Types of asbestos.
Asbestos has six naturally occurring fibrous minerals found in the veins of two different types of rock, Serpentine and Amphibole. Serpentine produces Chrysotile (white asbestos), and is made up of tiny needle fibres that can be spun to thread and woven to form a highly durable cloth, making it the most commonly used.
Amphibole rocks produce the remaining five types of asbestos, the fibres are softer and cannot be woven but they are still very heat resistant and durable.
The most common types of asbestos found in New Zealand are Chrysotile (white asbestos) and Amosite (brown asbestos) but Crocidolite (blue asbestos) is known to have it’s presence as well.
What is the hazard of asbestos?
Asbestos material is not a risk just by it’s presence unless in it’s raw form, is is however, a danger if an asbestos containing product is disturbed, this causes a release of small asbestos fibres, as the fibres are microscopic and invisible to the naked eye, this looks like plain dust but is much more deadly.
Asbestos is incredibly durable, after a disturbance the fibres will become airborne and lodge themselves to almost any surface. They will stay on this surface until removed or disposed of correctly, possibly contaminating the area around the disturbance and causing further health issues. As mentioned however, the fibres are invisible to the naked eye so you will be unaware of this contamination without sampling.
Unfortunately the contamination is not limited to just the exposed party, health issues have been observed in family members of those that have been exposed and carried the fibres home on their clothing.
A notable case concerning a family members exposure can be read about here.
What are the health impacts?
The asbestos fibres are inhaled and work their way to your lungs where the perforate lung tissue, causing scaring and / or damage that may not present itself for many years. Due to their rigid nature and chemical resistance the body is unable to break the fibres down. Although none of the impacts of asbestos exposure will present themselves immediately, this does not mean they have not effected you, in the years to come asbestos can cause serious lung disease including lung cancer, mesothelioma and asbestosis.
As a general rule, the longer and greater the exposure, the more chance you have of developing an asbestos related disease.
The National Asbestos Medical Panel received a massive 1299 notifications of asbestos related diseases between 1992 and 2012, only twenty short years. These notifications have come from both doctors and individuals, the disease seeming to present itself most commonly in individuals in their late 60’s, having been exposed 40 or so years earlier. The latency period of asbestos related health effects ranges from 15 to 50 years.
Over 60% of these cases were carpenters, builders, plumbers and such occupations and over 7% electricians.
A short history lesson.
Asbestos has been linked back to prehistoric times, it’s positive uses being apparent even then.
Romans and Greeks used asbestos tablecloths and napkins that they would throw into the fire to be cleaned, after which the would come out white and unused.
In Ancient Egypt, Pharaohs were wrapped in asbestos cloth after embalming to further hamper their bodies from deterioration.
In 1280, Marco Polo wrote of a clothing worn by the Mongolians from a “fabric which would not burn.” He even visited an asbestos mine is China to discredit a myth that asbestos came from the hair of a wooly lizard!
All around the world entire mining towns have been deserted due to extensive asbestos contamination.
Before the Second World War, asbestos was only present in New Zealand by way of imported items.
In 1938 however, James Hardie Ltd established a plant in Auckland producing asbestos cement products. The plant was operational until 1987. At it’s peak, the Auckland plant had a team of 600 employees.
Following suit shortly after, Fletcher Construction established their own plant in Christchurch in 1943, this was operational until 1974. The team members of this plant are not so clear due to the high amount of casual workers used, estimates say the plant employed up to 2000 over it’s 31 year life time.
Asbestos was mined in New Zealand in only small quantities from Cobb Asbestos Mine in the Tasman Region of the South Island. The vein was discovered in the 1880’s , in 1897 the Asbestos Cottage was built by prospectors, the hut is built out of wood and named only for it’s location. 100 tonnes of asbestos was brought out by pack horse by 1917 but the remote location made mining difficult.
In 1935 the Cobb Dam was constructed, resulting in a better road with good access and the Hume Company mined Cobb Asbestos Mine until 1964, bringing about 5000ish tonnes of local, pure asbestos. The mine as then closed due the the short length of asbestos fibres it produced, limiting it’s commercial use.
Remnants of the miners can still be found along the path to the mine, including boots and bottles.
Asbestos Cottage has a rich history, it became the secluded home of a runaway couple from 1914 to 1951, all the while trying to pick up commercial interest in the mine, Mr. Chaffey himself mined some 50 tonne of asbestos on his own. More on The Chaffeys can be read about here.
Asbestos Cottage is available to the public and often used for tramping and school field trips, for more information on the Cottage, and the walk to get there, visit Doc and / or Stuff.
Picture: “Asbestos miners, Upper Takaka” from The Nelson Provincial Museum, Tyree Studio Collection 54950/3.