Hazards vs. Hazardous Situation Confusion

[Marcelo Antunes]

Hazards are potential source of harm, per the definition.

For the hazard to become a hazardous situation, an exposure has to occur (P1). There's a combination or sequence of events that exposes the patient/user/environment to the hazard and then creates the hazardous situation. Sequence or combinations of events should be actions and events, not generic comments. Why is it important? Because generally you need to act on the sequence of events to lower the risk.

This can be seen in Figure E.1 of the standard. It's very important that this figure is created for each hazardous situation. My experience shows that users rely too much on techniques, such as FMEA, which do not provide all the information required, and this is part of the problems.

The best sugeestion for categorizing hazards (which is really not required but facilitates the implementation of ISo 14971) is found in table E.1 of the standard - energy hazards, biological hazards, physical hazards,operational hazards, etc, each with possible sub-hazards.

Failures are not hazards nor hazardous situations. Failures are part of the sequence of events which exposes the hazards and creates the hazardous situations.


Example:

Hazard: Functional (excessive output)

Sequence of events:
1 - user sets rotating output control with excessive strenght (X torque)
2 - rotating output control breaks (failure as p[art of the sequence of events)
3 - output control is lost

P1 is made of a conjunction of the probabilities for each part of the sequence of events.

Hazardous situations: Patient under excessive output from device (please note the link with the hazard - the hazard is potential, but the hazardous situation is a situation on which the user was exposed to the hazard - just as in the definition).

P2 is the probability of the hazardous situation leading to a harm. Please note ein the example that the hazardous situation is defined as excessive output. There's a probability that the failure of control leads to this.

In this case, let's say the severity of the harm would be burns.

The probability of ocurrence of the hard would be related to P1 and P2, for example, P1 x P2


You would need to add another hazardous situations, for example, the case where the failure lead to insufficient output.

Please note that in this case the sequence of events would be the same, but the hazard and hazardous situation, and harm, and (probably) the probability of ocurrence of harm, would be different:

Hazard: Functional (loss of function)

Sequence of events:
1 - user sets rotating output control with excessive strenght (X torque)
2 - rotating output control breaks due to strenght (failure)
3 - output control is lost

Hazardous situations: Device does not output and patient is not treated or thinks is treated


For both, note that the risk control options could be different.

[v9991]

In Reply to Parent Post by Marcelo Antunes

My experience shows that users rely too much on techniques, such as FMEA, which do not provide all the information required, and this is part of the problems.

i agree with the point; this is mainly because of,relying mainly/alone a single tool. & what we have done is to, before initiating FMEA ---> made it mandatory to have a process-mapping; identification of critical quality-material-process parameters (with rationale & justification)

so, that has solved the limitation to quite an extent; but then of course i did add additional steps to the FMEA process. ( this was also relevant, as we also need to consider to rolling the process out at multiple locations/units - teams etc.,)

In Reply to Parent Post by Marcelo Antunes

The best sugeestion for categorizing hazards (which is really not required but facilitates the implementation of ISo 14971) is found in table E.1 of the standard - energy hazards, biological hazards, physical hazards,operational hazards, etc, each with possible sub-hazards.

this aspect is met through adding a hazard category on the left hand side of FMEA table; also through including the criteria in the risk assessment/evaluation step.

In Reply to Parent Post by Marcelo Antunes

Failures are not hazards nor hazardous situations. Failures are part of the sequence of events which exposes the hazards and creates the hazardous situations.

agreed...i was trying to capture the same when i said in my earlier response...

In Reply to Parent Post by v9991

...(hazard and hazardous situation)failure mode ...

[ortho_engineer]

In Reply to Parent Post by Marcelo Antunes

Example:

Hazard: Functional (excessive output)

Sequence of events:
1 - user sets rotating output control with excessive strenght (X torque)
2 - rotating output control breaks (failure as p[art of the sequence of events)
3 - output control is lost

P1 is made of a conjunction of the probabilities for each part of the sequence of events.

Hazardous situations: Patient under excessive output from device (please note the link with the hazard - the hazard is potential, but the hazardous situation is a situation on which the user was exposed to the hazard - just as in the definition).

P2 is the probability of the hazardous situation leading to a harm. Please note ein the example that the hazardous situation is defined as excessive output. There's a probability that the failure of control leads to this.

In this case, let's say the severity of the harm would be burns.

Thanks for the response - I still need some clarification it seems, though...

In the example you gave, you stated the hazard as being excessive functional output, with a form of energy being an initiating event (user's force that breaks the device).

Why in your case is the excessive functional output the hazard, and the energy the initiating event, while the E.1 table in the standard lists both as their own hazards? This is the mental block I am having trouble with - how do you differentiate the circumstance where an Energy/Force is the hazard and the failure/fracture (or put another way, loss of function) is the Haz. Situation, from the circumstances where the failure/fracture (loss of function) is the hazard and the Energy/Force is an initiating event?

Or should I just list both as hazards (i.e. Hazard 1: Loss of function; Hazard 2 = Bending/Torsion Forces experienced during intended use).... If so, then where do I stop?

[Marcelo Antunes]

In the example you gave, you stated the hazard as being excessive functional output, with a form of energy being an initiating event (user's force that breaks the device).

Why in your case is the excessive functional output the hazard, and the energy the initiating event, while the E.1 table in the standard lists both as their own hazards? This is the mental block I am having trouble with - how do you differentiate the circumstance where an Energy/Force is the hazard and the failure/fracture (or put another way, loss of function) is the Haz. Situation, from the circumstances where the failure/fracture (loss of function) is the hazard and the Energy/Force is an initiating event?

Or should I just list both as hazards (i.e. Hazard 1: Loss of function; Hazard 2 = Bending/Torsion Forces experienced during intended use).... If so, then where do I stop?

You´re seeing too many energies :-)

Forget the (user's force that breaks the device) for a while.

The hazards is the potential source of harm. The initiating event may have nothing to to with the hazard, the only point is that in this example I used a situation normally seen. After the exposure of the hazards, there´s the hazardous situation.

The hazard, and hazardous situations, are related to the harm. The harm in the example comes because the device lost it´s output control (function). So, using table of ISO 14971, this would be an functional hazard related to excessive output.

Bending/Torsion itself is not a hazard. The exposure to bending/torsion does not create a hazardous situation. It´s the exposure of the hazard that creates the hazardous situation.