USP Class VI, ISO 10993, And FDA 21 CFR 177.2600: Which Medical Silicone Certification Do You Actually Need?

When sourcing medical-grade silicone — whether for tubing, catheters, respiratory circuits, or custom OEM components — you will inevitably encounter three certification standards referenced on supplier datasheets and product listings:

• USP Class VI

• ISO 10993

• FDA 21 CFR 177.2600

These are not interchangeable. They test different things, serve different regulatory purposes, and carry different weight depending on your target market and application. Yet they are routinely confused, misrepresented, and — in some cases — cited by suppliers who do not fully understand what they mean.

This guide cuts through the confusion. By the end, you will know exactly what each standard requires, how they relate to one another, and which combination your specific application demands.

Why Certification Clarity Matters More Than Ever

The stakes of getting this wrong are significant:

• Regulatory submissions rejected — submitting a 510(k) or CE Technical File with the wrong biocompatibility evidence is a common and costly mistake

• Product recalls — materials that passed one standard but not another have been implicated in adverse events

• Supplier qualification failures — accepting a certificate that doesn't cover your actual use case creates hidden liability

• Patient safety risk — ultimately, these standards exist because the wrong material in contact with the human body can cause cytotoxicity, sensitization, or systemic toxicity

Understanding these three frameworks is not just a regulatory checkbox — it is a fundamental competency for anyone involved in medical device procurement or development.

At a Glance: The Three Standards Compared

Understanding USP Class VI

What Is USP Class VI?

USP Class VI is a biological safety standard published by the United States Pharmacopeia, a nonprofit scientific organization that sets quality standards for medicines, food ingredients, and healthcare technologies. It is part of USP Chapter <88>, which classifies plastics and elastomers into six classes (I through VI) based on their biological reactivity.

Class VI is the most stringent classification — meaning a material that passes USP Class VI has demonstrated the lowest level of biological reactivity in the test series.

What Does USP Class VI Actually Test?

USP Class VI requires three specific in vivo (animal-based) tests:

1. Acute Systemic Toxicity Test

• A liquid extract of the material is injected into mice (both intravenously and intraperitoneally)

• Animals are observed for 72 hours for signs of systemic toxicity

• Tests for: toxic leachables that could enter the bloodstream

2. Intracutaneous Test

• Extracts of the material are injected into the skin of rabbits

• Injection sites are scored for erythema (redness) and edema (swelling) at 24, 48, and 72 hours

• Tests for: local tissue irritation from extractable chemicals

3. Implantation Test

• Strips of the material are surgically implanted into muscle tissue of rabbits

• Tissue reaction is evaluated at 5 days and 2–4 weeks post-implantation

• Tests for: chronic tissue reaction to the material itself

A material must pass all three tests to be classified as USP Class VI.

What USP Class VI Does NOT Test

This is where many buyers are misled. USP Class VI does not test for:

• Genotoxicity (DNA damage)

• Carcinogenicity (cancer risk)

• Reproductive toxicity

• Hemocompatibility (blood compatibility)

• Chronic systemic toxicity

For applications involving prolonged patient contact, implantation, or blood contact, USP Class VI alone is insufficient for regulatory submissions.

When Is USP Class VI Sufficient?

USP Class VI remains a widely accepted and valuable benchmark, particularly for:

• Pharmaceutical manufacturing — tubing and components in drug manufacturing equipment, where FDA and pharmacopeial standards are the primary framework

• Short-term patient contact — devices with limited, non-implant contact duration

• Supplier qualification — as a minimum baseline when procuring silicone materials

• Markets outside the EU — where ISO 10993 is not yet mandated

✅ All Chensheng Medical silicone products used in medical applications are manufactured from USP Class VI certified compounds. Full test reports — not just certificates — are available upon request.

Understanding ISO 10993

What Is ISO 10993?

ISO 10993 is the international standard series for the biological evaluation of medical devices, published by the International Organization for Standardization. It is a multi-part framework — currently comprising 23 individual parts — that provides a systematic approach to evaluating the biocompatibility of any material intended for patient contact.

