I believe the following is what should be followed:

1) Low Severity Hazards: Should be mitigated but it can also be considered trivial or negligible, however it it is a common problem then it should be considered looked into because it could be considered a faulty design.

2) Intermediate Severity Hazards: Can be considered conditional and a company can take a risk on overlooking it, if it plans to take the risk and purchase a good insurance as a backup. However, in general a company should strive to mitigate it and conduct a risk analysis and be reviewed.

3) High Severity Hazards: Should be prevented entirely, medical devices with this type of hazard would not be approved because it would go against all engineering ethics.

Low Severity Hazards is considered a risk passable condition where it can be accepted, depending that it is not high occurencem, this is where a risk analysis must be considered to ensure that it does not pass the acceptable threshold.