The asbestos epidemic, which is expected to cause up to 12,000 New Zealand cancer deaths, may be reaching its long-predicted peak.
Case numbers of mesothelioma, an aggressive cancer linked to asbestos inhalation, are reproduced in a report out today reviewing the risks of home exposure to the deadly fibres.
The Health Ministry sought the review because of concerns over the exposure of Cantabrians during the earthquake-linked destruction and repair of buildings containing asbestos.
The review by the Royal Society and the Office of the Prime Minister's Chief Science Adviser Sir Peter Gluckman found the risks were generally low. The science on exposures from the kinds of remediation works done in Canterbury "indicates that they are unlikely to result in a significant increase in risk to homeowners and occupants of damaged houses, unless they were performing the work themselves without taking proper precautions such as wetting the surfaces and using a respirator".
Using power tools, dry scraping or sanding can generate significant amounts of airborne fibres, creating risks if such work is done repeatedly.
The clean-up and home remediation works "did not always follow appropriate guidelines" for avoiding exposure but exposure level of workers and the public were uncertain, the report says.
A simulation study in some Christchurch houses was done to replicate typical dust exposures from removal work in the first year after the earthquakes, "before stricter procedures for asbestos monitoring and abatement were fully operational".
The results were well below the permissible workplace standard.
" ... it was therefore concluded the risk to occupants - who would have experienced only short duration exposures during this time - would have been extremely low."
Asbestos was widely used last century including to insulate pipes, decorate ceilings and in roofing tiles, wall claddings and in the backing of floor lino.
Exposure to asbestos is linked to many cancers, including lung and ovarian tumours, as well as asbestosis. Mesothelioma, which is incurable, occurs in the membrane around the lungs. It can take 30 years after exposure to cause symptoms.
A study in 2000 predicted up to 12,000 people in New Zealand, mostly former building industry tradesmen, would die of asbestos-related cancers. The researchers tracked imports of crude asbestos, which peaked in 1974 and fell to zero by 1992 and said with the time lag of asbestos disease development, the epidemic would likely peak between 2010 and 2015 before tailing off.
Asbestos Disease Register 2012 data reproduced in today's report shows a peak of 102 new mesothelioma cases in 2005, with the annual number subsequently hovering between 80 and 97.
A survey for the Environment Ministry last year found few uses of asbestos-containing products.
Only one - parts for some aircraft - was considered indispensable and a marine company indicated minor imports of asbestos-containing exhaust gaskets would be needed.
New cases of mesothelioma
1970 - 1
1980 - 16
1990 - 29
1995 - 55
2000 - 60
2005 - 102
2010 - 89
Source: Ministry of Health