The EPA makes decisions for the people and environment of Aotearoa. Risk assessment is a big part of this - but what is risk? Lee Bailey, a Senior Advisor in our Reassessments Team, explains.

By Lee Bailey

19 October 2020

Read the authors' biographies

It’s been a strange year, hasn’t it? The different approaches to the COVID-19 pandemic have highlighted the different choices that our employers, our governments, and we as individuals have to make to balance the risks to our health and the economy. It feels like science advice has never been as well respected as it is now.

There is a lot of information out there. As a geophysicist turned contaminant geologist turned chemical risk specialist, the details of these topics are way outside my area of expertise. However, as a risk specialist, these events got me thinking about risks and hazards; how do we go about assessing risks, how do we manage them, and how do we explain these to people?

So, what is risk?

We all have a slightly different understanding of what risk means, and how we interact with it in our daily lives. As we grow up we are taught that crossing a road is dangerous, and that we have to stop and look for traffic. We learn that using the green man at a crossing is safer than walking straight out into busy traffic. As we get older, we get better at judging how quickly cars can go, how quickly we can cross the road and what can happen if we get hit. We start to balance the time pressure of waiting or going based on our knowledge of traffic speed and accident statistics.

A bird's eye view of people crossing a busy road.

People crossing a busy road.

We might choose to take the risk by making a run for it across the road. But how do we weigh up the risks in more complex situations such as risks in the workplace, or the risks some chemicals can have on us and the environment?

Risk means different things to different people

Each profession that considers risk - for example, insurance, workplace safety, or chemical management - has its own definition of risk. The Society for Risk Analysis has identified 16 possible ways to express risk. As well, considering vulnerability or the ability to withstand or respond to an event (resilience), is another way to think about this.

Even within the same profession or area of industry, there can be different approaches to measuring risk. For example, ecotoxicologists look at how toxic chemicals are to plants and animals. They use different models for risk depending on what species they are looking to protect. Even the country they are working in can affect the choice of model used. Cultural differences can also play a part in what a community, or different communities, consider to be acceptable levels of risk. Although an ecotoxicologist will have a maximum acceptable level for a chemical being in the environment, a te ao Māori world view may mean that the presence of any chemical is not acceptable.

A common way to describe risk, which goes back to my road crossing example earlier, is a combination of how large the impact of something occurring is (usually negative) with how often or likely it is for that thing to happen.

Hazard versus risk

A hazard is an event or activity that has the potential to cause physical or psychological injury or damage. Hazards can be related to your physical environment (such as something that could trip you or fall on you), energy (fire, explosions and similar), materials (for example, how toxic a chemical is), and plants and animals (including pathogens and viruses).

Some organisations may look at what hazards are present, while others may look at how much people or the environment could be affected by that hazard. Some may focus on removing the hazards to manage harm. Others look at what rules are needed to make it safe.

For example, the World Health Organization’s (WHO) International Agency for Research on Cancer is hazard-based and looks at just the potential for a chemical to cause cancer. It considers the inherent characteristics of some chemicals to cause harm and not how the chemical is used or how people or the environment are exposed to the chemical. In contrast the Joint FAO/WHO Meeting on Pesticide Residues is risk-based. It looks at whether a chemical could end up in the food that people eat, how much of it gets there, and whether that concentration is sufficiently high enough to cause harm or if a limit is required.

These differing approaches explain why international bodies, or even different regulators in the same country, can reach different decisions on the same chemical.

A syringe dropping some liquid into a thimble, a beaker full of liquid, and a swimming pool filled with water.

Credit (thimble): Robert Couse-Baker.

The intrinsic properties of a chemical (its hazards) are the same whether it is stored in a thimble, beaker, or swimming pool. However, a full thimble inside a laboratory cupboard will result in much lesser exposure to that chemical than if a public swimming pool was filled with it. It is this combination of hazard and exposure that informs how risky the use of a chemical is. 

Managing chemical risks in Aotearoa New Zealand

At the Environmental Protection Authority Te Mana Rauhī Taiao (EPA) we look at both the hazards and risks from chemicals. We have rules governing the use of a chemical, with many of the rules based on the hazard of each chemical. We also conduct modelling to see how much of a chemical will reach either us or the environment. This information is used to develop new rules specific to that chemical to ensure that it can be used safely.

The Agricultural Compounds and Veterinary Medicines team at MPI and Food Standards Australia New Zealand do similar work looking at the risks from chemicals in the food we eat, with the Ministry of Health and Ministry for the Environment setting levels to protect waterways and public health. WorkSafe New Zealand works to eliminate and minimise the risks to workers, including from chemicals.

Perspective and risk

Risk is often and commonly understood to relate to a negative event. It equally as often acts as a shorthand for something that is unacceptable. What is unacceptable means different things to different people. Your experience, where you live, your world view, and possibly even your job, will affect what you consider to be an acceptable risk.

Next time you are crossing the road or using a chemical, think about how you weigh up the hazards and risks to get to the other side or the end of the day safely. What do you consider to be an acceptable risk? Does that acceptable risk stay the same if you have to balance a number of things against each other? This is what regulators and governments have to juggle every day.

References and further reading on this topic:

Lee Bailey's biography

Lee Bailey is a Senior Advisor in our Reassessments Team. He brings together the risk, benefit and Māori impact assessments on historically approved chemicals being reviewed by the EPA, advising decision-makers on whether new controls can ensure the safe use of chemicals or if they should no longer be in the country.  Lee wrote the EPA’s Risk Assessment Methodology in consultation with colleagues, setting out the approach and tools the EPA currently uses for this work.

Lee is a Chartered Geologist, with 16 years’ experience of assessing and cleaning up chemicals, specialising in groundwater pollution in the UK before joining the EPA in 2016. He is also the current President of the Society for Risk Analysis Australia New Zealand.