Moanataiari - Frequently Asked Questions

General Questions

What are the underlying assumptions that form part of the 20ppm standard?

At a recent community forum, the residential standard for arsenic was discussed (20 parts per million).

Members of the forum requested a plain-English explanation regarding some of the underlying assumptions that were made to formulate the national environmental standard.

The standard assumes:

  • That all of the arsenic is absorbed by the body if the soil is eaten (100% bioavailability)
  • A person's weight at 70kgs
  • That 10% of produce (fruit and veggies) consumed are grown at home
  • A life expectancy of 75 yrs
  • A person spends 350 days a year at the site (residential exposure frequency)

What is the Council doing about its own land?

The risk of ingesting soil from activities undertaken on Council land is very low, so people should not be concerned about road reserves and parks.

While inhalation of dust is not major health concern, we will continue to ensure that the grass is kept higher to reduce dust when it is mowed and we will continue to ensure there is good grass cover and limited bare patches. Our contractors are also aware of the situation at Moanataiari and need to adhere to guidelines to protect the health of workers digging in the area and to ensure the protection of residents.

How deep were the samples taken for the soil testing?

The samples were taken at surface (0-10cm), at 0.5m and 1.0m, which was also the same process for the preliminary testing

Where can I find more information about other areas around the world that have faced similar issues as Moanataiari?

Like many people, we have been reading much literature to understand more fully the issues we are facing at Moanataiari. Here are some links which maybe useful in your background study of arsenic and how other jurisdictions around the world have managed contamination.

  • Ministry for the Environment documents
    National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011 Contaminated Land Management Guidelines No. 4: Classification and Information Management Protocols FAQs about contaminated land
  • Environmental Protection Agency documents (USA)
    Guidance for Comparing Background and Chemical Concentrations in Soil Policy on background contaminants and contaminated site clean up Case study: Snow Creek Montan
  • Victorian State Government (Australia)
    Arsenic mine tailings and health Managing Risks Associated with Land Contamination: Guidance for Councils Arsenic and your health: Information brochure Case Study: City of Yarra

Why is Moanataiari being assessed?

Moanataiari has a known history as reclaimed land using rock and tailings from nearby mining activities in and around Thames, so it was registered as a site that required future investigation for contamination by the Regional Council.

Why has it taken so long to test Moanataiari?

The region's priorities have been with known contaminated sites such as the Tui mine. The following data available at the time also suggested that the site was not an initial priority.

  • Records indicated that the subdivision had a clean cap of clay over it
  • Public medical records did not indicate any known or related health issues
  • The good health of the plant life and trees
  • A soil test at the Primary School sports field came back negative for contamination

Why was Moanataiari School tested negative for contamination?

The school's field was tested in 2007 and the results were negative for contamination. We now believe that the sports field has been developed with introduced top soil given its higher elevation than surrounding land.

Why is there a problem if the subdivision was capped?

Our records indicate that a cap was placed over the subdivision as it was progressively formed over the years of development. The next round of testing will determine the extent of its effectiveness.

What is the Contaminated Sites Remediation Fund?

The Government can support councils to investigate and remediate contaminated sites through the Ministry for the Environment’s Contaminated Sites Remediation Fund.  If the application is approved, the Ministry will provide up to 50 per cent of the costs for:

  • the investigation of sites
  • remediation planning
  • site remediation

What is the purpose of the Ministry for the Environment’s Funding Priority List?

The Ministry for the Environment has developed a funding priority list to assist with prioritising funding for the remediation of contaminated and potentially contaminated sites. The Funding Priority List is based on information provided to the Ministry for the Environment from regional councils.

The Funding Priority List includes both known and potentially contaminated sites.  As a site goes through different stages of investigation or remediation – from ‘potential’ to ‘known’ – for example, it may change its priority on the list or be removed. 

  • A known contaminated site is where some physical investigation has been undertaken and elevated concentrations of contaminants are known to exist on site.
  • A site is considered potentially contaminated based on readily available information which confirms that a hazardous activity or industry has taken place on the site

What is on the Thames-Coromandel District Council's Land Information Memoranda (LIMs) for Moanataiari?

Property LIMs include all public information regarding the project. Specifically the LIMs include the information pack sent out to residents and ratepayers in October 2011 and the Phase 2 property reports sent out in June 2012. The LIM will be updated as the project progresses through the remaining phases. 

