Residents of Canberra's Mr Fluffy homes have an additional 16 in 100,000 lifetime risk of developing lung cancer or mesothelioma as a result of living in an asbestos-contaminated house, according to a Sydney public health expert.
Emeritus professor at the University of Sydney school of public health Bruce Armstrong, who speaks in Canberra on Tuesday, has analysed air monitoring results in Fluffy houses in the 1980s and NSW Fluffy houses more recently, and estimates an average concentration of 0.001 fibres per 1 millilitre of air inside a house that contained the loose-fill asbestos insulation.
That corresponds to 16 extra cases for every 100,000 people who have lived in a Fluffy house over their lifetimes - which, given about 1100 Fluffy homes in Canberra would mean at most about one case of mesothelioma caused by loose-fill asbestos insulation in Canberra.
While the numbers are small, Prof Armstrong said anything over one in 100,000 was considered an unacceptable risk to public health.
"Anything that confers a risk of cancer greater than one in 100,000 is generally not thought to be safe for exposure of the general population. And therefore it's reasonable to conclude that living in a Mr Fluffy house represents an unacceptable risk to life and health," he said, ahead of his public lecture at the Australian National University.
At the higher end, some Mr Fluffy houses had shown concentrations of 0.01 fibres per millilitres, which corresponds to an extra lifetime risk of 164 cases of mesothelioma or lung cancer per 100,000 people, and at the top end, a reading of 0.02 fibres per millilitre, corresponding to a lifetime risk of 328 per 100,000.
"Those are the upper limit measurements that anyone has measured," he said. "That is the maximum and it would appear from the measurements that have been done, that those kinds of levels are uncommon."
His results come as authorities begin the mass demolition of 1022 houses, with homes in Flower Place, Melba and Longerenong Street, Farrer, demolished on Monday, bringing to four the number down so far.
Prof Armstrong didn't have air monitoring results from Fluffy houses over the past 12 months. He had used a study of 22 Canberra buildings in the early 1980s, one of which appeared to have Fluffy insulation. Of the 59 samples from that building. the highest concentration was 0.022 fibres per millilitre of air, but most of the samples showed levels below 0.001, the number he has used as a Fluffy average. Ambient air in cities has a level of 0.0002 asbestos fibres per millilitre.
He had also used information from a 1988 report showing a concentration of less than 0.01 fibres per millilitre (the detectable level in that study) in 16 Canberra Fluffy houses. And he used data from NSW testing over the past 12 months 42 Fluffy homes, showing concentrations of less than 0.01 in all but one property.
Prof Armstrong said the estimate was "the best that can be made, it's as simple as that".
The data doesn't take account of extra exposure through renovations or other activity that could stir up the asbestos fibres. But he said one-off, short-term exposures were not as dangerous as longer term lifetime exposure.
Asbestosis was not a risk for people living in Fluffy houses, given the levels of exposure. Other than lung cancer and mesothelioma, two cancers were known to be caused by asbestos - ovarian cancer and laryngeal cancer, but there were no accepted models of exposure and risk from which their lifetime risk could be estimated.
To put the Fluffy risk of lung cancer and mesothelioma in perspective, Prof Armstrong said the lifetime risk in Australia of dying from Hodgkin lymphoma was 39 in 100,000; lip cancer, seven in 100,000; testicular cancer 18 deaths among 100,000 men; and anal cancer 29 in 100,000. The risk of common cancers were much higher, with the lifetime risk for women of dying of breast cancer at 1333 per 100,000.
The professor is part of a separate ANU-led study into the risk of living in a Fluffy house, which is using the Medicare database to track people who have lived in Fluffy homes and comparing them with cancer databases.
Health authorities confirmed two diagnoses of mesothelioma among Mr Fluffy residents in the first half of last year.
Prof Armstrong speaks at 6pm in the auditorium at the ANU Australian Centre on China in the World, Fellows Lane. People attending are invited to register.