New research has shown that up to 90 per cent of kangaroos that graze beside the Portland aluminium smelter have suffered tooth and bone deformities after breathing and ingesting fluoride emissions.

Autopsies performed at Melbourne University on 49 kangaroos culled at Alcoa on a single day last year found all but one were suffering from fluorosis, which leads to excessive bone growths, or lesions, on joints in the paws, ankles and calves.

It can also cause tooth and jaw deformities that hinder eating and foraging.

According to the latest figures in the Federal National Pollutant Inventory, the Portland plant is Victoria’s largest industrial emitter of fluoride dust.

The plant discharges 120 tonnes of fluoride into the air each year, which is equivalent to 22 per cent of the state’s total emissions of 540 tonnes from 74 facilities.

The Environment Protection Authority was first warned of the effect of fluoride dust and fumes on kangaroos living near the Alcoa smelter in 2005, although lameness was detected in some animals grazing there as early as 2001.

Jenny Charles, associate professor in veterinary pathology at Melbourne University, said research had found that up to 90 per cent of the roughly 130 kangaroos living at the Portland site had some form of fluorosis on their teeth and a quarter had visible limb lumps.

EPA director of environmental services Bruce Dawson denied the authority had been slow to reduce emission levels.

He said that while the levels were safe for humans, it was now clear they were too high for some animals and a new level was likely.

However it could take years before research indicated what that level should be.

‘‘We are taking this seriously. Clearly the impact on the local kangaroos and vegetation is not acceptable and action is required,’’ Mr Dawson said.

The eastern grey kangaroos live on the 500-hectare Portland Aluminium site, known as the “Smelter in the Park’’.

The area has been designed with wetlands and parks with recreational trails and activities for community and employee use.

Portland operations manager John Osborne said there had been many successes and challenges of managing the project which he termed “ambitious”.

“The levels of fluoride measured in air near to the smelter are well within human health guideline values and Portland Aluminium is one of the lowest fluoride-emitting smelters in the world,” Mr Osborne said.

“We are, however, deeply concerned by the potential for low-level emissions to affect the health of any animal grazing close to the smelter and will look for further improvement opportunities.”

The company commissioned ongoing research into the local kangaroo population after the issue was highlighted in a paper published in the Journal of Zoo and Wildlife Medicine in 2006.

Mr Osborne said the company had been “incrementally reducing” emissions.

Tuesday’s meeting will be held in the Portland Library at 5.30pm.

-With THE AGE