Wellington, Jan 25 NZPA - Scientists are investigating whether methyl bromide -- used to fumigate some exported goods -- may be linked to the death of four Nelson port workers.

The workers died of degenerative motor neurone disease between 2002 and 2004 after having worked at the port and their widows have claimed exposure to the chemical may have sparked the disease.

Research being carried out at Canterbury University research is in the early stages of looking at possible links, but toxicology professor Ian Shaw said a link had been found which involved a reaction when mixing methyl bromide with a protective chemical found in human cells, called glutathione, The New Zealand Herald reported.

The scientists' hypothesis was that if the human cells were exposed, it would reduce the cells' ability to protect against repeated exposure.

Exposure of nerve cells to the chemical could trigger motor neurone disease if the case were to be proved, Dr Shaw said.

Some countries require goods, including logs, to be treated with methyl bromide to kill insects and bugs, and the Ministry of Agriculture and Forestry wants to keep using it.

The Council of Trade Unions said safer options for fumigation are becoming available and wants methyl bromide banned because of its potential danger.

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