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The revision of ISO 10993-1 – what does it mean for medical devices?

Biological evaluation is essentially a toxicological risk management process and the revised edition of the standard, due to be published by the end of this year, finally presents the subject within its proper context. The principles of biological evaluation, set out in Clause 4 of the standard, remain unchanged but are now given due prominence. The revision aligns biological evaluation closely to both the risk management process specified by ISO 14971 and generally accepted principles of toxicological risk assessment. 

At the heart of the revision of ISO 10993-1 is the expectation that all relevant data sets should contribute to the risk estimate, their contribution being measured by their evidential value rather than by misguided unscientific precedent. By focussing on the scientific validity of the risk assessment and providing guidance on the use of all relevant types of data, the new edition should finally lead to a more comprehensive evaluation, based preferentially on the use of more conclusive and relevant techniques, rather than a predominantly test-based approach which does not stand up to scientific scrutiny. In more accurately reflecting the scientific basis of biological risk assessment, the standard will assist professional users to better judge the extent of testing and analysis needed to estimate biological risks sufficiently to demonstrate that relevant risk acceptability criteria are met. This should reduce the amount of testing needed to comply with the standard.

As with any risk management process, hazard identification is the first step. In this case, hazard is seen as the potential for a chemical constituent or material to cause an adverse biological effect. If a constituent or material that is known to be hazardous is present, at any level, in a medical device, this represents a hazardous situation and as per ISO 14971, the associated risk must be estimated. Conversely, if there is good evidence to show that no biological hazards are present, there is no hazardous situation, so there is no appreciable biological risk and the assessment is complete. Where biological hazards are present, the estimated risk must be compared to specified risk acceptability criteria, as required by ISO 14971. 

The toxicological risk is estimated from characterisation of the toxicological hazard (i.e., the toxic effect and dose-response) and the exposure estimate. In line with ISO 10993-17, if exposure to a toxic constituent is below a relevant toxicological threshold, it is accepted that the risk of toxicity to humans is tolerable. A similar, more qualitative approach is appropriate for biological hazards arising from the physical features of a device. If the available data are insufficient to reach a sufficiently robust risk estimate, a gap analysis should identify the most cost-effective way of gathering or generating additional data. Typically a biological risk estimate will lead to the conclusion that risk arising from exposure to the device is below a level that could cause harm to health. When this conclusion is not reached because residual biological risk remain, risk control measures must be implemented to the extent feasible, in line with ISO 14971.

As the title of the standard suggests, biological evaluation is carried out within a risk management process – it does not cover the management of biological risks in its entirety but concentrates on biological risk estimation. Thus, it does not address benefit-risk analysis, leaving this to ISO 14971 to cover. 

Concern has arisen in some quarters that publication of the new edition of ISO 10993-1 in advance of guidance that is currently in preparation will lead to difficulties implementing the standard. This emphasises the importance of the requirement in the standard that biological evaluation must be planned, conducted and reported by competent personnel, capable of making informed decisions based upon scientific data. The key to a cost-effective route through this complex process is sound advice from experts who properly meet the qualification requirements and are not conflicted by the need to promote testing.

To learn more about ISO standards around medical devices, read our biocompatibility spotlight entitled Biological evaluation – the past, the present and the future.

Author:

Jeremy Tinkler, ERT

Regulatory Affairs Director, ICON plc

Chair of ISO/TC 194: Biological and Clinical Evaluation of Medical Devices.

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