Contains Nonbinding Recommendations
Use of International Standard ISO 
10993-1, "Biological evaluation of 
medical devices - Part 1: Evaluation 
and testing within a risk management 
process"
Guidance for Industry and Food and 
Drug Administration Staff
    
Document issued on: September 8, 2023.
The draft of this document was issued on October 15, 2020.
This document supersedes Use of International Standard ISO 10993-1, 
"Biological evaluation of medical devices - Part 1: Evaluation and testing 
within a risk management process" dated September 4, 2020.
For questions about this document regarding CDRH-regulated devices, contact the Office of 
Product Evaluation and Quality (OPEQ)/Clinical and Scientific Policy Staff at 
CDRH.Biocomp@fda.hhs.gov or 301-796-5701. For questions about this document regarding 
CBER-regulated devices, contact the Office of Communication, Outreach and Development 
(OCOD) at 1-800-835-4709 or 240-402-8010, or by email at ocod@fda.hhs.gov.
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Devices and Radiological Health
Center for Biologics Evaluation and Research Contains Nonbinding Recommendations
Preface
Public Comment 
You may submit electronic comments and suggestions at any time for Agency consideration to 
https://www.regulations.gov. Submit written comments to the Dockets Management Staff, Food 
and Drug Administration, 5630 Fishers Lane, Room 1061, (HFA-305), Rockville, MD 20852-
1740. Identify all comments with the docket number FDA-2013-D-0350. Comments may not be 
acted upon by the Agency until the document is next revised or updated.
Additional Copies
CDRH
Additional copies are available from the Internet. You may also send an e-mail request to
CDRH-Guidance@fda.hhs.gov to receive a copy of the guidance. Please include the document 
number GUI00001811 and complete title of the guidance in the request.
CBER
Additional copies are available from the Center for Biologics Evaluation and Research (CBER), 
Office of Communication, Outreach, and Development (OCOD), 10903 New Hampshire Ave., 
WO71, Room 3128, Silver Spring, MD 20903-0002, or by calling 1-800-835-4709 or 240-402-
8010, by email, ocod@fda.hhs.gov,or from the Internet at 
https://www.fda.gov/vaccines-blood-biologics/guidance-compliance-regulatory-information-
biologics. Contains Nonbinding Recommendations
Table of Contents
I.  Introduction ......................................................................................................................... 1
II.  Scope ................................................................................................................................... 2
III.  Risk Management for Biocompatibility Evaluations .......................................................... 6
A.  Risk Assessment of the Medical Device ................................................................... 6
B.  Identification of Potential Risks................................................................................ 7
C.  Considering Available Information to Identify and Mitigate Risks ......................... 9
D.  Submission and Interpretation ................................................................................ 13
IV.  ISO 10993 - Part 1 and the FDA-Modified Matrix........................................................... 14
A.  Evaluation of Local and Systemic Risks ................................................................ 15
B.  FDA Use of ISO 10993-1 ....................................................................................... 16
C.  The FDA-Modified Matrix ..................................................................................... 18
D.  Endpoint Assessment .............................................................................................. 19
V.  General Biocompatibility Testing Considerations ............................................................ 20
A.  Use of Medical Device in Final Finished Form or Representative Test Article ..... 20
B.  Testing of In Situ Polymerizing and/or Absorbable Materials ............................... 20
C.  Biological Response Resulting from Device Mechanical Failure .......................... 21
D.  Submicron or Nanotechnology Components .......................................................... 22
E.  Test Article Preparation for Extract Testing ........................................................... 23
F.  Inclusion of Multiple Components or Materials in a Single Test Article ............... 24
VI.  Test-Specific Considerations ............................................................................................ 25
A.  Cytotoxicity............................................................................................................. 25
B.  Sensitization ............................................................................................................ 25
C.  Hemocompatibility ................................................................................................. 28
D.  Pyrogenicity ............................................................................................................ 32
E.  Implantation ............................................................................................................ 33
F.  Genotoxicity ............................................................................................................ 34
G.  Carcinogenicity ....................................................................................................... 36
H.  Reproductive and Developmental Toxicity ............................................................ 38
I.  Degradation Assessments ....................................................................................... 39
VII.  Chemical Assessment ....................................................................................................... 39
VIII.  Labeling Devices as -Free ............................................................................................. 43
Attachment A: Evaluation Endpoints for Consideration .............................................................. 44
Attachment B: Device Master Files for Biocompatibility Evaluations ........................................ 46
Attachment C: Summary Biocompatibility Documentation ......................................................... 48
Attachment D: Biocompatibility Evaluation Flow Chart ............................................................. 50
Attachment E: Contents of a Test Report ..................................................................................... 52
Attachment F: Component and Device Documentation Examples .............................................. 54
A.  Component Documentation .................................................................................... 54
B.  Device Documentation............................................................................................ 54
C.  New Processing/Sterilization Changes ................................................................... 55
D.  Formulation Changes .............................................................................................. 55 Contains Nonbinding Recommendations
Attachment G: Biocompatibility of Certain Devices in Contact with Intact Skin ........................ 57
A.  Which Types of Devices are Included? .................................................................. 58
B.  What Materials Are Included? ................................................................................ 59
C.  What Devices or Materials are Excluded? .............................................................. 60
D.  What Biocompatibility Information Should be Included in a Premarket 
Submission? ............................................................................................................ 61
E.  What is FDAs Recommended Content and Format for Certain Labeling 
Information Related to This Policy? ...................................................................... 63
Attachment H: Glossary ................................................................................................................ 64 Contains Nonbinding Recommendations
Use of International Standard ISO 
10993-1, "Biological evaluation of 
medical devices - Part 1: Evaluation 
and testing within a risk management 
process"
Guidance for Industry and Food and 
Drug Administration Staff
This guidance represents the current thinking of the Food and Drug Administration (FDA or 
Agency) on this topic. It does not establish any rights for any person and is not binding on 
FDA or the public. You can use an alternative approach if it satisfies the requirements of the 
applicable statutes and regulations. To discuss an alternative approach, contact the FDA staff 
or Office responsible for this guidance as listed on the title page. 
I. Introduction 
FDA has developed this guidance document to assist industry in preparing Premarket 
Applications (PMAs), Humanitarian Device Exceptions (HDEs), Investigational Device 
Exemption (IDE) Applications, Premarket Notifications (510(k)s), and De Novo requests for 
medical devices that come into direct contact or indirect contact with the human body1 in order 
to determine the potential for an unacceptable adverse biological response resulting from contact 
of the component materials of the device with the body. The purpose of this guidance is to 
provide further clarification and updated information on the use of International Standard ISO 
10993-1, "Biological evaluation of medical devices - Part 1: Evaluation and testing within a risk 
management process" to support applications to FDA. This guidance document also incorporates 
several considerations, including the use of risk-based approaches to determine if 
biocompatibility testing is needed, chemical assessment recommendations, and recommendations 
1For the purposes of this document, the term human body refers to either patient tissues or the clinical 
practitioner. For example, masks or gloves intended for protective purposes by clinical practitioners should be 
assessed for biocompatibility. Similarly, medical devices such as implants or skin electrodes also should be assessed 
for biocompatibility.
1 Contains Nonbinding Recommendations
for biocompatibility test article preparation for devices with submicron or nanotechnology 
components and for devices made from in situ polymerizing and/or absorbable materials.
When assessing new devices, the sponsorshould specifically state if the device does not have 
any direct or indirect tissue contact,2 and no further biocompatibility information would be 
needed.
When assessing device modifications, the sponsor should specifically state if the modification 
does not result in a change to any direct or indirect tissue-contacting components, and no further 
biocompatibility information would typically be needed. However, if the change could affect 
other parts of the device with direct or indirect contact that were not changed, a biocompatibility 
evaluation should be conducted to assess the potential impact of the change. For example, if a 
new non-contact internal component is added, but it requires the application of heat in order to 
join to another component that has patient contact, the patient-contacting component may be 
impacted by the application of heat such that biocompatibility could be impacted, and should be 
assessed.
For the current edition of the FDA-recognized consensus standard(s) referenced in this 
document, see the FDA Recognized Consensus Standards Database.3
Throughout this guidance document, the terms we, us, and our refer to FDA staff. You 
and your refers to the sponsor.
In general, FDA's guidance documents do not establish legally enforceable responsibilities. 
Instead, guidances describe the Agency's current thinking on a topic and should be viewed only 
as recommendations, unless specific regulatory or statutory requirements are cited. The use of 
the word should in Agency guidances means that something is suggested or recommended, but 
not required.
II. Scope 
The scope of this document and accompanying attachments is limited to the biological 
evaluation of sterile and non-sterile medical devices that come into direct or indirect contact 
with the human body. This document specifically covers the use of ISO 10993-1 but also is 
2For non-contactdevices, there is no direct or indirect contact with the body (e.g., stand alone software), so it would 
be sufficient for the biocompatibility evaluation to confirm that there are no direct or indirect tissue contacting 
components, and no further biocompatibility information is needed. However, for devices with transient contact, 
assessment of biocompatibility risk should be conducted to determine if testing is needed.
3Available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfStandards/search.cfm
2 Contains Nonbinding Recommendations
relevant to other biocompatibility standards (e.g., other parts of the ISO4 10993 series of 
standards, ASTM,5 ICH,6 OECD,7 USP8).
This document discusses the following topics: 
 use ofrisk assessments for biocompatibility evaluations for a proposed medical device;
 use of ISO 10993-1 and the FDA-modified matrix (Attachment A) to determine the 
relevant biocompatibility endpoints for an evaluation;
 general biocompatibility testing considerations, including test article preparation;
 specific considerations for the following testing: cytotoxicity, sensitization, 
hemocompatibility, pyrogenicity, implantation, genotoxicity, carcinogenicity, 
reproductive and developmental toxicity, and degradation assessments;
 chemical assessment recommendations;9 and
 considerations for labeling devices as -free.
In addition, this guidance includes the following attachments that are intended to serve as 
resources:
 Attachment B: Device Master Files (MAFs) for Biocompatibility Evaluations, which 
includes information that we recommend including in an MAF;
 Attachment C: Summary Biocompatibility Documentation, which includes an example 
table that we recommend using to summarize the biocompatibility information used to 
support a submission;
 Attachment D: Biocompatibility Evaluation Flow Chart, which illustrates how to 
proceed with a biocompatibility evaluation;
 Attachment E: Content of a Biocompatibility Test Report, which includes the 
recommended contents of a test report;
4ISO stands for International Organization for Standardization, an international standards development 
organization. See http://www.iso.org/iso/home.htmlfor more information.
5ASTM stands for American Society for Testing and Materials, an international standards development 
organization. See http://www.astm.org/ABOUT/overview.htmlfor more information.
6ICH stands for International Conference on Harmonisation, an international standards development organization. 
See http://www.ich.org/about/vision.htmlfor more information.
7OECD stands for Organisation for Economic Co-operation and Development, an international standards 
development organization. See http://www.oecd.org/for more information.
8USP stands for U.S. Pharmacopeial Convention, a United States standards development organization. See 
http://www.usp.org/aboutfor more information. 
9All issues specific to the evaluation of color additives in medical devices included in the draft version of this 
guidance were removed, and the intent is for these items to be addressed in a separate guidance document.  
3 Contains Nonbinding Recommendations
 Attachment F: Component and Device Documentation Examples, which outlines 
example documentation language that we recommend using when comparing the 
composition of a test article to the composition of a finished medical device or in 
comparing the composition of a previously legally marketed device to the composition 
of a current device;10
 Attachment G: Biocompatibility of Certain Devices in Contact with Intact Skin, which 
describes the recommended submission contents for devices in contact with intact skin 
that are fabricated from common polymers and fabrics; and
 Attachment H: Glossary, which includes terms and definitions used in this guidance.
If there are other FDA-recognized consensus standards11 that address biocompatibility issues for 
particular types of devices (e.g., ISO 7405 Dentistry  Evaluation of biocompatibility of medical 
devices used in dentistry), the recommendations in the more device-specific standard should be 
followed. In some cases, such as for dental devices, the biocompatibility recommendations in the 
device-specific standard should be used instead of the recommendations outlined in ISO 10993-
1. In contrast, some device-specific guidances include recommendations regarding 
biocompatibility evaluations, that should be considered in conjunction with ISO 10993-1. For 
example, the FDA guidance Content of Premarket Notifications for Conventional and High 
Permeability Hemodialyzers12 specifies that subcomponent testing is recommended due to the 
high surface area of the membrane component of a hemodialyzer, and testing of the complete 
device is only recommended if the extraction conditions (i.e., volume of solvent used per 
surface area of test article) are more rigorous than those recommended in ISO 10993. In this 
case, if biocompatibility testing of a hemodialyzer is conducted on the final device, FDA 
recommends that the hemodialyzer be filled to capacity with the solvent, resulting in a much 
higher surface area to extract volume ratio, as compared to recommendations from ISO 10993-12 
Biological evaluation of medical devices  Part 12: Sample preparation and reference materials. 
However, if non-membrane components are tested separately, then use of ISO 10993-12 
recommendations for test article preparation would apply.
Note that if your product is a combination product with a device constituent part,13 the general 
principles of this guidance would apply, although additional or modified testing may14 be 
needed. For example, sample preparation of biologic-device combination products may be 
dependent on the type of product and the endpoint being assessed, and such detailed guidance 
specific to biocompatibility evaluation of combination products are not within the scope of this 
document. As such, we encourage you to discuss combination products with the appropriate 
10For the purposes of this guidance, legally marketed devices are limited to devices marketed in the US.
11Refer to FDAs Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for Medical 
Devices: Guidance for Industry and Food and Drug Administration Staff available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/appropriate-use-voluntary-consensus-
standards-premarket-submissions-medical-devicesfor information regarding the recognition and use of national and 
international consensus standards during the evaluation of premarket submissions for medical devices. 
12Available at https://www.fda.gov/medical-devices/guidance-documents-medical-devices-and-radiation-emitting-
products/content-premarket-notifications-conventional-and-high-permeability-hemodialyzers-guidance-industry  
13Please refer to 21 CFR 3.2(e) for the definition of a combination product.
14The term may is used here and throughout the document to indicate that the final determination on whether 
additional information should be provided will depend on the specifics of the final device under consideration.
4 Contains Nonbinding Recommendations
Center and review division who will initiate proper consultation on combination product-specific 
biocompatibility concerns as appropriate.15
We also recognize that an ISO standard is a document that undergoes periodic review and is 
subject to revision. Through the FDA standards recognition process, we provide information 
regarding the extent of recognition of the ISO 10993 series of standards and other 
biocompatibility standards through Supplemental Information Sheets published on the FDA 
website.16 Unless testing is conducted under the Accreditation Scheme for Conformity 
Assessment (ASCA) program and it is determined that an ASCA Summary Test Report is 
sufficient,17 FDA recommends that complete test reports be provided for all tests performed 
because the ISO 10993 series of standards include general methods with multiple options, and in 
some cases do not include acceptance criteria or address assessment of results.18 Therefore, when 
a declaration of conformity is submitted for an FDA-recognized standard in the ISO 10993 
series, a copy of the supplemental information used to support the declaration (e.g., a copy of the 
study test report as described in Attachment E) should also be provided.19 FDA intends to make 
updates to this guidance document as appropriate, should future revisions to ISO 10993-1 or 
other FDA recognized biocompatibility standards result in significant changes to the 
recommendations in this document.
   
Sponsors are advised to initiate discussions with the appropriate Center and review division prior 
to the initiation of long-term testing of any new device to ensure that, if testing is needed, the 
proper testing will be conducted.
15For more information regarding combination products, see the FDA combination products website available at 
https://www.fda.gov/combination-products/guidance-regulatory-information. For additional information regarding 
ways in which combination product sponsors can obtain feedback from FDA on scientific and regulatory questions 
and best practices for FDA and sponsors when interacting on these topics, see the guidance Requesting FDA 
Feedback on Combination Products available at https://www.fda.gov/regulatory-information/search-fda-guidance-
documents/requesting-fda-feedback-combination-products
16See FDAs Database on Recognized Consensus Standardsand input 10993-1 for the Supplemental Information 
Sheet.
17Refer to FDAs Biocompatibility Testing of Medical Devices  Standards Specific Information for the 
Accreditation Scheme for Conformity Assessment (ASCA) Pilot Program available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/biocompatibility-testing-medical-
devices-standards-specific-information-accreditation-schemefor information regarding ASCA biocompatibility 
summary test reports.
18In the case of Abbreviated 510(k)s, a summary of the methods often is needed to ensure that the test was 
conducted in the same way as for a predicate device, and that the same evaluation criteria were used. If it is easier 
for the sponsor to submit a copy of the test report, which is not required by FDA, this would be acceptable. For 
Special 510(k)s, refer to the guidance The Special 510(k) Program available at https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/special-510k-programfor more information about FDAs 
recommended biocompatibility information that should be included.
19Refer to FDAs Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for Medical 
Devices: Guidance for Industry and Food and Drug Administration Staff for information regarding the recognition 
and use of national and international consensus standards, including declarations of conformity to these standards, 
during the evaluation of premarket submissions for medical devices.
5 Contains Nonbinding Recommendations
III. Risk Management for Biocompatibility Evaluations 
As stated in ISO 10993-1, the biological evaluation of a medical device (or a material component 
of such) should be conducted within the framework of a risk management process. Such a 
process should generally begin with assessment of the device, including the material 
components, the manufacturing processes, the clinical use of the device including the intended 
anatomical location, and the frequency and duration of exposure. Considering this information, 
the potential risks from a biocompatibility perspective should be identified. Such risks might 
include chemical toxicity, unacceptable biological response to physical characteristics of the 
device, and aspects of manufacturing and processing that could alter the physicochemical 
characteristics of the device, which could lead to changes in the biocompatibility response. Once 
the risks have been identified, the sponsor should assess what information is already available 
regarding those risks and identify the knowledge gaps that remain. Considering the potential 
biological impact, a plan should be developed to address the knowledge gaps either by 
biocompatibility testing or other evaluations that appropriately address the risks. The 
interpretation of the overall biocompatibility evaluation should be considered in the appropriate 
benefit-risk context.
