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  • Writer's pictureGary Moller

Is bathing in Central North Island thermal water endangering your health?

Updated: Mar 25

(updated April 2022)


Arsenic is the most common toxin seen in hair tissue analysis in New Zealand. Treated timber and geothermal water are the two most common sources of arsenic, with the third being contaminated bore water. These appear to be taboo topics for discussion, probably due to thermal pool tourism, and our reliance on softwoods as building materials. Some regions such as Central Otago rely on bore water. If arsenic is in the rock strata this may contaminate the water supply.

Softwoods usually require treatment with chemicals, including arsenic to prevent rotting and infestation by insects. Unlike manual saws, chisels and planes, modern high-powered woodworking machinery creates fine dust and the heat vaporises chemicals, including arsenic. So, despite modern health and safety practices, the problem is getting worse rather than better.

Bathing in geothermal waters is a popular past-time with many health claims. Some waters, particularly the central North Island have extremely high levels of arsenic.

Working with arsenic-treated timber or bathing in some geothermal pools exposes the person to the risk of arsenic contamination: This is a fact!

The questions to be answered are these:

  1. How many people in New Zealand have toxic levels of arsenic in their bodies?

  2. What are the consequences to their health?

  3. Assuming there is a public health problem here; what, if anything, is being done about it?

The evidence leads me to conclude that countless thousands of people have had their health compromised by exposure to arsenic. I have now had so many cases of arsenic-related ill health that it runs into the hundreds, perhaps more than one thousand: I have lost count.

This article is about the hazards of bating in geothermal water which contains toxic levels of arsenic.


Is bathing in Central North Island thermal water endangering your health?

In a word, the answer is "Yes!", if you bathe in the wrong waters. There are thermal pools in the Central North Island that are so toxic with arsenic that they should be shut down, or at least, come with health risk warnings. The highest levels of arsenic-contaminated thermal waters tend to concentrate in the Tokaanu region, bordering Lake Taupo. This may represent a hazard to health.

I asked this question myself, when my partner, Alofa fell unusually ill after bathing in private mineral pools in Tokaanu. It gradually dawned on us that she had been affected by a poison, which was later identified as arsenic. While she was successfully treated, the process of learning more about the source of contamination, then confirming it with laboratory tests of the suspect water and identifying other cases of ill health coinciding with bathing in the same water has taken a while. I am now confident of the evidence to put it out for public attention and scrutiny. Hence this report.

How arsenic gets into geothermal water

I am not an expert in geothermal geology; but here is my understanding of what is going on:

High levels of arsenic in thermal water happen when super-heated subterranean geothermal water passes through arsenic-laced rock while on its way to the surface, dissolving the mineral as it goes. One geothermal spring may be high in arsenic and/or other minerals; whereas another adjacent to it may have a different composition: it all depends on what kind of rock the water passes through.

Some, if not all geothermal springs in Tokaanu, pass through arsenic-laced rock, producing some extremely high readings of arsenic in the water.

Is Tokaanu a toxic thermal wonderland?

The answer is "Yes!"


"Total arsenic and four arsenic species; arsenite (iAsIII), arsenate (iAsV), dimethylarsinic acid(DMAV) and monomethylarsonic acid (MAV), are reported in 28 geothermal features from the Taupo Volcanic Zone (TVZ) and Waikato region of New Zealand. Samples were collected for arsenic speciation analysis via a solid phase extraction (SPE) kit allowing the separation, stabilisation and pre-concentration of the species at the time of sample collection in the field.

This is the first research to present data for arsenic species collected by this technique in geothermal waters from New Zealand. Total arsenic concentrations, determined by inductively coupled plasma mass spectrometry (ICP-MS), ranged from 0.008 to 9.08 mg l−1 As. The highest levels were discovered in three features in Tokaanu (Taumatapuhipuhi, Takarea #5 and #6), with arsenic concentrations of 8.59, 8.70 and 9.08 mg l−1 As, respectively. Inorganic arsenic species were predominant in the geothermal waters, with arsenite contributing to more than 70% of the total arsenic in the majority of samples. Organic species were also determined in all samples, indicating the presence of microbial activity.

