Can we define risk as an equation? Can we write it down in a mathematical way? The answer is yes, and here’s what’s typically described as the risk equation.

Risk is a function of likelihood and consequences. What are the chances of something happening and what is the outcome of that event? If you want to look at risk from a different perspective, considering likelihood and consequences, you can look at it from a time perspective, as you can see here on this graphic. This is a time line that runs from the left to the right. As you see, the incident is occurring in the middle of this time. First, we should consider the likelihood of this incident occurring, which is before the incident occurs in time. You should think about the factors that affect whether or not that incident could happen – the likelihood. Then, after the incident occurs, you should consider the factors that affect the severity of that incident – the consequences.

Therefore, risk is a function of likelihood and consequences. And since it’s an equation, we can graph it. Therefore, we can graph risk with likelihood on the left-hand side and consequences on the bottom, on a scale of low to high. We can then plot likelihood and consequences on the graph to give us an overall risk from very high to very low. The lines are called isoquants and they provide a risk graph. Now, I’m going to show you some examples of how this can be used in our biological risk assessments.

This is an example of an untrained worker wearing no protective personal protective equipment growing a multi drug resistant strain of TB. What do you think the likelihood and consequences would be of them getting infected, and where would that point fall on this graph? I’m sure you correctly identified that the risk would be very high. We have an untrained worker and no PPE and a very dangerous pathogen, so the risk of getting infected is very high.

What if we had a well-trained worker, now wearing protective personal protective equipment, growing a multi drug resistant strain of TB. We’ve given this worker, some protective equipment and some training, but they’re still using the same dangerous pathogen. Where do you think this would fall on our risk graph? As you probably correctly determined, we’ve lowered the likelihood of them getting infected and therefore the likelihood is now very low. As you can see, the blue star is down, but the consequences of their illness is still the same, because the pathogen did not change. Therefore, we put the blue star into the lower right-hand corner where likelihood is low, but consequences are high.

In another scenario, what if we had an untrained worker now with no protective PPE growing an attenuated antibiotic susceptible strain of TB? So now we still have the untrained worker, no PPE, but we’ve changed the pathogen. The bacteria is now very susceptible to antibiotics and it’s not pathogenic. What do you think the risk is now? As you probably correctly determined, the likelihood of getting infected with the strain of bacteria is still high, because the worker is untrained and has no protective PPE. But now the consequences of them getting sick is very low because the TB is attenuated and we could treat the patient, if they got infected. I’ll show you just one more.

So now we have a well-trained worker, with protective PPE growing, an attenuated antibiotic susceptible strain of TB. This is the best situation, where we’ve got good training, good protection and low virulence strain of bacteria that’s being grown. As you might have already determined the risk is going to be very low because we’ve lowered the likelihood of them getting infected through training and protective PPE and lowered the consequences of that potential infection by working with an attenuated, antibiotic susceptible strain. These are extreme and simplistic examples, but I wanted to clearly show that risk is a combination of likelihood and consequences.

So now that you had a chance to think about risk assessment itself, I also want you to think about what might be missing from this technical risk assessment. We’ve talked about risk as a function of likelihood and consequences, which is fine. It’s an equation and we can graph it, but there’s something else that is missing from this risk assessment process itself.

What is missing from a technical risk assessment is the concept of what is acceptable risk. You may determine what’s acceptable risk for you, but it may not be acceptable for other people. There is this concept of risk perception. Here you see a couple of different situations. On the left is somebody going into shark infested waters and on the right climbing a rock wall – is this acceptable risk or not. For some people it may be terrifying and unacceptable, but people do both these activities and therefore accept the risk. They know there is a certain amount of risk and they’re willing to accept it for the thrill or the accomplishment. It’s easy enough to graph out what risk is, but then we have to factor in what we and other people doing the work in our laboratory think is acceptable risk.

Let’s look again at this risk graph. This risk graph shows the rings of risk to be of equal size. We have very low risk on the bottom left-hand corner and very high risk on the top right-hand corner. You can see that the rings in between, from low to medium to high are all about the same size, but it doesn’t have to be that way.

Some places in the world, some cultures and some countries are very risk averse. Therefore, if you want to emphasis high risk all you have to do is make that area of the graph bigger, as shown here, and you make the other rings smaller. Now when you start plotting out risks, more of the points will fall into the high-risk category, which means then you have to take action. You can’t accept high risk, and so you have to spend more money and take more time to mitigate those risks.

Conversely, some societies, some countries, some people are very risk, tolerant and for whatever reason take on more risk in their daily activities. In this risk graph, we’ve taken away a few of the rings and the very high risk is now a very small area. Moderate risk is also very small leaving a large low risk area, which is the white part of this graph. Therefore, when plotting risk onto this graph, most of the points are going to fall into the low-risk category. Just by changing the size of the rings on this graph we have recharacterized the risk. This is risk perception. This then changes how much risk mitigation we’re going to do. Most people would not spend any money when it comes to low risk. These are just some small and simple examples to show you that risk perception is a big factor that varies from person to person, institute to institute and country to country. Therefore, there is no right or wrong when it comes to classifying risk.

Summary

A risk assessment is beneficial in many ways. This includes making the risk assessment process repeatable and reproducible. It is very important to show that you have a system for doing risk assessments that provide consistent results. Most importantly, having a good risk assessment process facilitates risk mitigation decisions. You can now justify spending time and resources on the known high-risk areas. Finally, a good risk assessment process provides assurance and quality control documentation.

As a summary for this entire module, I have here a little movie for you to watch, which goes over very simply the entire risk assessment process. So far, we have only covered the first step in the process which is characterizing the risk. In the later modules we will cover risk mitigation and performance evaluation. But for now just watch this video.

This video very simply summarized the main steps in the entire risk assessment and mitigation process. In reality it is a bit more complex than shown, but it can be done and in the next module we will cover a methodology to characterize and quantify the risk.

Thank you for taking this module on risk assessment. Please take the quiz to remind yourself of some of the important points we covered in the module. Thank you again and I look forward to having you take the next module.