A. Risk Assessment of the Medical Device 
The risk assessment should evaluate the final finished device. The Agency makes a 
clearance or approval decision for a medical device as it is supplied in its final finished 
form. The Agency does not clear or approve individual materials that are used in the 
fabrication of medical devices. Therefore, the risk assessment should evaluate not only 
the materials used in the device, but also the processing of the materials, the 
manufacturing methods (including the sterilization process), and any residuals from 
manufacturing aids used during the process.20
The risk assessment should also consider the proposed clinical use of the device, 
including the anatomical location, duration of exposure, and intended use population. For 
example, for pediatric patients with a limited life expectancy, the tolerance for risk 
associated with a permanently implanted medical device may be higher than the tolerance 
for risk from the same device in an otherwise healthy pediatric population. The potential 
exposure duration should also consider which material components of the device have 
direct or indirect contact with tissue, and whether exposure would be a one-time 
exposure, a constant exposure over time, or an intermittent exposure over time that could 
have a cumulative effect. For example, pacemaker pulse generators commonly contain 
internal electronic components made from chemicals that could be toxicto the body, but 
appropriate bench testing can demonstrate that the pulse generator is hermetically sealed 
and will limit exposure of those chemicals to the surrounding tissues.
20See Attachment Gfor special considerations for FDAs recommended biocompatibility evaluation for certain 
devices in contact with intact skin that are fabricated from common polymers and fabrics.
6 Contains Nonbinding Recommendations
B. Identification of Potential Risks 
An assessment of potential biocompatibility risk should include not only chemical 
toxicity, but also physical characteristics that might contribute to an unwanted tissue 
response. These characteristics can include surface properties, forces on surrounding 
tissue (e.g., mechanical, thermal, electromagnetic), geometry, and presence of 
particulates, among others. In addition, changes in manufacturing and processing 
parameters can also have an impact on biocompatibility. For example, the original 
processing for an implanted device might include placing the device in an acid bath to 
facilitate passivation of the implant surface. If this passivation process is changed to 
eliminate the acid bath in favor of a different method of passivating the surface, removal 
of the acid bath might unintentionally lead to a smaller reduction in pyrogenic material, 
which could result in pyrogenic reactions (fever) following implantation of the device. 
Another common change that might impact biocompatibility is a change in resin supplier. 
For example, if the new resin supplier does not remove all processing solvents (some of 
which may be known toxic compounds, such as formaldehyde), the final manufactured 
device could cause unexpected toxicities (e.g., cytotoxicity, irritation, sensitization, 
genotoxicity) that were not seen with devices manufactured from the original resin.
Sources of information on potential biocompatibility risks can include, but are not limited 
to, a manufacturers previous experience with the same material(s), preferably in the 
same or similar anatomical location; reported experience from other manufacturers using 
the same material in the same or similar anatomical location; information provided by the 
material supplier (e.g., in a master file,21 see Attachment B); chemical or surface analysis 
of the device in its final finished form; and the published literature. In certain situations, 
clinical experience, such as postmarket surveillance information, may be informative. For 
example, for a limited duration, skin-contacting device, patient experience that includes 
information on potential for irritation or sensitization can be useful to the risk assessment.
When leveraging data from experience with a particular device for a new device 
submission to FDA, it is important to understand how the tested device compares to the 
device under consideration. In general, the more similar the tested device and device 
under consideration are, including their intended use, the more applicable the risk 
information is likely to be. For example, for a vascular catheter comprised of a certain 
polymer, citing experience with the same polymer in a blood-contacting device will be 
more applicable than experience with a similar polymer in a device that only contacts 
mucosal membranes. Similarly, experience with device components made using the same 
formulation and processing (e.g., for devices within a product family) will be more 
applicable than experience with device components made by a different manufacturer 
where the formulation and processing are unknown.
A master file for a material, device component, and/or device may be useful if it includes 
information on recommended processing of the material or component and any biological 
21Additional information regarding master files for devices is available online at: https://www.fda.gov/medical-
devices/premarket-approval-pma/master-files
7 Contains Nonbinding Recommendations
testing already performed (see Attachment B). A master file should also contain a risk 
assessment provided by the supplier that includes a discussion of the chemical 
formulation and structure of the material or component and information on how to 
evaluate a device made from that material.
In certain situations, a sponsor may propose to use a material that has known toxicities 
but where the material could be acceptable for the end use. In this case, the risk 
assessment should include consideration of the intended use population that will use (e.g., 
protective mask for clinician) or be treated with the device and a discussion of potential 
benefits of using the chosen material as well as potential mitigations that have been 
considered (e.g., hermetically sealing). 
A chemical analysis of the materials used in a device in its final finished form can be 
informative. Chemical analysis can be particularly helpful to demonstrate that chemical 
toxicity testing from a previously cleared or approved medical device is relevant to a 
device under review by the Agency. For example, in some circumstances, a chemical 
analysis can demonstrate that the extractablesand leachablesin a biocompatibility extract 
have not changed, supporting that additional biocompatibility testing using that type of 
solvent is not needed. In addition, chemical analyses can be used to assess the 
toxicological risk of the chemicals that elute from devices. For example, chemical 
analysis using exhaustive extraction techniques (per ISO 10993-18) can also be helpful to 
evaluate long-term toxicity endpoints such as potential carcinogens. Extraction 
techniques could also be used to identify intermediate and final breakdown products in a 
material that is either synthesized in vivo (e.g., in situ polymerizing materials) or intended 
to be absorbable (e.g., degradable materials). However, chemical analysis is usually 
insufficient to identify all of the risks of the device in its final finished form, because it 
will not consider aspects of the finished device such as surface properties (e.g., rough 
versus polished surface) or device geometry that could affect the biological response in 
certain scenarios (e.g., thrombogenicity, implantation). In addition, the outcomes of 
chemical analyses are often sensitive to the parameters of the test. Extraction solvents 
should be selected to optimize compatibility with the device materials and provide 
information on the types of chemicals that are likely to be extracted in clinical use. 
Solvents that swell the polymer, cause the polymer to degrade or dissolve, or interfere 
with detection of chemicals should be used with caution.
Finally, there may be potential hazards that are not addressed by available information. In 
certain cases, such as the addition of a new chemical to a standard formulation, individual 
toxicity information for the added chemical and starting material may be insufficient due 
to the potential for chemical interactions between the material and added chemical. Thus, 
the risk assessment should consider what is known about the additional material, the base 
material, and potential chemical interactions between the two.
8 Contains Nonbinding Recommendations
C. Considering Available Information to Identify and 
Mitigate Risks 
In order to reduce unnecessary testing, including animal testing,22 FDA recommends that 
sponsors consider all available relevant information when conducting their risk 
assessment. FDA believes that the following information should be included in your risk 
assessment, if applicable: 
1. Literature and other publicly available information: Sponsors should review all 
available toxicity literature and other publicly available information to determine 
the toxicity risks for the materials used to manufacture their medical device. If 
data are not available to evaluate the safety of a compound, then the concept of 
Threshold of Toxicological Concern (TTC)23 can be used to assess some 
biocompatibility endpoints.
Sponsors should also review available literature and other publicly available 
information to identify specific risks associated with the use of their device and 
possible mitigation measures. For example, literature could inform manufacturers 
that nitinol passivation of a peripheral stent should be conducted appropriately to 
ensure that nickel, a chemical with known toxicities, does not leach from the 
device when implanted. Literature could also be useful in identifying the potential 
breakdown products of an absorbable device, allowing the sponsor to conduct 
more focused testing to characterize and analyze these chemicals as a device 
degrades. Sponsors should be selective in how literature and other publicly 
available information are used to inform their risk assessment; all available 
information should be considered in the context of how relevant the information 
might be to a specific medical device. For example, status of a device material or 
component as generally recognized as safe (GRAS) by FDA as a food additive 
may or may not be informative for a medical device risk assessment because it 
may not be appropriate to extrapolate use in food to device-specific tissue contact, 
such as muscle or circulating blood. In addition, when considering available 
literature with respect to specific device materials, sponsors should also evaluate 
whether such information is relevant in light of the manufacturing and processing 
for the medical device. Similarly, literature or other publicly available information 
such as clinical data may become less relevant when changes in materials or 
suppliers occur. Such changes may affect the safety or effectiveness of a medical 
22FDA supports the principles of the 3Rs, to replace, reduce, and/or refine animal use in testing when feasible. 
We encourage sponsors to consult with us if it they wish to use a non-animal testing method they believe is suitable, 
adequate, qualified for use with medical devices, and feasible. We will consider if such an alternative method could 
be assessed for equivalency to an animal test method.
23Refer to ICH M7 Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit 
Potential Carcinogenic Risk available at https://www.fda.gov/regulatory-information/search-fda-guidance-
documents/m7r1-assessment-and-control-dna-reactive-mutagenic-impurities-pharmaceuticals-limit-potentialfor 
information on use of the TTC and structure activity relationship (SAR) modeling to address genotoxicity and 
carcinogenicity issues within a risk management process.
9 Contains Nonbinding Recommendations
device and should be considered appropriately in any risk assessment provided to 
FDA.
If literature is used in lieu of testing for certain biocompatibility endpoints, the 
submission should include information on the applicability of the dose, route, and 
frequency of exposure from the literature report(s) as compared to the proposed 
device use. In addition, while literature may be appropriate to evaluate certain 
biocompatibility endpoints, it may not be appropriate for all biocompatibility 
endpoints. For example, No Observed Adverse Effect Level (NOAEL) and 
Lowest Observed Adverse Effect Level (LOAEL) data should be derived from 
studies relevant to the endpoint under consideration. For example, NOAELs and 
LOAELs from a systemic toxicity study can often be used to address acute, 
subchronic, or chronic system toxicity endpoints, but might not be relevant for 
genotoxicity, local and systemic carcinogenicity, sensitization, irritation or 
reproductive toxicity assessments, if these endpoints are not assessed in the 
studies selected to develop NOAELs or LOAELs. However, NOAEL/LOAEL 
values developed to consider reproductive toxicity may be used to assess the 
potential reproductive toxicity of compounds released from devices that are not in 
direct contact with reproductive tissues.
2. Clinical experience: Clinical experience should be considered in the overall 
benefit-risk profile for the device where the totality of the data available for the 
device may inform whether more testing is needed, or if any testing is needed at 
all. For example, clinical experience may be useful to mitigate problematic 
findings in an in vitro biocompatibility or in vivo animal study. In other cases, 
testing to address long-term biocompatibility endpoints (e.g., genotoxicity, 
chronic toxicity, or carcinogenicity) may not be necessary if the patients life 
expectancy in the intended use population is limited. 
 
Generally, clinical studies are not sufficiently sensitive to identify 
biocompatibility concerns. Clinical or sub-clinical symptoms that result from the 
presence of a non-biocompatible material may not be identifiable, or may result in 
symptoms that are indistinguishable from the disease state such that the clinical 
data may not be informative to the biocompatibility evaluation. For example, 
blood vessel occlusion at the site of an implanted stent could be indicative of a 
toxic response to the stent materials or be related to damage to the stent during 
implantation (e.g., due to operator error or a delivery device malfunction). 
However, in limited circumstances, clinical experience may mitigate certain 
identified risks. For example, if there is previous clinical experience with a 
particular medical device (either from a clinical study or via marketing outside of 
the US), and there have been no issues with anaphylaxis, then biocompatibility 
testing for complement activation may not be necessary. Similarly, in an 
Investigational Device Exemption (IDE) study, first in human study data may be 
useful to initiate a study on a revised device design, while biocompatibility 
evaluations are being completed in parallel, and it may be acceptable to provide
10 Contains Nonbinding Recommendations
complete biocompatibility information once the device design is finalized for 
commercialization, depending on the risks posed to patients.24
Clinical experience may also inform biocompatibility evaluation of next 
generation devices. For example, some clinical studies of specific absorbable 
medical devices demonstrated that the absorption kinetics were not accurately 
predicted by the nonclinical performance (bench or animal) studies. This 
information has been helpful when evaluating a next generation device using an 
improved bench model for the absorption of the device, and for assessing how the 
type and amount of chemicals released with absorption over time might affect 
biocompatibility.
However, there are also situations where FDA has not found clinical experience 
to provide relevant biocompatibility information. For example, providing clinical 
information that a particular implant material has a long history of use would not 
typically be sufficient to support the biocompatibility of an implant made from the 
same material because manufacturing and processing could affect the final 
chemistry presented to the body. In addition, such information is often too broad 
and general to be useful.
3. Animal study experience: Data from an in vivo animal study of the medical device 
in its final finished form may be used in lieu of some biocompatibility tests. 
Testing performed in a relevant animal model can be used if the study was 
designed to include assessments for biocompatibility endpoints. These studies 
should evaluate the biological response to the test article implanted in a clinically 
relevant implantation site. For example, separate biocompatibility assessments for 
implantation, in vivo thrombogenicity, and acute, subchronic, and chronic toxicity 
may not be needed if these endpoints were included in the in vivo animal study 
design with an appropriate study endpoint, and the scientific principles and 
recommendations in the appropriate ISO 10993 test method were considered and 
applied.
If animal study data (e.g., histology, necropsy) identifies adverse biological 
responses, some additional biocompatibility testing may be warranted. For 
example, glutaraldehyde-fixed tissue heart valves may show toxic effects in 
animal studies as well as some standard biocompatibility assays, such as 
24FDA considers biocompatibility information, collectively with other nonclinical information, in the review of 
Early Feasibility Study (EFS) IDE applications and through the review of devices granted Breakthrough designation 
and determines, through our benefit-risk analysis, what biocompatibility endpoints should be evaluated prior to 
initiation of clinical studies as well as what evaluations may be appropriately conducted in parallel with clinical data 
collection. For more information, see Investigational Device Exemptions (IDEs) for Early Feasibility Medical 
Device Clinical Studies, Including Certain First in Human (FIH) Studies: Guidance for Industry and Food and Drug 
Administration Staff available at https://www.fda.gov/regulatory-information/search-fda-guidance-
documents/investigational-device-exemptions-ides-early-feasibility-medical-device-clinical-studies-includingand 
Breakthrough Devices Program: Guidance for Industry and Food and Drug Administration Staff available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/breakthrough-devices-program  
11 Contains Nonbinding Recommendations
cytotoxicity and genotoxicity. These findings would usually trigger the need for 
additional studies, such as chemical characterization and dose ranging 
cytotoxicity and genotoxicity studies of suspected chemical toxins released from 
the device to confirm the cause of the adverse findings and to determine if 
additional mitigations are needed.
Animal experience may also inform biocompatibility evaluation of next 
generation devices. For example, animal study data from the literature regarding 
absorbable adhesion barriers made of a certain material could provide information 
related to the timeframe of absorption and potential adverse effects for a new or 
modified device.
However, there are also situations where FDA has not found animal data to 
provide relevant biocompatibility information. For example, data from the 
literature indicating that a particular implant material is biocompatible may not be 
sufficient to support the biocompatibility of a device made from the same material 
because manufacturing and processing likely will affect the final device chemistry 
presented to the body. Similarly, animal studies designed to assess human factors 
and studies conducted in animal cadavers would not typically include assessment 
of biological response, and therefore may not be useful to support a 
biocompatibility evaluation.
4. Consensus standards: Consensus standards specific to a particular device type or 
material may be helpful to inform a risk assessment; however, the extent to which 
the standard could be utilized may be dependent on the specificity of the standard 
and/or the specific material. Ideally, a standard would have sufficient specificity 
to provide useful information regarding material risks. For example, standards 
that outline both mechanical and chemical properties of a device type with 
pass/fail criteria may be particularly informative to FDAs review because of the 
specificity of such a standard. Standards that address bulk material composition 
can also be informative as a starting point for incorporating material 
characterization into a risk assessment. For example, it may be appropriate to use 
material standards to support the biocompatibility evaluation of 316L stainless 
steel surgical vascular clamps, as long as any risks associated with manufacturing 
are appropriately considered and mitigated (see Section IV.A). Given the effects 
that manufacturing and processing may have on a polymer as incorporated into 
the final finished medical device, use of material standards may not be sufficient 
to identify biocompatibility risks for devices made from polymers.
5. Devices previously reviewed by FDA: Experience with medical device materials 
previously reviewed by FDA (e.g., in previous generation devices, PMA-
approved devices, predicate devices) are also relevant for consideration as part of 
a risk assessment. Such information may be more informative when a sponsor is 
able to leverage their own experience, rather than that from another manufacturer 
or supplier as the manufacturing and processing of the device material may be 
unknown. Sponsors should be specific in their risk assessment regarding how 
12 Contains Nonbinding Recommendations
devices previously reviewed by FDA are being utilized to identify potential risks 
and/or mitigate identified risks. Sponsors should be as specific as possible when 
referencing devices previously reviewed by FDA, including submission numbers 
or master file numbers, and references to specific test reports or data in a 
submission (if applicable). Sponsors should also provide a specific comparison of 
the subject device materials to device materials previously reviewed by FDA. It 
may be helpful to use the documentation examples provided in Attachment Fto 
provide such a comparison.
D. Submission and Interpretation 
FDA recommends that sponsors provide their risk assessment at the beginning of the 
biocompatibility section in a submission to CDRH or CBER. Based on the considerations 
outlined above, the sponsor should clearly summarize their conclusions regarding their 
risk assessment and explain the relationship between the identified biocompatibility risks 
and the information available to mitigate the identified risks, and identify any knowledge 
gaps that remain. The sponsor should then identify any biocompatibility testing or other 
evaluations that were conducted to mitigate any remaining risks.
The sponsor should also explain any toxicities and adverse effects identified in their 
biocompatibility testing or other evaluations. As a part of the risk assessment, the sponsor 
should discuss any other available information (such as the results of in vivo animal 
studies) that might provide additional context for interpretation. For example, if a device 
made from polypropylene shows a grade 2 cytotoxicity with L929 cells, which might be 
acceptable per ISO 10993-5 Biological evaluation of medical devices  Part 5: Tests for 
in vitro cytotoxicity, the sponsor should provide additional information regarding the 
potential source of the toxicity, since polypropylene is generally not expected to elicit a 
cytotoxicity response of this level. Conversely, skin-contacting electrodes with adhesives 
containing detergents might be expected to have higher than grade 2 cytotoxicity with 
L929 cells, which could be acceptable if the sponsor is able to confirm that there are no 
other chemical constituents causing the adverse cytotoxic response. In general, potential 
toxicities identified through biocompatibility testing should be evaluated considering the 
intended use of the device and as part of the overall benefit-risk assessment. 
During the biocompatibility evaluation, if chemical characterization testing is conducted 
per ISO 10993-18 Biological evaluation of medical devices  Part 18: Chemical 
characterization of medical device materials within a risk management process or 
ISO/TS 10993-19 Biological evaluation of medical devices  Part 19: Physico-chemical, 
morphological and topographical characterization of materials, it is important to 
understand that these standards include only general information regarding multiple 
analytical techniques and no acceptance criteria. Therefore, to support a declaration of 
conformity, as a part of the supplemental information used to support the use of these 
standards, we recommend that a rationale for the selected method(s) and protocols be 
presented with your results so that FDA can assess whether the information obtained will 
support the biocompatibility of your device.
