Medical Device Biological Tests (ISO 10993): Subcontracting and EO Residuals

Most medical devices headed for registration or export need a biological evaluation file, and cytotoxicity, sensitization, irritation and implantation tests are among the questions manufacturers ask most often. This article explains how SUNGO arranges those tests, which supporting tests on the same sample batch the SUNGO Shanghai laboratory performs within its accreditation scope, what to prepare before submitting samples, and how subcontracting appears on the report. Statements about SUNGO's capability are based on the certificate scope schedules.

Key points

• Biological tests are subcontracted: cytotoxicity, sensitization, irritation, implantation and similar biological tests are not within the accreditation scope of either SUNGO laboratory. SUNGO subcontracts them to laboratories holding the relevant qualifications. Under accreditation rules, the client's agreement is obtained before any work is subcontracted, and the report identifies the subcontracted items and the subcontractor.
• Supporting tests are performed in Shanghai: ethylene oxide/ethylene chlorohydrin residuals (ISO 10993-7, GB/T 16886.7), sterility testing (Chinese Pharmacopoeia general chapter 1101, ISO 11737-2, GB/T 19973.2-2025), microbial limits (general chapter 1105) and determination of a population of microorganisms on products (ISO 11737-1) fall within the Shanghai laboratory's accreditation scope. The accreditation type (CNAS, CMA or IAS) and any ECH (2-chloroethanol) limitation vary by item; the tables below are the reference.
• Evaluate before you test: which biological tests are needed follows from a biological evaluation under the ISO 10993-1 / GB/T 16886.1 approach. This evaluation is carried out by the client, based on the nature of body contact, contact duration and material information, and the test items are then decided.
• Biocompatibility clauses in assistive product standards are also outside scope: in the wheelchair, walking aid and walking stick standards accredited at the Hefei laboratory, the biocompatibility-related clauses are marked as excluded or not tested, or are not listed in the schedule. Where this testing is needed, SUNGO likewise subcontracts it to laboratories holding the relevant qualifications.

Standards and scope

ISO 10993-1 / GB/T 16886.1: the overall framework

ISO 10993-1 is Part 1 of the biological evaluation series for medical devices. It sets out the requirements and general principles for biological evaluation within a risk management process. The FDA Recognized Consensus Standards database shows that FDA has recognized the sixth edition (2025-11) as recognition number 2-313, with partial recognition. The same entry states that FDA will accept declarations of conformity to the 2018 (fifth) edition, recognition number 2-258, in support of premarket submissions until July 1, 2029.

According to the scope summary in that database, ISO 10993-1 applies to medical devices that have direct or indirect contact with a patient's body during intended use or reasonably foreseeable misuse, and to devices intended for personal protection (the summary gives medical gloves and surgical masks as examples) when they contact the body of users who are not patients. The evaluation considers biological risks from the device's constituents and from tissue-device interactions, including physical effects. Risks from infectious agents such as bacteria, moulds and viruses are outside the scope of the standard.

The Chinese counterpart is GB/T 16886.1-2022, Biological evaluation of medical devices - Part 1: Evaluation and testing within a risk management process. It was issued on 2022-04-15, took effect on 2023-05-01, is identical to ISO 10993-1:2018, and fully replaces GB/T 16886.1-2011. China's national standards information platform lists a revision project (plan number 20263430-T-464) as under review; the new Chinese edition applies only once it is formally published.

How devices are categorized by contact and duration

FDA's guidance on the use of ISO 10993-1 (issued September 2023) refers to ISO 10993-1:2018 clause 5.2, categorization by nature of body contact, and clause 5.3, categorization by duration of contact. Table A.1 in Attachment A of the guidance organizes evaluation endpoints along these lines (for Chinese terminology, follow GB/T 16886.1):

• Surface devices: intact skin, mucosal membrane, breached or compromised surface;
• Externally communicating devices: blood path, indirect; tissue/bone/dentin; circulating blood;
• Implant devices: tissue/bone; blood;
• Contact duration: A, limited (<24 h); B, prolonged (>24 h to 30 d); C, long term (>30 d).

The guidance also says Table A.1 is a framework for developing a biocompatibility evaluation, not a checklist for testing, and a particular device may warrant more or fewer endpoints than the table shows. These are the 2018 categories; for categorization details under the 2025 edition, refer to the standard itself and to the requirements of the target market.

