On 25/1/2003 Ray Stephens wrote:

How does asbestos cause cancer (mesothelioma -sp?) when it is, afaik, a fibrous kind of serpentine which is only an hydrated magnesium silicate?

Talc, as in the stuff bath powder has been made of (soapstone or steatite) is a magnesium silicate, so what different influence does the hydrous formhave?

(assuming talc isn't carcinogenic too)

Gerald Cairns responded:

Sorry I can't dwell on the subject but you will find a fair bit of information and downloadable reports on the Commonwealth NICNAS National Chemical Registration Assessment Scheme or something like that) site.

There is a huge amount of information and good links there including reports on acrylamide etc. etc. Sorry haven't got the link but Google NICNAS and it will all fall out.

For the benefit of those who do not know many of the reports are in PDF format and some are large so take time to download. My tip is that to save bandwidth and your own time as soon as the link to the file begins opening the document over the Net the PDF Tool Bar will pop up and at the extreme left there is a floppy icon which activates saving the file to disc. PDF files will allow you to save simultaneously while downloading, therefore you don't have to wait until the whole document opens to save it, thereby saving a lot of time.

David Maddern added:

Kevin Phyland commented:

I forget who asking about asbestos related disease but I just found an interesting article partially explaining why it's so nasty, and serendipitously how we may eventually dispose of it!
http://www.nature.com/nsu/030120/030120-2.html



Chris Munson wrote:

Asbestos/asbestosis
Corrugated fibro used to be used for poultry shed roofing. In the late 1950s, and early 1960s, when dad's arm got tired, I used to saw through the fibro sheets for him. Because they were corrugated, we couldn't use the flat fibro cutter we had, which sliced through with no dust or shavings. I can distinctly remember bundles of the asbesto fibres coming away when we cut the sheets up. This fibro was from poultry farm sheds built in the early 1920's. The more recent (1950s to 1970s) flat fibro sheets, didn't ever seem to have the atual bundles of asbestos fibres that the corrugated sheets had.

I spent many hours cutting these sheets when we converted poultry sheds to pig pens. I do cough every now and then, but am never worried when picking up a piece of fibro.

What is my "use by date?"



On 28/11/2005, Podargus wrote:

James Hardie is in the news again. However they were not the only manufacturers of asbestos products. For instance Wunderlich. Did Hardie take over all the other players?


Gerald Cairns added:

Ruth and I have been exposed to asbestos in the days when we were refining and using asbestos gloves to handle hot ladles. I would sometimes be covered in white dust or fibres and Ruth had to wash my green/white overalls. I have recently had a check up and no signs of lung or other possible symptoms. I think that the disease is subject to multiple factors such as individual susceptibility, lung function in terms of mucus clearance (smokers can have severely impaired bronchial flagella) and of course the individual competence of DNA repair mechanisms. We were then alerted rather late and moved to mineral fibre gloves instead - nowhere near as good e.g. abrasion resistance, but no dust. The OHS asked what we wanted silicosis or asbestosis? :-(

The sad part about it all is that many lives could have been saved by chemically treating the asbestos to alter the structure. I have a technique that I tried on some asbestos cement board and it seems to work without significant loss of strength though haven't tested thermal properties BUT no dust. I still have a pair of old worn out asbestos gloves that I kept for experimental purposes if ever I had had the time and funding to look more closely at the problem. If I were removing asbestos boards I would wet them out with a vegetable oil or something similar and save all the hot protective clothing. Of course there is always the accumulated dust in the cavities. The technique of altering the crystal structure chemically is not a new concept others have done similar things but maybe it was too expensive to apply. I did find links to the subject on the Net but can't lay hands on them right now - try Googling the subject that should bring up something.


Peter Macinnis replied:

BRIDGES: There is a book by Henry Petroski in which he argues that bridges fail on average, about once every thirty years: Tay bridge in  1879, Quebec in about 1907, Tacoma Narrows in about 1940, several box girder bridges around 1970. I think he also pointed out an earlier one, the River Dee bridge around 1846 or 7 -- his thesis was that 30 years is the time taken for chastened engineers to get daring again after a catastrophe.

On that basis, we are overdue for the next one by a bit.  Maybe the engineers have learned to be more careful, but there are some awfully
ambitious stayed-cable designs in the planning stage.

ASBESTOS: I was threatened with disciplinary action when I threw out all of the asbestos mats in my lab at Fort Street Boys' High in about 1972 or 1973.  I had seen a cloud of dust come out of the drawer when a boy closed it, so I pitched the lot and tossed the drawer for good measure.

Because I was in the habit of reading 'New Scientist', I was aware that asbestos dust was extremely dangerous.  I did not consult, I acted, in
the interests of myself and my students.  I had not expected there to be any reaction from my superordinates.

The guilty parties, for the record, were Wally Bray (a complete moron who was appointed to his post by a clerical error) who reported me to the principal, Tom Cooke, a total nonentity (and I worked in Head Office for many years, so believe me, I apply exacting technical standards
before attaching that sort of descriptive label to anybody).

I was ordered to replace the mats, and I declined.  I may even have grinned -- I do that, sometimes.  I was then threatened with disciplinary action of an unspecified sort, because I was endangering the nicely painted bench tops.

I asked them to give me, in writing, a statement that, in their professional opinion, asbestos dust was safe.  I added that I would, of course, require their statements to be witnessed as stat decs, and that they must agree that their statements could be shown in any hearing to which I was subjected, and that the statements could be supplied to the media.