13 Contains Nonbinding Recommendations
Attachment C provides an example biocompatibility risk assessment summary table, 
which FDA has generally found useful from a review perspective. Sponsors may find that 
utilizing this approach and format is helpful when developing their own biocompatibility 
risk assessment. FDA reviews these risk assessments as part of the overall 
biocompatibility evaluation to determine whether the risks, mitigations, and 
biocompatibility testing or other information is appropriate to support the 
biocompatibility of a medical device. Sponsors may wish to discuss their plan for 
conducting an appropriate risk assessment with FDA early in their device development 
process. FDA recommends that sponsors use the Q-Submission process to facilitate these 
discussions.25 While FDA generally cannot review a detailed risk assessment under the 
Q-Submission process, it is often helpful to discuss the planned approach for such a risk 
assessment. Pre-Submissions may be particularly helpful to obtain feedback regarding a 
risk assessment in the following and other instances:
 When developing an in vitro test battery for hemocompatibility to determine 
whether the validation information being developed might be appropriate for a 
particular clinical indication;
 When determining whether additional biocompatibility evaluations may be 
needed if questionable or inconclusive findings have occurred in any previously 
conducted biocompatibility evaluations, or in the event that novel materials are 
used;26
 When designing in vivo or ex vivo studies intended to address biocompatibility 
endpoints; 
 When designing chemical analysis protocols that use accelerating factors (e.g., 
heat) to simulate patient exposure to medical device materials over time;
 When determining how to prepare absorbable devices for biocompatibility testing 
(e.g., unpolymerized, pre-polymerized, partially degraded, or fully degraded test 
articles).
IV. ISO 10993  Part 1 and the FDAModified Matrix
 
This guidance considers the assessment of biocompatibility to be an evaluation of the medical 
device in its final finished form, including sterilization, if applicable. However, sponsors should 
understand the biocompatibility of each device component and any interactions between 
components that could occur. This is particularly important when the combination of device 
25Refer to FDAs guidance document Requests for Feedback and Meetings for Medical Device Submissions: The 
Q-Submission Program: Guidance for Industry and Food and Drug Administration Staff available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/requests-feedback-and-meetings-
medical-device-submissions-q-submission-program
26Novel materials are not commonly used to manufacture medical devices. Novel materials are mentioned 
throughout this document to provide transparency regarding FDAs current thinking and recommendations 
regarding biocompatibility evaluation of devices made from these materials. However, we recognize that these 
recommendations will not apply to the majority of device submissions. 
14 Contains Nonbinding Recommendations
components could mask or complicate interpretation of a biocompatibility evaluation. For 
example, if a metal stent has a polymer coating that may separate over time, then the results of a 
final device biocompatibility assessment may not fully reflect the longer-term clinical 
performance of the device, and biocompatibility evaluation of the stent with and without the 
coating may be needed. Similarly, for an in situ polymerizing and absorbable sealant, where the 
materials present will change over time, separate evaluations of the pre-polymerized, 
polymerized, and degrading sealant may be needed.
A. Evaluation of Local and Systemic Risks 
Biological evaluation of medical devices is performed to determine the acceptability of 
any potential adverse biological response resulting from contact of the component 
materials of the device with the body. The device materials should not, either directly 
(e.g., via surface-bound chemicals or physical properties) or through the release of their 
material constituents: (i) produce adverse local or systemic effects; (ii) be carcinogenic; 
or (iii) produce adverse reproductive and/or developmental effects, unless it can be 
determined that the benefits of the use of that material outweigh the risks associated with 
an adverse biological response. Therefore, evaluation of any new device intended for 
human use warrants information from a systematic analysis to ensure that the benefits 
provided by the device in its final finished form will outweigh any potential risks 
produced by device materials over the intended duration and use of the device in or on 
the exposed tissues.
    
When selecting the appropriate endpoints for biological evaluation of a medical device, 
one should consider the chemical characteristics of the device materials and the nature, 
degree, frequency, and duration of exposure to the body (i.e., intended use), as outlined in 
Attachment A. In general, the biocompatibility endpoints to be considered include: in 
vitro cytotoxicity; acute, subchronic and chronic toxicity; irritation; sensitization; 
hemocompatibility; implantation; genotoxicity; carcinogenicity; and effects on 
reproduction, including developmental effects. However, depending on device physical 
properties (e.g., surface topography, device geometry),27 the intended use of the device, 
target population, and/or the nature of contact with the body, not every biocompatibility 
endpoint will warrant testing. In contrast, the biocompatibility endpoints identified in 
Attachment Amay not be sufficient to demonstrate the safety of certain devices (e.g., 
devices that include submicron or nanotechnology components, see Section V.D). In 
addition, biocompatibility endpoints such as neurotoxicity and immunotoxicity should be 
considered for devices where local or end organ toxicity assessments relevant to the 
implant location or toxicity issues of concern would not be assessed in a traditional 
biocompatibility study. For example, a neurological device having direct contact with 
brain parenchyma and cerebrospinal fluid (CSF) may necessitate an animal implant test 
to evaluate its pathological and physiological effects (e.g., effects on the brain 
parenchyma, neurobehavioral effects and/or neurological deficits, and effects on the 
functional mechanisms of the choroid plexus and arachnoid villi to secrete and absorb 
CSF). The specific clinical application and the materials used in the manufacture of the 
27For example, a material may be selected to provide a certain stiffness required for the device to perform 
appropriately (i.e., device characteristic), but may also have other material characteristics that could impact the 
biological response to the device (e.g., hydrophilic or hydrophobic surface).
15 Contains Nonbinding Recommendations
new device will guide selection of the appropriate biocompatibility evaluations. Where 
available, device-specific guidance documents may include additional safety assessments 
to be considered within the context of a biocompatibility evaluation.
Some devices are made of materials that have been well characterized both chemically 
and physically in the published literature and/or have a long history of safe use in legally 
marketed medical devices. It may not be necessary to conduct testing for all or a portion 
of the biocompatibility endpoints suggested in the FDA matrix of this guidance. For 
example, if the sponsor is able to document the use of a particular material (e.g., 316L 
stainless steel) in a legally-marketed predicate device or a legally-marketed device with 
comparable tissue exposure, and is able to explain why manufacturing is not expected to 
adversely impact biocompatibility, additional testing may not be necessary to address 
some or all of the biocompatibility endpoints recommended for consideration in 
Attachment A. Sponsors may also leverage information from existing marketing 
applications to support a rationale that the biocompatibility of the device has been 
established.28 Refer to Section III, Risk Management for Biocompatibility Evaluations, 
for additional information on how to use prior information in lieu of new testing. Also, 
refer toAttachment F, Component and Device Documentation Examples, for additional 
information on comparisons to a legally-marketed device.
B. FDA Use of ISO 10993-1  
The International Organization for Standardization (ISO), in an effort to harmonize 
biocompatibility testing, developed a standard for biological evaluation of medical 
devices (ISO 10993). The scope of this multi-part standard is to evaluate the effects of 
medical device materials on the body. The first part of this standard, "Biological 
evaluation of medical devices - Part 1: Evaluation and testing within a risk management 
process," provides a framework in which to plan biological evaluation of medical 
devices, and if needed, guidance for selecting tests to evaluate the biological response to 
medical devices. Most of the other parts of the ISO 10993 standard series discuss 
appropriate methods to conduct biological tests that may be identified when following 
Part 1 of the standard.   
With the 2009 and then the 2018 revisions to the ISO 10993-1 standard, the focus of the 
document changed from how to determine which biocompatibility tests to conduct, to an 
approach that considers existing information prior to determining if biocompatibility 
testing is needed. With the advancement of scientific knowledge regarding the basic 
mechanisms of tissue responses, FDA agrees with the ISO 10993-1:2018 revision focus 
on minimizing the number and exposure of test animals by giving preference to in vitro 
models and to chemical, physical, morphological, and topographical characterization 
testing, in situations where these methods yield equally relevant information to that 
obtained from in vivo models.29 For FDA submissions, biocompatibility information for 
the device in its final finished form, either developed through the risk management 
28For the purposes of a biocompatibility evaluation, leveraging information from other marketing applications could 
be appropriate in support of 510(k)s, PMAs, De Novos, HDEs, and initiation of IDEs.
29ISO 10993-1:2018 Biological evaluation of medical devices  Part 1 Evaluation and testing within a risk 
management process.
16 Contains Nonbinding Recommendations
process or from biocompatibility testing (using both in vitro and in vivo models), and/or 
adequate chemical, physical, morphological, and topographical characterization in 
conjunction with supplementary biocompatibility information that adequately address the 
biocompatibility risks of the device should be provided.
ISO 10993-1 uses an approach to biocompatibility evaluation that includes these seven 
general principles.
1. The selection of material(s) to be used in device manufacture and its 
biocompatibility evaluation should initially take into account the likelihood of 
direct or indirect tissue contact and any available information for the materials of 
manufacture, for example, chemical formulation for each component material, 
including adhesives, known and suspected impurities, and constituents associated 
with processing. 
 
For the purposes of submission to the FDA, in situations where details pertaining 
to the materials of manufacture may be proprietary information held by the 
material supplier, a master file for the material component(s) may assist in 
determining the formulation of some components of the final device (see 
Attachment B). However, this information alone may not be sufficient to establish 
the biocompatibility of the device. Currently there is no standard established for 
the content or completeness of a device master file. Because the information in a 
master file may be specific to the material and may not address device fabrication, 
the information contained in master files may be insufficient to address all of the 
characterization or biocompatibility questions that pertain to the medical device in 
its final finished form.
2. The material(s) of manufacture, the device in its final finished form, and possible 
leachable chemicals or degradation products should be considered for their 
relevance to the overall biocompatibility evaluation of the device.
3. Endpoints relevant to the biocompatibility evaluation should take into account the 
nature, degree, frequency, duration, and conditions of exposure of the device 
materials to the body. This principle may lead to the categorization of devices that 
would facilitate the selection of appropriate endpoints for inclusion in the overall 
biocompatibility evaluation.
4. Any in vitro or in vivo biological safety experiments or tests should be conducted 
in accordance with recognized Good Laboratory Practice (GLP) regulations30
including, but not limited to, the assignment of competent trained staff in the 
conduct of biocompatibility testing.
30FDA does not recognize ISO/IEC 17025 General requirements for the competence of testing and calibration 
laboratories.
17 Contains Nonbinding Recommendations
For the purposes of submission to the FDA, if information on these types of 
nonclinical laboratory studies31 is provided, a statement that all such studies have 
been conducted in compliance with applicable requirements in the Good 
Laboratory Practice regulation in 21 CFR 58 should also be provided. If any such 
study was not conducted in compliance with such regulation (e.g., for supporting 
historical data included with a regulatory submission), FDA recommends you 
include a statement in your submission explaining the reasons why the study was 
not in compliance with the GLP Regulations, as well as a detailed description of 
all deviations from the regulation. FDA recommends the statement include 
information that will help FDA reconstruct the study, explain any confounding 
variables, and demonstrate that authentic and complete test data have been 
collected and reported.
5. When test data are provided, complete experimental data, complete to the extent 
that an independent conclusion could be made, should be submitted to the 
reviewing authority. 
 
For the purposes of submission to the FDA, if testing is conducted according to an 
FDA-recognized consensus standard that does not include data reporting, 
submission of the test data is optional.
6. Any change in chemical composition, manufacturing process, physical 
configuration (e.g., size, geometry, surface properties) or intended use of the 
device should be evaluated with respect to possible changes in biocompatibility 
and the need for additional biocompatibility testing.
7. The biocompatibility evaluation performed in accordance with this guidance 
should be considered in conjunction with information obtained from other 
nonclinical tests, clinical studies, and postmarket experiences for a safety 
assessment that incorporates all available relevant information.
C. The FDA-Modified Matrix 
Like ISO 10993-1:2018, this guidance also uses a tabular format (matrix) to outline the 
recommendations for biological effects evaluation based on the various factors discussed 
above for biocompatibility information to be submitted in support of an IDE or marketing 
application.
Attachment A, Evaluation Endpoints for Consideration, includes biocompatibility 
endpoints for consideration recommended by ISO 10993-1:2018, and additional 
endpoints FDA recommends for consideration. Attachment Dis a biocompatibility 
evaluation flow chart explaining when additional biocompatibility evaluations beyond 
those recommended in ISO 10993-1 may be requested to fully characterize the 
biocompatibility profile, such as when novel materials or manufacturing processes are 
31See definition of nonclinical laboratory study at 21 CFR 58.3(d).
18 Contains Nonbinding Recommendations
used (i.e., materials or processes that have not previously been used in a legally marketed 
medical device with the same type and duration of contact).
If the device has multiple types of exposure, you should include information to address 
each exposure category identified for the device,32 even though testing may not be 
necessary for every exposure category, in your overall biocompatibility assessment. For 
example, a pacemaker may include both a pulse generator that is implanted 
subcutaneously and leads that are implanted within the cardiovasculature. Therefore, we 
have considered these devices to be classified as both tissue contact and blood contact 
devices for the evaluation of biocompatibility.   
In general, FDA agrees with the framework established in ISO 10993-1 for identification 
of the nature and duration of contact (e.g., cumulative effects with repeat use).33
However, FDA has made several modifications to the evaluations identified in that 
standard for the reasons outlined in Section IV.D and Attachment A.
D. Endpoint Assessment 
As described in Attachments A and C, sponsors should evaluate each biocompatibility 
endpoint and whether there is a need for additional testing. All biological effects included 
in the matrix may not be relevant for all devices. Thus, the modified matrix is only a 
framework for the selection of endpoints for consideration and not a comprehensive 
checklist of biocompatibility testing. A scientific rationale to support the use of 
previously collected information in lieu of additional biocompatibility testing should be 
included with the submission for each endpoint identified in Attachment A. Chemical 
formulation and processing information may not always be needed for all medical device 
submissions; however, this information may assist the sponsor to support justifications 
for waiving testing for any recommended endpoints.
ISO 10993-1:2018, Clause 4.1 states that Evaluation can include both a review of 
relevant existing preclinical and clinical data and actual testing. Such an evaluation might 
result in the conclusion that no testing is needed if the material has a demonstrable safe 
history of use in a specified role and physical form that is equivalent to that of the 
medical device under design. To conclude that no additional biocompatibility testing is 
needed, the sponsor should provide evidence that for each material, the type and duration 
of tissue contact, physical form, formulation, processing, component interactions, and 
storage conditions are the same as for the comparator device(s), or the comparator device 
is demonstrated to be worst case compared to the proposed device. In cases where there 
are differences, such differences should be explained and justified as to how prior data 
are applicable to support a biocompatibility assessment of the medical device in its final 
finished form. In vivo animal data and/or clinical data may be of limited utility (as 
discussed previously in Section III) if specific biocompatibility endpoints are not 
included as part of the data collected for these studies.
32We encourage sponsors to contact the appropriate Center and review division if there is a question about the 
appropriate evaluations for a particular device type.
33See ISO 10993-1:2018, Clause 5.2 Categorization by nature of body contact and Clause 5.3 Categorization by 
duration of contact.
19 Contains Nonbinding Recommendations
V. General Biocompatibility Testing Considerations 
Test article preparation is a critical variable in the conduct of the biocompatibility tests. 
Therefore, it is important to understand how the test articles compare to the medical device in its 
final finished form (e.g., sterile, if applicable). The example test article documentation language 
included in Attachment F can be used to detail how any differences may or may not affect 
biocompatibility of the medical device in its final finished form.
A. Use of Medical Device in Final Finished Form or 
Representative Test Article 
When biocompatibility testing is warranted, the Agency recommends testing medical 
devices in the condition that they will be used, whenever possible. This could include 
final packaged devices, or as sterilized by an end user, if appropriate. If the medical 
device in its final finished form cannot be used for biocompatibility testing, a test article 
(e.g., coupons or representative components) may be considered. The representative 
test article should undergo the same manufacturing and sterilization processes, have the 
same chemical, physical, and surface properties, and have the same ratio of component 
materials as the medical device in its final finished form. In situations where differences 
exist between the medical device in its final finished form and the test article, additional 
information describing how these differences could impact study findings should be 
provided. For example, when testing an individual device component, a low-level tissue 
response could be observed, but when all of the components are tested within a medical 
device in its final finished form, a more robust tissue response could occur. If there are 
differences between the medical device in its final finished form and the representative 
test article, additional information may aid in determining the appropriateness of the 
selected test article. For example, extraction and surface characterization techniques may 
be appropriate to demonstrate that the surfaces are equivalent in geometry and surface 
properties, and that the chemicals leaching from the test article display the same kinetics, 
chemical identity and relative quantity as those eluting from the medical device in its 
final finished form. For example, for long term or absorbable implants, FDA may request 
data from exhaustive extraction studies (per ISO 10993-18) and surface characterization 
information to support use of the representative test articles. See also Attachment F.
B. Testing of In Situ Polymerizing and/or Absorbable 
Materials 
Fordevices made from in situ polymerizing and/or absorbable materials, we recommend 
that test article preparation be representative of the device in its final finished form. In 
addition, we recommend that biocompatibility be evaluated for the medical device in its 
final finished form as well as at various time points over the course of polymerization 
and/or degradation to ensure that starting, intermediate, and final degradation products 
are assessed. Should biocompatibility assessment of the materials during degradation be 
needed, preparation of test articles using in vitro degradation methods may be considered 
with appropriate technical justification. Test articles degraded in vitro may be used for 
20 Contains Nonbinding Recommendations
biological testing, and/or chemically analyzed to show that the material breaks down into 
intermediate or final degradation products that are known to be non-toxic at the levels 
present. However, depending on the materials of manufacture and the degradation testing 
conditions, accelerated degradation testing may not result in the same intermediate or final 
degradation products and therefore may not be acceptable.
For in vivo tests for devices made of in situ polymerizing or absorbable materials, the 
assessment time points would depend on the polymerization and degradation kinetics. We 
recommend that assessments be targeted to demonstrate how the device materials degrade 
over time and continue until the absorbable material and/or its degradation products are no 
longer present in the tissue (e.g., microscopically), if possible. Alternatively, it may be 
acceptable to provide a rationale for ending the study earlier, if the rationale includes an 
estimate of the percentage (%) of absorbable material remaining in the tissue, and 
confirmation that a steady state biological tissue response is achieved.