A potential risk to human health was highlighted due to the high levels of arsenic, mainly as arsenite, in geothermal features linked to bathing pools. Further research is needed into dermal absorption as a potential route of arsenic exposure whilst bathing in these hot pools, as it may contribute to an occurrence of acute arsenic-related health problems."

Arsenic speciation of geothermal waters in New Zealand Gillian Lord, Nick Kimb and Neil I. Ward J. Environ. Monit., 2012,14, 3192-3201 DOI: 10.1039/C2EM30486D First published online 12 Nov 2012


I have corresponded with one of the authors of this study, Neil Lord, who has been very helpful. There is no question that arsenic levels are extremely high in some or all geothermal waters in Tokaanu. The one question coming from his research, that is yet to be answered, is how much of this toxin is absorbed into the body of a person while bathing in these waters? I find it astonishing that public health officials have not made it a priority to answer whether people are being contaminated with arsenic and their health damaged.

Years have passed with little apparent action and one must wonder just how many people have been harmed in the meantime.

New Zealand markets itself to the rest of the world as being a clean and green paradise, including where one can bathe in health-enhancing geothermal hot pools.

Is this one Big - Fat lie?

This article presents compelling evidence that there is a relationship between bathing in arsenic-contaminated waters and elevated levels of body tissue arsenic after the bathing - as well as the subjects then falling ill with ailments that are consistent with arsenic toxicity.

In addition, I supply evidence below of tissue analyses showing low levels of arsenic prior to the bathing and I can show tissue levels returning to low after avoiding further exposure and after giving nutrients that help chelate arsenic out of the body.

The most compelling evidence is all of these people reported feeling ill shortly after bathing in these waters, sufficient to seek medical assistance.

What is arsenic and what is arsenic toxicity?

Arsenic is an element of the Universe that is classed as a "metalloid". Arsenic is toxic to human health when in concentrations of more than a few parts per million. Enzyme activity within cells is what drives metabolism (life). Arsenic displaces desirable elements within enzymes, such as selenium, zinc and sulphur, causing the enzyme to either slow down or stop completely. It also interferes with anti-oxidants such as beta carotenoids.

In this article, we are discussing arsenic "toxicity" not "poisoning". Toxicity refers to low levels of exposure to a toxin that may lead to chronic and often subtle symptoms of ill health that gradually weaken and wear a person down as the months turn into years. "Toxicity" levels of exposure and their health consequences are usually ignored or dismissed by health experts as being insufficient to cause illness. This is, of course, disputed.

Symptoms of arsenic toxicity

Symptoms of arsenic toxicity centre around chronic fatigue, aching muscles, aching joints, sore tendons, rapid onset of arthritis, various connective tissues disorders, including frozen shoulder and tendon contractures, thyroid issues, poor hair, skin and nails, brain fog, viral infections and a long list of immune-related disorders, such as rheumatoid arthritis, psoriatic arthritis and psoriasis.

Arsenic is a carcinogen, possibly because of its interference with zinc and selenium.

Arsenic - the quiet poison

Arsenic was once the poison of choice by disaffected wives, as a means of quietly knocking off the man she had come to hate. Arsenic was fed to Napoleon Bonaparte and was the most likely cause of his death. The legendary NZ racehorse, Phar Lap, was nobbled by a massive dose of arsenic, possibly added to his oats. Not nice!

Hair Tissue Mineral Analysis (HTMA) were used to confirm the presence of arsenic in toxic amounts in both Phar Lap and Napoleon Bonaparte at their times of death. The same test, using mass spectrometry, is what is employed here as evidence of arsenic toxicity from bathing in geothermal waters.

The fascinating origins of "Drop-Dead Gorgeous" and "Green with envy"

Arsenic was used during Victorian times as a medicine for the treatment of diseases, such as cancer and syphilis. I guess, in these cases, the diseases were worse than the treatment!

What is not so well known is that arsenic-soaked fabrics were popular for their brilliant green sheen. Arsenic was also popular for blemish-free skin.

Arsenic - the secret to a good complexion

"Beauty Soap". Popular during Victorian times, probably producing a slightly green complexion.

Skeleton dressed in an arsenic laced Victorian Gown

A stunning Victorian woman attired in a gown that was the envy of the day.

Arsenic laced Victorian Gown

A drop-dead gorgeous gown from Victorian times.