The subdivision also appears on the regional council's register called the Selected Land Use Register, which contains information on properties known to be contaminated on the basis of chemical measurements, or are potentially contaminated. Information about Moanataiari's inclusion on the register was placed on LIMs by the Thames-Coromandel District Council earlier this year.

What are the HAIL and SLUR lists?

The regional council's Hazardous Activities and Industries List (HAIL) defines industries and activities that typically use or store hazardous substances. Properties within our region that either historically or currently have any of these activities operating are in the process of being registered on the Selected Land Use Register and tested for contamination.

Please contact the regional council on 0800 800 401 for more information.

Science Questions

Why did the Phase 3 natural background study get changed to a Health Risk Assessment trial (HRA)?

The agreed method to find natural background levels meant that the soil samples had to be taken in areas that hadn't been 'touched' by human activity. This meant that the proposed sample sites would not be representative of Moanataiari and Thames to be any use for the project.

Also, the Governance Group made a decision to focus the Moanataiari project on managing the risks to people, which made a Health Risk Assessment trial much more important than understanding the levels of naturally occurring minerals.

What is an Health Risk Assessment (HRA)?


For this project, the HRA is a scientific study that will focus on assessing the bioavailability of arsenic in the soil. This will help us make a decision about the risk to human health from ingesting soil. The National Standard assumes the arsenic is 100% bioavailable when it formulates the 20 parts per million standard for arsenic.

Why are you doing an Health Risk Assessment (HRA) trial first?

Before we spend large amounts of public money on a full HRA, we thought it would be a good idea to test the soil we've already taken from private property to see what the bioavailability might be.

If the bioavailability is low (e.g. 10 - 30%), then it is likely we will need to order the full HRA to ensure the science and the results are more robust. If the bioavailability from the trial is high (e.g. 80%) it is unlikely we will need a full HRA.

What does the HRA apply to the western zone and not the eastern zone?

Phase 3 does not impact the majority of eastern properties because the levels of contamination are high, even if the bioavailability was low. We don't need an HRA to know that something needs to be done for these properties to reduce the risk to human health, which is why the eastern zone properties move straight to Phase 4 (remedial action planning).

The western zone has much lower levels of contamination so we need an HRA to better determine the risks to human health for these residents.

What's the difference between bioavailability and bioaccessibility?

For this project bioavailability refers to how much arsenic is actually absorbed by the body (as opposed to just passing through the body). Because we can't test on animals or humans to find the bioavailability of arsenic, scientists test for 'bioaccessibility' in a lab (how much arsenic is available in the soil in a lab situation).

Phase three of the project is testing for the bioaccessibility of arsenic in a lab environment for the project team to make a decision on how bioavailable arsenic might be in the soil at Moanataiari.

What is arsenic?

Arsenic is a naturally occurring mineral found in soil, bedrock, and water (often in higher concentrations around seams of gold).  In its pure form, arsenic is a silver-gray or white brittle metal.  Arsenic has no odour.

Why are there high levels of arsenic in the soil?

All of the trace elements detected are from the minerals and rocks themselves, i.e. the minerals that were mined and then used as fill in the reclamation process. None of the elements are present as a result of any chemicals that were added as part of the mining process.  Historically, mercury itself was used for gold extraction, but the results suggest that the mercury we have detected is also just part of the natural make-up of the minerals that were mined.

Testing has confirmed mercury is not a contamination issue for Moanataiari.

In general, how toxic are the surface level results for arsenic?

The National Soil Contaminant Standard (SCS) for arsenic in residential soils is 20 mg/kg or 20 parts per million and it is generally accepted that an extremely dangerous and life threatening exposure of arsenic would be around 2000 - 3000 parts per million.

Natural arsenic can be found in most soils at around 4 - 20 parts per million.

The two highest surface results at Moanataiari are 320 and 350 mg/kg.

So on the surface results alone, there is no acute health risk to human beings in the short term, but the results are higher than the national standards and therefore present a chronic or long term health risk that needs to be addressed.

What is lead?

Lead is a metal that occurs naturally in the Earth's crust. It is rarely found naturally as a metal but is usually combined with two or more other elements to form lead compounds.

