Biocompatibility (ISO 10993)
Biocompatibility is the assessment of whether a medical device is biologically safe for its intended contact with the human body — whether its materials, and anything that leaches from them, cause an unacceptable biological response. It is governed by the ISO 10993 series, and the single most important thing to understand about the modern approach is that it is a **risk-based evaluation, not a fixed battery of tests**. ISO 10993-1:2018 made this explicit: you evaluate biological safety within a risk-management process and test only to fill the gaps that evaluation reveals. This page covers that framing; the wider device quality system is the [medical device quality](/topics/medical-device-quality) explainer and the risk method underneath it is [quality risk management](/topics/quality-risk-management).
What an explainer is not
A topic explainer is SPEQ’s synthesis of what a practice involves, cited to the standards that govern it. It does not reproduce their text, and it does not determine which of them apply to your product or process.
[ POSITION IN THE FRAMEWORK ]
7 DIMENSIONS · 21 LINKSISO 10993-1 reframed biocompatibility as a risk-based biological evaluation inside the device QMS, not a fixed test battery — you test only where existing data and chemical characterisation leave a genuine gap.
06 · QUALITY MATURITY — BIOCOMPATIBILITY (ISO 10993), REACTIVE TO ADAPTIVE
Biocompatibility means running the full biological test battery to pass, with no evaluation and no material history.
A testing SOP exists, but the same endpoints are ordered for every device regardless of contact category.
A biological evaluation categorises by contact nature and duration, and tests only endpoints existing data cannot address.
Chemical characterisation and toxicological assessment address endpoints without animal tests; material changes trigger re-evaluation.
Biological safety is designed in through material selection and characterisation, integrated with the ISO 14971 risk file across the lifecycle.
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07 · REGULATORY & EVIDENCE
GOVERNING STANDARDS · 3
Derived from the 3 standards SPEQ maps to this subject, across 2 regulatory bodies: ISO, EC.
RECORDS & OBJECTIVE EVIDENCE
- A biological evaluation plan and report structured to ISO 10993-1 within the ISO 14971 risk process
- Device categorisation by nature and duration of body contact
- Endpoint-by-endpoint gap analysis justifying which tests were and were not performed
- Chemical characterisation (ISO 10993-18) and toxicological risk assessment (ISO 10993-17) data
- Change-control records re-evaluating biocompatibility after a material, supplier, or sterilisation change
COMMON INSPECTION FINDINGS
- Full test battery run with no biological evaluation or gap analysis
- Biological endpoints not matched to the device's contact category
- Material or supplier changed without re-evaluating the biological conclusion
- Biocompatibility conclusion resting on a material the device no longer uses
- Evaluation not integrated with the ISO 14971 risk-management file
A risk-based evaluation, not a test checklist
The common misconception is that biocompatibility means running a standard list of biological tests — cytotoxicity, sensitisation, irritation, and so on — and passing them. **ISO 10993-1:2018** deliberately reframed this: its full title is "Biological evaluation of medical devices — Part 1: Evaluation and testing *within a risk management process*," and the ordering is the point. You conduct a biological *evaluation* first — gathering and analysing what is already known about the materials, the manufacturing, the chemistry, and prior data — and testing is the step you take only where that evaluation leaves a genuine gap. The standard sits inside the ISO 14971 device risk-management framework rather than beside it.
This matters for real reasons beyond doctrine. Defaulting to the full test battery wastes resources, delays devices, and — for animal-based tests — raises ethical concerns the standard explicitly seeks to reduce by favouring existing data and non-animal methods. More importantly, it can be *scientifically weaker* than a good evaluation: a chemical characterisation of what a material actually releases, assessed toxicologically, can address biological risk more directly than a generic irritation test. The 2018 revision’s emphasis on chemical characterisation and toxicological risk assessment as a route to demonstrate biocompatibility — sometimes in place of biological testing — is one of its most consequential shifts.
Categorising by contact — nature and duration
The evaluation is driven by how the device contacts the body, because a device that never touches the patient and one implanted for life carry entirely different biological risk. ISO 10993-1 categorises devices by the **nature of body contact** (surface-contacting — skin, mucosal membrane, breached surface; external communicating — blood path, tissue/bone; or implant) and by the **duration of contact** (limited, ≤24 hours; prolonged, 24 hours to 30 days; long-term, >30 days). The intersection of nature and duration places a device in a category that indicates which biological endpoints are relevant to consider.