Standard parts behind common biological tests

None of the following parts is within SUNGO's certificate scope; SUNGO subcontracts the related tests to laboratories holding the relevant qualifications. Adoption relationships are taken from China's national standards information platform.

• In vitro cytotoxicity: ISO 10993-5; the Chinese standard is GB/T 16886.5-2017, identical to ISO 10993-5:2009.
• Skin sensitization: ISO 10993-10; the Chinese standard is GB/T 16886.10-2024, identical to ISO 10993-10:2021, effective 2025-09-01.
• Irritation: ISO 10993-23; the Chinese standard is GB/T 16886.23-2023, identical to ISO 10993-23:2021, effective 2024-12-01.
• Local effects after implantation: ISO 10993-6; the Chinese standard is GB/T 16886.6-2022, identical to ISO 10993-6:2016.
• Sample preparation and reference materials: ISO 10993-12; the Chinese standard is GB/T 16886.12-2023, identical to ISO 10993-12:2021.

ISO 10993-7 / GB/T 16886.7: ethylene oxide sterilization residuals

According to the scope summary in the FDA database, ISO 10993-7 specifies allowable limits for residual ethylene oxide (EO) and ethylene chlorohydrin (ECH) in individual EO-sterilized medical devices, procedures for measuring EO and ECH, and methods for determining compliance so that devices may be released. EO-sterilized devices with no patient contact, such as in vitro diagnostic devices, are not covered. The Chinese standard GB/T 16886.7-2015 is identical to ISO 10993-7:2008; it took effect on 2017-01-01 and was confirmed as still valid at its review on 2023-12-28. SUNGO's CNAS and CMA schedules list ISO 10993-7:2008+A1:2019 and GB/T 16886.7-2015; IAS accredits Annex B of both, with no edition year on the certificate. For limit values, consult the standard; this article does not quote them.

Sterility, bioburden and microbial limits

ISO 11737-1 covers determination of a population of microorganisms on products; the scope summary in the FDA database refers to its results as bioburden data, and the item is commonly called bioburden. ISO 11737-2 and GB/T 19973.2-2025 cover tests of sterility performed in the definition, validation and maintenance of a sterilization process. Chinese Pharmacopoeia Volume IV general chapter 1101 is the sterility test method, and general chapter 1105 corresponds to the "microbial limit" item on the certificate. Which of these applies depends on whether the product is supplied sterile, the sterilization method, and the product standard your registration relies on.

Test item tables

Shanghai laboratory: supporting tests on the same sample batch

The table lists only certificate rows whose test object is "medical devices" or that are not tied to a specific product. Item names, clauses, editions and limitations follow the certificates; Chinese item names are translated.

Hefei laboratory: accreditation status of biocompatibility-related clauses in assistive product standards

The table reproduces the biocompatibility-related exclusions and limitations on the Hefei certificates.

Where the work is done and under which accreditation

• EO/ECH residuals, sterility testing, microbial limits, determination of a population of microorganisms on products: Shanghai SUNGO Medical Technology Co., Ltd., laboratory at No. 958 Kangqiao East Road, Pudong New Area, Shanghai. Certificates: CNAS L22083, CMA 240015340087, IAS TL-1019. The accreditation type for each item is shown in the notes column of the table above.
• Testing of wheelchairs, walking aids, walking sticks and other assistive products: Hefei SUNGO Medical Technology Co., Ltd., located in Zipeng Town, Feixi County, Hefei, Anhui Province. Certificates: CNAS L24279, CMA 260015342945, IAS TL-1119. The biocompatibility content of the clauses listed above is outside its accreditation scope; clause 4.9 of GB/T 14728.3-2008 and ISO 11199-3:2005 and clause 4.4 of GB/T 19545.4-2008 are listed in the CNAS schedule (the two GB/T items also in the CMA schedule) with the limitation "biocompatibility not tested".
• Cytotoxicity, sensitization, irritation, implantation and similar biological tests: subcontracted by SUNGO to laboratories holding the relevant qualifications. Under accreditation rules, the client's agreement is obtained before any work is subcontracted, and the report identifies the subcontracted items and the subcontractor.