ISO 10993 is now the primary biocompatibility framework required by:

• FDA for 510(k) and PMA submissions (per FDA's 2016 guidance on use of ISO 10993-1)

• EU MDR 2017/745 for CE marking

• Health Canada, TGA (Australia), PMDA (Japan), and most other major regulatory bodies worldwide

The ISO 10993 Framework: A Risk-Based Approach

Unlike USP Class VI, which specifies a fixed set of tests, ISO 10993 takes a risk-based approach. The specific tests required depend on:

1. The nature of body contact — surface contact, externally communicating, or implant

2. The duration of contact — limited (<24 hours), prolonged (24 hours to 30 days), or permanent (>30 days)

3. The type of contact — skin, mucosal membrane, blood, tissue/bone, etc.

Key ISO 10993 Parts for Medical Silicone

ISO 10993 vs. USP Class VI: The Critical Difference

The most important distinction is scope and regulatory acceptance:

• USP Class VI is a pass/fail test battery — it tells you whether a material passed three specific biological tests

• ISO 10993 is a risk management framework — it tells you what tests are needed for your specific application, and requires documented scientific justification for any tests that are waived

For modern regulatory submissions (FDA 510(k), EU MDR Technical File), ISO 10993 is required. USP Class VI alone is no longer sufficient for most device submissions, though it remains valuable as supporting evidence.

Practical implication: When a supplier provides only a USP Class VI certificate for a product intended for prolonged tissue contact or blood contact, ask for the full ISO 10993 biological evaluation report. If they cannot provide it, that is a significant qualification concern.

Understanding FDA 21 CFR 177.2600

What Is 21 CFR 177.2600?

Title 21 of the Code of Federal Regulations, Part 177.2600 is an FDA regulation — not a testing standard — that governs rubber articles intended for repeated use in food contact and medical applications. It specifies:

• Which raw materials (polymers, vulcanizing agents, accelerators, antioxidants, fillers) are permitted in the rubber compound

• Extractable limits — maximum allowable levels of substances that can migrate from the rubber into contact media

• Compliance testing methods — specific extraction and analytical procedures

What 21 CFR 177.2600 Covers

This regulation is fundamentally about chemical composition and extractables — it answers the question: "Are the ingredients in this rubber compound permitted, and do they stay in the rubber?"

Key requirements include:

• The rubber compound must be formulated only from FDA-listed ingredients

• Chloroform-extractable content must not exceed 0.5% of the rubber article's weight (for repeated-use articles)

• UV absorbance of aqueous and n-hexane extracts must not exceed specified limits

What 21 CFR 177.2600 Does NOT Cover

This regulation does not address:

• Biological safety (no animal or cell-based tests)

• Biocompatibility with specific tissue types

• Device-level safety or performance

It is a material composition standard, not a biocompatibility standard. A material can be compliant with 21 CFR 177.2600 and still fail ISO 10993 cytotoxicity testing if it contains permitted-but-reactive ingredients.

When Is 21 CFR 177.2600 Relevant?

• FDA-regulated medical devices — compliance is expected for rubber/elastomer components

• Pharmaceutical manufacturing equipment — tubing, gaskets, and seals in drug production

• Food processing equipment — silicone components in food contact applications

• As supporting evidence in FDA 510(k) submissions alongside ISO 10993 data

How the Three Standards Work Together

The three standards are complementary, not competing. Think of them as three layers of assurance:

┌─────────────────────────────────────────────────────────┐

│ LAYER 1: Chemical Composition │

│ FDA 21CFR177.2600 │

│ "Are the ingredients permitted and do they stay │

│ in the material?" │

└─────────────────────────────────────────────────────────

↓

┌─────────────────────────────────────────────────────────┐

│ LAYER 2: Basic Biological Safety │

│ USP Class VI │

│ "Does the material cause acute toxicity, │

│ irritation, or implant reaction?" │

└─────────────────────────────────────────────────────────┘

↓

┌─────────────────────────────────────────────────────────┐

│ LAYER 3: Comprehensive Biocompatibility │

│ ISO 10993 │

│ "Is the material safe for this specific patient │

│ contact type, duration, and application?" │

└─────────────────────────────────────────────────────────┘

A fully compliant medical silicone product for most regulated markets should satisfy all three layers.

Which Certifications Does Your Application Require?

