Contaminated soil not a health risk, says Ministry

Sep 26, 2002

A New Plymouth suburb is contaminated with dioxin but not at levels high enough to affect residents’ health, says the Ministry for the Environment.

In what it says is the single biggest investigation of dioxin-contaminated soil on residential properties ever undertaken in New Zealand, the Ministry concludes there is a “negligible” health risk to current and future residents of Paritutu.

But the study, begun in March this year using 45 soil samples from about 30 properties, did find toxic contamination at Paritutu when other sites in New Zealand typically show no contamination.

The testing, undertaken by environmental consultants Pattle Delamore Partners Ltd, also found dioxin at twice the level recommended by international guidelines at one site.

Some New Plymouth residents have argued for years dioxin contamination at Paritutu was a health risk because of toxic emissions from the former Ivon Watkins-Dow chemical plant which began manufacturing the agricultural herbicide 2,4,5-T in Paritutu in the 1960s.

The plant stopped making 2,4,5-T in 1987 after increasing concerns about a cancer-causing byproduct of the manufacturing process called TCDD.

World health authorities have also linked TCDD to skin disorders, liver damage and reproductive and behavioural problems.

Long-time campaigner on the issue, Andrew Gibbs, called the Pattle Delamore report a “PR whitewash”.

“You won’t get contamination from the soil, that was never the issue,” he said.

The damage to residents’ health happened in the 1960s and 1970s when emissions from the manufacture of toxic herbicides was at its peak, said Mr Gibbs.

The report said while Mt Moturoa Domain had dioxin soil concentrations at 92 ng/kg (nanogram per kilogram, 1ng/kg equals one gram of dioxin per million tonnes of soil), more than twice the US Environmental Protection Agency guideline, residents only used the area for recreation.

Also, the guideline was a “trigger” level, meaning it should trigger further investigation. It was not a level at which health risks would occur, the report says.

Dioxin contamination at other sites around the Dow plant was in the range 5 to 15 ng/kg.

Samples were taken at depths from 7.5 to 15cm. Because dioxin was very stable in soil, levels measured now were considered to be an accurate reflection of historical levels when 2,4,5-T was being manufactured, the report says.

Environment Ministry chief executive Barry Carbon said the Government would continue to investigate claims of ill-health caused by dioxin emissions at New Plymouth.

The Ministry of Health was conducting a blood serum study to measure dioxin levels in past and current residents of Paritutu and a study of cancer and mortality rates in New Plymouth was also underway.

The Pattle Delamore report concludes no further soil tests at New Plymouth need be carried out.

Sep 26, 2002 | by ANNE BESTON | nzherald.co.nz
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