Dioxin probe free from bias, study leader vows

02 April 2008

One of the world’s biggest worker health studies will be released in Taranaki later this month.

Chemical manufacturer Dow contracted Otago University’s Dr David McBride to head the investigation into dioxin in the blood of workers at New Plymouth’s Dow AgroSciences site in Paritutu.

Between 1962 and 1987 the Ivon Watkins-Dow site produced 2,4,5-T and 2,4-D. Both produce toxic dioxins. During that time IWD employed 1500 workers.

In an exclusive interview with the Taranaki Daily News, Dr McBride said the latest study of 376 workers was one of the biggest of its kind in the world.

It was probable the study would find that the workers’ blood dioxin levels are higher than those of 52 Paritutu residents tested by the Ministry of Health in 2003, he said.

On average, the blood-serum dioxin levels in residents was found to be three times higher than the New Zealand population.

“We do expect the workers to be slightly higher,” Dr McBride said.

However, he rubbished some claims that his study lacked credibility because it had been paid for by Dow.

The blood tests alone have cost $500,000.

“Some would say that you are in the pocket of the company, but it’s not like that at all because the university has academic independence,” he said.

“I’m a doctor, so it wouldn’t be very good if I tried to hush things up.

“Dow has an interest in its workforce and it is it that should be spending the money and it is not something public money should be spent on, investigating worker health,” Dr McBride said.

“We had to make sure everything was right with this study because it is going to be under intense scrutiny.

“When you have got the co-operation of the company you know you are going to get good data from them, including employment data and inside information, and everybody is involved in the project, which is a really good thing.”

Dr McBride was pleased workers had willingly come forward to be tested.

“They are worried about these things. It’s been going on for a long time and we’d like to give them some resolution and be able to tell them something.

“We had a marvellous response from the Taranaki community, from people who previously worked at the plant. We were very pleased with that.

The scientists back-calculated the exposure to dioxin. “It was a very technical and time-consuming procedure. It was a huge effort.”

The workers will hear what their levels are before the report is publicly released this month.

Dr McBride said the study would be used to ensure safe exposure levels for future workers. “The horse has bolted on this one (IWD exposure).”

The two McBride studies will be used to work out whether there is any direct association between dioxin exposure and a number of health conditions.

“Along with other studies, you can get a coherent body of data that leads you down certain tracks where you can make informed decisions.”

The latest study is linked to Dr McBride’s study of 1700 workers, released in 2006, which looked into cancer deaths of people who worked at the New Plymouth site from 1969 to 2001.

It found the death rates were not dissimilar to those among the general population but suggested a slightly increased risk from multiple myeloma.

In 2003 the Ministry of Health serum study into the dioxin levels of 52 long-term Paritutu residents found on average they had dioxin levels three times the national level.

Experts believe toxins could mean a slightly elevated chance of suffering from cancers, especially soft tissue sarcoma or non-Hodgkins lymphoma.

About four IWD workers’ dioxin exposure health claims have been accepted by ACC.

02 April 2008 | accfocus.org  | NEWS-2008-M04-02-001


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