Where does lead come from?

In addition to its natural occurrence, lead may come from a number of sources. These include old paint, some industries, for example battery manufacture, and old plumbing fittings. With the removal of lead from petrol in 1996, the main source of non-occupational exposure to lead in New Zealand is lead-based paint on and around houses built before 1970, but particularly before 1945. On many older houses, the old paint may still be in place, painted over or flaking off. When paint is removed, the lead in it may settle in nearby dust or soil.

In Moanataiari, waste rock and mine tailings were used to reclaim land and this soil has been found to contain relatively high levels of lead in some locations. For residents, the risk from lead is from eating contaminated food or putting contaminated objects, including fingers, in the mouth. Breathing contaminated dust may make a small contribution to exposures; lead absorption through skin is not a concern (only organic lead is absorbed through the skin eg the tetraethyl lead that used to be present in petrol).

What about the other contaminants found?

While there are isolated areas on the subdivision where other elements are above guidelines, when the arsenic levels are managed or remediated this will also remove or reduce the risk of exposure to any other contaminants in the soil too. The Ministry of Health advice will also protect your family from these contaminants as well.

Why are the plants and trees thriving on the subdivision with such high levels of arsenic?

Trees and plants can cope with high levels of arsenic. When assessing contaminated sites, it is often the plant life that is a good indicator of contamination because of heavy metal contamination in the soil. This site does not generally have a heavy metal contamination problem and arsenic is not a heavy metal.

What does surface level mean?

In this instance, surface level means tests that were conducted at 10cm below the grass or ground surface.

Was lead used in gold processing?

Our research indicates that lead was not used in the processing of gold at Moanataiari.

Is the presence of lead a natural phenomenon?

We can't be 100% certain yet about where the lead has come from. Past mining activity or industrial activity may also be a contributory factor. We expect that the source of contamination will be identified in the course of the investigation. However, our current focus is on managing risk to human health. We will do more work to get the conclusive answer to this question.

Health Questions

What is the Ministry of Health doing about the health risks for Moanataiari residents?

The Ministry of Health is working with the Waikato DHB's Medical Officer of Health to provide expert advice and information. The Ministry is using toxicologists, epidemiologists and public health medicine specialists to assess the potential risks and provide advice on how to avoid exposures to toxic substances. The Ministry has provided advice for people to take action to reduce their exposures to the toxic chemicals that are present in the soil. This advice is available on the Thames Coromandel District Council website and in the pamphlet Arsenic and Your Health, which was provided to residents and is available from the District Health Board, Council offices and local Moanataiari outlets. It is also available on the Ministry's website

What is the Waikato District Health Board doing to help residents?

The Waikato District Health Board's staff, including their Medical Officer of Health and other public health staff, are working with the regional and district councils to assess the risks for residents and are providing advice to concerned residents. The Medical Officer of Health attends the Governance Group,, to provide independent advice and is also working with General Practitioners, nurse practitioners, hospital staff, pharmacists, school and early childhood centre staff and others to discuss the potential risks and people's concerns and to advise on how these can be managed to protect people's health.

Why is the Ministry of Health not doing a survey to see if people are exposed?

The Ministry recommends that anyone who feels unwell, is concerned about possible symptoms or feels they may have significant exposure should visit their GP. However, any biological tests will only show recent exposures to arsenic and lead. If residents have been following the public health messages since November 2011, then there is expected to be only low levels of any exposure to lead or arsenic from living on the contaminated land.. Any poisoning from contaminated land (eg lead, arsenic poisoning) is required to be reported to the Medical Officer of Health. All test results will be checked by the Medical Officer of Health..

Once the final soil testing results are available it will be possible to consider whether there would be benefit from a survey involving biological testing of people living in Moanataiari. Biological tests would give information only about recent exposures, and not historic or chronic exposures.

Why are young children at greater risk of getting lead poisoning?

Infants and preschool children in contact with lead-contaminated dust or soil or flaking paint are particularly at risk of developing lead poisoning. This is because they often put objects (such as toys or fingers) into their mouths that may be contaminated with dust or soil. Young children absorb more of the lead they take in than older children and adults. Some children will eat soil (known as 'pica') and so take in higher amounts of lead.

Are adults at risk?