The Shanghai and Hefei companies are separate legal entities. CMA covers only the items in its schedule and is valid only within the People's Republic of China. The CNAS certificate states that CNAS is a signatory to the ILAC and APAC mutual recognition arrangements, and the IAS certificates carry the ilac-MRA mark. Whether a particular overseas regulator accepts a given type of report depends on that regulator's requirements.

How subcontracting shows on the report

Under accreditation rules, the client's agreement is obtained before any work is subcontracted, and the report identifies the subcontracted items and the subcontractor, so you can tell which results come from the subcontractor. You can check the following yourself:

• Using the subcontractor named in the report, check its certificate status and validity on its accreditation body's website; the CNAS website has a search for accredited testing and calibration laboratories.
• Check that the subcontractor's accreditation scope lists the standard number and edition of each test performed (for example GB/T 16886.5-2017), and look for any limitations.
• If CMA status is required, confirm that the item is in the subcontractor's CMA schedule. If your target market sets specific requirements for testing laboratories, confirm them before agreeing to the subcontracting.

Preparing for testing

• Product information: name, models and specifications, construction and configuration. If models differ in materials, describe each one separately.
• Contact information: body site, direct or indirect contact, single and cumulative contact time, and whether the device is reused.
• Materials list: material name, grade and supplier for every component with direct or indirect body contact, plus any formulation information you can obtain. FDA's guidance notes that material selection and evaluation should take into account the chemical formulation of each component material, including adhesives, known and suspected impurities, and constituents associated with processing.
• Sterilization and packaging: sterilization method and batch number or date. Flag EO-sterilized products so EO/ECH residual testing can be scheduled on the same batch.
• Sample condition: FDA's guidance recommends testing devices in the condition in which they will be used whenever possible, which could include final packaged devices, or devices as sterilized by an end user, if appropriate. A representative test article should go through the same manufacturing and sterilization processes, have the same chemical, physical and surface properties, and have the same ratio of component materials.
• Components with different contact durations: FDA's guidance recommends conducting extract-based tests separately for components in different duration categories, for example testing implants separately from delivery systems.
• Documents: instructions for use and labelling; any existing biological evaluation report, previous test reports or material certificates.
• Target market and standard edition: state the registration or export market, and whether the GB/T 16886 series or the ISO 10993 series applies, including the edition.
• Sample quantity: depends on the tests and standard requirements; confirmed at quotation.

Frequently asked questions

Can SUNGO issue an accredited cytotoxicity test report?

No. Cytotoxicity, sensitization, irritation, implantation and similar biological tests are outside SUNGO's accreditation scope. SUNGO subcontracts them to laboratories holding the relevant qualifications; under accreditation rules, the client's agreement is obtained beforehand, and the report identifies the subcontracted items and the subcontractor.

Where is EO residual testing done, and is ECH included?

At the Shanghai laboratory. ISO 10993-7:2008+A1:2019 is within the CNAS and CMA scopes; IAS accredits ISO 10993-7 Annex B (gas chromatographic determination of EO and ECH; no edition year on the certificate). GB/T 16886.7-2015 appears in the CNAS scope as two rows, "ECH not tested" and "ECH only". The report type is confirmed at quotation.

Who decides which biological tests are needed?

The client, following the ISO 10993-1 / GB/T 16886.1 evaluation approach and based on the nature of contact, contact duration and material information. FDA's guidance quotes ISO 10993-1:2018 clause 4.1: an evaluation might conclude that no testing is needed if the material has a demonstrable safe history of use in a specified role and physical form equivalent to that of the device under design.

Do wheelchairs need biocompatibility testing?

EN 12183 clause 5.6 and EN 12184 clause 6.6 are biocompatibility and toxicity clauses, and these clauses are outside the Hefei laboratory's accreditation scope. Where this testing is needed, SUNGO subcontracts it to laboratories holding the relevant qualifications; under accreditation rules, the client's agreement is obtained beforehand, and the report identifies the subcontracted items and the subcontractor.

Requesting a quotation

If you need biological tests arranged by subcontracting, send an enquiry through our contact page. For EO/ECH residuals, sterility testing and bioburden on the same sample batch, see our sterilization-related services; for wheelchairs and assistive products, see wheelchair testing. Please include the product description, materials list, contact type and duration, sterilization method and target market. We will reply based on our certificate scope and the subcontracting arrangement.