The Big Read: NZ health and safety reform: How Brazilian dam disaster illustrates problem with ‘likely’ risk in new law
Tuesday, 7 April 2026
ANALYSIS: When the Fundão dam in Brazil failed it sent 43.7 million cubic metres of water and toxic mine refuse tearing through the villages of Bento Rodrigues and Paracatu de Baixo killing 19 people.
Multi-national mining giant BHP was ruled responsible for the collapse of the dam in a High Court ruling in London in November, though it intends to appeal the decision.
The disaster was raised before New Zealand lawmakers this week as they heard evidence from companies and experts on the Government’s plans to remove health and safety red tape, which will be done through Workplace Relations and Safety Minister Brooke van Velden’s Health and Safety at Work Amendment Bill.
The Government’s law reforms centre on the idea of lessening the health and safety load of smaller employers with fewer than 20 employees, and only requiring them to focus on managing “critical risks”, which it intends to define as being “likely to result in a death, a notifiable injury, illness or incident or one of the 50 occupational diseases listed in a schedule to ACC legislation”.
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And this is where the lesson from the Brazilian dam collapse comes in.
Events like dam collapses are unlikely, but potentially devastating.
Critical risks should not be defined by the likelihood of them occurring, said Professor Maureen Hassall, who heads the Minerals Industry Safety and Health Centre at the University of Queensland.
“Critical risks should be defined … based on the actual maximum seriousness of the consequence, irrespective of the likelihood,” Hassall said.
She also drew a parallel with the 2016 Dreamworld roller coaster disaster, which killed four people.
Port of Auckland also queried the Government’s proposed definition of critical risks, focusing on the phrase “likely to cause”.
“Including the likelihood factor in the definition is problematic and runs counter to international standard practice of focusing on the foreseeable outcome of exposure to critical risks, rather than how frequently such exposure happens,” the port company said.
“Many uncontrolled critical risks are encountered rarely, but often result in life-changing or life-ending outcomes. This definition is likely to result in [people conducting a business or undertaking, or PCBUs] declassifying legitimate critical risks on the basis that exposure to those outcomes is unlikely.”
Auckland International Airport felt similarly, telling the Government the use of “likely” might unintentionally narrow the scope of risks requiring active management or create uncertainty.
It recommended clarifying what “critical risk” meant, but it sided with Hassall’s view that consequences, not likelihood, was the approach needed.
“Auckland Airport’s view of a critical risk is any work-related hazard in which uncontrolled exposure to and/or contact with it could credibly lead to life-ending, life-threatening, or life-changing consequences.”
And, the airport wasn’t the only big company in a high-risk sector to raise the issue.
Oceana Gold, which operates the Waihi gold mine, told MPs: “The concern with the current drafting is that, without further clarification, the term ‘likely’ may be interpreted by some duty holders, regulators or inspectors as requiring a probability threshold approaching ‘more likely than not’.”
That, it said, might be seen as a 49%/51% view of risk, where a 49% likelihood was not seen as being likely.
“That interpretation would sit uneasily with accepted safety practice, which treats hazards with catastrophic consequences as requiring sustained attention even where the probability of occurrence is low, provided the exposure is foreseeable,” the gold mining company said.
“If that interpretation were adopted, it would create a perverse outcome whereby hazards that present a real and foreseeable risk of fatal harm, but occur infrequently due to existing controls or operational context, could be de-prioritised in favour of risks that are more frequent but significantly less severe.”
Expert Steffan Cavill-Fowler from the Safety Quest consultancy warned MPs: “By narrowing the statutory purpose and relying on the flawed ‘likely’ test, the bill creates a framework that may ignore catastrophic, low-probability risks.”
Critics of the Government’s reforms include big companies, including Port of Auckland, Downer NZ and Woolworths, trade unions, safety professionals and opposition parties.
They all want the Government to abandon its plan for a two-tier health and safety system in which larger employers would have to minimise both critical and non-critical risks to workers and other people in workplaces, while small businesses only have to focus on critical risks.
Among the criticisms levelled by trade unions is that workers deserve the same protections regardless of how many people their employer employs, or as one employer group put it: “Risk is hazard-driven, not headcount-driven”
But even if the definition of critical risk is tweaked to bring it into line with common international safety norms, what could the Government do to make life easier for smaller businesses, many of whom lack health and safety expertise?
Those calling for change say the answer isn’t removing duties to keep people safe from them.
During the select committee hearing National’s Grant McCallum, MP for Northland, asked Hassall what would work to make life easier for small business owners.
Hassall’s answer was one the Government has heard from many businesses and safety experts: Have regulators provide clear guidance for small businesses.
“Typically, these fatality risks are known. The same risks are killing people globally,” Hassall said.
“How to control these risks? The controls are known as well,” she said.
Some countries require people holding certain positions in high-risk industries to be competent in safety management, she said.
She also suggested that New Zealand should be looking to harmonise its standards with Australia, which has a far lower per capita rate of death and serious injury at work, to create trans-Tasman health and safety practices.
There’s another group of critics that think the Government’s plan for small businesses risks serious harm. They are those who specialise in trying to fix the misery caused by musculoskeletal injuries caused at work.
Kirsten Davie, president of Physiotherapy New Zealand, might have told MPs that their reforms would just create a glut of new business for physios.
Instead she said the focus on critical risks was a narrowing of protections for workers, implying that workplaces can place even less attention than is currently the case on those ‘minor injuries’ such as musculoskeletal conditions.
But, she said: “The evidence is clear from current ACC and WorkSafe data that these ‘minor injuries’ make up 75%, and growing, of ACC work injury costs, making it a significant concern for New Zealand”.
And for those workers affected, the impacts could be life-changing and potentially career-ending through disability.
Davie said: “Occupational health physiotherapists treat workers exposed to high levels of manual handling, repetitive tasks, or sustained physical load, daily. Shifting health and safety legislative attention away from musculoskeletal harm will likely see this risk escalate, increasing long-term work-disability, and adding additional pressure on the ACC Scheme, the broader health system, with downstream impacts across the productivity of industries and the nation.”
There was one other group of safety experts the Government has worried: those involved in managing hazardous substances who fear more people will end up being poisoned at work.
“Hazardous substances are a leading cause of work-related disease and death in New Zealand, contributing to an estimated 750 to 900 premature deaths each year,” Kevin Mair from Hazardous Substances Professionals NZ told MPs.
“The bill’s focus on ‘critical risks’ must not inadvertently deprioritise long-latency health risks, which are often under-recognised and under-regulated,” he said, especially as New Zealand underfunded its health and safety regulation.
“WorkSafe NZ is the sole agency with enforcement authority when certifiers identify serious non-compliance. However, our members have observed significant delays in regulatory response, even in cases involving imminent risk,” Hazardous Substances Professionals NZ said in its submission.