Those endpoints — cytotoxicity, sensitisation, irritation, acute/subacute/chronic systemic toxicity, genotoxicity, implantation effects, haemocompatibility, and others — are *considerations*, not a mandatory checklist. For each endpoint relevant to the device’s category, the evaluation asks whether existing data (material history, chemical characterisation, literature, prior use) already addresses it, and only where it does not is new testing justified. This category-driven, endpoint-by-endpoint gap analysis is what makes biocompatibility a structured evaluation rather than a blanket test order, and it is why two devices in the same category can legitimately need very different testing.
Chemistry, materials, and where E&L meets biocompatibility
Because biological risk ultimately comes from what the body is exposed to, **chemical characterisation** has become central: understanding the materials of construction and what can migrate out of them (the extractables and leachables story) is often the most direct route to a biological safety conclusion. Identified chemical species are assessed toxicologically against the patient’s exposure, and this chemistry-led route can, under ISO 10993-1 and -18 (chemical characterisation) and -17 (toxicological risk assessment of constituents), demonstrate safety for endpoints that would otherwise require animal testing. Biocompatibility and extractables/leachables are therefore two views of the same underlying question — what does the patient actually receive, and is it safe?
This is also why biocompatibility is not settled once. It is contingent on the exact materials, suppliers, and manufacturing processes evaluated, so a change to any of them — a new resin, a different supplier grade, a changed sterilisation method, a manufacturing-site move — can invalidate the biological evaluation and must run through change control against the question "does the existing biocompatibility conclusion still hold?" A device whose material was quietly changed without re-evaluating biocompatibility has a safety conclusion resting on a material it no longer uses.
Biocompatibility in the device quality system
Biocompatibility sits inside design controls and risk management rather than beside them. The biological evaluation is part of the design inputs and the risk-management file: the risks it identifies feed the ISO 14971 risk analysis, its conclusions become part of the design outputs and the technical documentation a notified body or the FDA reviews, and its dependence on specific materials ties it into change control for the life of the device. It is not a standalone lab report but an integrated element of demonstrating the device is safe.
The regulatory reception reinforces the risk-based framing: the FDA recognises ISO 10993-1 through its own guidance on using the standard, and the EU MDR requires biological safety to be demonstrated as part of the general safety and performance requirements. Both expect a reasoned evaluation, proportionate to contact and risk, backed by data — not a reflexive full test battery and not an unjustified claim of equivalence. A biological evaluation that runs everything, or that asserts safety without addressing the relevant endpoints, misreads the standard in opposite directions; the discipline is the reasoned middle that ISO 10993-1 lays out.
FREQUENTLY ASKED
Is biocompatibility a fixed set of tests?
No. ISO 10993-1:2018 reframed biocompatibility as a biological evaluation within a risk-management process — you evaluate what is already known about the materials, chemistry, and prior data first, and test only to fill the gaps that evaluation reveals. Defaulting to the full battery of tests wastes resources, raises animal-testing ethics concerns, and can be scientifically weaker than a good chemical characterisation and toxicological assessment.
How is a device categorised for biocompatibility?
By the nature of body contact (surface-contacting; external communicating with the blood path, tissue, or bone; or implant) and the duration of contact (limited ≤24 hours; prolonged 24 hours–30 days; long-term >30 days). The intersection places the device in a category that indicates which biological endpoints — cytotoxicity, sensitisation, irritation, systemic toxicity, genotoxicity, implantation, haemocompatibility, and others — are relevant to consider.
How does biocompatibility relate to extractables and leachables?
They are two views of the same question — what does the body actually receive, and is it safe? Chemical characterisation of what migrates out of a device’s materials (the extractables/leachables story), assessed toxicologically against patient exposure, is often the most direct route to a biological safety conclusion, and under ISO 10993-1/-17/-18 can demonstrate safety for endpoints that would otherwise require animal testing.
Can a material change invalidate a biocompatibility evaluation?
Yes. The evaluation is contingent on the exact materials, suppliers, and processes assessed, so a new resin, a different supplier grade, a changed sterilisation method, or a site move can invalidate it. Such changes must run through change control against whether the existing biocompatibility conclusion still holds. A device whose material was quietly changed without re-evaluation has a safety conclusion resting on a material it no longer uses.