For in vitro biocompatibility tests conducted with extracts of an in situ polymerizing or 
absorbable device, chemical analytical testing of the extract may be useful to determine 
whether the extract is representative of leachables during the polymerization or 
degradation processes, and if multiple biocompatibility tests with different extracts are 
needed to represent different stages of the polymerization or degradation processes. If test 
articles are pre-polymerized prior to extraction, unreacted constituents that may be available 
during physiologic polymerization may or may not be available for extraction from a pre-
polymerized test article. For systems that may not be polymerizable in traditional extraction 
media, alternative approaches may be necessary.
C. Biological Response Resulting from Device Mechanical 
Failure 
Thescope of ISO 10993-1 includes biological hazards arising from mechanical failure, 
and FDA agrees this potential risk is important to consider when conducting 
biocompatibility evaluations. For some devices, it may be possible that mechanical 
failure could alter the biological response to the device. For example, if coating particles 
or wear debris are released from a device, those particles could lead to a biological 
response because of their material properties, such as geometric and/or physicochemical 
properties.34 In addition, coating delamination or component release or failure could 
expose the biological system to leaching of different chemicals, or to an increased level 
of chemicals from a substrate material. Another consideration is whether the surface 
topography could change with mechanical loading in such a way that the biological 
response changes. We recommend that your test article selection for any biocompatibility 
testing incorporate these considerations. If your biocompatibility evaluation does not 
include testing to evaluate potential biological hazards due to mechanical failure, your 
34FDAs Guidance for Industry and FDA Staff:  Preparation and Review of Investigational Device Exemption 
Applications (IDEs) for Total Artificial Discs available at https://www.fda.gov/regulatory-information/search-fda-
guidance-documents/preparation-and-review-investigational-device-exemption-applications-ides-total-artificial-
discsrecommends that wear particles, which result from dynamic device loading during use, be assessed to 
evaluate the local and systemic responses (e.g., biocompatibility, neurologic response, tissue response, and toxicity) 
to the wear debris. 
21 Contains Nonbinding Recommendations
rationale for why such testing is not needed may include the results of other nonclinical 
tests, such as bench testing or in vivo animal studies. For example, inadequate surface 
treatment of nitinol devices might result in non-optimized passivation layers that can be 
further compromised by mechanical loading, such as during device placement. This could 
result in nickel, a known renal toxin, sensitizer, genotoxin and possible co-carcinogen, 
being released at levels that could be toxic. If processing includes an adequate passivation 
method, and corrosion testing confirms that an appropriate passivation layer exists, the 
risk for nickel toxicity is minimized, and testing to assess biological endpoints and/or 
nickel leaching may not be necessary.35
D. Submicron or Nanotechnology Components 
There can be unique properties associated with submicron (< 1 micron) or 
nanotechnology components such as aggregation, agglomeration, immunogenicity, or 
toxicity.36,37 Medical devices with submicron components may warrant specialized 
techniques if characterization and biocompatibility testing is needed.38 Limitations may 
apply when using chemical leachates-based ISO 10993-12 test conditions for the analysis 
of submicron component biocompatibility assessments. The sponsor should consult 
relevant literature and standards during the development of test protocols for device-
specific submicron or nanotechnology component biocompatibility assessments, and 
contact the respective Center and review division prior to initiation of any tests.
For biocompatibility assessment of devices with submicron components, you should 
consider the following:
 Careful characterization of the test article.
 Selection of extract conditions (e.g., solvent type) that avoid testing artifacts.
 Assurance that the test article used is representative of the device that is intended 
to be used clinically. 
For test selection, the following items are also important:
 Consideration of standard biocompatibility tests in the context of contemporary 
literature regarding the validity of individual tests for assessment of devices with 
submicron components.
35Refer to FDAs guidance document Technical Considerations for Non-Clinical Assessment of Medical Devices 
Containing Nitinol available at https://www.fda.gov/regulatory-information/search-fda-guidance-
documents/technical-considerations-non-clinical-assessment-medical-devices-containing-nitinolfor additional 
recommendations on assessing the biocompatibility of nitinol devices.
36Kunzmann, A., et al., Toxicology of engineered nanomaterials: Focus on biocompatibility, biodistribution and 
biodegradation. Biochim Biophys Acta, 2011, 1810(3): 361-373.
37Rivera, G.P., et al., Correlating physico-chemical with toxicological properties of nanoparticles: the present and 
the future. ACS Nano, 2010, 4(10): 5527-5531.
38For example, ASTM F1903 Standard Practice for Testing for Cellular Responses to Particles in vitro or ASTM 
F1904 Standard Practice for Testing the Biological Responses to Medical Device Particulate Debris and 
Degradation Products in vivo.
22 Contains Nonbinding Recommendations
 Assurance that the submicron components will not interfere with the conduct of a 
chosen test.
 Consideration of any additional toxicity issues that might be relevant to 
submicron particles, such as absorption, distribution, and accumulation into 
organs, potential metabolism, and elimination, since there are greater concerns 
associated with submicron particles that cannot be readily detoxified and/or 
eliminated from the body.
E. Test Article Preparation for Extract Testing 
For biocompatibility testing conducted using extracts of the test article,39 we recommend 
that you:
 Determine the appropriate amount of test article as outlined in ISO 10993-12 or 
another FDA-recognized standard (e.g., ASTM F619 Standard Practice for 
Extraction of Materials Used in Medical Devices), using surface area to extract 
volume ratios. Mass to extract volume ratios should only be used if surface area 
cannot be calculated, or if use of mass will result in a test article with a larger 
surface area to extract volume ratio than recommended by ISO 10993-12. If there 
is a need for an alternate extraction ratio, appropriate justification should be 
provided. For example, for fluid path devices or components (where fluids contact 
the channels in the device or component, and then the fluid enters the body), the 
fluid path can be filled to capacity. If the ISO 10993-12 recommended surface 
area to extract volume cannot be achieved, the fluid contacting surface area and 
extraction volume should be noted in the test report. This approach can be used 
for both static and dynamic extractions. For some test systems, there may be 
standardized alternatives for test-specific extraction conditions that provide a 
different level of extraction (e.g., guinea pig maximization testing per ISO 10993-
10 Biological evaluation of medical devices  Part 10: Tests for skin 
sensitization). 
 Use both polar and nonpolar solvents, such as those described in ISO 10993-12. 
In some cases, other solvents may be used, where appropriate. For example, a 
mixed polarity solvent (e.g., cell culture medium with 5-10% serum for 
cytotoxicity testing) is appropriate to extract both hydrophilic and lipophilic 
chemicals. Also, where devices do not have direct contact with the body but only 
have indirect contact via a polar solution (e.g., assessment of the inner channel 
material of a cardiovascular catheter where the inner channel is only used for the 
infusion of saline), a rationale for waiving testing with a non-polar solution 
should be provided. For some tests such as material-mediated pyrogenicity, where 
the extract is injected intravascularly, a polar extract is sufficient.
39For biocompatibility testing, extracts could include leachable residuals at the surface of test articles or extractables 
migrating from the bulk of test articles.
23 Contains Nonbinding Recommendations
 Use extraction conditions that are adequate for testing of extractables and 
leachables from the device given its intended use. Traditional biocompatibility 
extraction methods, such as those in ISO 10993-12:2021 (e.g., 37 C for 72 hours; 
50 C for 72 hours; 70 C for 24 hours; or 121 C for 1 hour) are acceptable for 
many biocompatibility tests. For prolonged contact devices and those categorized 
as long term devices, extraction at 37 C may not be sufficient to obtain an extract 
that represents the chemicals extracted over the duration of device use. However, 
in some cases, temperatures above 37 C result in chemicals that may not occur in 
clinical use and may result in adverse biological responses not representative of 
the medical device in its final finished form. For example, for devices that contain 
heat labile or heat sensitive materials (e.g., drugs, biomolecules, tissue-derived 
components), which may have the potential to undergo deformation or material 
configuration/structural change at high temperature, extraction at 37 C per ISO 
10993-12 is recommended, but some additional information on how the chemistry 
of the device will change over time may also be needed. In all cases, a 
justification for the selected extraction conditions should be provided.
 Describe the condition of the test extract (e.g., color, presence of any particles), 
and describe any changes in the extraction solvent (pre- and post-extraction) and 
explain the source of these changes (e.g., test article degradation).
 Use the extracts without additional processing (e.g., no filtration, centrifugation, 
or other methods to remove particulates; no pH adjustment), unless otherwise 
justified.
 If test article extracts are not used immediately, we recommend that you use them 
within the time frame outlined in ISO 10993-12 or an equivalent method. We 
recommend that you describe the details of storage conditions for the test extract, 
and explain why storage will not affect your test results (i.e., as stated in ISO 
10993-12:2021, stability and homogeneity of the extract under the storage 
conditions shall be verified).
F. Inclusion of Multiple Components or Materials in a 
Single Test Article 
For devices that include components with different lengths of contact (e.g., categorized as 
limited, prolonged, or long term), we recommend that any extract-based biocompatibility 
testing be conducted separately.40 If the components are combined into a single test 
article, this will dilute the amount of component materials being presented to the test 
system and may not accurately identify potentially toxic agents that would have been 
found if the components were tested separately. For example, we recommend testing 
implants separately from delivery systems or other kit components.
40In many cases, it is acceptable to combine components with limited (< 24 hour) use, with an appropriate 
supporting rationale. However, separate assessments of devices with prolonged (24 hour to 30 day) or long term (> 
30 day) duration of contact are recommended.
24 Contains Nonbinding Recommendations
For devices or device components that contain multiple materials with differing surface 
areas or differing exposure to the body, if one or more materials is new (i.e., not used 
before in devices with the same type and duration of contact), it may also be necessary to 
test the new material component(s) separately as well, to further understand the potential 
toxicity of this component. For example, for a catheter-based delivery system that contains 
a new balloon material, tests of the delivery system separate from the balloon may be 
necessary to ensure adequate assessment of each of the materials.
VI. TestSpecific Considerations 
If your risk assessment indicates that testing is warranted, we recommend that you consider the 
following issues when conducting any of the tests identified below. While there are other 
biocompatibility endpoints identified in Attachment A, only certain tests are discussed below. 
The test-specific issues discussed in this section have been included because they are often areas 
where deficiencies are frequently identified in premarket submissions.
A. Cytotoxicity 
If not otherwise addressed during the risk assessment process, for tests where the test 
article is extracted in growth media, we recommend that extractions be conducted at 37 
C for 24 to 72 hours using a vehicle that will allow for extraction of both polar and 
nonpolar constituents from the test article, such as mammalian cell culture media (e.g., 
MEM) supplemented with 5-10% serum. 
For novel materials (i.e., materials that have not previously been used in a legally 
marketed medical device with the same type and duration of contact), we recommend that 
both direct contact and elution methods be considered. For some devices, a direct contact 
study per ISO 10993-5 may be needed to better reflect clinical use. Depending on the 
nature and function of the material (e.g., coatings or surface topography modifications), a 
non-standard direct contact study, where the cells are grown on a material surface, may 
be needed if no implantation data are available.
For materials that are inherently cytotoxic, additional testing using various dilutions of 
the test solution may be necessary to determine the level at which cytotoxicity no longer 
occurs. This information can be evaluated with respect to the clinical dose as well as 
other mitigating factors such as duration of contact and clinical need (e.g., clinical 
benefits versus risks). For some devices, such as dental acid etchants, devices containing 
a known cytostatic/cytotoxic agent, or uncured polymer resins, additional comparative 
cytotoxicity testing using a legally marketed medical device may be necessary to 
demonstrate that the new device is no more cytotoxic than the comparative device with 
the same type and duration of contact.
B. Sensitization  
There are two types of sensitization tests that are generally submitted in support of IDE 
and marketing applications: the Guinea Pig Maximization Test and the Local Lymph 
25 Contains Nonbinding Recommendations
Node Assay. In addition, the Buehler method can be used for topical devices only (i.e., 
those in contact with skin), per ISO 10993-10.
Guinea Pig Maximization Test (GPMT) 
For this test, male and/or female healthy young adult animals should be used. If female 
animals are used, we recommend that test reports confirm that the animals are nulliparous 
and non-pregnant, as pregnancy can reduce the ability of a female animal to detect a 
sensitization response.
Assays with positive controls using the same source and strain of animals should be 
performed regularly (at least once every six months, or if longer, concurrent with the test 
assays) to ensure the reproducibility and sensitivity of the test procedure. We recommend 
that test reports include positive control data from concurrent testing or from positive 
control testing within three months (before or after) of the device testing using the same 
methods and source and strain of animal.41 We also recommend that your positive control 
testing include a minimum of five animals to demonstrate a reproducible and 
appropriately positive response in the test system. If a periodic positive control fails, all 
GPMT data generated after the last valid positive GPMT response should be considered 
invalid because there is no assurance that the test system is working appropriately. 
Therefore, repeating positive control testing to justify a failed positive control test would 
not be sufficient. If root cause analysis confirms the loss of sensitivity of the animal herd 
to the positive control, repeating device testing using a new animal herd is recommended 
for any GPMT data collected between the successful and failed periodic positive control 
testing.
If a preliminary irritation study is not included in the sensitization protocol, adverse 
findings at the end of the study may be due to irritation or sensitization, and additional 
irritation studies to determine the causality may be needed.
Local Lymph Node Assay (LLNA)
FDA intends to evaluate use of LLNA tests for medical devices on a case-by-case basis 
for medical device extract/residuals that are composed of chemical mixtures. LLNA tests 
may be appropriate in the following circumstances: 
 The LLNA can be used for testing metal compounds (with the exception of nickel 
and nickel-containing metals) unless there are unique physicochemical properties 
associated with these materials (e.g., nanomaterials) that may interfere with the 
ability of the LLNA to detect sensitizing materials.
41ISO 10993-10:2021 Biological evaluation of medical devices  Part 10: Tests for skin sensitization states that for 
sensitization testing a positive control does not need to be included in every assay, but may be run at regular 
intervals which shall not exceed six months. The standard further states that Using a positive control only once 
every six months can have consequences for the results obtained in the previous six months period when this 
positive control shows a negative outcome. FDA has not historically recommended that sponsors wait up to six 
months for the subsequent positive control data to support submissions to the FDA. Instead, FDA has historically 
accepted studies with positive control data conducted within three months of the device test.
26 Contains Nonbinding Recommendations
 The LLNA can be used for testing device materials in aqueous solutions unless 
there are unique physicochemical properties associated with these materials (e.g., 
nanomaterials) that may interfere with the ability of the LLNA to detect 
sensitizing chemicals. When testing device materials in aqueous solutions, it is 
essential to use an appropriate vehicle to maintain the test extract in contact with 
the skin (e.g., 1% Pluronic L92)42 so that adequate exposure can be achieved, as 
demonstrated by positive control results.
LLNA should not be used in the following circumstance:
 For devices made from novel materials (i.e., that have not been previously used in 
a legally marketed medical device), or when testing substances that do not 
penetrate the skin but are used in devices that contact deep tissues or breached 
surfaces [per ASTM F2148-18, Section 1.2], we recommend the use of the 
GPMT test. For novel materials, it is unknown whether chemicals will be able to 
penetrate the skin in an LLNA test, so GPMT (which includes intradermal 
injection at induction) is recommended.  
 
If LLNA testing is performed, FDA recommends that a fully validated standardized 
method be used. Currently, the only FDA-recognized validated method is a radioactive 
LLNA test performed in accordance with ASTM F2148 Standard Practice for Evaluation 
of Delayed Contact Hypersensitivity Using the Murine Local Lymph Node Assay (LLNA).
The following test methods may be used as alternatives. If a nonradioactive LLNA 
method, such as the LLNA: 2-Bromodeoxyuridine-Enzyme Linked Immunosorbent 
Assay (BrdU-ELISA) test or the LLNA: Daicel Adenosine Triphosphate (DA) test, is 
used, we recommend you also consider the following:
 For the LLNA: BrdU-ELISA test, the accuracy and reliability supports the use of 
the test method to identify device materials as potential skin sensitizers and non-
sensitizers using a stimulation index (SI)  1.6 as the decision criterion to identify 
substances as potential sensitizers. For borderline positive responses between an 
SI of 1.6 and 1.9, there is a potential for false positive results that could limit the 
usefulness of this type of LLNA test.
 For the LLNA: DA test, the accuracy and reliability support use of the test 
method to identify device materials as potential skin sensitizers and non-
sensitizers using a stimulation index (SI)  1.8 as the decision criterion to identify 
substances as potential sensitizers. For borderline positive responses between an 
SI of 1.8 and 2.5 there is a potential for false positive results that could limit the 
usefulness of this type of LLNA test. In addition, the LLNA: DA is not 
appropriate for testing device materials that affect ATP levels (e.g., chemicals that 
function as ATP inhibitors) or those that affect the accurate measurement of 
42Boverhof, D.R., et al., Interlaboratory validation of 1% pluronic L92 surfactant as a suitable, aqueous vehicle for 
testing pesticide formulations using the murine local lymph node assay. Toxicol Sci, 2008, 105(1): 79-85.
27 Contains Nonbinding Recommendations
intracellular ATP (e.g., presence of ATP degrading enzymes, presence of 
extracellular ATP in the lymph node).
C. Hemocompatibility  
Fordevices having direct contact with circulating blood (regardless of contact duration), 
we recommend that you consider hemolysis, complement activation, and 
thrombogenicity testing, if not otherwise addressed during the risk assessment process. 
For devices having indirect contact with circulating blood (regardless of contact 
duration), we recommend that you consider only hemolysis testing, as complement 
activation and in vivo thrombogenicity testing are generally not needed for indirect blood-
contacting devices. However, for novel materials not previously used in legally marketed 
devices with cardiac or vascular applications, or for devices intended to release a 
chemical into the circulating blood, some in vitro assessment of thrombogenicity (e.g., 
the effect of extractables and leachables on platelets and the coagulation system) may 
also be needed for devices with indirect contact with blood.  
 
Where a risk assessment has determined that hemocompatibility testing is not necessary, 
we recommend that you provide a summary of the assessment that supports waiving 
these specific tests. For example, to support waiving thrombogenicity testing, the 
materials used in formulation and processing, as well as the geometry of the device (e.g., 
shape, dimensions, surface roughness, surface defects), should be compared to a legally 
marketed device with similar blood contacting duration and an acceptable history of use 
(see Attachment F).
Hemolysis
For hemolysis testing of devices having direct contact with circulating blood, we 
recommend that both direct and indirect (extract) methods for material/surface-mediated 
hemolysis be conducted per ASTM F756 Standard Practice for Assessment of Hemolytic 
Properties of Materials or an equivalent method. For hemolysis testing of devices having 
indirect contact with circulating blood, we recommend that only an indirect (extract) 
method be conducted per ASTM F756, or an equivalent method. For devices or device 
components that do not have direct or indirect contact with circulating blood, this testing 
is generally not needed. For example, devices applied to the external surface of a blood 
vessel may not need hemolysis testing, unless there is a risk for some components to 
access the circulating blood (e.g., hemolysis testing should be performed on sealants 
applied to vessel sutures).
