Gas Links With Disease Unfounded

Gas Links With Disease Unfounded

Renewed concerns that the fumigation of logs and lumber might be linked to motor neurone disease have no scientific basis, says the forest industry.

“Methyl bromide gas is obviously toxic at the doses used to fumigate logs. But outside fumigation envelopes or containers it poses no risk to the public or to wharf workers who follow normal safety procedures,” says Stakeholders in Methyl Bromide Reduction (STIMBR) spokesperson Gordon Hosking.

Dr Hosking was responding to media reports of research by a PhD student at Canterbury University that showed a reaction when methyl bromide was mixed with glutathione, a protective chemical found in living cells.

“The research supervisor, toxicology professor Ian Shaw, has said the findings do not prove that motor neurone disease and methyl bromide are linked. But the possibility that they might has alarmed maritime and wharf workers,” he says.

“No-one knows what causes motor neurone disease. So it is understandable that family members and fellow workers should see possible exposure to the gas as an explanation for cases involving workers at sites where fumigation is carried out.

“Their concerns were fully investigated in an official enquiry five years ago and no link was found. Further reassurance comes from more recent investigations by the Institute of Environmental Science and Research, Environmental Risk Management Authority (ERMA) and the Ministry of Health that also found no link,” Dr Hosking says.

Glutathione is a chemical produced in all living organisms to protect cells from damage by the chemicals that occur in the environment.

“Permanent cell damage only occurs in real life when excessive exposure to a toxin overwhelms glutathione and the body’s other natural defences. This does not happen to workers in our ports because gas levels in working areas have been shown to be well below levels that might cause harm.”

Methyl bromide is used at some ports to fumigate logs and lumber for export and some imported food products, such as garlic from China and grapes from Australia.

“Internationally it is the most widely accepted biosecurity fumigant, because it is effective against a wide range of pests and diseases, safe when used correctly, and does not harm the treated produce. However, because it damages the planet’s ozone layer, the hunt is on world-wide to find alternatives,” Dr Hosking said.

“We are making progress. China, our largest export log market, accepts in-ship treatment with phosphine. But India and several other important markets still insist on methyl bromide fumigation before shipment from New Zealand.”

The forest industry and MAF Biosecurity are working with scientists and researchers in other countries who are exploring alternative treatments, including many that don’t involve chemicals of any sort.

“In the meantime, however, we have no alternative but to continue using methyl bromide as it is so effective in keeping our country protected against biosecurity pests and enabling our valuable exports to be accepted overseas,” says Dr Hosking.

ENDS

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