Evaluating Genotoxicity under ISO 10993-1:2025

Key Changes and Challenges

Genotoxicity refers to a material’s potential to damage genetic material (i.e., DNA) which is important because it can signal a risk of mutations and carcinogenesis. In the context of medical devices, genotoxicity is one of the biological endpoints (or biological effects as the updated standard refers to them) evaluated during biocompatibility testing. Traditionally, genotoxicity testing has been required as part of a comprehensive biological risk assessment for certain devices (primarily long-term implants or devices with intimate tissue exposure or incorporating novel materials). As specified in ISO 10993-3, testing starts with in vitro studies and involves in vivo studies as needed; however, approaches to genotoxicity evaluation are evolving.

The updated ISO 10993-1:2025 standard (the 6th edition, published November 2025) was a technical revision with a complete reorganization and alignment to ISO 14971 risk management principles. One significant area of change is the treatment of genotoxicity. In fact, the prior standard (the 5^th edition, 2018) had some inconsistencies regarding when genotoxicity testing was recommended for devices with similar contact types and durations. The new edition resolves these gaps by expanding and clarifying genotoxicity requirements:

• Testing is still not required for surface devices that contact intact skin (all contact durations) unless special concerns such as novel materials or sensitive populations apply.
• No routine testing is required for limited (< 24 hour) contact with internal tissues unless the device employs novel materials or targets sensitive patient populations or has direct contact with circulating blood (extracorporeal circuits or implantable medical devices). The risk of genotoxicity should be assessed, but testing may be waived with justification.
• Evaluation of genotoxicity is now clearly required for all devices with prolonged (> 24 hour) contact with any tissue (except intact skin) or circulating blood. (The requirement to evaluate genotoxicity for devices with prolonged contact was previously ambiguous or considered optional in some cases.)
• Evaluation of genotoxicity remains required for all long-term contact devices (except for those contacting intact skin).

To summarize, any device with prolonged or long-term direct or indirect body contact must be evaluated for genotoxic potential unless contact is limited to intact skin. In addition, carcinogenicity evaluation is now explicitly required for all long-term (> 30 days) contacting devices where chronic toxicity is a concern; genotoxicity testing also serves as a screen for carcinogenic risk – if any genotoxic constituents are detected, further carcinogenicity assessment is expected. These changes better align the standard with regulators’ expectations and current scientific understanding, but they also mean that more devices will require a genotoxicity evaluation as part of their biological safety evaluation.

In practice, device manufacturers are expected to:

• Identify potential genotoxic risks early by analyzing device materials, chemicals, and processing (including residual monomers, additives, or contaminants).
• Leverage existing data whenever possible (for example, past data pertaining to the same materials, published toxicity studies, supplier data) to determine if genotoxicity testing is warranted.
• Use chemical characterization and toxicological risk assessments to address genotoxicity. If knowledge of materials and processing provides sufficient data (i.e., the device’s materials of construction and processing are well understood and have a proven safety profile) or if chemical analyses of device extracts (per ISO 10993‑18) show no hazardous potential leachables, then dedicated genotoxicity tests might be scientifically unnecessary.
• Apply a threshold-based toxicological risk assessment on potential leachable chemicals (per ISO 10993-17), including evaluation of genotoxicity data and calculation of safe exposure limits.
• Consider special cases such as the presence of a known genotoxic substance or use of novel materials (which almost always warrant genotoxicity testing since no prior data exist). When a known genotoxic substance is used in the manufacture of a medical device, a positive result from testing is expected and focusing on quantifying its release and performing a risk-benefit analysis may provide better information than running another genotoxicity assay.

The bottom line for device manufacturers is that if your device stays in direct or indirect contact with patient internal tissues or bone, intact mucosa, or circulating blood for more than 24 hours, be prepared to address genotoxicity in your biological safety evaluation. Even for some shorter exposure devices (i.e., ≤ 24 hours), such as those involved in extracorporeal circuits, regulators may expect justification (via risk assessment) that genotoxic risks are negligible, especially for sensitive patient populations (like neonates or pregnant patients) or devices with chemical constituents of concern.

The broadened requirements raise practical questions about how to evaluate genotoxicity effectively. The modern paradigm gives manufacturers flexibility in how to demonstrate safety but making that decision is itself a hurdle. Manufacturers must decide whether to conduct biological tests or rely on chemical data and toxicological risk assessment. High-quality analytical data can sometimes substitute for biological tests, but only if it is comprehensive. Challenges include detecting trace impurities or reaction by-products that might be genotoxic.

Genotoxicity tests are usually performed on device extracts (solvent extracts of the device) to represent potential leachates that could reach patient tissues. A technical hurdle is designing extraction studies that realistically simulate worst-case clinical exposure without overly degrading the device. Achieving the right balance: exhaustive enough to detect trace genotoxins, but relevant to clinical use, requires expertise in chemistry and materials science.

FDA guidance recommends a battery of two complementary in vitro tests for robust coverage (because no single assay catches all genotoxic mechanisms). Typically, this includes: (a) a bacterial reverse mutation test (Ames test) to detect DNA point mutations, and (b) an in vitro mammalian cell assay, such as the mouse lymphoma thymidine kinase gene mutation assay or an in vitro micronucleus/chromosomal aberration test. An in vivo assay (like a rodent bone marrow micronucleus test) is generally optional and only considered if in vitro results are equivocal or if novel materials are involved. The updated standard stresses expert judgment: for example, if an in vitro test is positive, manufacturers should investigate and identify the causative agent rather than blindly proceeding to animal tests. If the genotoxic substance cannot be removed, a scientific rationale should be developed that demonstrates that there is no potential route of exposure to patients or that patient exposure to the device-related chemical is below the safe threshold. An equivocal result or a positive in vitro assay result might necessitate repeating the assay or performing an additional confirmatory test. These interpretative steps demand toxicological expertise and sometimes consultation with regulators.

A full battery of genotoxicity tests can be time-consuming and costly; however, not conducting these tests requires confidence in the chemical data and a thorough risk analysis. The push for risk-based evaluation means chemical characterization data are often the linchpin of genotoxicity assessments. A cornerstone of the modern approach is to perform detailed chemical characterization (per ISO 10993-18) and then conduct a toxicological risk assessment (per ISO 10993-17) to evaluate genotoxic and carcinogenic risks of any identified compounds. Any compound with structural “alerts” for mutagenicity or evidence of DNA reactivity must be flagged. If such compounds are present in amounts above accepted toxicological safety thresholds, the manufacturer faces either removing/reducing those substances or justifying device safety with additional data.

MED Institute provides comprehensive biological risk assessment services to support the safety evaluation of medical devices in accordance with ISO 10993; our multidisciplinary team of professionals offers expert guidance on material characterization, biological equivalence assessment, toxicological evaluation of chemical constituents, and even support in responding to submission deficiencies. MED Institute technical experts have extensive experience in developing biological evaluation plans and biological evaluation reports in compliance with global regulatory standards and based on sound scientific principles. By engaging with our team of experts, several manufacturers have designed safer products and accelerated their regulatory submissions and successful market entry.

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