For some devices where high shear stress due to blood flow may be an issue, dynamic 
hemolysis assessment under clinical use conditions may also be important. See relevant 
device-specific guidance documents.43
43For example, FDAs guidance document Implanted Blood Access Devices for Hemodialysis  Guidance for 
Industry and Food and Drug Administration Staff available at https://www.fda.gov/regulatory-information/search-
fda-guidance-documents/implanted-blood-access-devices-hemodialysisincludes information on mechanical 
hemolysis testing recommendations for these devices.
28 Contains Nonbinding Recommendations
Complement Activation
Medical device-mediated complement activation is a complex process and is a function 
of physical and chemical properties of the device. Many factors such as device surface 
area, surface architecture, and chemical composition (e.g., functional groups)44 may 
affect complement activation. If complement activation testing is performed for devices 
having direct contact with blood, we recommend that you perform this testing with the 
device (i.e., a direct contact study) instead of with an extract of the device. For in vitro 
complement activation testing, we recommend assessment of SC5b-9 fragment activation 
using an established ELISA test method. Functionally intact serum is preferred for in 
vitro static complement activation testing.45,46 If whole blood or plasma is used, the 
type of anticoagulant should be carefully selected to ensure that it does not inhibit or 
potentiate complement activation caused by the test device itself. If whole blood or 
plasma is used, test validation information should be provided to confirm that the testing 
is capable of detecting differences between negative and positive reference controls. For 
data interpretation, the test results are deemed satisfactory if there is no statistically 
significant difference between the test article and the negative control. However, if the 
differences between the test article and the negative control are statistically significant, 
performing complement activation testing using a legally marketed comparator device 
may be helpful for data interpretation. This is because there are no established pass/fail 
criteria for a clinically acceptable level of complement activation. This comparator data 
can therefore be used to assess the biological relevance of the results obtained with the 
test device in the in vitro model. Equivalent methods for testing complement activation 
such as in vivo animal models, in vitro static methods such as ASTM F1984 Standard 
Practice for Testing for Whole Complement Activation in Serum by Solid Materials, or in 
vitro dynamic testing using simulated clinical flow conditions can be used if 
accompanied by appropriate validation information as outlined above. Alternatively, you 
can provide a rationale for waiving complement activation testing, if all the materials 
used in the formulation and processing of the device have a history of previous use in 
blood-contacting devices with comparable or larger surface area and equivalent contact 
duration. 
Thrombogenicity
In keeping with the Agencys position on minimizing animal use for device testing, we 
recommend that thrombogenicity be assessed as part of a safety or functional study 
conducted in a relevant animal model, if such a study is generally conducted for a 
particular device type. For example, the safety of cardiovascular stents is commonly 
evaluated in an animal model and could include thrombogenicity assessments of the 
delivery system and the implanted device. Protocols for studies with thrombogenicity 
endpoints should include appropriate methods to assess device-associated thrombus 
formation (e.g., photographic evidence) and thromboembolism in relevant downstream 
44Moghimi, S.M., et al., Material properties in complement activation. Adv Drug Deliv Rev, 2011, 63(12): 1000-
1007.
45Harboe, M., et al., Advances in assay of complement function and activation. Adv Drug Deliv Rev, 2011, 
63(12): 976-987.
46Lachmann, P.J., Preparing serum for functional complement assays. J Immunol Methods, 2010, 352 (1-2): 195-
197.
29 Contains Nonbinding Recommendations
organs. If device thrombus is evident at explantation, or the device is intended for use 
upstream from a vital organ, additional histopathological analysis may be helpful to 
assess local, upstream, and downstream tissue(s).
When performing in vivo tests, there are many parameters that could affect the results of 
the test, including:
 animal species;
 positioning of the animal during the operation to simulate clinical positioning;
 anticoagulation regimen, if applicable;
 implantation technique to minimize vessel trauma at the implant site;
 vessel to device diameter ratio, where larger vessels should be used for larger 
diameter devices to maintain a diameter relationship similar to what will be seen 
in patients, and to avoid artifactual disruption of blood flow and contact with the 
vessel wall;
 device positioning and securement to ensure blood flow around the device; and
 explantation technique to ensure minimal disruption of adhered thrombus and to 
minimize post-mortem clot formation.
When performing in vivo studies, fluoroscopy may be useful to ensure proper device 
placement. If only a portion of the device is being utilized for thrombogenicity testing, 
the sponsor should confirm that the test article is representative of all materials and 
important geometrical/surface features that would have direct contact with the blood. In 
addition, we recommend that for all in vivo thrombogenicity assessments, color 
photographs of the device/vessel explants be provided.
For some devices such as oxygenators, for which in vivo animal studies are generally not 
conducted, a series of in vitro or ex vivo blood damage assessments may be used to 
support regulatory submissions. In particular, a battery of in vitro tests to include 
assessment of platelets (e.g., adhesion, activation), and the coagulation system [e.g., 
Thrombin-Antithrombin Complex (TAT), Partial Thromboplastin Time (PTT)47] may be 
used as a substitute for in vivo thrombogenicity testing. For assessment of changes only 
to the material, but not to the geometry or surface characteristics of the device, testing in 
a static environment (e.g., with gentle agitation of the blood in the absence of simulated 
clinical flow conditions) may be sufficient. However, for new devices, and/or for changes 
to the geometry of an existing device, assessment of flow-mediated thrombosis under 
47This would not be the activated PTT (aPPT) test that is used clinically. As noted in ISO 10993-4:2017 Biological 
evaluation of Medical Devices  Part 4: Selection of tests for interaction with blood, the activated PTT (aPTT) test 
is rarely useful in the in vitro evaluation of the thrombogenic properties of blood-contacting devices/materials 
because the activating substances mask any activation caused by the device or its component materials. 
30 Contains Nonbinding Recommendations
simulated clinical flow conditions is recommended. This study design should include the 
assessment of platelets, the coagulation system, and macroscopic thrombus formation.
For in vitro tests, the use of human blood is preferred. If blood from multiple donors 
cannot be pooled together for use in a single test, we recommend that blood from a 
different donor be used for each repeat test to demonstrate that results arent impacted by 
donor variability. For tests that require large blood volumes, animal blood may be used 
with justification. The flow conditions (e.g., gentle agitation versus clinically relevant 
flow), and the type and concentration of anticoagulation used for in vitro testing, may 
depend on the test system and the clinical indication of the device. We recommend 
validation of the test conditions to confirm that the test can differentiate between positive 
and negative responses.
In some cases additional thrombogenicity evaluation may be needed, for example, if:
 your device includes novel materials that have not previously been used in legally 
marketed devices with blood-contact, especially if the potential exists for use of 
the device in non-anticoagulated patients, or
 there are questionable or inconclusive hemocompatibility findings from an in vivo 
safety study or previously conducted in vitro thrombogenicity studies.
This evaluation might include additional in vitro or in vivo testing, depending on the 
specific device type, intended clinical use, and concerns (if any) from prior testing.
In certain instances, an acute (e.g., four to six hours) non-anticoagulated animal study 
may be needed, for example:
 for devices that are not always used with anticoagulation (e.g., diagnostic cardiac 
catheters), 
 for patients where anticoagulants cannot be used for clinical reasons (e.g., for 
devices intended to treat patients with hemophilia), or
 when investigating design features intended to reduce the potential for 
thrombogenicity (e.g., the effectiveness of a coating).
While non-anticoagulated in vivo studies have limitations, when performed correctly, 
they can provide useful information on how synergistic mechanisms (e.g., material and 
geometry of the device, arterial versus venous blood flow) influence thrombosis.
If a non-anticoagulated in vivo study results in elevated thrombus scores (i.e., the device 
is not thromboresistant), it may be necessary to screen for device-related characteristics, 
such as surface defects (e.g., microscopy with at least 40x magnification), that may 
contribute to the thrombogenicity. In some cases, a detailed analysis of your device 
geometry and surface as compared to a legally marketed device may also be beneficial. 
Depending on the level of thrombus seen, the surface analysis results, and the potential 
31 Contains Nonbinding Recommendations
risk to the patient, we may recommend that you repeat the in vivo study with clinically 
relevant levels of anticoagulant to confirm that the anticoagulant will counter the 
thrombogenic response seen in the non-anticoagulated model.48 In this case, labeling may 
also be needed to contraindicate the use of the device in non-anticoagulated patients.
D. Pyrogenicity  
Implants (due to their contact with the lymphatic system), as well as sterile devices 
having direct or indirect contact with the cardiovascular system, the lymphatic system, or 
cerebrospinal fluid (CSF) (regardless of duration of contact) and devices labeled as non-
pyrogenic, should meet pyrogen limit specifications.49 Pyrogenicity information is used 
to help protect patients from the risk of febrile reaction. There are two sources of 
pyrogens that should be considered when addressing pyrogenicity. The first, material-
mediated pyrogens, are chemicals that can leach from a medical device during device 
use.50 Pyrogens from bacterial endotoxins can also produce a febrile reaction similar to 
that mediated by some materials.  
If recommended for consideration perAttachment A, material-mediated pyrogenicity 
testing is not needed if chemical characterization of the device extract and previous 
information indicate that all patient-contacting components have been adequately 
assessed for pyrogenicity. Otherwise, we recommend that you assess material-mediated 
pyrogenicity using traditional biocompatibility extraction methods (e.g., 50 C for 72 
hours; 70 C for 24 hours; or 121 C for 1 hour per ISO 10993-12:2021), using a 
pyrogenicity test such as the one outlined in USP <151> Pyrogen Test (USP Rabbit Test) 
or an equivalent validated method. For devices that contain heat labile or heat sensitive 
materials (e.g., drugs, biomolecules, tissue-derived components), which may have the 
potential to undergo deformation or material configuration/structural change at high 
temperature, extraction at 37 C per ISO 10993-12:2021 is recommended.
48Historically, some have proposed the use of anticoagulant in a four hour canine in vivo thrombogenicity study to 
support regulatory submissions. Anticoagulant use in this type of study may significantly affect the ability of the 
study to provide informative data regarding the thrombogenic potential of a device. Therefore, data from this type of 
study is generally only useful for comparative purposes (i.e., to determine if clinically relevant anticoagulation will 
counter any thrombogenic effects seen in non-anticoagulated studies).
49Refer to FDAs Guidance for Industry  Pyrogen and Endotoxins Testing:  Questions and Answers (June 2012) 
for information on pyrogen limit specifications.
50Even over a relatively short duration of use, chemical pyrogens can be released within the body and initiate a 
febrile reaction.
32 Contains Nonbinding Recommendations
Bacterial pyrogens51 are traditionally addressed as part of the sterility assessment. We 
recommend that you refer to the most recent sterility guidance document52 for 
recommendations related to testing to determine endotoxin levels for sterile devices.53
If a sponsor would like to label their device non-pyrogenic even if there are no 
endotoxin limit specifications based on the nature of body contact, we recommend that 
both the bacterial endotoxin and rabbit material-mediated pyrogen testing be conducted.
E. Implantation 
For implantation testing, if there are characteristics of the device geometry that may 
confound interpretation of this test, it may be acceptable to use device sub-components or 
coupons instead of the device in its final finished form, with appropriate justification. For 
example, it may be acceptable to use a coupon instead of a stent, if information is provided 
to demonstrate that the manufacturing and resulting surface properties are comparable.
Instead of a traditional toxicology implantation study in subcutaneous, muscle, or bone 
tissues, a clinically relevant (e.g., brain, vascular) implantation assessment may be more 
appropriate for certain implant devices with relatively high safety risks, as described in 
ISO 10993-6 Biological evaluation of medical devices  Part 6: Tests for local effects 
after implantation. Clinically relevant implantation54 studies are critical to determine the 
systemic and local tissue responses to the implant in a relevant anatomical environment 
under simulated clinical conditions.55 In some cases, the toxicity outcomes that would be 
obtained from a clinically relevant implantation study can be assessed as part of in vivo 
animal studies that are performed to assess overall device safety (e.g., the protocol for an 
animal study to evaluate delivery and deployment of a device may also include 
assessment of relevant toxicity endpoints).
51This section of the guidance is addressing only the potential issues with febrile reactions, but bacterial endotoxins 
can also lead to inflammation (e.g., swelling, pain).
52Refer to FDAs guidance document Submission and Review of Sterility Information in Premarket Notification 
(510(k)) Submissions for Devices Labeled as Sterile  Guidance for Industry Food and Drug Administration Staff 
available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/submission-and-review-
sterility-information-premarket-notification-510k-submissions-devices-labeled. Refer also to FDAs Guidance for 
Industry  Pyrogen and Endotoxins Testing:  Questions and Answers https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/pyrogen-and-endotoxins-testing-questions-and-answersfor information 
on testing for bacterial endotoxin.
53Although the sterility guidance was written to address sterility information for 510(k) submissions, the 
information about bacterial endotoxin testing is also relevant to devices submitted in IDE or other marketing 
applications.
54For information on FDAs recommendations for animal studies intended to evaluate medical devices, see FDAs 
guidance titled General Considerations for Animal Studies Intended to Evaluate Medical Devices available at
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/general-considerations-animal-studies-
intended-evaluate-medical-devices
55For active implantable devices, see relevant device-specific guidance documents for information regarding the 
need for active stimulation during implantation studies, such as FDAs Guidance for Industry and FDA Staff  
Guidance for the Submission of Research and Marketing Applications for Pacemaker Leads and Lead Adaptor 
510(k) Submissions available at https://www.fda.gov/medical-devices/guidance-documents-medical-devices-and-
radiation-emitting-products/submission-research-and-marketing-applications-permanent-pacemaker-leads-and-
pacemaker-lead-adaptor
33 Contains Nonbinding Recommendations
Clinically relevant implantation and muscle or subcutaneous implantation tests may be 
informative to the overall biocompatibility assessment of both the material components 
of the device and the device in its final finished form when used in its intended 
anatomical location. Muscle or subcutaneous implantation tests often are not needed 
when clinically relevant implantation studies are conducted. However, the muscle or 
subcutaneous implantation study may be helpful as a screening test to assess local 
toxicities. For example, because the muscle implants tend to form a fibrous capsule 
around the implant, any materials eluted over time from the test article may be contained 
within the capsule, and therefore may result in an exaggerated response not observed in 
the site-specific implantation study. In addition, a well-defined muscle implantation study 
is often helpful to interpret the data from clinically relevant implantation studies that may 
include other confounding factors (e.g., concomitant treatments may interfere with tissue 
response). Therefore, muscle implantation studies should be considered as a supplemental 
test even when clinically relevant implantation studies are performed, especially when 
new materials/chemicals are used in a medical device or the results of a clinically 
relevant implantation study raise toxicity concerns.  
For implantation testing of devices with materials that are intended to degrade, we 
recommend that tests include interim assessments to determine the tissue response during 
degradation (i.e., when there is minimal or no degradation, if applicable; during 
degradation to demonstrate a pattern of progressive degradation; and once a steady state 
has been reached with respect to material degradation and tissue response). Selection of 
interim assessment time points may be based on in vitro degradation testing.
F. Genotoxicity 
Genotoxicity testing may not be needed if chemical characterization of device extracts 
and literature references indicate that all components have been adequately tested for 
genotoxicity.
Genotoxicity testing may not be informative for devices containing materials already 
known to be genotoxic, because a positive result will be assumed to be due to the known 
genotoxin. Thus, a second genotoxin from another source may be overlooked. If 
genotoxicity testing is performed, a negative result should be interpreted as a negative for 
the other device components or interaction products, but does not necessarily negate the 
risk of the known genotoxin. Chemical characterization may be needed to demonstrate to 
what extent the genotoxin is released from the device. For known genotoxins, the overall 
benefit-risk determination will depend on the device indication and human exposure.
Genotoxicity testing is requested when the genotoxicity profile has not been adequately 
established. As described in Attachment A, CDRH and CBER traditionally requests 
genotoxicity information for some devices with prolonged contact (> 24 hours to 30 
days) or long term contact (> 30 days) with blood, bone, mucosa or other tissue, or any 
materials that have not previously been used in legally marketed medical device 
applications regardless of the duration of use.
34 Contains Nonbinding Recommendations
Genotoxicity evaluations are also requested for all devices used in extracorporeal blood-
contacting circuits, even if the contact is less than 24 hours, genotoxicity evaluations are 
recommended because of the high surface area, the associated increased potential for 
chemical leaching, and introduction of any leachables into the systemic circulation. If 
these devices include leachables with an unknown genotoxicity profile (i.e., no 
toxicology information in the literature), some additional genotoxicity information may 
be necessary.
Because no single test can detect all genotoxins, we recommend the following two in 
vitro tests be conducted, as well as an optional third in vivo test:56
 Bacterial gene mutation assay. This test is conducted with engineered strains of 
Salmonella typhimurium and Escherichia coli designed to detect all possible 
single base pair changes as well as frameshift mutations (OECD 471 Guidelines 
for Testing of Chemicals  Bacterial Reverse Mutation Test).
 An in vitro mammalian genotoxicity assay. A choice of one of the following is 
recommended: 
a) the mouse lymphoma gene mutation assay (OECD 490 Guidelines for the 
Testing of Chemicals  In Vitro Mammalian Cell Gene Mutation Tests using 
the Thymidine Kinase Gene), which is preferred since it detects the broadest 
set of genotoxic mechanisms associated with carcinogenic activity;57
b) an in vitro chromosomal aberration (CA) assay (OECD 473 Guidelines for the 
Testing of Chemicals  In Vitro Mammalian Chromosome Aberration Test); or
c) an in vitro micronucleus assay (OECD 487 Guidelines for the Testing of 
Chemicals  In Vitro Mammalian Cell Micronucleus Test).
 An in vivo cytogenetics assay should be considered, for example, for devices 
containing novel materials. However, if the quantities of materials in the test 
extract following exhaustive extraction of the devices are below the threshold of 
detection of the in vivo assay, the test does not need to be performed.  
 
When an in vivo assay is needed, a choice of one of the following is 
recommended: 
a) a bone marrow micronucleus (MN) Assay (OECD 474 Guidelines for the 
Testing of Chemicals  Mammalian Erythrocyte Micronucleus Test); or
56All of the OECD guidelines referenced in this section are incorporated by reference in ISO 10993-3 Biological 
evaluation of medical devices  Part 3: Tests for genotoxicity, carcinogenicity and reproductive toxicity, which is 
FDA-recognized.
