Page 236 - Safety Risk Management for Medical Devices

Relationship Between ISO 14971 and Other Standards 215

the identification, estimation, and evaluation of biological risks of the medical device.
Additionally, the plan must include activities for the identification, review, and
approval of: biological Risk Controls, residual biological risk, and disclosure of the
residual biological risks.
One of the activities of biological risk analysis is the identification of biological
hazards. This involves the consideration of the level of toxicity of utilized materials,
and their route and duration of exposure. Sometimes the physical properties of mate-
rials play a role in the level of toxicity of the material. This includes factors such as
surface roughness or porosity of the material. Chemical properties of materials can
also introduce biological hazards. For example, dissimilar metals may create a galvanic
and corrosive process, which creates a biological hazard.
As part of Hazard identification, potential contributors such as the choice of materials,
additives, processing-aids, and catalysts should be considered. Also, downstream processes,
e.g., welding, sterilization, degradation materials, and packaging can introduce Hazards.
Characterization of the biological hazards of a device includes identification of the
type and duration of exposure to materials. For example, exposure to intact skin is
very different from exposure to internal tissues such as blood or brain.
Risk estimation requires knowledge of the probability of exposure to the toxicant
and the potential Harm that could ensue. Probability of exposure can be derived from
the availability of the toxicant and the dose response in the exposed tissue. Severity is
related to the biological response and can be estimated based on published literature
or animal studies.
Risk Controls aim to reduce the potential risks. Some examples of Risk Controls
are:

• Design changes to eliminate toxic materials from the design or manufacturing
process
• Changes to physical/geometric properties
• Reduction of exposure time
• Avoidance of the more hazardous exposure routes
Biocompatibility can also guide the device risk management by contraindication
of patients who could be more vulnerable. For example, a product may be adequately
safe for adults, but not safe for infants.
Evaluation of the biological risks of a medical device is part of the overall residual
risk evaluation. Risk evaluation requires knowledge of risk acceptance criteria. The
criteria for risk acceptability are established in the risk management plan, at the start
of the design process.
Risk Controls must be verified for implementation and effectiveness. Verification of
implementation can typically be achieved via the normal design verification testing.
Biological evaluation could serve as verification of biological Risk Control effectiveness.