Cancer scare in mothball chemicals

Written by Eloise Dortch - 30 March 2009

Chemicals commonly used in mothballs and as deodorants in men's urinals can cause cancer, a US study has found.

A research paper published in Nature Chemical Biology has revealed that the vapours emitted by the chemicals, naphthalene and para-dichlorobenzene, blocked enzymes which promoted normal cell growth in microscopic worms.

The report comes after previous tests on laboratory rats and mice which developed cancer after inhaling, the chemicals at high concentrations.

Naphthalene flakes and mothballs sold in WA supermarkets are 99 per cent naphthalene while some yellow and blue toilet blocks used in many urinals are 99 per cent para-dichlorobenzene.

Para-dichlorobenzene is often used instead of other toilet fresheners because it does not dissolve in water. Instead it deodorises by sublimation, or turning from solid to vapour.

A spokesman for the Federal regulator, the National Industrial Chemicals Notification and Assess¬ment Scheme, said 500 to 1000 tonnes of para-dichlorobenzene was imported into Australia a year for air fresheners and toilet deodorant blocks.

About 300 tonnes of naphthalene was used in Australia a year in insecticides, fumigants, fuel and lubricant additives, dye dispersants, plasterboard, manufacture, fragrance formulation, salt-making and tanneries.

He said NICNAS had already planned to review the use of naphthalene and would now consider the US study.

Naphthalene was acutely toxic and had caused nasal tumours in rats which inhaled it in tests but it was not thought to cause cancer in humans.

He said para-dichlorobenzene should be used only in well-ventilated areas because it was a skin and eye irritant.

Although tests showed it caused tumours in rat kidneys, there was no scientific proof it was carcinogenic for humans.

WA Health Department principal toxicologist Martin Matisons said studies of workers in naphthalene factories showed they did not have a higher risk of cancer.

"We know it can cause cancer in the respiratory tracts of animals but we haven't concluded it's carcinogenic to humans," he said.

NICNAS and Dr Matisons urged people to follow product warnings.