Biological risk assessment, questions and answers

In this article, we explore the questions we are regularly asked when dealing withbiological evaluation.

Lauriane Sauge, Head of Regulatory Affairs and Quality at Cisteo MEDICAL, took part in the exercise, first on video, then in writing.

Biological risk assessment in accordance with ISO 10993-1 is an analytical process designed to determine potential risks to the health of patients or users of a medical device. It takes into account the biocompatibility of the device, i.e. the absence of adverse effects when used in accordance with its intended purpose. This assessment is based on the nature of the device, its mode of contact with the body, its duration of contact and its material.

The main factors to consider include :

• Duration of contact with the human body (short term, medium term, long term).
• The nature of the contact (direct contact with the fabric or indirect contact, such as via body fluids).
• Anatomical location (contact with skin, mucous membranes or internal tissues).
• The type of materials used in the device, their possible degradation and the substances they could release.
• The device's function, which could influence its interaction with body tissues or organs.

ISO 10993-1 lists various tests depending on the risk associated with the device, which may include:

• Cytotoxicity tests: to assess the toxicity of materials on cells.
• Sensitization tests: to identify whether the material may induce an allergic reaction.
• Irritation tests: to detect tissue irritation.
• Hemocompatibility tests: to analyze the effects of the material on the blood.
• Genotoxicity tests: to determine whether the material can induce genetic mutations.
• Systemic toxicity tests: to assess general toxic effects.
• Implantation tests: if the device is to be implanted in the body.

The need for testing is determined by theinitial biological risk assessment. If a medical device is intended for low-risk use, and does not contain materials likely to cause undesirable biological reactions, testing may be deemed unnecessary. On the other hand, for a more complex device, or for implantable or extended-use devices, a more thorough series of tests will be required.

If a specific biological test cannot be performed, it is possible to justify its absence by means of a risk assessment, taking into account existing data, previous experience or tests on similar devices. ISO 10993-1 allows for exemptions, but each justification must be well documented and scientifically proven.

Contact time is one of the key variables in risk assessment. According to ISO 10993-1, devices are classified into three categories:

• Short-term contact: less than 24 hours.
• Medium-term contact: between 24 hours and 30 days.
• Long-term contact: more than 30 days. Classification of contact duration determines the type of tests required.

Don't forget to take repeated use of the device into account.

No, although in vitro testing is often the first step in biocompatibility assessment, in some cases in vivo testing (on animals or under real-life conditions) is necessary, particularly for implantable devices or those in prolonged contact with human tissue. Assessment must be adapted to the type of device and the nature of contact with the body.

The assessment must be documented in a detailed report which includes an analysis of the materials used, the tests carried out, the results obtained and the scientific justification for each decision taken. The report must enable competent authorities and stakeholders to understand the biological risks associated with the device and the measures taken to minimize them.

In short, ISO 10993-1 biohazard assessment is a rigorous process designed to guarantee the safety of medical devices through appropriate testing and in-depth analysis of each device and its materials.