The Ministry of Health has announced a review of the scientific literature on nitrates in drinking water. On the surface that sounds reassuring. Government agencies are examining the evidence and considering whether current standards remain appropriate.
But it also raises an uncomfortable question.
Why, after years of debate, are we still reviewing other people’s research rather than conducting comprehensive investigations of our own?
The current nitrate standard is primarily based on preventing methemoglobinemia, commonly known as “blue baby syndrome”. That standard has served New Zealand for decades. However, concerns have increasingly been raised about possible links between nitrate exposure and a range of other health outcomes, including colorectal cancer and adverse pregnancy outcomes.
The key word is “possible”.
The science remains contested. Some researchers argue there is sufficient evidence to justify tighter limits. Others point out that many studies demonstrate statistical associations rather than direct causation. Even today, experts continue to debate the strength of the evidence.
That uncertainty is precisely why more investigation is needed.
A literature review has its place. Reviewing published studies is a sensible first step in understanding the current state of knowledge. But a review can only assess research that already exists. It cannot answer questions unique to New Zealand.
New Zealand’s geology, farming systems, groundwater conditions and population distribution differ significantly from those found overseas. Denmark’s recently proposed reduction in nitrate limits has generated considerable attention, but Denmark is not New Zealand. Its intensive agriculture, groundwater characteristics and environmental conditions are different from our own.
Surely the more important question is not what Denmark has found, but what New Zealand knows.
How many communities are experiencing rising nitrate levels?
What trends have occurred over the last twenty years?
What are the long-term health outcomes for populations exposed to differing nitrate concentrations?
Which land-use practices contribute most significantly to nitrate contamination?
How effective have existing mitigation measures been?
Most importantly, who is responsible for answering these questions?
Government agencies frequently cite international guidelines. Yet those guidelines themselves often rely on limited reviews conducted many years apart. Waiting for overseas organisations to revisit the science every decade or so may not be sufficient when public concern continues to grow.
If nitrates are ultimately found to pose little risk beyond established concerns, New Zealanders deserve to know that. If the risks are greater than currently understood, New Zealanders deserve to know that as well.
Either outcome requires evidence.
Science is not advanced by repeating reviews of existing papers. It advances through observation, measurement, testing and investigation.
The public should not have to choose between alarmism and complacency. Instead, they should be able to expect robust, transparent, New Zealand-based research capable of informing policy decisions with confidence.
The Ministry’s review may be a useful beginning.
But it should not be mistaken for the finish line.
The real question is why the country is still reviewing the debate rather than resolving it.
The New Zealand approach is to conduct “risk assessments” on issues like nitrate and pesticide toxicity,
The NZEPA is the body who does this for agricultural chemicals and veterinary medicines.
Such a risk assessment uses published data from the scientific literature which may include suspect saftey provided by the manufacturer. “Tobacco Science” as we learned from The Monsanto Papers.
These risk assessments are essentially a cost benefit exercise balancing (health) risks against economic benefits from continued use by agribusiness.
NZ shows a marked reluctance to fund costly studies, even the Otago Med School’s study looking into the strong correlation between short term pregnancies and premature birth where women drink water containing half the current NZ Maximum Allowable Value for drinking water struggled for funds.
I.e. we won’t pay for our own studies, instead select evidence from overseas work to fit our political focus on putting the economy first.
This really leaves aquatic ecosystems exposed as they begin to show proven adverse effects below one tenth the NZ MAV for drinking water.
NZFFA supported Peter Troloves finding after years of investigation, his research findings should have rang bell through out parliament but nothing came out of the findings other than cover ups.
History proves that all governance only act when the horse has bolted
The comprehensive Danish study on nitrates in drinking water and its relationship to bowel cancer rates doesn’t need ministry bureaucrats dithering around. People in South Canterbury/Canterbury are dying of bowel cancer since the region has among the highest rates in the world.
For heaven’s sake, Ministry of Health and the Health minister, have you no heart? Current health minister is Simeon Brown with associate health ministers Casey Costello, Matt Doocey, David Seymour.
The Denmark Landmark 2018 Study: A large nationwide population study tracking 2.7 million Danes over two decades found that people exposed to nitrate concentrations above 9.25 mg/L had a 15% higher risk of bowel cancer compared to those with the lowest exposure
I’m not aware of any physiological differences between Danes and Kiwis, so if they have fundamentally the same human makeup, why are we not responding in the same way as the Danish government and lowering our nitrate limits – the precautionary principle surely?
Or does that only apply when the WHO dictate?
Are the NZ Government so afraid of the reaction of the agricultural lobby that they choose to sacrifice human lives, kiwi lives, on the altar of the mighty dollar?