57Applegate, M.L., et al., Molecular dissection of mutations at the heterozygous thymidine kinase locus in mouse 
lymphoma cells. Proc. Natl. Acad. Sci. USA, 1990, 87(1): 51-55.
35 Contains Nonbinding Recommendations
b) a bone marrow chromosomal aberration (CA) assay (OECD 475 Guidelines 
for the Testing of Chemicals  Mammalian Bone Marrow Chromosome 
Aberration Test); or
c) a peripheral blood MN assay (OECD 474 Guidelines for the Testing of 
Chemicals  Mammalian Erythrocyte Micronucleus Test).
Since the different genotoxicity assays detect different types of genotoxicity, a positive in 
any assay is considered a positive result. In the event of an equivocal result in any of the 
in vitro assays, the same assay should be repeated. In the event of a positive result, we 
recommend further investigation to identify the source of the genotoxin. We recommend 
this information be used to help evaluate the overall benefit-risk of the device using a 
toxicological risk assessment with respect to carcinogenicity, as described in Section 
VI.G, below. An in vivo genotoxicity assay is not recommended as a follow-up to rule out 
a positive in an in vitro assay because the amount of the chemicals in a device extract 
may be below the limit of detection of the in vivo assay.
All assays should be performed on undiluted extracts only, unless cytotoxicity is shown 
to interfere with the performance of the test. For the in vitro mammalian cell-based 
assays, we recommend that cytotoxicity be evaluated using a quantitative method (i.e., 
not confluence estimations).
For combination products that include a drug, if genotoxicity data are not available from 
the literature, the drug should be tested separately in a dose-response study (not as an 
extract). In addition, the final combination product should be evaluated by standard 
extraction methods. If the device is tested without the drug, additional chemical 
characterization information should be provided to confirm that final manufacturing of 
the device with the drug does not introduce any new chemical moieties that could be 
potential genotoxins. For combination products that include a biologic, the need for 
genotoxicity evaluation will be reviewed on a case-by-case basis.
G. Carcinogenicity 
As described in Attachment A, FDA recommends that carcinogenicity potential be 
evaluated (usually via a risk assessment) for devices with long term contact (i.e., greater 
than 30 day exposure). This includes devices in contact with breached or compromised 
surfaces (i.e., wound healing), as well as externally communicating and implanted 
devices. If novel materials (i.e., not previously used in a legally marketed device) are 
used to manufacture devices in contact with breached or compromised surfaces, 
externally communicating devices, or implant devices, we also recommend a review of 
the carcinogenicity literature. In the absence of experimentally derived carcinogenicity 
information, structure activity relationship (SAR) modeling for these materials may be 
needed regardless of the duration of contact, to better understand the carcinogenicity 
36 Contains Nonbinding Recommendations
potential for these materials.58 Because there are carcinogens that are not genotoxins59
and carcinogenesis is multifactorial, the assessment of carcinogenicity should not rely 
solely on genotoxicity information. Therefore, the following elements should be 
considered in conjunction with genotoxicity information to evaluate carcinogenic risk of 
the medical device in its final finished form:
 Include the complete chemical formulations and manufacturing residuals for all 
components of the device with the potential for tissue contact. For device 
materials or components that are provided by third-party suppliers where the 
chemical formula is proprietary, sponsors should request that suppliers use master 
files to provide chemical formulation information to the FDA. Refer to 
Attachment B for details regarding the chemical formulation information that 
would be helpful to a carcinogenicity evaluation.
 Quantify the total amount of extractables and leachables using analytical 
chemistry methods with an appropriate sensitivity (i.e., ppm or ppb). The elution 
methods and analytical techniques should be designed to evaluate the presence of 
device materials, any breakdown products, chemical interaction products, or 
processing agents (e.g., adhesives, mold cleaning agents, mold releasing agents, 
sterilization chemicals, etc.). The TTC approach can be used to determine if 
quantification without chemical identification is sufficient to assess the toxicity 
risk of the device.60 Otherwise, chemical identification is needed.
 Evaluate how much of each chemical would be present in an individual worst-
case patient exposure situation. For this assessment, one would assume the patient 
is exposed to 100% of the chemical in the device or 100% of the byproduct that 
could be generated from the device. Alternatively, a worst-case scenario could be 
justified based on exhaustive extraction data from chemical characterization. As a 
part of this assessment, consider the situation where a patient might receive 
multiple devices of the largest device size to calculate the estimated worst-case 
patient exposure. An exposure assessment should also address the following: any 
intermediate degradation chemicals, route-to-route extrapolation of dose, and 
local versus systemic exposure potential.
 Evaluate the genotoxicity and carcinogenicity potential of the chemicals, 
including:
58Refer to ICH M7 Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit 
Potential Carcinogenic Risk available at https://www.fda.gov/regulatory-information/search-fda-guidance-
documents/m7r1-assessment-and-control-dna-reactive-mutagenic-impurities-pharmaceuticals-limit-potentialfor 
information on use of the TTC and SAR modeling to address genotoxicity and carcinogenicity issues within a risk 
management process.
59Benigni, R., et al., Nongenotoxic carcinogenicity of chemicals: mechanisms of action and early recognition 
through a new set of structural alerts. Chem Rev, 2013, 113(5): 2940-2957.
60Refer to the ICH M7 Guideline Assessment and Control of DNA Reactive (Mutagenic) Impurities in 
Pharmaceuticals to Limit Potential Carcinogenic Risk available at https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/m7r1-assessment-and-control-dna-reactive-mutagenic-impurities-
pharmaceuticals-limit-potentialfor details on the level of sensitivity needed.
37 Contains Nonbinding Recommendations
o a thorough literature review with identified search terms, 
o assessment of any evidence of carcinogenicity from long-term in vivo 
animal studies (e.g., inflammation, pre-neoplastic lesions, or tumor 
findings in animal studies), 
o the relevance of animal data to assess risks in humans, and
o assessment of human data from epidemiological studies if available or any 
other relevant long-term clinical study findings, including susceptible 
population and life stages, and device implant site and propensity of the 
site to develop local tumors.61,62
 If potential carcinogens [e.g., International Agency for Research on Cancer 
(IARC) monograph chemicals]63 are identified in the device, a cancer risk 
assessment should also be provided with literature evidence to demonstrate that 
the amount of the potential carcinogen(s) available in a device does not pose an 
unacceptable carcinogenic risk.64  
If carcinogenicity testing is warranted (e.g., when data are not available to provide an 
adequate assessment or when an assessment indicates that there is a probable risk), 
consider use of transgenic animal models (e.g., RasH2), with confirmation of stability of 
transgene status, or other validated models.
Prior to conducting carcinogenicity testing, the sponsor is advised to discuss proposed 
testing with FDA to ensure that the study design is appropriate to assess the probable 
carcinogenic risks using a statistically-based sample size, with documentation of the 
statistical power.
H. Reproductive and Developmental Toxicity 
FDA recommends that reproductive and developmental toxicity be assessed to evaluate 
the potential effects of medical devices, materials and/or their extracts on reproductive 
function, embryonic development (teratogenicity), and prenatal and early postnatal 
development as described in ISO 10993-1. If the biocompatibility evaluation identifies a 
known or a potential reproductive or developmental toxicity risk, and/or there is 
inadequate reproductive and developmental toxicity information in the literature to 
address the risk, testing and/or labeling mitigations will most likely be necessary. Some 
examples include:
61Huff, J., et al., Chemicals associated with site-specific neoplasia in 1394 long-term carcinogenesis experiments 
in laboratory rodents. Environ Health Perspect, 1991, 93: 247-70.
62Gold, L.S., et al., Target organs in chronic bioassays of 533 chemical carcinogens. Environ Health Perspect, 
1991, 93: 233246.
63Refer to the IARC Monographs on the Evaluation of Carcinogenic Risks to Humansavailable at 
https://monographs.iarc.who.int/monographs-available/
64ISO 10993-17 Biological evaluation of medical devices  Part 17: Establishment of allowable limits for leachable 
substances.
38 Contains Nonbinding Recommendations
 novel implant materials if there is a potential for chemical leachables to contact 
reproductive organs, regardless of the type or duration of contact, and 
 device materials or components in contact with reproductive organs.
Testing in animals of reproductive age should also be considered, if device materials may 
be systemically distributed (e.g., absorbable devices), and reproductive and 
developmental toxicity literature is not available.
I. Degradation Assessments 
FDA recommends that in vivo degradation assessments be conducted in an appropriate 
animal model if the device is designed to be absorbable. As described in ISO 10993-1, 
parameters that affect the rate and extent of degradation should be described and 
documented. Sponsors should report the rate of degradation based upon physiologically-
relevant data and the biological response to the degrading device. If an adverse biological 
response is observed, additional in vitro assessments are recommended to identify the 
source of the toxicity, such as potential chemicals of concern. Some additional testing 
(e.g., degradation testing and/or chemical characterization testing) on the medical device 
in its final finished form may be necessary. FDA recommends that prior to conducting in 
vivo degradation or chemical characterization testing, the sponsor discuss proposed 
testing with FDA to ensure that the design of the proposed testing is appropriate to assess 
the potential risks to the patient, such as toxicological risks and loss of mechanical 
properties. Protocols and test reports (see Attachment Efor recommended elements to 
include in a test report) from characterization of degradation products should be provided 
in the submission. 
VII. Chemical Assessment  
FDA evaluates the safety of medical devices based on duration of exposure and nature of 
contact. Inherent in the review of medical devices is an understanding of the bodys entire 
exposure to the medical device, including all chemical entities contained within the device. For 
devices where the patient-contacting portions may contain potentially toxic chemicals, the 
evaluation of safety should include both chemical risk (i.e., the level of toxicological concern) 
and the type and duration of exposure.  
 
FDA may request that additional chemistry information be provided in the following situations: 
 
  For devices made from novel materials never before used in a legally marketed medical 
device, toxicology information (i.e., data from the literature, additional biocompatibility 
testing of the final device, or toxicity testing of the chemicals of concern) may be 
necessary so a complete toxicity assessment of the new materials can be conducted. This 
toxicity assessment may not necessarily be limited to those endpoints identified by ISO 
10993-1 for a specific type and duration of contact. To more fully evaluate novel 
materials, which may raise unique toxicological concerns, FDA will typically request 
additional toxicology information as described in ISO 10993-1, to more fully understand 
39 Contains Nonbinding Recommendations
the toxicological risks of materials that are novel and to ensure the safety of such 
materials when used in medical devices.
 For submissions proposing the use of new chemicals to modify the material formulation 
or device manufacturing (e.g., surfactants, antioxidants, plasticizers),65 toxicology 
information (i.e., purity and impurity information, data from the literature, or additional 
toxicity testing on the chemical(s) of concern) may be necessary to address the endpoints 
identified by ISO 10993-1 for the relevant type and duration of contact.
 For some devices including chemicals with known toxicities (e.g., drugs or biologics 
used in combination products),66 it may not be possible to mitigate the toxicological risks 
with traditional biocompatibility testing conducted on the medical device in its final 
finished form. For example, genotoxicity, carcinogenicity, and developmental toxicity 
endpoints may be better assessed through chemical characterization and a review of the 
literature. Therefore, in these particular situations, data from chemical characterization 
and toxicology information from the literature may be necessary to support the risk 
assessment.
 For some devices manufactured from materials that change over time (e.g., combination 
products, or in situ absorbable or degradable materials), it may not be appropriate to only 
use the biocompatibility information from the as-manufactured device to predict the 
toxicity of the device over its implant life. Therefore, data from chemical characterization 
and toxicology information from the literature may be necessary to support the risk 
assessment.
 For some devices where an unexpected finding is observed in a biocompatibility study, 
additional chemical characterization and toxicology information from the literature may 
be necessary to determine the cause of the toxicity, and whether additional mitigations 
are needed to reduce the risk.
 For devices using materials where a long history of safe use rationale would not be 
sufficient to understand the effect of formulation additives and manufacturing methods 
and conditions on the biocompatibility of the medical device in its final finished form, 
additional chemical characterization and toxicology information from the literature may 
be necessary to support the risk assessment.
When additional device or device component chemical information is needed, the following 
descriptive information should be provided:
65Per requirements under purchasing controls (21 CFR 820.50), if a new material supplier is being considered, 
comparative chemical characterization can be used with incoming material or component specifications to confirm 
whether there are additional types or quantities of impurities in the new material or component that could impact 
biocompatibility such that additional testing may be needed, or if it is sufficient to document the change in the 
Device Master Record because testing was determined to be unnecessary.
66The amount of information available, within the submission or by reference to a device or drug master file, new 
drug application (NDA), or biologic licensing agreement (BLA), may impact how much additional information on 
the chemical constituents is needed to fully assess the level of toxicological concern.
40 Contains Nonbinding Recommendations
1. The identity of the chemical by common name, chemical name, Chemical Abstract 
Services (CAS) number, and trade name.
2. If known,67 the composition, formula and formula weight, structural information, and 
manufacturing and purity information for the chemical, such as a detailed description of 
the manufacturing process (including the substances used, the amounts used in the 
synthesis, and reaction conditions), specifications for the chemical, analysis of multiple 
batches of the chemical, and identification of major impurities.
3. The specific amount of each chemical in the formulation by weight percent of the 
applicable device component and total amount (e.g., g) in the device. If this information 
is not available (e.g., from a material supplier), it would be acceptable to use a worst-case 
estimation approach for the risk assessment. For example, one might assume 100% of the 
material (e.g., resin pellet) used in the final device formulation is the chemical of concern 
(i.e., any chemical components of the supplied material).
4. The identity of any other devices marketed in the US (by device name, manufacturer, and 
submission number) where the chemical entity with direct or indirect tissue contact has 
been previously used, if known, and comparative information on the composition and 
amount(s) used. This information is generally available only for components made by the 
same manufacturer.
If information on identity and quantity of component chemicals cannot be obtained (e.g., from a 
material supplier), chemical characterization of device extracts generated using polar (e.g., water, 
physiological 0.9% saline), semi-polar (e.g., isopropyl alcohol, ethyl alcohol, alcohol/water) and 
non-polar (e.g., hexane) solvents may be sufficient to support the biocompatibility evaluation of 
the device. Choice of solvents will depend on device materials and should be justified. For 
example, physiological 0.9% saline should be used for the polar extraction of devices with metal 
components to optimize ion release. In addition, extraction conditions (i.e., solvent, temperature, 
and duration) should not compromise device integrity.
In addition, to evaluate the patient exposure to the device or device component chemical(s), the 
following exposure information should be provided:
5. An exposure assessment for each chemical (including any related impurities) to which the 
patient has direct or indirect contact. If repeat dosing is possible or probable, this should 
be considered in the patient exposure calculation. This includes chemicals that can 
migrate from the surface or bulk of the device. If testing is needed to assess if chemicals 
migrate from the device, this testing can be conducted using the chemical 
characterization testing methods described above for elution. For this testing, provide the 
test report, including details of the test conditions, to confirm that the chemical is stable 
under the intended conditions of use. As discussed in the risk assessment section, 
descriptive information may also be sufficient in lieu of any new testing. 
67The amount of information available, within the submission or by reference to a device or drug master file, may 
impact how much additional information on the chemical constituents is needed to fully assess the level of 
toxicological concern.
41 Contains Nonbinding Recommendations
If the information above confirms that there are no toxicity concerns for the device or device 
component chemical(s), either because the chemical is physically sequestered in a device 
component with no direct or indirect tissue contact, or based on the results of testing conducted 
as described in #5 above, no further information is necessary.
If the information above suggests that there is patient exposure to the device or device 
component chemical, the following toxicological information should be provided:
6. A safety assessment for each chemical entity using toxicity information from the 
literature and any available, unpublished data that the sponsor may have generated for all 
known toxic effects. Where the full toxicology profile for the chemical entity is not 
available, either in the literature, from the supplier, and/or from a previous medical 
device submission, a complete battery of toxicity tests on the chemical entity (i.e., tests in 
addition to those outlined in Attachment A, including but not limited to genotoxicity, 
reproductive and developmental toxicity, and carcinogenicity) may also be needed unless 
a scientific rationale is provided to explain why these additional tests are not needed. For 
example, if extractables and/or leachables data demonstrates exposure will be below the 
derived tolerable intake (TI) for a particular chemical, or the TTC (if a TI cannot be 
derived), then further toxicological assessment is unnecessary for the evaluation of some 
biological endpoints (e.g., systemic toxicity, genotoxicity, carcinogenicity).
The level of toxicological concern should be based on patient exposure to the chemical entity 
and the available toxicological data. One approach to this assessment is to consider the total 
patient exposure of the device or device component chemical in relation to the amount at which 
toxicities are known or probably exist.
If available toxicity information suggests that even if all of the chemical(s) were released, no 
toxicity concern would exist with this level of exposure (i.e., the amount is well below the 
amount at which toxicity concerns are present), no further information is necessary.
However, if potential toxicity concerns exist if all of the chemical(s) are released, further 
information will generally be needed to determine how much of the chemical(s) are released, as 
well as the fate of the chemical(s) within the body. Specifically, the following information 
should be provided:
7. Data to demonstrate the amount of chemical(s) to which the patient may be exposed (e.g., 
amount released) through 30 days (or worst-case exposure that might be reasonably 
encountered in clinical use plus a safety margin).
8. If data indicate that the patient will be exposed to the chemical(s) (e.g., through elution), 
assessment(s) of the fate of the chemical(s) from the device in a clinically relevant animal 
model may be necessary to assess the timing of elimination and to perform 
pharmacokinetic analyses (e.g., absorption, distribution, metabolism, and excretion 
(ADME)). We recommend that a sponsor consider relevant device-specific guidance 
documents, if available, or contact the review division to discuss the appropriate animal 
model in these circumstances.
42 Contains Nonbinding Recommendations
VIII. Labeling68 Devices as Free
FDA notes that to communicate with users regarding potential allergenic or toxic compounds, 
some sponsors have requested to include statements in the device labeling such as latex-free, 
DEHP-free, BPA-free, or pyrogen-free. It may not be possible with current test methods to 
reliably assure that there is an absence of the allergen or toxic compound in the medical device at 
levels that could produce an adverse event in highly sensitive individuals. Use of such terms may 
give users a false sense of security when using a medical device. If a sponsor elects to include a 
statement in medical device labeling indicating that a specific material was not used in the 
manufacture of their medical device or medical device container, FDA recommends the use of a 
statement such as Not made with natural rubber latex or Not made with BPA based on a 
material certification to indicate that natural rubber latex or BPA is not used in the device or 
device component. If this statement is made without any qualification, it should apply to the 
entire device and all of its packaging. A sponsor can also elect to make a statement that certain 
components of the medical device or device container are not made with the material of concern. 
