Public Health Mapua Report Released

Monday 15 March 2010, 3:41PM
By Ministry of Health


Expert advice to the Ministry of Health is that it is unlikely there are adverse long-term health effects for local residents from the Mapua clean-up process. 

The advice was released today along with a health impact report to the local Mapua community.

Today’s public health impact report
 is the latest in a series of Government reports into the site clean-up, which began with a Parliamentary Commissioner for the Environment investigation just before the clean-up was completed in 2007. 

A further report on health impacts for workers on the site is being completed by the Department of Labour and is expected to be released in mid-April.

The public health impact report was held up by delays in obtaining expert advice including the unfortunate death of a key scientist.

The key finding of the health report is that it is unlikely there are adverse long-term health effects for local residents from the clean-up process although the report sets out some of the limitations of the comprehensiveness of the monitoring. 

Those limitations in monitoring are addressed in the recommendations in this report, which aim to further reduce any remaining uncertainty.

The expert advice from the independent Organochlorines Technical Advisory Group is that it is unlikely that local residents would have experienced a significantly elevated level of exposure to chemicals of concern for a sufficient period to result in any chronic health effects from that exposure.

At the release of the report, the Ministry of Health is offering time over the next six weeks for local people to discuss this report and give their views on what steps they think are now needed to address the report’s recommendations.

Ministry Deputy Director of Public Health Dr Fran McGrath says: “Many local people will be pleased with this result showing that adverse health effects for local residents are unlikely from the clean-up process.”

“We recognise that there is still some uncertainty about the precise levels of a small number of chemicals. We have some sympathy with the local community who would have hoped all these questions to be answered.”

“We have sought expert advice from the independent Organochlorines Technical Advisory Group. That advice confirmed that the existing evidence as part of the clean-up does give us reassurance that any exposure is unlikely to have resulted in long-term health effects."

The expert advice is also that blood testing will not result in either the community or the individual being much wiser. 

“We know that we are all exposed to some level of the chemicals of concern largely through our diet. Unfortunately, knowing the level of a contaminant such as dioxins in our bodies does not predict the health consequences, which are affected by other lifestyle factors such as smoking and exercise.”

The Ministry of Health will begin a process of community engagement over the next month to six weeks to gauge community concerns and preferences for next steps for the Ministry.



1. Who was most likely to be exposed to contaminants during the soil clean-up process?

The steps taken to protect public health during the clean-up process meant that people living to the north or west of the site were unlikely to have been adversely affected by the organochlorines and heavy metals.

However, the confidence with which we can say this for those living to the south is weaker because of limitations in the comprehensiveness of monitoring. This uncertainty about organochlorine exposure is for around 30 households to the south of the former site, in particular Tahi St or closer than 31 Tahi St.

2. What were the chemicals local people may have been exposed to and what is the public health risk?

Exposure Public Health Risk
PM10 Likely – numerous instances where the level exceeded consent limits Likely – low to medium
Ammonia Likely – low Likely – very low
Dioxins Probable (Nov 04 – Mar 06) Unknown
PCBs (non-dioxin like) Possible Unknown
Benzene possible Unknown
OCPs, arsenic Possible (south of site*)
Low (north and west of site)
    A summary of information provided in the report: * west side of Tahi St and closer to the site than 31 Tahi St for those on the east side of the street.

3. What was the expert advice received by the Ministry of Health on public health risks in the report?

The Ministry sought preliminary advice from the Organochlorines Technical Advisory Group (OTAG), which has representation from experts in this area. Their advice is available on the Ministry of Health website www.moh.govt.nz. In summary the advice was:
‘…it is highly unlikely that people would have experienced a significantly elevated level of exposure for a sufficient period to result in any chronic health effects’

OTAG advised that the safety margin in the modelling done as part of the public health impact report gives further reassurance. The group also advised that the short exposure period – 18 months for some chemicals and three years for others – in terms of lifetime exposure risk means health consequences are considered unlikely.

The expert group advised that while biological testing is feasible, the available scientific evidence does not support testing. OTAG recommended that biological testing is not undertaken on the residents of Mapua.

OTAG further advised that if the Ministry of Health should decide to offer biological testing, such testing should not take place until the results of soil testing are available to help inform the sampling framework.

4. What are the next steps?

The Ministry over the next month to six weeks will be seeking community views about the report, its recommendations and next steps. The Ministry will be contracting an independent company (Allen & Clarke Ltd) to facilitate that process and report options to the Ministry (4-6 weeks).

The Ministry will then be advising Government on the preferred options and informing that advice with community views, evidence, cost, feasibility, fairness and expert advice.

To provide your views or ask about the process, contact the Ministry of Health from Tuesday, 16 March 2010, on 0800 288 588.