Use this decision matrix to determine your minimum certification requirements:

Note: This matrix provides general guidance. Your specific regulatory submission requirements depend on your device classification, intended use, and target market. Always consult with a qualified regulatory affairs professional for your specific device.

Navigating Market-Specific Requirements

Certification requirements also vary by geography. For a detailed breakdown of FDA vs. CE vs. NMPA regulatory pathways for silicone medical devices, see our dedicated guide: FDA vs. CE vs. NMPA: Navigating Medical Device Regulations for Silicone Products

United States (FDA)

• Primary framework: ISO 10993-1 (per FDA 2016 guidance)

• Supporting evidence: USP Class VI + 21 CFR 177.2600 compliance

• Submission: 510(k) or PMA depending on device class

• Key requirement: FDA now expects a biological evaluation plan and report (BEP/BER) per ISO 10993-1, not just a list of passed tests

European Union (EU MDR 2017/745)

• Primary framework: ISO 10993 series — mandatory

• Key requirement: Full biological evaluation report with risk-based justification

• Additional: REACH compliance for chemical substances; no direct USP Class VI requirement, but accepted as supporting data

China (NMPA)

• Primary framework: YY/T 0268 (equivalent to ISO 10993-1) + GB/T standards

• Testing: Must be conducted at NMPA-designated laboratories

• Registration: Class II or III device registration required

What to Request From Your Silicone Supplier

When qualifying a medical silicone supplier, do not accept a certificate image alone. Request the following documentation package:

Minimum Documentation Checklist

• ISO 10993-5 cytotoxicity test report — full report with actual cell viability data, not just "pass"

• USP Class VI test report — issued by an accredited laboratory (e.g., Nelson Labs, SGS, Intertek)

• 21 CFR 177.2600 compliance statement — with chloroform extractables data

• ISO 13485 certificate — verify scope covers the specific product category

• Material composition disclosure — confirms platinum-cured vs. peroxide-cured, filler types

• Lot-specific Certificate of Analysis (CoA) — for the specific batch you are purchasing

• Biological Evaluation Report (BER) — for ISO 10993-1 compliance (required for 510(k)/CE submissions)

• For applications involving prolonged tissue contact or pharmaceutical fluid paths, also request:

• ISO 10993-10 sensitization and irritation report

• ISO 10993-11 systemic toxicity report

• Extractables and leachables (E&L) study — especially for drug-contact applications

For a complete guide on supplier qualification documentation, see: How to Choose a Reliable Medical Silicone Manufacturer in China

A Note on "Medical Grade" Claims

One of the most important takeaways from this guide: "medical grade" is not a regulated term.

Any supplier can label their silicone as "medical grade" without holding a single certification. The only way to verify a genuine medical-grade claim is to review the actual test reports against the standards described in this article.

When a supplier says their silicone is "medical grade," your response should always be:

"Which specific standards have been tested, by which laboratory, on which material formulation, and can you provide the full test reports?"

A supplier who cannot answer this question clearly and provide documentation is not a qualified medical silicone manufacturer.

For a deeper look at how curing chemistry affects material purity and biocompatibility, see: Platinum-Cured vs. Peroxide-Cured Silicone: Which Is Right for Your Application?

Chensheng Medical: Full Certification Transparency

At Jinan Chensheng Medical Technology Co., Ltd., we provide complete certification transparency for every medical silicone product we manufacture. Our standard documentation package includes:

Our medical silicone products are manufactured using platinum-cured compounds — the only curing system that produces zero by-products and meets the purity requirements for sensitive fluid-contact and patient-contact applications.

Explore our certified product range:

• Medical Silicone Tubing — USP Class VI · ISO 10993 · FDA · CE

• Silicone Foley Catheters — 2-way & 3-way, platinum-cured

• Breathing & Anesthesia Circuits — disposable, full biocompatibility documentation

• Closed Wound Drainage Systems — CE/ISO certified

• Custom OEM Medical Silicone Components — engineered to your specification

Frequently Asked Questions (FAQ)

Q1: Does USP Class VI certification expire?

A: The USP Class VI test results themselves do not have a fixed expiry date, but they are tied to a specific material formulation. If the manufacturer changes the silicone compound — including raw material suppliers, filler types, or curing agents — the certification is no longer valid for the new formulation and retesting is required. Always confirm that the certificate applies to the current production compound, not a historical formulation.