For example, The <vial stopper> is not made with natural rubber latex.69
If a sponsor elects to include a -free statement, in their labeling, at the time of submission, 
FDA recommends that the sponsor provide data to support that the device does not include the 
material at a level that could result in an adverse event (e.g., allergic reaction or toxicity).
68Although final labeling is not required for 510(k) clearance, final labeling must comply with the requirements of 
21 CFR Parts 801, and if applicable, 809 before a medical device is introduced into interstate commerce. In addition, 
please be aware of the implications of 21 CFR 801.109 for final labeling for prescription devices.    
69Refer to the FDAs guidance document Recommendations for Labeling Medical Products to Inform Users that 
the Product or Product Container is not Made with Natural Rubber Latex  Guidance for Industry and Food and 
Drug Administration Staff available athttps://www.fda.gov/regulatory-information/search-fda-guidance-
documents/recommendations-labeling-medical-products-inform-users-product-or-product-container-not-made-
natural
43 Contains Nonbinding Recommendations
Attachment A: Evaluation Endpoints for Consideration
 
The following is a framework for the development of a biocompatibility evaluation and is not a 
checklist for testing. For particular medical devices, different biological endpoints may warrant 
evaluation, including either additional or fewer endpoints than indicated. If it is unclear in which 
category a device falls, we recommend consulting device-specific guidances or contacting the 
appropriate Center and review division for more information.70 For example, FDA has 
historically considered devices used to drain fluids (such as Foley catheters) as externally 
communicating devices rather than as surface devices contacting mucosal membranes. 
Table A.1: Biocompatibility Evaluation Endpoints
Medical device categorization by Biological effect
Contact
Nature of Body Contact
Duration ty y#
Category Contact (BC>A  2 (4 ( p>l< o hr l23n iot4m0gol o   hidt3nt)e)e0grd emdd) Cytotoxicity Sensitization Irritation or Intracutaneous Reactivi Acute Systemic Toxicity Material-Mediated Pyrogenicity Subacute/Subchronic Toxicity Genotoxicity Implantation Hemocompatibility Chronic Toxicity Carcinogenicity Reproductive/Developmental Toxicit Degradation@
A X X X
Intact skin B X X X
C X X X
A X X X
Mucosal 
Surface device B X X X X O X X
membrane
C X X X X O X X X X
Breached or  A X X X X X
compromised  B X X X X X X X
surface C X X X X X X X X X X
A X X X X X X
Blood path, 
B X X X X X X X
indirect
C X X X X X X X X X X X
External 
A X X X X X
communicating  Tissue+/bone/
B X X X X X X X X
device dentin
C X X X X X X X X X X
Circulating  A X X X X X X^ X
blood B X X X X X X X X X
70Device categorization information can be obtained informally via email, or as a part of the Q-Submission process. 
Refer to FDAs guidance document Requests for Feedback and Meetings for Medical Device Submissions: The Q-
Submission Program: Guidance for Industry and Food and Drug Administration Staff" available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/requests-feedback-and-meetings-
medical-device-submissions-q-submission-program
44 Contains Nonbinding Recommendations
Medical device categorization by Biological effect
Contact
Nature of Body Contact
Duration ty y#
Category Contact (BC>A  2 (4 ( p>l< o hr l23n iot4m0gol o   hidt3nt)e)e0grd emdd) Cytotoxicity Sensitization Irritation or Intracutaneous Reactivi Acute Systemic Toxicity Material-Mediated Pyrogenicity Subacute/Subchronic Toxicity Genotoxicity Implantation Hemocompatibility Chronic Toxicity Carcinogenicity Reproductive/Developmental Toxicit Degradation@
C X X X X X X X X X X X
A X X X X X
Tissue+/bone B X X X X X X X X
C X X X X X X X X X X
Implant device
A X X X X X X X X
Blood B X X X X X X X X X
C X X X X X X X X X X X
X = ISO 10993-1:2018 recommended endpoints for consideration*
O = Additional FDA recommended endpoints for consideration*
Note * All Xs and Os should be addressed in the biological safety evaluation, either through the use of existing 
data, additional endpoint-specific testing, or a rationale for why the endpoint does not warrant additional assessment.
Note + Tissue includes tissue fluids and subcutaneous spaces
Note ^ For all devices used in extracorporeal blood-contacting circuits
Note # Reproductive and developmental toxicity should be addressed for novel materials, materials with a known 
reproductive or developmental toxicity, devices with relevant target populations (e.g., pregnant women), and/or 
devices where there is the probability for local presence of device materials in the reproductive organs. 
Note @ Degradation information should be provided for any devices, device components, or materials remaining in 
contact with tissue that are intended to degrade.
ISO 10993-1:2018, Table A.1 includes separate columns for subacute and subchronic toxicity 
endpoints. FDA recommends that if a subacute or subchronic test is conducted to evaluate these 
endpoints, the choice of test be based on the duration of the test as it compares to the duration of 
device use. For example, devices used for greater than 14 days should not be assessed using a 14 
day test.
Sponsors are advised to consider conducting a separate evaluation to assess chemical 
components of device materials that may be pyrogenic. This type of material-mediated 
pyrogenicity is identified as a subset of acute systemic toxicity in ISO 10993-1:2018. However, 
it may not be appropriate to use data from an acute systemic toxicity or implantation study in 
place of a separate pyrogenicity evaluation if the study did not include periodic temperature 
measurements (e.g., every 30 minutes for the first three hours) or was not conducted in an 
appropriate animal model (i.e., rabbit). See also Section VI.Dfor more information about 
assessment of pyrogenicity.
45 Contains Nonbinding Recommendations
Attachment B: Device Master Files for Biocompatibility 
Evaluations
There are no specific content requirements for a device master file (MAF).71 However, the 
following information should be included to support a biocompatibility evaluation:
1. Material name(s) and trade name(s).
2. Formulation information (for each material) to include:
a. Chemical name(s), Chemical Abstract Services (CAS) number(s), Supplier and 
Trade Name;
b. Weight percent (% w/w) of each chemical in the formulation;
c. Function of each chemical component; and
d. Structure of each chemical and simplified molecular-input line-entry system 
(SMILES) code.
3. Manufacturing information to include:
a. Recommended processing methods (e.g., injection molding, time and temperature 
conditions);
b. Recommended processing additives (or processing additives to avoid); and
c. Known or suspected impurities.
4. Sterilization compatibility (e.g., gamma radiation, steam, ethylene oxide).
5. Chemical characterization methods recommended for this material (per ISO 10993-18) to 
include:
a. Identification of material(s);
b. Analysi(e)s for heavy metals;
c. Sterilization residuals, if relevant (e.g., ethylene oxide);
d. Recommended extraction conditions (solvents, temperatures) and an explanation 
of such conditions based on material chemistry (e.g., solubility, transition 
temperature); 
e. Recommended data presentation (i.e., to allow for comparison with the original 
material); and
f. Results from testing of the material test articles used for biocompatibility 
screening studies (item 7 below).
6. Surface characterization methods recommended for this material (per ISO/TS 10993-19) 
that may be relevant to implantation and/or hemocompatibility responses, to include:
a. Recommended analytical techniques;
71Additional information regarding master files for devices is available online at: https://www.fda.gov/medical-
devices/premarket-approval-pma/master-files
46 Contains Nonbinding Recommendations
b. Recommended test article preparation conditions relevant to a particular 
analytical technique and an explanation of such conditions based on material 
chemistry; 
c. Recommended data presentation (i.e., to allow for comparison with the original 
material); and
d. Results from testing of the material test articles used for biocompatibility 
screening studies (item 7 below).
7. Biocompatibility screening studies performed on the material test articles to include:
a. Intended use of the material and associated ISO contact category (per ISO 10993-
1);
b. Test article description (e.g., dimensions, manufacturing conditions, number and 
type of sterilization cycles);
c. Test performed (e.g., cytotoxicity, sensitization, irritation, systemic toxicity, 
hemocompatibility, etc.);
d. Extraction conditions, if applicable, and methods (i.e., time, temperature, test 
article ratio per extract volume);
e. Compliance and/or deviations to relevant standards, if applicable (e.g., ISO 
10993-5, ISO 10993-12); and
f. Copies of test reports to include methods, results, and conclusions.
47 Contains Nonbinding Recommendations
Attachment C: Summary Biocompatibility Documentation
The example table (Table C.1) is provided to illustrate one possible approach to documentation of the biocompatibility information 
included or referenced in a submission; other approaches are acceptable. Manufacturers are encouraged to use an approach that works 
for their specific purposes, taking into account the considerations discussed in this guidance document. Note that these are generalized 
examples to demonstrate documentation and do not necessarily account for every possible consideration. 
Table C.1 - Example Table of Summary Biocompatibility Evaluation Information for a Device Submission
Biological  Location of new  Location of test  Supporting  Citation Test article Rationale for why additional 
endpoint test reports  reports leveraged  data from  information isnt needed
provided in  from previous  literature
submission submission
Cytotoxicity Implant: L929  Implant:  n/a n/a Identical - see  Testing conducted on final, 
testing (V2, App  [DEVICE NAME]  documentation  sterilized device (implant tested 
A-1, pdf p.x/200) (K# V2, App X-1,  (per Attachment  separately from implantation 
Implantation  pdf p.x/200) F) V1, pdf  accessory)
accessory: L929  Implantation  p.x/100
testing (V3, App  accessory: 
B-1, pdf p. x/300) [DEVICE NAME] 
(K# V3, App X-1, 
pdf p.x/300)
Genotoxicity Implant:  n/a Test name  Author,  Slight differences  Genotoxicity tests are hazard 
chemical  (e.g.,  Title,  between test  identification tests. Chemical 
characterization  chromosomal  Journal,  article and final,  characterization data can be used 
(V2, App A-2,  aberration):  date,  sterilized device  to confirm that chemicals which 
pdf p. x/200) doses with  volume,   see comparison  elute from the device are not 
effects and/or  and  information: V1,  genotoxic per literature.
doses without  pages pdf p.x/100
effects
48 Contains Nonbinding Recommendations
Biological  Location of new  Location of test  Supporting  Citation Test article Rationale for why additional 
endpoint test reports  reports leveraged  data from  information isnt needed
provided in  from previous  literature
submission submission
Carcinogenicity  n/a Rationale for use  Probable  Citation  n/a Material X is a known carcinogen, 
of material (K#,  human  (e.g.,  but device is used in patients with 
V2, App Y-1,  carcinogen  website  < 6 month life expectancy, and 
p.x/200) (Group B1)  link) benefits outweigh risks, so no 
IARC  mitigations or additional testing 
Monograph  needed.
Vx, date
All other 
endpoints 
identified in 
Attachment A 
...
49 Contains Nonbinding Recommendations
Attachment D: Biocompatibility Evaluation Flow Chart 
The flow chart below is provided to illustrate how one might proceed with a biocompatibility 
evaluation.
MAIN CHART
50 Contains Nonbinding Recommendations
CHART A
51 Contains Nonbinding Recommendations
Attachment E: Contents of a Test Report
Whenever biocompatibility or chemical characterization testing information is included in a 
submission, FDA recommends that complete test reports be provided for all tests performed 
unless testing is conducted under the ASCA program and it is determined that an ASCA 
Summary Test Report is sufficient or a declaration of conformity without supplemental 
information can be appropriately provided.72,73 Test reports for GLP studies must address the 
reporting requirements of 21 CFR 58 and all test reports (for both GLP and non-GLP studies) 
should also include the sections described below. Test reports should address the reporting 
provisions of any referenced standards, as well as the information outlined below.
Test Article Preparation
As described in Section V.Aabove, the test report should identify the test specimen; if the test 
article is not the medical device in its final finished form, a justification for the test article used 
should be provided either in the test report or in the submission to FDA. If the test uses extracts, 
the report should explain how those extracts were prepared, and indicate the appearance of the 
extract (color, cloudy versus clear, and presence of particulates).
Test Method
The test report should provide a summary of the method used. If the method used is not in a 
published guidance document or FDA-recognized standard, a complete description of the method 
should be provided. If the test method is a modified version of a method in a published guidance 
document or FDA-recognized standard, the test report should include an explanation of the 
differences and their potential impact on the interpretation of the results.
The test report should identify any protocol deviations and their impact on the conclusions drawn 
from the test.
Test Parameters and Acceptance Criteria
The test report should identify the test parameters and acceptance criteria applied. If the test 
method is not in accordance with a published guidance document or FDA-recognized standard
72Refer to FDAs Biocompatibility Testing of Medical Devices  Standards Specific Information for the 
Accreditation Scheme for Conformity Assessment (ASCA) Pilot Program available at 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/biocompatibility-testing-medical-
devices-standards-specific-information-accreditation-schemefor information regarding ASCA biocompatibility 
summary test reports.
73The ISO 10993 series of standards do not specify either a method or test outcome, because these standards are 
both compendia and guidance. As such, these standards allow one to select different tests and methods, and do not 
necessarily include acceptance criteria. Therefore, to support a declaration of conformity and for FDA to assess 
conformance, for any tests selected under the ISO 10993 paradigm, the rationale for the test battery selected and the 
criteria used to determine acceptance should be provided. It has been FDAs experience that test reports often 
address this, and raw data is usually not necessary. There may be other testing for which a declaration of conformity 
can be submitted to FDA without supplemental information. Refer to FDAs Appropriate Use of Voluntary 
Consensus Standards in Premarket Submissions for Medical Devicesavailable at https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/appropriate-use-voluntary-consensus-standards-premarket-
submissions-medical-devicesfor more information on when to provide supplemental documentation.
52 Contains Nonbinding Recommendations
that includes defined acceptance criteria, a rationale for the acceptance criteria should be 
provided.
Analysis of Results
The test report should provide a summary of the test results and include tables with each data 
point and statistical analyses, where appropriate. For example, the test report for hemolysis 
testing per ASTM F756 should include a description of the test, blank, positive, and negative 
supernatant conditions, in addition to the absorbance and percent hemolysis data.
For any test in which the results indicate a potential toxicity, the report should include a 
discussion of any test-specific issues that might have affected results.
Conclusions
The test report should describe the conclusions drawn from the test results. The clinical 
relevance of the study conclusions should be described in the test report or in the submission to 
FDA.
53 Contains Nonbinding Recommendations
Attachment F: Component and Device Documentation 
Examples 
The examples below are provided to illustrate one possible approach to documentation of how a 
test article compares to the proposed medical device in its final finished form; other approaches 
may also be acceptable. Manufacturers are encouraged to use an approach that works for their 
specific purposes, taking into account how any changes might impact the biocompatibility of the 
device. Note that these are generalized examples to demonstrate documentation and do not 
necessarily account for every possible consideration.
A. Component Documentation 
For each component and any joining processes/materials (e.g., adhesives, sintering processes), 
either of the following statements can be provided:
Comparison to test article: "The [polymer/metal/ceramic/composite name] [component 
name] of the test article is identical to the [component name] of the medical device in its 
final finished form in formulation, processing, sterilization, and geometry, and no other 
chemicals have been added (e.g., plasticizers, fillers, additives, cleaning agents, mold release 
agents)."
Comparison to previously marketed device: "The [polymer/metal/ceramic/composite 
name] [component name] of the medical device in its final finished form is identical to the 
[component name] of the [name] (legally marketed device)74 in formulation, processing, 
sterilization, and geometry, and no other chemicals have been added (e.g., plasticizers, fillers, 
additives, cleaning agents, mold release agents)."
B. Device Documentation 
If the above statement is true for all of the device component material formulations, processes, 
and sterilization methods (if applicable) in the device, either of the following general statements 
can be provided:
Comparison to test article: "The test article is identical to the medical device in its final 
finished form in formulation, processing, sterilization, and geometry and no other chemicals 
have been added (e.g., plasticizers, fillers, additives, cleaning agents, mold release agents)."
Comparison to previously marketed device: "The medical device in its final finished form 
is identical to [name] (previously marketed device) in formulation, processing, sterilization, 
and geometry and no other chemicals have been added (e.g., plasticizers, fillers, additives, 
cleaning agents, mold release agents)."
74We recommend that you include the submission number and date where the legally marketed device was given 
marketing authorization.
54 Contains Nonbinding Recommendations
C. New Processing/Sterilization Changes 
If there are any processing or sterilization changes that the sponsor believes will not alter the 
biocompatibility of the medical device in its final finished form, the sponsor should use the 
component documentation language and include either of the following qualifiers:
Comparison to test article: "...with the exception of [identify change]. FDA submission 
exhibit [#], page [#], submitted on [date], provides scientific information to demonstrate that 
the [processing/sterilization] change does not alter the chemical or physical properties of the 
medical device in its final finished form, and therefore, results from the test article can be 
applied to the medical device in its final finished form.
Comparison to previously marketed device: "...with the exception of [identify change]. 
FDA submission exhibit [#], page [#], submitted on [date], provides scientific information to 
demonstrate that the [processing/sterilization] change does not alter the chemical or 
physical properties of the medical device in its final finished form, and therefore, results from 
the [name] (legally marketed device) can be applied to the medical device in its final 
finished form.
NOTE: The information provided to support a claim that processing and sterilization changes 
will not affect chemical or physical properties of the medical device in its final finished form 
should be provided in sufficient detail for FDA to make an independent assessment during 
our review and arrive at the same conclusion.
NOTE: Changes in raw material suppliers or raw material specifications could introduce 
different types or quantities of residual chemicals and could result in a toxic response (even if 
the base material has a long history of safe use in similar applications).75
NOTE: The impact of surface alterations due to processing, even at the micron or submicron 
level, should be evaluated when there is a reasonable possibility that they could result in 
geometrical or chemical changes at the surface which, in turn, could result in an adverse 
biological response (even if the base material has a long history of safe use in similar 
applications).
D. Formulation Changes 
If there are any formulation changes the sponsor believes will not alter the biocompatibility of 
the medical device in its final finished form, the sponsor should use the component 
documentation language and include the following qualifier:
Comparison to test article: "...with the exception of [identify change]. FDA submission 
exhibit [#], page [#], submitted on [date], provides scientific information to demonstrate that 
75In some cases, chemical characterization at the raw material level may be sufficient to show comparability and to 
justify not conducting device level testing. However, some resin changes may result in changes to physical 
properties and/or surface characteristics of the medical device in its final finished form that could affect the 
biological response.