Images source: The Pragmatic Costumer

Blood tests for assessing arsenic contamination

Blood tests are most helpful because the test can tell if exposure to arsenic has been very recent, or if a therapy, like chelation, has been successful in mobilising a deposit that is hidden deep within the body.

Blood tests can be misleading if the exposure to the toxin has been longer than a few weeks ago. This is because toxins like arsenic will not remain in the circulation for longer than a few days before dropping steeply in blood concentration. The body will do all it can to get this poison out of circulation as quickly as it can so as to minimise the damage. It does this by excreting the toxin via the bile, urine, sweat and shedding hair, skin and nail tissue. What can not be immediately excreted via these pathways is sequestered in "safe" or relatively inert tissues, such as the bones and fat, and also in organs like the liver. As the body is able, these sequestered deposits will be gently excreted in fits and starts over time, often years, if not decades. Its a slow process if not assisted by chelation therapies.

The Hair Tissue Mineral Analysis (HTMA) for assessing arsenic contamination

Any episodes of the ingestion of a toxin such as arsenic and any later episodes of detoxification can be identified by way of the HTMA - so long as the hair sample is of hair that was growing at the time of the exposure and/or detoxification. As with Phar Lap and Napoleon Bonaparte, their hair samples remained an accurate forensic record, valid many decades later.

Why do polluters and their insurers tend to favour blood tests over the HTMA?

Polluters and their insurers always seem to favour the blood test over the HTMA for measuring worker or public exposures to toxins. A cynic, which I am, may assume that "polluters" will tend to favour the scientific tests that minimise the downsides of their polluting ways.

A blood test will show only recent exposure - not historical. So long as there is a delay of a week or two after being contaminated the affected population will tend to produce "clean" blood test results. Not so with the HTMA which can pick up the tell-tale traces months and even years later.

As a hypocritical contradiction, the very same agencies that poo-pooh the HTMA for toxic exposures may use the exact same test for detecting and firing employees who may have smoked a joint several months ago. By the way, the HTMA service that I provide never ever will test for illicit substances.

You can learn more about the HTMA by going here:

Tokaanu thermal water is known to be highly toxic with arsenic

Please Note:

This report does not apply to hot pools that use municipal water that is heated by geothermal water by way of a closed heat exchange system. In this report, we are referring to geothermal waters that have come directly from geothermal hot springs.

The image below is the HTMA for my partner, Alofa, who fell ill within days of bathing in a natural thermal hot pool in Tokaanu, in November 2014. Symptoms included extreme fatigue, and muscle and joint pain.


We had contacted the pool owners, in December 2016, while researching for this report, inquiring about any water testing they may have done on their natural thermal pools. No details have been received. Their input to this report is still welcome at any time and we will gladly update it accordingly.

Highly elevated arsenic after bathing in thermal hot pools in Tokaanu

Alofa's HTMA above shows extremely high levels of arsenic (As). It took some months to figure out the possible source of the arsenic and only after identifying similar cases involving elevated arsenic after bathing in the same pools at the same motel in Tokaanu. We subsequently took a water sample from the pool, in the photo below, for testing.

She soaked in these pools, to be specific (note the green tinge, arsenic?):

Oasis Motel & Holiday Park Turangi Thermal Pool

The presence of extremely high levels of arsenic was confirmed by independent laboratory testing of a sample of water collected from this pool.

The report:

Dated 12 June 2015

"Hi Gary, Your water report is attached. The arsenic result is elevated in this water sample. We expected to see some arsenic as it is thermal water but it was higher than we expected. We don’t have any references for thermal water for arsenic but as a general comparison the upper limit for drinking water is 0.01 g/m3 (equivalent to mg/L or ppm)".

Sharon van Soest

Laboratory Manager – Chemistry

Eurofins-ELS Ltd.

Lower Hutt

Eurofins Report 12 June 2015

By any measure, 1.59 mg of arsenic per litre of water is a massive concentration of this toxic element.

Previous testing

Here is an earlier HTMA for Alofa, taken several years prior to soaking in the thermal waters of Tokaanu Oasis Motel and Holiday Park:

Arsenic levels prior to bathing in Tokaanu pools

Arsenic (As) levels were close to nil in this earlier test.

