Tests of soil near where a fire burned for three months underground at a Waikato landfill have not found any dangerous levels of highly toxic dioxins.
Tests for 17 types of dioxin had found traces in three out of nine samples, the Waikato Regional Council says, adding that all were at levels below national guidelines. Photo: Puke Coal Landfill
The Waikato Regional Council ordered the soil and air tests after residents at Pukemiro and Glen Afton complained that the smell of the fire was making them sick.
Tests for 17 types of dioxin had found traces in three out of nine samples, the council said in an update to locals.
All were at levels well below national guidelines, and might not even have come from the fire.
"These levels do not pose an increased concern for human health," the council said.
"The low levels detected in three samples were of Octachlorodibenzodioxin (OCDD) which can be found in smoke emissions, but can also occur as a result of other dioxins that have been modified by exposure to sunlight.
"So it's possible these low-level dioxins could have come from historically used chlorinated pesticides, for example, which is common in a rural area."
A dioxin alert for pregnant or breastfeeding women to move away from the area was lifted in November, after Fire and Emergency checks - including by overhead drone - at the dump, showed no remaining trace of the fire.
Results of the dioxin air testing are due next month from Australia.
Emails newly released under the Official Information Act show a researcher into a Canadian landfill fire approached for advice by Waikato agencies, warned them about the impacts.
"He is sure that we will also find that dioxins are elevated," a council senior scientist said on 11 November, just before the alert to pregnant women was issued.
The scientist pushed for money to be spent testing for dioxins rather than for heavy metals, as the risk from those appeared much lower.
The test results and "the pattern of detection" meant "scientists do not believe that there is sufficient evidence that the Puke Coal landfill fire has impacted the soil", the council now says.