The highest levels of lead in adults occur in some occupations such as painters and as a result of some hobbies such as indoor small bore rifle shooting and lead lighting. In the home, adults may be exposed to lead by breathing in dust from old paint removal from older houses. Not washing lead-contaminated hands properly before smoking or eating may cause exposure to lead.

How does lead leave the body?

Once in the body, lead may pass into the bloodstream or be excreted via faeces and urine. The rate of absorption depends upon many factors, not least the chemical and physical form of lead and the person's nutritional status. Once in the bloodstream, lead tends to accumulate in hard tissues such as bones and teeth, from which it may be slowly released back into the bloodstream. Up to 90 percent of body lead burden may be found in bones.

How does lead affect children?

Contact with low levels of lead may not cause any obvious illness. However low lead levels can affect the developing brain and may impair young children's development and later performance at school. High levels of lead can cause symptoms such as vomiting, stomach pains, difficult sleeping, constipation and loss of appetite. It is important to know, however, that there are many causes of these symptoms other than lead. If untreated, very high blood lead levels can result in more serious problems and lead to seizures, brain damage or even death. Poisoning of such severity is most unlikely from routine exposure to contaminated soil but could theoretically happen if a child eats soil from an area with a particularly high level.

If you are concerned that your child has been affected, see your doctor.

How does lead affect adults?

The lower blood lead levels generally found in adults may have a small effect on blood pressure. As with children the early stages of lead poisoning are non-specific and affect the gastrointestinal and nervous systems. In adults, symptoms of lead poisoning can include mood changes (such as depression or irritability), memory impairment, sleep disturbance, headaches and tingling and numbness in fingers and hands. Other symptoms can include lack of appetite, nausea, diarrhoea, constipation, stomach pains and weight loss. Symptoms may eventually develop in the blood, kidneys, bones, heart and reproductive systems and may, at very high levels, cause death.

How does lead affect an unborn child?

Lead can be carried to the unborn child through the mother's blood. Therefore, exposing the mother to lead through repainting, through her work or through hobbies involving lead exposure (eg lead lighting, indoor small bore rifle shooting) may affect the baby while it is still being formed. Exposure to lead can cause premature birth or low birth weight as well as later problems with brain development.

How can you protect your family from lead or arsenic poisoning?

You can reduce any health risk by reducing the amount of soil and dust from mine tailings that you or your children swallow. Here are some simple steps that you can take.

  • Do not let children, especially young children, play on mine tailings. The soil and dust can stick to their hands and toys and can be swallowed when they put them in their mouths.
  • Prevent young children from putting mine tailing sand or soil in their mouths. Do not put mine tailing sand in your child's sand pit.
  • Wash your hands before eating and sleeping.
  • Wash young children's hands frequently, particularly before eating.
  • Wash dummies and toys frequently, especially those used outside, to remove soil and dust.
  • Wash family pets often. Remove footwear before going indoors to avoid carrying soil dust indoors, especially if your household includes babies or young children.
  • Mop and dust often. Mop and dust with a damp cloth.
  • Wet-dust floors, ledges, window sills and other flat surfaces at least once a week.Using a vacuum cleaner or broom may spread dust around. If using a vacuum cleaner only a vacuum fitted with high-efficiency particulate air (HEPA) filters should be used.
  • Do not eat fish caught from areas with mine tailings, which may be in the waterways.
  • If mine tailings are in a children's play area, cover them with a layer of clean soil and grow grass over the top. Keep it watered during dry weather if possible.
  • Cover mine tailings with soil and plants (especially groundcover plants) to reduce dust and stop direct access by young children.
  • Make sure your child has a good diet. Calcium and iron can help prevent your child's body from absorbing lead. Include at least two servings of milk products (equivalent to two glasses of milk) and one serving of lean meat, chicken or fish (equivalent to one small piece) each day.
  • Take special care with home renovations. If renovating older houses, seek advice. If the house was built or repainted before 1970, assume the paintwork is lead-based, unless a test shows that it is not.

Can I eat home-grown fruit and vegetables?