Here are her arsenic levels after treatment, including avoidance of bathing in thermal hot pools. Recovery of energy and reduction in muscle and joint pain has been gradual and most encouraging; but despite all that she has done, including the benefit of the passage of time, she is yet to fully return to her previous levels of health and vitality.

After treatment for arsenic toxicity

Gary Moller's hair tissue tests

For comparison, here is the HTMA (below) for me a few months prior to bathing in the same pools:

My arsenic levels were very low back then.

In contrast, the image below is of my HTMA taken a month after the suspected exposure to arsenic:

Although low, my arsenic levels, have doubled. The smaller increase may be due to a number of factors including, shorter hair (so a less accurate record over the period immediately following bathing), less permeable skin and, either better detoxification pathways or rapid sequestering of arsenic deep in the body so that it does not appear in the hair sample.

It is suspected that I absorbed less arsenic despite similar exposure. This assumption is because I did not experience the same acuteness of symptoms as Alofa.

Here is a repeat of my HTMA several months after bathing. Arsenic levels are again very low which is excellent.

HTMA prior to bathing in thermal pools at Tokaanu

Corroborating evidence that other people bathing in the same Tokaanu arsenic-laced water results in dermal absorption of arsenic

This health-conscious woman, who I had known for several years, mysteriously suffered extreme fatigue, frozen shoulders, severe viral infection and autoimmune-related hyper and hypothyroid diseases. She lost an enormous amount of weight and required medication to alleviate her symptoms.

An HTMA was performed and high levels of tissue arsenic were identified. Looking back, it was confirmed that she has bathed in the same hot pools as Alofa and me in Tokaanu. The onset of her multiple symptoms of ill-health occurred almost perfectly with bathing in these pools. Refer to the image below.

The next image, below, is from a repeat HTMA several months later and indicates success in treatment for arsenic toxicity. Her health has improved considerably but there is more progress to be made.

On a positive note, I bumped into her last month while mountain biking. She was hiking with friends and looking much better.

Yet more evidence!

The report below is for a woman suffering unusual extreme fatigue, as well as rheumatoid inflammation of joints. These things are often simply dismissed, medically, as

"You're getting old, so what do you expect?

Take these anti-depressants and go have a good life - what's left of it anyway!".

It turned out that she had bathed in the same thermal pools in Tokaanu!.


At what level does waterborne arsenic begin to pose a health risk to bathers?

This is the million-dollar question for which there is currently no real answer. The following is an excerpt from advice received from a highly respected environmental chemistry scientist:

In parts-per-billion units, the Maximum Acceptable Value (MAV) for arsenic in Drinking Water is 10 µg/L (micrograms per litre), which is the same as 0.010 mg/L (milligrams per litre). Note that this is really a maximum intended for long-term consumption, so it doesn’t really denote an immediate or acute risk level. It is a bit harder to calculate one of those. However, the MAV could be used to signal the existence of a problem that should be examined more closely. For reference, the water of Lake Taupo also has about 0.010 mg/L arsenic, because of the geothermal systems in the lake bed. It’s measured at the Taupo Control Gates each month by Waikato Regional Council as part of their regional water monitoring. What you’re looking for here is guidance on when the arsenic would be high enough to pose an acute risk to bathers who swallowed some water or spent a long time in water containing skin-absorbed forms of arsenic. That is going to be somewhere well above 0.010 mg/L but the actual figure will be hard to work out, and depend on whether any water is swallowed and how much. There are some good comments on acute risks from inorganic arsenic ingestion in this article: , e.g. “Most cases of acute arsenic poisoning occur from accidental ingestion of insecticides or pesticides and less commonly from attempted suicide. Small amounts (<5 mg) result in vomiting and diarrhoea but resolve in 12 hours and treatment is reported not to be necessary.44 The lethal dose of arsenic in acute poisoning ranges from 100 mg to 300 mg.45” It doesn’t give a lower boundary when acute risks might kick in but indicates that at total doses to the body of about 5 mg, the effects should be reversible. ATSDR site is the best source for a detailed toxicological overview: One excerpt: “Gastrointestinal Effects. Both short-term and chronic oral exposures to inorganic arsenicals have been reported to result in irritant effects on gastrointestinal tissues. Numerous studies of acute, high-dose exposure to inorganic arsenicals have reported nausea, vomiting, diarrhea, and abdominal pain, although specific dose levels associated with the onset of these symptoms have not been identified. Chronic oral exposure to 0.01 mg As/kg/day generally results in similar reported symptoms…” That long-term dose level given there would be equivalent to 0.6 mg/day in a 60 kg adult, or 0.7 mg/day in a 70 kg adult.