Q2: Can a supplier claim ISO 10993 compliance without running all 23 parts?

A: Yes — and this is correct practice. ISO 10993-1 uses a risk-based approach, meaning only the tests relevant to your specific device's contact type and duration are required. A supplier or device manufacturer must document their rationale for including or excluding each test category in a Biological Evaluation Plan (BEP). A claim of "ISO 10993 compliance" without a BEP is incomplete and should be questioned.

Q3: Is USP Class VI still accepted by the FDA for 510(k) submissions?

A: USP Class VI data is accepted as supporting evidence in FDA submissions, but it is no longer sufficient on its own. Since FDA's 2016 guidance update aligning with ISO 10993-1, the FDA expects a complete biological evaluation report (BER) that addresses all relevant biocompatibility endpoints for the device's intended use. USP Class VI test data can contribute to that evaluation but does not replace it.

Q4: What is the difference between ISO 10993 "compliant" and ISO 10993 "certified"?

A: Strictly speaking, ISO 10993 does not issue "certifications" — it is a testing and evaluation framework. A material or device can be described as "evaluated per ISO 10993" or "compliant with ISO 10993-1" based on completed testing. Be cautious of suppliers who claim ISO 10993 "certification" without providing the underlying test reports — the reports are the evidence, not a certificate document.

Q5: My device only contacts skin for less than 24 hours. Do I still need full ISO 10993 testing?

A: For limited-duration (<24 hours) skin surface contact, the minimum required biocompatibility endpoints are typically cytotoxicity (ISO 10993-5) and sensitization (ISO 10993-10). A full ISO 10993 evaluation including systemic toxicity and implantation tests would not normally be required. However, your specific regulatory submission requirements depend on your device classification and target market — always confirm with your regulatory affairs team.

Q6: Can Chensheng Medical provide application-specific biocompatibility documentation for our device submission?

A: Yes. We can provide the full material-level biocompatibility documentation package described in this article, including ISO 10993-5, -10, -11 test reports, USP Class VI reports, and 21 CFR 177.2600 compliance statements. For applications requiring extractables and leachables (E&L) studies or additional ISO 10993 endpoints, we can arrange testing through accredited third-party laboratories. Contact our regulatory affairs team to discuss your specific submission requirements.

Q7: What is the lead time for receiving certification documentation after placing a sample request?

A: Standard certification documents (ISO 13485 certificate, USP Class VI report, ISO 10993-5 report, CoA) are available immediately and can be sent within 24 hours of request. For material composition disclosures, an NDA is required before release. For custom E&L studies or additional biocompatibility testing, typical turnaround from an accredited laboratory is 4–8 weeks depending on the test scope.

Q8: Do your certifications cover all silicone product types, or only specific products?

A: Our certifications are compound-specific and product-category-specific. The ISO 10993 and USP Class VI reports cover the specific silicone formulations used in our medical product lines. When you request documentation, we will confirm which specific compound and product category the reports apply to, ensuring there is no ambiguity about the scope of coverage for your application.

Ready to Request Certification Documentation?

Whether you are preparing a regulatory submission, qualifying a new supplier, or simply verifying that your current silicone materials meet the standards your application requires, our regulatory affairs team is ready to assist.

What we provide within 24 hours:

• Full certification documentation package

• Material-specific test reports (ISO 10993, USP Class VI, 21 CFR 177.2600)

• Lot-specific Certificate of Analysis for your order

• Technical consultation on application-specific certification requirements

→ Request Certification Documentation→ Explore Certified Medical Silicone Products→ Contact Our Regulatory Affairs Team

By Robert Chen, Director of Regulatory Affairs | Jinan Chensheng Medical Technology Co., Ltd.Updated: May 2026 · 14 min read

Related Articles:

• How to Choose a Reliable Medical Silicone Manufacturer in China

• Platinum-Cured vs. Peroxide-Cured Silicone: Which Is Right for Your Application?

• FDA vs. CE vs. NMPA: Navigating Medical Device Regulations for Silicone Products

• How to Choose Medical Grade Silicone Tubing: A Practical Guide for Healthcare Buyers