers with ISO 10993 documentation.
USP Class VI vs ISO 10993: Understanding the Relationship
USP Class VI (United States Pharmacopeia <88>) and ISO 10993 are complementary rather than competing. The table below clarifies the distinction:
| Aspect | USP Class VI | ISO 10993 |
| Scope | Plastic materials and polymers | Complete medical devices (materials + processing + sterilisation) |
| Testing | Systemic injection, intracutaneous, implantation | Endpoint-specific based on device category and contact duration |
| Geographic focus | US market | International (EU MDR, FDA, Health Canada, TGA) |
| Regulatory basis | USP chapter <88> | International standard series (ISO 10993-1:2025) |
| Practical role | Material certification foundation | Device-level biological evaluation for regulatory submissions |
Practical implementation: Many medical device manufacturers require both USP Class VI material certification and ISO 10993 device-level evaluation. For our LSR medical components, we use Wacker LR 3003/60 — a USP Class VI certified platinum-cured silicone. This provides the material foundation for subsequent ISO 10993 device testing.
The relationship matters because USP Class VI addresses material biocompatibility, while ISO 10993 evaluates the finished device — including processing effects, sterilisation impact, and packaging interactions. A material can pass USP Class VI but still fail ISO 10993 if manufacturing introduces contaminants or if device geometry creates unfavourable tissue-contact conditions.
Practical Implementation: From Material Selection to Production
Material Selection Criteria
For medical LSR components, material selection must balance three factors:
- Biocompatibility documentation: USP Class VI, ISO 10993 series testing data from material supplier
- Processing characteristics: Shore A hardness range, cure kinetics, mold flow properties
- End-use requirements: Temperature resistance, sterilisation compatibility, mechanical properties
We typically specify Wacker LR 3003 series (Shore A 40–60) for medical applications. The platinum cure chemistry ensures no peroxide residuals that could affect cytotoxicity results.
Manufacturing Environment Controls
Cleanroom classification impact:
- Class 1000 (ISO 7): Our standard for medical LSR molding
- Particulate control: ≤1,000 particles ≥0.5 μm per cubic foot
- Environmental monitoring: Continuous particle counting with alert/action limits
Process parameters for biocompatibility assurance:
- Mold temperature: 170 ± 2°C (validated optimal range)
- Curing time: 5 seconds per mm wall thickness
- Vacuum level: -0.08 MPa for bubble-free molding
- Post-cure: 4 hours at 200°C for complete crosslinking
Mold Design for Biocompatibility
Mold design directly impacts biocompatibility through surface finish, parting line control, and gate design. Mirror-polished cavities (Ra ≤ 0.2 μm) minimise bacterial adhesion and protein retention. Flash ≤ 0.03 mm prevents material degradation at trim points. Cold runner valve-gate systems reduce material residence time and thermal degradation.
Our in-house mold manufacturing — with 7 wire EDM machines achieving ±0.002 mm precision — enables mold designs optimised for medical component quality. The DLC coating we apply to mold surfaces (hardness ≥2200 HV, friction coefficient 0.1–0.2) extends mold life to 50,000+ cycles while ensuring consistent part quality.
Batch Release Testing
- Visual inspection: 100% automated optical inspection for defects
- Dimensional verification: CPK ≥ 1.67 process capability with 2.5D measurement (±0.003 mm precision)
- Cytotoxicity screen: MTT assay on representative samples
- Documentation: Full batch traceability from raw material to finished component
Frequently Asked Questions About ISO 10993 Testing
How long does ISO 10993 testing typically take?
Timelines vary by device category and required endpoints. Cytotoxicity testing typically takes 2–4 weeks; sensitisation and irritation studies require 4–8 weeks. The critical path is often implantation studies for long-term devices, which can extend to 12–24 weeks depending on required observation periods.
Can ISO 10993 testing be performed in parallel?
Yes, with proper planning. In vitro tests (cytotoxicity, some genotoxicity screens) can run simultaneously. In vivo studies typically require sequential execution or at least staggered starts, to manage risk if early screens indicate problems.
What’s the difference between material-level and device-level testing?
Material-level testing (like USP Class VI) evaluates the raw material. Device-level testing (ISO 10993) evaluates the finished device including all manufacturing processes, sterilisation effects, and packaging interactions. Both are typically required for regulatory submissions.
How does ISO 10993-1:2025 affect existing market devices?
This is the question we’re hearing most frequently. According to Congenius’s analysis of the final standard, ISO 10993-1:2025 does not mandate re-testing of devices already on the market [4]. However, manufacturers need to document how historical biocompatibility information maps to the new requirements, and perform a gap analysis identifying whether any data gaps exist — particularly regarding contact-day recalculation for reusable devices and foreseeable misuse scenarios.
How often should biocompatibility testing be repeated?
Testing should be reviewed and potentially repeated when material suppliers change, manufacturing processes are modified, sterilisation methods change, or regulatory requirements update. Annual review of biocompatibility documentation is recommended as part of quality system maintenance.
Conclusion and Next Steps
The November 2025 publication of ISO 10993-1:2025 is the defining biocompatibility ISO 10993 news event of this cycle. The 6th edition’s shift from endpoint-matrix to exposure-driven risk management requires manufacturers to revisit existing biological evaluation plans — even for devices already on the market.
For medical device manufacturers working with silicone components, success in 2026 requires:
- Gap analysis of existing BEPs against ISO 10993-1:2025 requirements — particularly contact-day recalculation for reusable devices
- Early material selection with established biocompatibility documentation (USP Class VI and ISO 10993 data from the material supplier)
- Controlled manufacturing environments (Class 1000 cleanroom or better) with documented process parameters
- Validated processes with appropriate in-process and batch release testing
- Proactive engagement with regulatory consultants on FDA’s position regarding ISO 10993-1:2025 acceptance in premarket submissions
At Fecision, our ISO 13485:2016 certified medical molding operation produces 2 million LSR components monthly with full biocompatibility traceability. From material certification through Class 1000 cleanroom molding to batch release testing, we provide the quality foundation your medical device requires.
References & External Citations
All sources publicly available. Accessed April 2026.
[1] ISO. ISO 10993-1:2025 — Biological evaluation of medical devices – Part 1: Requirements and general principles. https://www.iso.org/standard/10993-1
[2] Emergo by UL. ‘US FDA revises guidance on ISO 10993 and biocompatibility requirements.’ https://www.emergobyul.com/news/us-fda-updates-final-guidance-iso-10993-medical-device-biocompatibility
[3] Measurlabs. ‘ISO 10993-1:2025 — Key Changes at a Glance.’ February 2026. https://measurlabs.com/blog/changes-to-iso-10993-1-standard/
[4] Congenius. ‘ISO 10993-1:2025 | What’s new in the revised standard?’ December 2025. https://congenius.ch/iso10993-biocompatibility-whats-new-in-the-2025-standard/
[5] RQS. ‘ISO 10993-1:2025 Approved & Pending Publication — FDA Recognition Status.’ October 2025. https://rookqs.com/blog-rqs/iso-10993-12025-update
[6] Advisera. ‘ISO 10993-1:2025 Changes: Risk-Based Biocompatibility.’ January 2026. https://advisera.com/articles/iso-10993-1-2025-what-has-changed/
[7] Wikipedia. ‘ISO 10993 — standard parts list and publication dates.’ https://en.wikipedia.org/wiki/ISO_10993
[8] PMC interlaboratory cytotoxicity study referenced in article text (2023). See ISO 10993-5 section for details.
