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  • Writer's pictureGary Moller

Arsenic in Geothermal Waters

Updated: Feb 20

Is Central North Island geothermal water making people sick by exposing them toxic arsenic?

Arsenic bottles

I am more convinced than ever that it is.

Some Central North Island sources of geothermal water, especially that in the Tokaanu region, have extremely high levels of arsenic that vastly exceed the maximum set by the World Health Organisation for drinking water. This is not disputed by anyone. The presence of toxic levels of arsenic in these waters is a fact that has been verified by researchers many times over. Hey - you do not even need to test for it - you can see it - the water is green with arsenic!

What is being disputed by a few Government health officials and scientists, is the concern that bathing in these waters may be a risk to health. Because of the extraordinarily high levels of arsenic in this hot water, common sense says this has to be a health hazard. The evidence I have presented to them and the evidence of independent scientists points to these waters being a health hazard.

Despite the evidence from scientific testing and the display of clinical symptoms in now more than a dozen people who have sought my assistance, the Central North Island Region's Medical Officer of Health and scientists at the Government's Institute of Environmental Science and Research (ESR) dismiss my claim that bathing in these greenish, arsenic-laced waters is making some people very sick.

Please read my original report that is linked below this paragraph, then come back and read the rest of this. These scientists and health officials have got things so wrong. Is this a case of being wilfully blind? Are the commercial interests of tourism and geothermal power development taking precedence over environmental and human health? Is this simply too big a problem to even think about, let alone to do anything about it? Or am I wrong and barking loudly for no good reasons?

Please start by reading carefully my original report.

Now that you have read my report, please read the following correspondence from Dr Phil Shoemack, Medical Officer of Health, and Peter Cressey's ESR report. What you will quickly realise is that it appears they did not read my report very well at all!

Thank you.

Gary Moller


Dear Mr Moller,

My apologies for taking so long to reply to your enquiry. Our conclusion is that there is not a serious public health issue associated with the levels of naturally occurring arsenic in the geothermal areas of the North Island to which you refer. In particular, bathing in this geothermal water is most unlikely to result in the absorption of harmful levels of arsenic. In support of this conclusion we have received the attached report from ESR which reviews most of the issues you have raised. As with most substances arsenic can be harmful to people who are exposure to elevated concentrations. However, the risk of harm is related to the concentration of the substance, the duration of exposure, and the route of absorption or exposure. As can be concluded from the report from ESR the levels of arsenic in our geothermal water is not a concern in terms of the likelihood of what you have called poisoning. I appreciate you bringing this issue to our attention.

regards, Phil Shoemack Medical Officer of Health Toi Te Ora – Public Health Service


Here is the report from Peter Cressy of ESR:


Here is my response

My impression while reading their report, is that Peter Cressy and his supervisor, Dr Chris Noakes, are downplaying the health-risks of bathing in Central North Island hot pools such as the ones at Tokaanu. It appears they did not read my report carefully enough to even realise that I presented FOUR cases - not just the one person who they refer to in their report. They have overlooked the others (I now have over a dozen cases of ill people who all bathed in teh same natural geothermal pool). All of the hair tissue mineral analyses (HTMA) were from people who had bathed in exactly the same hot pool at various times over a number of years and all showed not just elevated hair arsenic levels but, in three cases, they were suffering health issues that can be associated with acute and chronic exposure to this toxin. These cases can not all be mere coincidence.

I think Mr Cressy has produced a report that supports a predetermined conclusion that there is not a public health risk. He has not my report carefully and, along with Dr Shoemack, he has not responded to my recommendations, other than to dismiss them by ignoring them. Open-minded scientific minds would have concluded that there is sufficient evidence for some concern, as was concluded by Gillian Lord and her research associates. As with Lord and her associates, they could have, st the least, recommended that there be further investigation of the matter.


To dismiss this evidence with no further investigation is irresponsible.