The MoH and DHB, after analyising fruit and vegetables grown at Bright Smile Garden have issued the following interim advice: 

  • Consumption of seasonal fruit, including tomatoes, is unlikely to create a health risk provided the current health advice provided to Moanataiari residents is followed. This is available via the Ministry of Health’s booklet “Arsenic and Health”.
  • It is reasonable to follow the same approach in respect of other locally grown produce if it is seasonal and does not normally constitute a major proportion of an adult diet.
  • Root crops and other vegetables which are typically eaten all year (e.g. potatoes, carrots, cabbage) could potentially create a higher risk and the advice not to eat these vegetables must stand until the Ministry of Agriculture is able to comment. This advice is particularly important for pregnant women and young children.
  • If you do choose to eat fruit and vegetables from your own or local gardens, they should be well washed before eating to remove surface deposits of soil.

Can I remove the contaminated soil?

If you decide to remove soil from your property, first contact us for guidance. There are restrictions on the disturbance of contaminated soils and controls on how these soils must be handled, moved and disposed of.

How is lead poisoning diagnosed?

If you are concerned about your health, or that of your family, visit your GP. Lead poisoning is diagnosed by measuring the amount of lead in the blood. This test shows if you have been recently exposed to lead. Lead can also be measured in teeth or bones by x-ray techniques, but these methods are not widely available. These tests show long-term exposures to lead.

Can lead poisoning be treated?

There is no drug treatment for low blood lead levels. However advice about how to reduce lead exposure and absorption of lead is given.

In certain situations if the blood lead level is very high a special treatment using a drug which binds to the lead may be advised by a specialist doctor (paediatrician or physician).

Should everyone be tested?

Testing everyone is not required. If you are unwell or concerned about possible symptoms you should discuss this with your GP. A survey involving biological testing of people living in Moanataiari could be considered once the final results of soil testing are available, as all these results would be needed to design an appropriate study. The tests would only give information about recent exposures, and not historic or chronic exposures. If residents have been following the public health messages since November 2011, then testing people for lead (or arsenic) is unlikely to show anything from living on contaminated land. Elevated blood lead levels in Thames residents have in the past been at similar levels to those reported from other parts of the Waikato DHB's area.

If you are concerned about exposures to arsenic, please see Arsenic and Your Health:

Why is the Waikato DHB not represented on the Governance Group?

  • There is no current statutory role for the Medical Officer of Health in the Moanataiari situation.  The Health Act provisions which might apply at this stage are the nuisances provisions (s29) which are the responsibility of the territorial authority, but there is more specific legislation relevant to contaminated land in the Resource Management Act.  
  • In having an advisory role to the entire project, being outside the structure of the committee allows the MOH (and representatives) to give advice independently to all levels of the Council and to the public, rather than via the Committee's chair.

Is a health study worthwhile for the Moanataiari project?

  • All humans are exposed to naturally occurring arsenic (As); the concern for Moanataiari residents is a matter of degree of exposure.
  • The range of diseases known to have a higher incidence in communities with higher exposure to As is considerable, involving different organ systems, and most are common in the general population. 
  • The Moanataiari population is small, and individuals vary in the duration and intensity of their exposure.  Any form of stratification reduces the study population further.
  • A control community would need to come from outside Thames-Coromandel District, which would introduce new confounding factors.
  • Study design would therefore be difficult, and however good the design, no clear outcome might be able to be established
  • Such a study would require separate funding and other resources.

Notwithstanding these issues, the possibility of some form of health study has been discussed with the Ministry of Health and remains under their active consideration.

Is it safe to drink water from my tap?

If your house is supplied by the Council's reticulated water supply, then it is safe to drink. This water is supplied from clean sources and it is also treated. If you are using water from a personal well/bore (we are not aware of any bores), then it is advised that you do not use this water until it has been tested.

Can I let my kids play on our grassed areas?

Yes you can, established gardens and grassed areas pose very little health risk. The risk of exposure is greatly increased when people come into contact with exposed dirt (i.e. vegetable gardens and exposed dirt under playground equipment). Exposed dirt should be covered where practicable, especially in areas where there are high-volumes of people movement (i.e. paths and dirt under playground equipment).

How are people exposed to arsenic?