At that point, there was a loud noise, as of two poltroons back-pedalling.  They were stupid, but they were not complete muppets.

It was my good fortune to have read the Icelandic sagas as a boy, and to have known that the very thought of a berserker strikes terror into the heart even of normal men, while sapping the will to live and gnawing the remnant vitals in the gutless.

The issue sort of evaporated after that, but I can see why some of those problems carry on for a while.

But thanks for those advances to my thinking, Toby!



Toby Fiander replied:

Asbestos is nasty stuff and casual exposure can be enough to give you cancers of several possible types later, but later usually means decades later.  So care is a good idea - keeping doors and windows closed is reasonable precaution in the first instance.  Don't stir up the dirt and dust of a known affected area.

Fibro is one manifestation but more dangerous is lagging on old pipes.  You need space suits and masks to handle anything that resembles this stuff and there are Standards and procedures and training and certificates and inspections - and it is all rather over the top.

If there is any doubt about any dust or dirt or other material any place, make it wet and keep it that way.  You even used to be able to work fibro pipes relatively safely as long as they were wet - not that I think this is a good idea.

Also, make sure you take some photos of what is going on and make sure next door's experts know you are doing that.  Their reputations and insurance are then at risk.  Ask them for their company name, that usually frightens everyone.

However, so saying, asbestos is everywhere.  It is hard to think of any building site, even in the bush where you won't find small pieces of asbestos, unless someone has gone to the trouble to pick up the pieces. Asbestos tiles and even old pipe lagging can be found in illegal land fills which are also relatively common, in spite of the best efforts of Council officers.  Pretty dangerous and undesirable, but the stuff is around.  Like lead, with which we will live for centuries yet, even though it has not been used in paint since about 1970.

Anyway, my point is: you need to act with some balance.  Minimising exposure is good, and getting the information from the experts who are inspecting the site is a good idea, too.

Can you let me know how you get on - perhaps offlist?  I will be on the northern beaches next week at a site in Brookvale, as it happens....


Kevin Phyland commented:

I note the recent de-gazetting of Wittenoom...is this another case of revisionist history? Pretend it didn't happen?

odd...


Ray Stephens added:

My father worked with fibro for many years when it was still fashionable for things like sealed roof eaves.

At the time he preferred using only hand tools, and the fibro-board cutting tools were doubtlessly significantly less dusty than power saws, which is probably why he has passed through without any repercussions upon his health.


Ray Stephens answered:

Either I think Alan, but there may be a slight difference between yellow-white chrysotile and blue crocidolite asbestos in prevalence of microfibres, which do the damage.


Gerald Cairns replied:

It is my theory that a lot depends on the capacity of your lungs to flush out the micro fibres in the normal mucus flow. I am mildly asthmatic and have a modestly excessive mucus flow that probably does not allow the fibres to linger long. This does not explain why other members of my family who are not asthmatics have not been affected either. The "precipitation" or gathering up of the microfibres tends to coat them in a protective membrane as they are slowly moved up the airway and make their exit. It could be that some people possess a less effective filtration/flow mediated by the cellular cilia and if this has been damaged by smoking or other illness well they are at an increased risk. You might expect this to be more common in the elderly with impaired lung function.

I suspect probability has a lot to do with the incidence, high concentrations or over long periods = high probability the body's defences will be swamped. I am pretty certain that one or two fibres getting into my lungs would simply be ejected along with all the other particulates that are acquired in normal breathing.

This system of cleansing the airways is reminiscent in reverse of the mucus feeding mechanisms of certain filter feeding organisms. You could post this to another site where a certain very capable person would be more competent to answer these questions.

and:

Further to my previous post on this subject;

In using new asbestos furnace gloves they are so loose they shed fibres like snow and I am not satisfied with the "mask" regulation, in my experience the bloody stuff still gets past the seal around your cheeks and you end up with white nostrils - you end up looking like Father Christmas only all over. A full air filtered had hood is about the only practical approach. Its a bit like these paper masks we see people wearing in flu outbreaks, the air takes the line of least resistance and most by passes the filter material. I still have an old pair of asbestos furnace gloves that I keep for a source of fibre for experimental use only. Once broken in they shed few fibres in comparison with new gloves. The latest mineral gloves are a great improvement - tough abrasion resistant and light weight with little fibre shedding if any. My old gloves used to be disposed of by being melted into the slag in the furnace. Alkaline slag at around 1500 dissolves it into a glass.

I suspect the fibres that do the damage are those that are absorbed by the macrophages rather than isolated by proteins and mucopolysaccharides. The macrophages probably become the malignant medium.

My reason for suggesting vegetable oil or derivative is simply that it penetrates well and forms tight durable bonds with the fibres and it does not dry out too quickly and there is a good chance of some beneficial ground chemistry modifying the dumped material later reducing the risks to anyone accidentally disturbing a "dump" site in the future. Water has to be repeatedly applied especially in hot weather and I have seen removal people working with dried out material - a lack of diligence.

The soils around the cities are heavily contaminated from years of wear of vehicle brake linings, you are right it is difficult to avoid. Our current house is lined with "asbestos cement sheeting" but I suspect this is probably of the cellulosic variety anyway it is painted. Not our choice but was here when we got kicked out of NSW and had to make quick decisions but we are not losing any sleep over it.