To allude that it is safe to bathe in hot water with a toxin like arsenic dissolved in it is preposterous. This goes against everything that we know about arsenic. Referring to a few studies involving rats and cadavers does nothing to reassure anyone, other than a fool.

In a living person - not a cadaver - the skin is like blotting paper that soaks up just about everything (Hormone patches make good use of this dermal porosity to deliver hormones directly to a person). When soaking in hot water, protective waxes and oils are softened and dissolved, thus increasing the porosity of the skin. As the person warms up, blood flow to the skin increases many-fold and the pores of the skin open, all intended to help dissipate excess body heat. As you read this it is easy to imagine the concentrated arsenic in the hot geothermal waters being literally sucked into the body and then distributed to every nook and cranny by the blood flow to and from the skin.

Men sweat: Women glow

Each person is a little different in the way their bodies respond to heat and skin varies in permeability. For example, some people have thick, oily skin while others have thin, dry skin. Men tend to sweat more than women when hot, whereas women tend to rely more on shunting blood-flow to the skin. Sweating sucks fluid from under the skin and discharges it out of the body, so it may be removing some arsenic from the body as it enters through the skin.

Therefore, a male who is sweating heavily while bathing in arsenic-laced hot water may be less vulnerable to toxicity as compared to his female companion who is "glowing" more than she is sweating.

Females tend to have thinner and softer skin as compared to males. Thyroid insufficiency is epidemic in New Zealand, especially among women. An under-active thyroid may result in very dry and thin skin. Older people tend to have dry and thin skin.

My impression is that the women I have identified as having bathed in these pools appear to have been more seriously harmed than the men.

To ignore and dismiss all of this complexity by referring to a handful of rat and cadaver studies shows an appalling lack of understanding of human physiology.


Soft woods, such as pine, are soaked in arsenic, thus preventing fungal rot and damage by wood-eating bugs. Arsenic kills just about every living organism on the planet. Are human-beings any different from fungus and bugs? Are we special in some miraculous way?


If they are suggesting that dermal exposure to arsenic is safe, then tell that to all those women during Victorian times who shortened their lives by caking arsenic on their skin to look beautiful and wearing arsenic-dyed dresses.

If those "beauty" practices of the past are now regarded as being a really dumb, vain health hazard, then how come bathing in hot, arsenic-laced water is not?

If there is a minimal risk of absorption by skin contact, how do they explain the HTMA below of a fencing contractor with chronic health issues who would carry arsenic-treated timber posts on his shoulder. By the end of the day the side of his neck was green with arsenic. This HTMA shows the results of DERMAL exposure to arsenic. I have many more examples, such as fencing contractors, builders and farmers, where dermal exposure to the toxin is clearly reflected in the HTMA.

HTMA showing arsenic levels in a fencing contractor

You are not alone!

I have since identified several more cases of people with chronic health issues who have all bathed in the same geothermal pools in Tokaanu. Fatigue, thyroid and connective tissue disorders, such as frozen shoulder and carpal tunnel syndrome, continue to be common themes. Each HTMA shows elevated arsenic.

When taking a hair sample, we are careful to ensure that the hair has grown AFTER the exposure to the suspected toxin, in this case, arsenic from bathing in thermal hot pools that have been independently tested and shown to have extremely high levels of arsenic in them. Some of these samples are more than a year after the exposure, so the arsenic must have come from within the body itself.


Let me explain what happens when a person is exposed to a toxin such as arsenic. As the toxin enters the blood stream mechanisms kick into gear to protect the cells from damage. A toxin such as arsenic must not be allowed to circulate and the body will do all it can to stop this continuing. This consists of neutralising the toxin as best it can, then filtering and excreting the toxin via the liver, kidneys, and other pathways that include sweating and the shedding of hair skin and nails.