Drinking/Eating:  Eating contaminated soil is the most common form of exposure usually from unwashed fruit and vegetables or when children are playing in the dirt and accidentally or purposefully eat soil. Fruit and vegetables also absorb arsenic and hold it internally. Marine fish and seafood contain naturally high amounts of arsenic.  However, the arsenic in these foods is a non-toxic form called "fish arsenic." 
Breathing:  Arsenic in food or water does not evaporate into the air. However, burning arsenic-containing materials such as treated lumber will put arsenic fumes into the air.  Burning treated wood in a wood stove or fireplace may expose people to dangerous levels of arsenic.  Tobacco smoke contains traces of arsenic.
Touching: Levels of arsenic typically found in the environment are not easily absorbed by touching.

What are the health conditions generally associated with long-term exposure to arsenic?

Chronic ingestion of arsenic (consuming arsenic by eating or drinking it over a long period of time) is known to cause some types of cancers and cause some types of cardio-vascular problems.

Who can I see if I am worried about my own health?

Please visit your GP or Medical Centre for advice; they have been briefed about this issue and are able to help. In the meantime, please put into practice the health advice we are recommending until we have more information.

Gardening Questions

Can I eat home-grown fruit and vegetables?


The MoH and DHB, after analyising fruit and vegetables grown at Bright Smile Garden have issued the following interim advice: 

  • Consumption of seasonal fruit, including tomatoes, is unlikely to create a health risk provided the current health advice provided to Moanataiari residents is followed. This is available via the Ministry of Health’s booklet “Arsenic and Health”.
  • It is reasonable to follow the same approach in respect of other locally grown produce if it is seasonal and does not normally constitute a major proportion of an adult diet.
  • Root crops and other vegetables which are typically eaten all year (e.g. potatoes, carrots, cabbage) could potentially create a higher risk and the advice not to eat these vegetables must stand until the Ministry of Agriculture is able to comment. This advice is particularly important for pregnant women and young children.
  • If you do choose to eat fruit and vegetables from your own or local gardens, they should be well washed before eating to remove surface deposits of soil.

Can I mow my lawns?

Yes you can, but to minimise any dust, do what we're doing and raise the mower up a 'notch' and keep your lawns a bit longer. We've had a lot of rain this month, so the grass should be nice and green and be providing a good 'cap'. Just cover bare patches and keep the grass growing well with water and fertiliser.

Can I continue to tend to my garden?

Yes you can, just wash your hands afterwards and try not to create dust. If you have to disturb the soil, keep it damp to avoid creating dust. Many people wear gloves when gardening as well, which is a good idea.

Can I compost my grass clippings and garden waste?

If you follow the health advice, composting of garden waste should pose very little risk to human health. Levels of arsenic in plants will be much lower than in the soil. Remember ingesting soil is what needs to be avoided. If you have any doubts, we suggest you take grass clippings and garden waste to the Refuse Transfer Station and dispose of it to landfill.

Can I dig up my own veggie garden and replace the soil myself?

We think you should wait until the remedial action plan has been developed for your property.

I want to keep growing my own fruit and vegetables, what can I do?

If you can't wait for the testing programme to give you more definitive answers, raised garden beds are the way to go if you want to establish a new veggie garden plot now. At Moanataiari School we remediated to a depth of 1 meter and placed a clay cap at the base followed by a plastic membrane, just to be sure. Then we used commercial compost and top soil to refill the gardens.

Questions about the future

What will happen if the next round of testing confirms the soil is contaminated at my house?

It is too early to give any details of what will be required, but a management and/or remediation plan may be developed for your property.

How long will this all take?

It's hard to tell, but we will work as fast as we can but it will take some months to work through. We aim to have the project finished by the end of 2013.

If any remediation is required, we will apply for support from the Ministry for the Environment’s Contaminated Sites Remediation Fund (CSRF).  If this application is approved this fund can provide up to 50 percent of the costs of any clean up required.

Our planning is well underway for the next round of testing on private property.

Any remediation of land will take some time, but we won't know the full extent of the project and the timeframes until we have completed the next round of tests.

In the meantime, please put into place the health recommendations to minimise any potential health risks until we have more information and please feel free to contact us or visit for regular updates.

What will happen to the value of my house?

We know from previous residential projects of this nature, house prices are not generally affected in the long-term. We acknowledge in the short-term the project is taking a toll on people's ability to rent or sell their homes.

We have also invited the real estate companies to the various Residents Meeting and have also added them to our database so they are fully informed about the project and can help prospective buyers and tenants understand the project and the very low risks associated with living on the subdivision.