Gary: Levels measured by Eurofins EFS on 19 December 2016 found 0.026 grams of arsenic per cubic meter of Waikato River water at Lake Maraetai. Bathing in this water appears to result in an elevation of tissue arsenic and is, by coincidence, associated with some people feeling chronically unwell giving these people sufficient motivation to fund investigations.

This begs the question of whether there is really a safe lower limit for arsenic? The better way to look at arsenic contamination may have a sliding scale of toxicity ranging from levels that produce severe symptoms, including death to tiny exposures with near-undetectable symptoms?

Setting a lower "safe" level for bathing is further complicated by evidence that there are variations between people in how they absorb arsenic, their sensitivity to the toxin and how efficiently their bodies neutralise and excrete it.


  1. Some Central North Island geothermal waters have levels of arsenic that vastly exceed safe drinking water standards. One Tokaanu geothermal water sample had an astronomical 1.59 mg of arsenic per litre of water.

  2. I have presented evidence of elevated internal levels of arsenic in four subjects who bathed in the Tokaanu geothermal water that was tested.

  3. Three of the four people came to be independent of the other, seeking assistance for a number of health issues that are associated with arsenic toxicity.

  4. In two cases, Alofa and myself, we had multiple hair tissue analyses that showed insignificant levels of arsenic prior to bathing in Tokaanu.

  5. Further testing after bathing in Tokaanu shows elevated levels of arsenic, especially in Alofa who suffered ill health, as compared to me.

  6. Upon avoiding further exposures to the Tokaanu water source and with therapies to remove arsenic from their bodies, further testing has shown a reduction in tissue arsenic levels.

  7. Signs and symptoms that are consistent with arsenic toxicity have improved in line with the testing that indicates detoxification of arsenic.

  8. Careful questioning of each person makes their contamination from other sources of arsenic, such as working with treated timber, most unlikely.

  9. There appears to be no "safe" lower level for arsenic.


We have therefore demonstrated a consistent and compelling link between bathing in arsenic-laced geothermal water and the onset of symptoms consistent with arsenic toxicity.

Before and after tissue analyses support our conclusion that bathing in hot arsenic-laced water will result in dermal absorption of arsenic.

It is bathing in this water that is the primary cause of their contamination with arsenic and this is what caused their decline into ill health.


Main conclusion

Bathing in Central North Island geothermal water is a health hazard



  1. That the public is cautioned about bathing water that exceeds 0.010 mg/litre (milligrams per litre) which is the same as 0.010 g/m3 (grams per cubic metre). of arsenic (The safe maximum level of arsenic for drinking water).

  2. Any pools that contain levels such as 1.59 mg of arsenic per liter of water should be closed until there is proof that such concentrations are safe to bathe in.

  3. That all commercial, public and private geothermal bathing pools be required to clearly display current tests for water contaminants including toxic elements.

  4. That further research be urgently conducted to confirm, or refute the findings in this report that bathing in hot geothermal water that is laced with arsenic results in dermal absorption of the toxin and with consequent ill health in some people.

  5. That further research be conducted to determine what is the safe level for arsenic in bathing water.

  6. That the "Precautionary Principle" be exercised and done so with urgency.

  7. Clearly, there is at least one bathing pool in Tokaanu that should be closed forthwith.

The "Precautionary Principle" says that, when it comes to health, one must err on the safe side.

"First do no harm". In this case, a very large "Red Flag" has been raised high. Health red flags require action to prevent harm, even if the risk is theoretical, and this action should be in place for as long as it takes to either refute the claim or confirm it.

Response of the Medical Officer of Health and ESR to this report:

Supporting research and reading


  2. Arsenic contamination of the Waikato River

  3. Arsenic speciation of geothermal waters in New Zealand!divAbstract






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