If the acute exposure is too great to handle, the body has a further mechanism and that is to sequester the toxin in relatively inert tissues such as fat and bone where it may remain for many years - even decades - where it gradually erodes health, unseen and undetected, a bit like rust in the chassis of your car. Over time, usually years, these deposits are, hopefully, slowly mobilised and excreted from the body, depending on the ability to safely do this without too much stress to the body. Traces of this gradual mobilisation and excretion may show in the hair sample - only if these toxic deposits were being mobilised and excreted while that hair sample was growing.

Nutritional therapies can safely speed this "detoxification" process. This may be captured in subsequent hair sampling and will show as a spike in the toxin, as can be seen in the HTMA above of the fencing contractor. The contractor's chart is a repeat test after commencing nutritional therapy and continuing for several months. It is hair that grew AFTER commencing our interventions. You can see that hair tissue arsenic leapt from .155 to .310. This increase was despite him taking great care to avoid further environmental exposure to arsenic. We can therefore assume that the arsenic in the hair in this repeat HTMA most likely came from within the body and not from contamination from external sources. This is consistent with numerous other cases that I have managed over many years.

Incidentally, rapid weight loss may inadvertently release sequestered toxins into the circulation, potentially compromising physical and mental health, as can be seen in replays of the reality programme, "Biggest Loser".


I never expected my reports to be declared perfect, and I acknowledge that I got my water concentrations wrong, but they are still toxic concentrations by drinking water standards. What I did expect was the health authorities would exercise the "Precautionary Principle" when it comes to protecting the health of the public, including tourists.

In my article I quoted this from the research by Gillian Lord, Nick Kimb and Neil I. Ward:

"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."

This was published in the scientific journals in 2012. It appear that heir report has been mostly ignored since then by the very authorities who are charged with safeguarding our health and safety.

Despite their recommendations, there has been no further research that I know of to determine whether or not there is a real health risk presented by bathing in these geothermal pools.

I have published robust evidence that these pools are actually ruining people's health. This is not theoretical or fictitious: I have had these people sitting with me in my office all wondering why their health has gone South and desperate for solutions. My findings add weight to the concerns of Lord and her associates that these Central North Island geothermal pools may be causing arsenic-related health problems. I think the lack of any kind of positive action by officialdom is absolutely appalling.

Which geothermal hot pools are safe to bathe in?

Geology Map of New Zealand

Arsenic is generally most concentrated in volcanic regions which are the red areas of this map of New Zealand. If you are going to be bathing in geothermal hot water and it is in any of the red areas of this map, then you must suspect that there is arsenic in the water, especially if there is any hint at all that the water is greenish.

Not all geothermal water has toxic levels of arsenic in it. If the super-heated subterranean water has not passed through rock that contains arsenic, then you might be safe. But how can you be sure?

Ask the operators

I have contacted a number of the commercial hot pool operators for information about their water testing. While there has been no hesitation to inform me of the test results for organic contaminants such as bacteria, the shutters have come down when arsenic is mentioned. To date, no commercial hot pool operator has given me any information at all about levels of arsenic in their water.

Have a look here at what Wairakei Terraces has to say:

"Arsenic: new studies report benefits for plasma and tissue growth. "

They refer to health benefits of arsenic but give no references. While there may be some possible benefits are nano-trace levels, to imply that arsenic is good for you in their promotional material is preposterous. What is significant is they acknowledge the presence of arsenic. What is more significant is they do not say how much is actually in the water. That is the most important piece of information and this is missing. Despite asking, I have not yet received any information about the levels of arsenic in the water.

I might have to do what we have done with Tokaanu and take our own sample for testing.

If a pool operator can not, or will not tell you what the levels of arsenic are in the water, then do not bathe in that water.

Which pools are safe?

You can safely bathe in water that is from municipal tap water and heated by heat-exchange. Many public pools are heated this way and are safe to bathe in. The pools that are described as geothermal mineral hot pools are the ones to be very cautious about.


My recommendations remain the same:

  1. That the public be cautioned about bathing water that exceeds 0.010 mg/litre (milligrams per litre) of arsenic 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 litre 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 always 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 to confirm it.

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