An expert in occupational and environmental medicine familiar with a controversial agri-chemicals plant in New Plymouth says a targeted risk assessment of the production facility is a good idea.
Photo: CC / Phillip Capper
Corteva Agrisciences -- previously the agricultural arm of DowDupoint -- recently closed the 16-hectare site which borders Paritutu Centennial Reserve and residential housing.
Under previous management it produced the herbicide 2,4,5T which has been linked to health concerns.
From the 1960s through to 1987, Ivon Watkins (later Ivon Watkins-Dow) made the herbicide 2,4,5T at Paritutu - which contained the toxic dioxin TCDD.
In the mid '80s elevated levels of TCDD were found in the soil on the site's boundaries with reserve land and a residential street.
In 1998, similar levels were found on Mt Moturoa some distance away.
Dioxins are insoluble and break down very slowly in soil, if at all.
New Plymouth Mayor Neil Holdom, with the support of Taranaki iwi, has written to Environment Minister David Parker asking that the government put pressure on Corteva to investigate the site for potential contamination before it sells or leaves.
"The ideal outcome for New Plymouth would be for Corteva to commit to assessing and removing the contamination.
"Our understanding is that to do so to a high standard would likely incur costs in the mid tens of millions of dollars as the contaminated materials will need to be removed and taken to Europe to be processed in a high temperature incinerator," Holdom said in the letter.
Associate Professor Dave McBride of Otago University has studied dioxin levels in the blood of Dow workers at Paritutu and contamination at the former the Fruitgrowers' Chemical Company in Mapua.
McBride said a targeted risk assessment of the Paritutu site made sense.
"There was an incinerator on site and one of the buildings contained the TCP reactor, where the risk of dioxins was higher at certain points and there was an accident where a disc burst and there was a release of dioxins.
"It wasn't a huge release and it didn't extend to contaminating the environment, but certainly people involved in fixing or inspecting the damage did have higher levels of dioxin."
McBride said there were also stories about chemical dumping at the site.
"The only other thing would be there were reports -- I don't know whether they are true or not -- of drums being buried at other areas and that along with the incinerator may have resulted in some local contamination."
He said decontaminating all of the 16 hectare coastal site would not be straightforward.
"If you go to decontaminate an entire area it's a huge process and certainly what they are suggesting of taking all the soil offsite to somewhere in Europe ... seems a huge undertaking when that land would be better used for industry as it's zoned industrial at present. That would seem to make common sense.
"It would be hugely expensive and you've got to look at the cost-benefit argument. You could argue that Corteva pay for it to be pay for it to be completely remediated, but it has been an industrial site and that's what happens when you have an industrial site in an area there will be some contamination.
"But are the levels of contamination going to be harmful if its going to be used as an industrial site? Probably not."
McBride, who has previously raised concerns about the land being rezoned residential, said disturbing the soil was not ideal.
"Well it does present more problems. If it was going to be used for industrial use -- in other words people weren't going to grow vegetables in it or use it recreationally -- there shouldn't be any problem at all."
He could see some merit in combining the Paritutu site with the nearby reserve.
"Absolutely, and in which case target high risk areas and see if they are contaminated and that's they way to deal with it.
"The land should be returned to it's original state as nearly as possible, but the risk assessment needs to be done first and then there could be further discussion ... the local iwi [and council] needs to be assured that the levels of contamination there at present are safe if the land is to be used for recreational purposes."
Environment Minister David Park replied to Holdom's letter saying that it was up to the district and regional council to make sure the Corteva property was safe and he expected the company to cooperate with any further investigations required to do so.
The Taranaki Regional Council said it was not aware of any soil contamination at the Paritutu site at present, but it has previously acknowledge there are no records for soil contamination under the building where 2,4,5-T was made.
It said any chance of land use for the site trigger a requirement for further investigation.
"Any future development or subdivision would need to meet the requirements of the National Environmental Standards for Assessing and Managing Contaminants to Soil to Protect Human Health, with site investigations by suitably qualified environmental professionals required to demonstrate suitability for that purpose."
Under the Resource Management Act, the New Plymouth District Council would be responsible for ensuring that the site was suitable for the proposed new land use.