The history of asbestos in New Zealand
The sad, sorry saga of asbestos in New Zealand is a story of unintended consequences.
Asbestos came into widespread use in the early 1900s. At the time, the advent of new technologies using steam, kerosene, and electricity, saw the emergence of catastrophic new fire hazards. Fires in public theatres, schools, office buildings and on ships, some involving 100s of casualties, spurred the search for a building and insulating material that was non-combustible and had low thermal conductivity.
Read more → Asbestos and its use over the centuries
Asbestos, long known for its strength and resistance to fire and chemical breakdown, seemed ideal. A miracle material.
Unprocessed asbestos was first imported into New Zealand in the late 1930s; and building products made from asbestos mixed with cement were produced over a 50-year period up until the mid-1980s. Locally manufactured asbestos-cement building products contained around 5 to 15% asbestos. From around 1960, the predominant asbestos type used in buildings in New Zealand and most other industrialised countries was chrysotile. Smaller amounts of crocidolite and amosite were used in building products before 1960.
Besides construction, asbestos was used in New Zealand for machinery insulation, insulating tapes and cloths, gaskets and seals (particularly in the aviation and marine industries), and brake linings for motor vehicles.
Most New Zealand houses built in the 1940s-60s used tile or asbestos-cement sheet roofing. Asbestos cement was easily moulded, so was ideal for corrugated roofing. As well as being fire resistant, it was also inexpensive, durable, and easy to install. Asbestos-cement cladding in the form of sheets (e.g. Fibrolite) or planks (e.g. Hardiplank) was popular for the same reasons.
From the 1950s through the 1960s and 70s, many asbestos materials were spray-applied, including textured decorative coatings on ceilings and walls that contained chrysotile asbestos. Other asbestos building products included vinyl sheet floor coverings (“lino”) with a chrysotile paper backing, vinyl-asbestos floor tiles, sprayed fire protection, and roofing membranes.
In terms of kilograms of asbestos used per capita per year, asbestos use in New Zealand was lower than in many industrialised countries until the 1970s-1980s, when per capita use exceeded that of the USA and the UK, though it remained substantially lower than in Australia, Canada, Germany, and Denmark.
Because of this near ubiquitous use, future asbestos-related cancers in New Zealand are projected to involve mainly people employed in the building trades who were exposed to the mineral during construction, renovation and remediation projects.
This legacy is dreadful enough, but something even more insidious may be playing out as well.
While the risks associated with working with raw asbestos or regularly handling materials containing asbestos as part of an occupation are now relatively well understood, the level of risk arising from non-occupational exposure is less well known. It is apparent though, that even brief but intense or intermittent non-occupational exposure may increase the risk of asbestos diseases, particularly mesothelioma. Malignant mesothelioma is a diffuse cancer that spreads over the lining of the lungs or stomach. It has a long latency period, rarely developing within 15 years of first exposure. And it is universally fatal – the average survival rate, after diagnosis, is nine months.
Read more → Asbestos is nasty but do you know why?
The assessment of risks associated with non-occupational exposure has had to rely on extrapolation from studies of highly-exposed workers such as miners, mechanics, and builders. While most reports of disease resulting from, exposure to asbestos in the non-occupational setting involve environmental exposures related to living near asbestos mines or factories, the first reports of increased mesothelioma risk in people who did not have workplace exposure to asbestos occurred in family members of asbestos workers.
When asbestos products are cut, sanded, or ground toxic fibers are released into the air. Aside from the obvious risks of first hand exposure, suspended asbestos fibers would have contaminated workers’ clothing, their hair, hands, and shoes. The introduction of power's tools such as skilsaws on to building sites in the 1950s and 60s compounded the dust problem.
It's now apparent that asbestos fibres inadvertently brought home from construction sites can cause serious health complications. This is known as secondary asbestos exposure, and it applies to not only children, but also to spouses, siblings and anyone else sharing the house.
The laundering of asbestos-contaminated clothing is a highly plausible pathway for indirect exposure. If a child’s clothes are washed with his or her father’s contaminated work clothes, the consequences could be asbestos contamination. Only relatively recently has it become apparent that household exposure to asbestos puts children at risk for a myriad of conditions that doctors once thought only affected occupationally exposed workers.
Although a wealth of journal articles involving dozens of countries describe the repercussions of indirect asbestos exposure for children, the answers to many crucial questions are speculative and have yet to be proved.
Some researchers believe children exposed at an early age may be more likely to develop the disease than people first exposed later in life. However, one Australian study showed a reduced risk of mesothelioma in asbestos-exposed children, which the researchers believe may be explained by their having a more effective defense mechanism than adults. There is also some evidence that children younger than 15 years of age when first exposed experience lower rates of mesothelioma mortality.
And to make matters worse, growing evidence suggests asbestos exposure may cause more diseases than we thought. The relationship between asbestos exposure and diseases such as malignant mesothelioma and lung cancer is well established, but now it seems other diseases not typically associated with asbestos may be linked to occupational and non-occupational forms of exposure.