55 Contains Nonbinding Recommendations
the formulation change does not alter the chemical or physical properties of the medical 
device in its final finished form, and therefore, results from the test article can be applied to 
the proposed medical device in its final finished form.
Comparison to previously marketed device: "...with the exception of [identify change]. 
FDA submission exhibit [#], page [#], submitted on [date], provides scientific information to 
demonstrate that the formulation change does not alter the chemical or physical properties of 
the medical device in its final finished form, and therefore, results from the [name] (legally 
marketed device) can be applied to the medical device in its final finished form.
For example, if your legally marketed comparator device contains a PEBAX resin, and your 
subject device contains a different grade of PEBAX, your documentation should include a 
qualifier that states that the untested PEBAX grade varies only in the concentration of 
specific formulation components. Formulation changes that introduce novel components, or a 
higher concentration of an existing component, may warrant a new risk assessment or new 
testing if the upper and lower bounds of each component have not been previously evaluated.
NOTE: The information provided to support a claim that formulation changes will not affect 
chemical or physical properties of the medical device in its final finished form should be 
provided in sufficient detail for FDA to make an independent assessment during our review 
and arrive at the same conclusion. To support this assessment, FDA requests that the 
following be discussed:
a. formulation of the test article and possible impurities or leachable chemicals;
b. formulation of the medical device in its final finished form and possible impurities or 
leachable chemicals; and
c. a discussion of why the differences would not necessitate additional testing.
56 Contains Nonbinding Recommendations
Attachment G: Biocompatibility of Certain Devices in 
Contact with Intact Skin
Many devices have intact skin contacting materials that are made from synthetic polymers and 
natural fabrics. FDA believes that these materials pose a very low biocompatibility risk because 
they have a long history of safe use in legally marketed medical devices that contact intact skin.
The policy outlined in this Attachment describes a least burdensome76 approach for these devices 
that recommends specific material information to be included in a premarket submission in lieu 
of biocompatibility testing. This approach also supports the principles of the 3Rs, to replace, 
reduce, and/or refine animal use in testing when feasible.77 This approach is partially based on 
FDAs review experience in premarket submissions with these common synthetic polymers and 
natural fabrics. This approach also relies on certain parts of the Quality System Regulation (QS 
Regulation, 21 CFR 820) and other postmarket controls78 to identify potential biocompatibility-
related issues.
For example, quality system and other postmarket controls have requirements that should 
identify biocompatibility issues for devices in contact with intact skin if procedures established 
and maintained, and records maintained in the Device Master Record79, by the manufacturer 
include sufficient:
 Purchasing controls (21 CFR 820.50) over material suppliers,
 Production and process controls for manufacturing (21 CFR 820.70). Manufacturing 
materials that could adversely affect device biocompatibility should be removed or 
limited to an amount that does not pose toxicity concerns,
 Receiving, in-process, and finished device acceptance (21 CFR 820.80) for component 
and manufacturing materials,
 Analysis of quality data (21 CFR 820.100(a)(1)), including complaints, to detect quality 
problems, such as those that may reveal issues of cytotoxicity, irritation, or sensitization. 
FDA recommends that such an analysis occurs routinely (at least annually), and
 Complaints (21 CFR 820.198) should be received, reviewed, evaluated, and, when 
necessary, investigated.80 We recommend that manufacturers process complaints in a 
uniform and timely manner to look for issues related to cytotoxicity, irritation, or 
sensitization. Indications of these issues may include:
76https://www.fda.gov/regulatory-information/search-fda-guidance-documents/least-burdensome-provisions-
concept-and-principles
77Russell WMS, Burch RL. The Principles of Humane Experimental Technique. London: Methuen & Co.; 1959. 
Special edition published by Universities Federation for Animal Welfare, 1992. Available online at:
https://caat.jhsph.edu/russell-and-burchs-principles-of-humane-experimental-techniques/
78For example, see 21 CFR 803.
7921 CFR 820.181.
80Pursuant to 21 CFR 820.198(a)(3) and 820.198(d), complaints can represent events that must be reported to FDA 
under 21 CFR 803. 
57 Contains Nonbinding Recommendations
 redness (erythema),
 swelling (edema), 
 irritation, 
 sensitization (delayed Type IV hypersensitivity), 
 allergy, and
 immune response or other reactions on the skin where the device has contact.
FDA intends to periodically reassess the list of device materials and exclusion characteristics 
identified in Section B and Section C of this Attachment. FDA recommends that external 
stakeholders submit comments to the docket to suggest the addition or removal of device 
materials or exclusion characteristics from the policy outlined in this Attachment, including a 
rationale. We also recommend the following information be included when suggesting the 
addition of a material: (1) the generic chemical name, (2) identification of the FDA medical 
device product code(s) where the material is commonly used with intact skin, and (3) a specific 
rationale for why the proposed material(s) pose a low biocompatibility risk for intact skin. FDA 
intends to review comments received in the docket and periodically assess whether any changes 
to this policy are warranted. When FDA believes changes are warranted, FDA will issue updated 
guidance in accordance with the procedures in the Good Guidance Practices Regulation (21 CFR 
10.115).
A. Which Types of Devices are Included? 
Devices included in the policy outlined in this Attachment should meet all of the following 
characteristics:
 Medical devices or components that contact intact skin surfaces only, as described in 
section 5.2.2 (a) of ISO 10993-1:2018: Biological evaluation of medical devices  
Part 1: Evaluation and testing within a risk management process,
 Limited (24 hour), prolonged (>24 hours to 30 days), and long term (>30 days) 
durations of contact, including repeat use devices, and
 Composed of materials outlined in Section B below.
FDA recommends additional discussion through the Q-Submission process81 to determine if the 
policy outlined in this Attachment could be applicable to specific products in the following 
situations:
 If a legally marketed device made from the same material was found to be toxic in 
previous testing. For example, if a rationale was used to support a previous premarket 
submission where the material was found to be toxic in a biocompatibility test, additional 
information (e.g., data or rationale) may be needed for the subject device;
81For more information, see FDAs guidance titled Requests for Feedback and Meetings for Medical Device 
Submissions: The Q-Submission Program available at https://www.fda.gov/regulatory-information/search-fda-
guidance-documents/requests-feedback-and-meetings-medical-device-submissions-q-submission-program
58 Contains Nonbinding Recommendations
 If a legally marketed device made from the same material resulted in adverse clinical 
findings (e.g., redness (erythema), swelling (edema), allergy, and immune response or 
other reactions on the skin where the device has contact) after marketing that may be 
related to cytotoxicity, irritation, or sensitization; 
 If the proposed device is indicated for use with neonates. Neonatal skin and the skin of 
infants with low birthweight is more permeable, and therefore the risk that leachables 
may permeate the skin is higher;82,83
 If the proposed device is indicated for use in pregnant women. Physiological alterations 
during pregnancy may lead to higher unsafe levels of toxicants that would otherwise be 
deemed safe in a non-pregnant woman. In addition, if chemicals absorb through the 
skin, they may be transferred from a pregnant woman to her fetus; or
 If it is a device-led combination product,84 or a device comprised of biologically-derived 
material (e.g., tissues derived from animal or plant material).85 Such products can cause 
adverse biological responses (e.g., cytotoxicity, irritation, or sensitization).
B. What Materials Are Included? 
FDA has identified specific materials in the final finished devices that are included in the policy 
outlined in this Attachment when they are in contact with only intact skin surfaces. The materials 
can include other processing chemicals and additives (e.g., plasticizers, fillers, color additives, 
cleaning agents, mold release agents). With the exception of color additives, these chemicals 
would not need to be disclosed in a marketing submission for devices with this type of tissue 
contact. 
Devices made from the following materials are included and can be made from a single material 
or multiple materials, such as polymer blends:
Synthetic polymers:
 Acrylonitrile-butadiene-styrene plastic (ABS);
 Cellulose Acetate
 Cured epoxy adhesives (used to attach medical device components to each other);
 Fluoropolymers including polytetrafluoroethylene (PTFE), expanded 
polytetrafluoroethylene (ePTFE), poly(vinylidene fluoride) (PVDF), and 
perfluoro(ethylene-propylene) plastic (FEP);
 Nitrile Butadiene Rubber (NBR);
82Yosipovitch, G., et al., "Skin barrier properties in different body areas in neonates." Pediatrics, 2000, 106(1): 105-
108.
83Fernandez, E., et al., "Factors and mechanisms for pharmacokinetic differences between pediatric population and 
adults." Pharmaceutics, 2011, 3(1): 53-72.
84A combination product is defined in 21 CFR 3.2(e).
85See Section II. Scope regarding feedback for combination products with a device constituent part that are not 
device-led. The Q-submission process should not be used to obtain feedback for combination products that are not 
device-led.
59 Contains Nonbinding Recommendations
 Parylene;
 Polyamides (PA), such as nylon and Velcro;
 Poly(butylene terephthalate) (PBT);
 Polycarbonate (PC);
 Polychloroprene, such as neoprene;
 Polyetheretherketone (PEEK)
 Polyetherketoneketone (PEKK);
 Polyether block amide (PEBA), such as PEBAX;
 Polyether imide (PEI);
 Polyethylenes, including low-density polyethylene (LDPE) and high-density 
polyethylene (HDPE);
 Poly(ethylene terephthalate) (PET), such as Velcro;
 Poly(methyl methacrylate) (PMMA);
 Polyoxymethylene (POM);
 Poly(phenylene sulfone) (PPSU);
 Polypropylene (PP);
 Polystyrene (PS), including high impact polystyrene (HIPS); 
 Polyurethanes (PUR), such as Lycra; 
 Polyvinyl alcohol (PVA); or
 Silicone
Natural Fabrics:
 Cotton fabrics;
 Rayon fabrics; or
 Silk fabrics
C. What Devices or Materials are Excluded? 
Medical devices, components, or materials excluded from the policy outlined in this Attachment 
are described in Table G.1below.
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Table G.1: Exclusion Characteristics
Medical Device Characteristic Reason for exclusion
Intact skin contacting components  There are known risks or we do not have adequate 
fabricated from materials that are not  experience with these materials that may introduce 
explicitly included in the above list,  toxicity risks. Biocompatibility testing or detailed 
including novel materials and bulk  rationales for omission of this testing could address 
metals (e.g., titanium, stainless steel,  these concerns.
nickel, nitinol, gold, cobalt, chrome)
Stored in or containing fluids or  There is an increased risk that leachables can be 
creams transferred into the fluid or cream and then absorbed 
through the skin.
Fabricated from in-situ polymerizing  There is an increased risk that polymerization or 
materials, absorbable materials, or  degradation products can change over time. The 
hydrogels manufacturing process can impact the type and quantity 
of intermediate and final chemicals present in the 
device, which could introduce a toxicity risk.
Contacts breached or compromised  There is an increased risk that leachables can be 
surfaces, such as open or healing  transferred through breached or compromised skin.
wounds
Reprocessed single-use devices FDA is unaware of a history of safe use of single-use 
devices that are reused after reprocessing. Reprocessing 
of such devices can cause adverse biological responses 
(e.g., irritation)
Adhesives used to attach a device  Adhesives can cause adverse biological responses (e.g., 
directly to the skin (e.g., electrode  irritation)
pads, on-body pump attachment 
systems)
D. What Biocompatibility Information Should be Included in a Premarket 
Submission? 
(1) All premarket submissions (PMAs, HDE applications, IDE 
applications, 510(k)s, and De Novo requests) 
We recommend the following information be included in the premarket submission for device 
types within the scope of the policy outlined in this Attachment:
 A list of all materials (including color additives)86 used to fabricate the device or 
component with only direct or indirect skin contact;
86For more information regarding color additives, see the FDA website for color additives for medical devices, 
available athttps://www.fda.gov/medical-devices/biocompatibility-assessment-resource-center/color-additives-
medical-devices  
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 A statement confirming that the device materials are listed in Section B, and have a 
documented history of safe use in legally marketed medical devices in contact with intact 
skin (e.g., through Medical Device Reporting (MDR) analysis, literature search); and
 A statement confirming that none of the exclusions listed in Section C apply.
(2) Additional recommendation for IDE applications 
In addition to the content recommended in Section D(1)above, FDA recommends that study 
sponsors discuss any adverse biological responses from devices within this intact skin policy in 
IDE progress reports87 submitted pursuant to 21 CFR 812.150(b)(5). Specifically, FDA 
recommends that study sponsors describe any redness (erythema), swelling (edema), irritation, 
sensitization (delayed Type IV hypersensitivity), allergy, immune response, or other reactions 
observed by investigators during the course of a clinical study with observations attributed to a 
specific device, if relevant.
(3) Additional recommendations for marketing submissions (510(k)s, 
PMAs, HDE applications, and De Novo requests) 
In addition to the content recommended in Section D(1)above, FDA recommends manufacturers 
include a statement that the manufacturer has documented in their Device Master Record (DMR) 
how they have determined that biocompatibility risks for their device are addressed such that 
biocompatibility testing, and a detailed rationale regarding manufacturing is not necessary to 
include in a premarket submission. The following statement is an example of the format and 
content to support such an approach:
We have documented in the Device Master Record (DMR) that we have addressed any 
concerns that have been identified through biocompatibility testing (i.e., cytotoxicity, 
irritation, and sensitization), manufacturing information (based on the type of materials, 
formulation (if available) and nature of contact), and/or relevant quality system 
requirements and postmarket controls related to:
 Purchasing controls (21 CFR 820.50) of device materials, 
 Production and process controls (21 CFR 820.70) for manufacturing materials , 
 Acceptance activities (21 CFR 820.80) for component and manufacturing 
materials, 
 Corrective and preventative action (21 CFR 820.100),
 Complaint files (21 CFR 820.198), and
 Medical device reporting (MDR) (21 CFR 803).
87https://www.fda.gov/regulatory-information/search-fda-guidance-documents/suggested-format-ide-progress-
report
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E. What is FDAs Recommended Content and Format for Certain Labeling 
Information Related to This Policy? 
This section contains FDAs format and content recommendations for certain labeling 
information, and to help illustrate, FDA has provided an example. When the device is intended 
for use in a patient population that may not have the ability to identify adverse biological 
reactions related to cytotoxicity, irritation, or sensitization (e.g., patients with epilepsy or 
dementia, or the vision impaired), FDA recommends that manufacturers using the policy 
outlined in this Attachment, in lieu of conducting biocompatibility testing, inform caretakers in 
the labeling by including a precaution discussing common adverse skin reactions. This applies to 
medical devices used in health care settings by health care personnel as well as medical devices 
used by patients and/or their caretakers. 
An example of a precautionary statement that follows FDAs recommendations is below:
Caretakers should assess patients for adverse reactions on the skin where the device has 
contact, such as redness (erythema), swelling (edema), irritation, sensitization (delayed 
Type IV hypersensitivity), allergy, immune response, or other reactions.
63 Contains Nonbinding Recommendations
Attachment H: Glossary
For the purposes of this guidance, the following definitions apply:
Agglomerate/agglomeration  collection of weakly or medium strongly bound particles 
where the resulting external surface area is similar to the sum of the surface areas of the 
individual components88
Aggregate/aggregation  particle comprising strongly bonded or fused particles where the 
resulting external surface area is significantly smaller than the sum of surface areas of the 
individual components89
Biocompatibility  the ability of a device material to perform with an appropriate host 
response in a specific situation90
Contact:
 Direct contact  term used for a device or device component that comes into 
physical contact with body tissue
 Indirect contact  term used for a device or device component through which a fluid 
or gas passes, prior to the fluid or gas coming into physical contact with body tissue 
(in this case the device or device component itself does not physically contact body 
tissue)
 Non-contact  term used for a device or device component that has no direct or 
indirect contact with the body (e.g., stand-alone software or database), and for which 
no biocompatibility information would be needed other than confirmation that there 
is no contact with the human body
 Transient contact  term used for a device or device component that comes into 
very brief/transient contact with body tissue (e.g., hypodermic needles that are used 
for less than one minute)
Degradation  decomposition of the device, possibly through the generation of new 
chemicals or absorption of the material, leading to loss of mechanical and/or physical 
properties of the device (device function) over time
88ISO/TS 80004-6:2021(E) Nanotechnologies - Vocabulary - Part 6: Nano-object characterization.
89ISO/TS 80004-6:2021(E) Nanotechnologies - Vocabulary - Part 6: Nano-object characterization.
90Black, J., "Biological Performance of Materials: Fundamentals of Biocompatibility." Boca Raton: CRC Press, 
2006.
64 Contains Nonbinding Recommendations
Extraction, exhaustive  extraction conducted until the amount of extractable material in a 
subsequent extraction is less than 10% by gravimetric analysis (or that achieved by other 
means) of that detected in the initial extraction91
Extractable  substance that can be released from a medical device or material using either 
extraction solvents or extraction conditions, or both, that are expected to be at least as 
aggressive as the conditions of clinical use92
Final finished form - term used for a device or device component that includes all 
manufacturing processes for the to be marketed device including packaging and 
sterilization, if applicable
In vivo animal study  a nonclinical animal study designed to provide initial evidence of 
device safety, potential performance when used in a living system, and/or the biologic 
response to the device
Leachable  substance that can be released from a medical device or material during clinical 
use93
Material  the substance or substances of which a thing is made or composed94
Novel material  material that has not previously been used in any legally marketed medical 
device
Risk assessment  overall process comprising a risk analysis (systematic use of available 
information to identify hazards and to estimate the risk) and a risk evaluation (process of 
comparing the estimated risk against given risk criteria to determine the acceptability of the 
risk)95
Sponsor  manufacturer, submitter or applicant
Toxic  capable of causing injury or death, especially by chemical means96
Toxicological hazard  potential for a chemical substance or material to cause an adverse 
biological reaction, taking into account the nature of the reaction and the dose required to 
elicit it97
91ISO 10993-12:2021 Biological evaluation of medical devices  Part 12: Sample preparation and reference 
materials.
92Ibid.
93Ibid.
94Materials, DICTIONARY, http://dictionary.reference.com/browse/materials (last visited May 2, 2016). 
95ISO 10993-1:2018 Biological evaluation of medical devices  Part 1: Evaluation and testing within a risk 
management process.
96Toxic, The American Heritage Medical Dictionary (2d ed. 2007).
97ISO 10993-1:2018 Biological evaluation of medical devices  Part 1: Evaluation and testing within a risk 
management process.
65 Contains Nonbinding Recommendations
Toxicological risk  probability of a specified degree of an adverse reaction occurring in 
response to a specified level of exposure98
Toxicity  the degree to which a substance is toxic
98ISO 10993-1:2018 Biological evaluation of medical devices  Part 1: Evaluation and testing within a risk 
management process.
66