The Ivon Watkins-Dow plant in 2001. Photo: Getty Images / David Hallett
The Ministry of Health is refusing to correct mistakes in its Paritūtū serum dioxin study, and has instead shut down access to data revealing the errors.
From the 1960s through to 1987, Ivon Watkins (later Ivon Watkins-Dow, or IWD) made the herbicide 2,4,5-T, which contained the toxic dioxin TCDD, at Paritūtū, Taranaki.
In 2005, the Institute of Environmental Science and Research (ESR) carried out a study of local residents exposed to the dioxin.
The raw data has been available on the ministry's website for almost two decades, but has been taken down following a plea from a former resident to have his mother's record corrected.
Listen to Robin Martin's full report here
Jimmy Stoppard grew up on Marama Crescent in Paritūtū, and later worked at the IDW agrichemicals plant.
His mother Susan Stoppard Raynor recorded the highest level of dioxin exposure in the 2005 study. But she was incorrectly grouped as a long-term resident, despite living in Paritūtū for just seven years.
Stoppard feared the study's results had been skewed by wrong information about his mother and others who lived in the area in the 1960s. He wanted to set the record straight - for everyone's sake.
"Yes, for the simple reason that if that's the case and they put those people's results back in the right place, does that mean it's more liable that there'll be some form of compensation and some form of admission for all of the birth defects and the cancers and everything else?"
The Ministry of Health had previously dismissed the mistake involving Stoppard Raynor, saying it was an error in the text only. But it was clear from the ministry's own website that the error was still in the data - and therefore affecting its charts and figures.
The herbicide 2,4,5-T was a key component of Agent Orange - the defoliant used by the US military in the Vietnam War - which has been linked to cancers and birth defects.
Stoppard Raynor died in her 90s, but Stoppard was living with stage 4 lymphoma - a cancer US authorities had linked to herbicide exposure. He was angry at the Ministry of Health.
"They obviously knew about it. They knew what was going on. They knew people were being infected and affected by the plant being there.
"They knew about the birth defects, they knew about all the various types of cancers, they knew about all the smells and rainwater runoff - otherwise they wouldn't have conducted the study in the first place."
Varying views
Dioxin researcher Andrew Gibbs said Stoppard Raynor's incorrectly recorded data is part of a wider issue.
"Officials have repeatedly denied there were any errors in the study and claimed it's been peer-reviewed.
"If it had been peer-reviewed why are those errors still in the study data, but more importantly why were all the adults resident by 1966 removed from the temporal analysis?"
Temporal analysis is the ability to measure concentrations of dioxin in the population over time. Gibbs said by removing all the adults resident in Paritūtū by 1966 - the high-exposure period - from the temporal analysis, officials watered down the findings.
"What it would've have meant is that the highest exposure would've matched precisely the significantly elevated rates of birth defects both around the plant and in New Plymouth.
"There are few studies around the world with maternal exposure outside of Vietnam, so this study would've basically have supported the Vietnamese position that the chemicals used in Vietnam did in fact lead to reproductive problems."
Ministry of Health acting deputy director-general, Public Health Agency, Ross Bell said without a deep-dive into all the underlying data, it was unable to definitively reconcile the anomalous data points, including those that related to Stoppard Raynor.
He said accessibility of the data sitting behind the graphs was complicated by only a portion of raw data being provided in the report, which may allow it to be misconstrued.
"The Ministry of Health will work with Te Whatu Ora, the agency now responsible for the delivery of health services in this area, to remove the link to the underlying raw data - as this is no longer required for the report, nor is it now regarded as best practice."
Bell said irrespective of this, the central issue of demonstrating that dioxin levels in people living close to the plant were higher than seen in other people remained valid.
"The report concluded that elevated dioxin concentrations were observed in residents living near the former IWD plant in New Plymouth, compared with the New Zealand population baseline.
"This was the first time such evidence had been found, despite repeated investigations and reviews over many years, and supported residents' long standing concerns."
Bell said the study found TCDD exposure in the community, most likely through emissions during 2, 4, 5-T manufacture. It included much more than residence time in the analysis, he said.
"It pulled together many factors including serum dioxin levels, air quality monitoring data, analysis of soils, consumption of homegrown food, as well as residence time and location.
"This was a groundbreaking report nationally and internationally, as was recognised by the international peer reviewers."
Bell did not answer questions about why adult residents in 1966 had been isolated from the long-term group.
Jimmy Stoppard recently at work in Australia, and while undergoing chemotherapy. Photo: Supplied / Jimmy Stoppard
Any additional work requiring the review of data in the study was complicated by practically all those involved in the 2005 study no longer working in the agencies that employed them at the time, Bell said.
The ministry would consider a reanalysis of the data from the historical studies if it was clear that it could improve the health of the affected people.
"However, given that a review or reanalysis of the years of residence in Paritūtū during the 2,4,5-T manufacturing years would not lead to a change in the dioxin health support service offered, such a review is not warranted.
"That notwithstanding, the ministry remains open to new evidence and points of view, and in particular it remains essential that the community voice is heard."
Multigenerational impacts
Following the 2005 ESR study, a dioxin health service was established in 2008. Individuals may be eligible if they lived or worked or went to school near the former IWD factory between 1962 and 1987.
Since it started 799 people had been approved for the service, the majority of which still lived in Taranaki, and more than 4775 health checks done.
Bell said the focus of the dioxin service was on keeping people well, and facilitating early diagnosis of any illnesses that may develop whether such illnesses were related to dioxin exposure or not.
Gibbs said unlike the plan developed for New Zealand Vietnam veterans, the 2008 early intervention health plan for Paritūtū excluded impacts in offspring.
"Numerous animal experiments have now demonstrated multigenerational impacts from dioxin exposures," he said.
"It's time to correct both the exposure and birth defects reports and stop dismissing the apparent impacts from Vietnam level pre-1968 exposures that now span four generations in some Paritutū whānau."