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DanIsaacs  
#1 Posted : 31 May 2017 17:09:47(UTC)
Rank: Forum user
DanIsaacs

I'm not involved in occupational hygiene, I'm a statistician, I joined this forum just to ask this question of some people who I hope might be experts in the field.

I've been doing some modelling of environmental contaminants and comparing the mathematical models to the epidemiological data on whatever illnesses they cause. I came to do some work on asbestos but found a huge discrepancy that I couldn't explain with the figures.

Basically, without going too heavily into the maths, any Acm (even ones with quite a low proportion of asbestos are made up of potentially hundreds of billions of fibres in every cubic centimetre. So any fully destructive activity (say drilling a hole) creates potentially hundreds of billions of fibres. It must do, because, being a hole, the stuff isn't there any more.

Now the poor worker drilling the hole might be exposed to something up to 100f/ml,but the air that effects can only be so big (say 2x3x3) which is millions of millilitres, multiply that by the 100f/ml and you get hundreds of millions, a thousand times out at least! So, where have all the fibres gone?

1. They fell straight to the floor in big lumps. That explains the air concentration, but then all those fibres are still on the floor. Hundreds of billions of fibres is enough to contaminate a whole house at millions of fibres per square centimetre. Even using conservative values for how many get put back into the air, every 1960s flat and office block would have been a deaths trap for years, way more than the generally very low air concentrations found in public buildings.

2. They're lost to air changes. Problem is we've just established that they didn't end up in the air, they weren't in the original disturbance otherwise the air concentration would have been higher, and they're not getting entrained into the air later otherwise the air in public buildings would be much worse than it is.

3. They got cleaned up. But conventional cleaning methods don't work with asbestos, they just spread it around and make matters worse.

So, as per the question title, where did all the fibres go? Every drill hole, every cut, scrape and knock throughout the 60s and 70s must have made trillions of potential fibres and yet public buildings even with damaged ACMs routinely show very low air concentrations.

I'd be really grateful if anyone with expertise in this field could answer this puzzle for me.

thanks 1 user thanked DanIsaacs for this useful post.
Qusay Qasem on 01/06/2017(UTC)
DaveBridle  
#2 Posted : 01 June 2017 07:19:56(UTC)
Rank: Forum user
DaveBridle

I think your starting point would be to look at a buildings' Asbestos Register.  This would highlight (providing it was a proper survey) where any asbestos has been identified.

Then with this information you would then look at the inspections of any ACM undertaken over time subsequent to the survey.  If there has been no work in the area to either dispose of/remove or to disturb any ACM then there will be none in any air monitoring.  The majority of ACM will probably be either hidden within in accessible areas of the fabric of the building, or encapsulated (think being over painted a number of times on a textured ceiling for example).  If at regular inspection the ACM has not changed or become damaged or unsafe, then it will have been left alone.

The control measure put in place for removal would mean that air quality monitoring would be undertaken during any licenced work and equipment used to prevent accidental release and the thorough capture of any fibres (use of H-Type vaccuums etc.).  Once removal has been undertaken a certificate of re-occupany would be issued based on subsequent air quality monitoring.

Hope this helps.

thanks 1 user thanked DaveBridle for this useful post.
jodieclark1510 on 01/06/2017(UTC)
DanIsaacs  
#3 Posted : 01 June 2017 09:05:19(UTC)
Rank: Forum user
DanIsaacs

Thanks for taking the time to reply. I'm not sure I quite understand what you're suggesting, if you could spare a little more time to explain, I'd be very grateful.

What I'm having trouble understanding is the discrepency in numbers between the fibres released from a something small like a single drill hole (which could potentially number in the billions since the fibres are so small) and the air concentrations actually found in buildings even with damaged ACMs (regularly below 0.0003f/ml). I see what you're saying about investigating the asbestos history of a building and that might be a good route to go down for more accurate figures, but surely every building must have had at least a few holes drilled in it's ACM at some point in time, and yet no building to date has yet been found to have more than a few thousandths of a fibre per millitre of air, so I don't immediately see how the actual building history might help explain this discrepancy.

Secondly, I should have made it clearer in the actual post for which I apologise, but being a statistician I'm interested in the modelling of the processes, not any actual real life work. The time period I'm interested in is the 1960s and 70s, there would have been no H-class vaccum cleaners and no air monitoring to ensure safe re-occupation and yet the epidemiological data for non-occupational exposures during the 60s and 70s does not match with even a moderate exposure level. Out of all the people who went to school in CLASP buildings, worked in asbestos-ceilinged offices and lived in high-rise flats (which must be close to the entire population, especially when considering schools) less than 200 a year went on to develop asbestos related diseases fourty years later. Now at this point I should re-iterate I'm interested only in the statistics, 200 is still 200 too many and I applaud the work that's being done to reduce this figure, but 200 out of 700,000 deaths is a risk of just under 3:10,000, which, according to Hodgson and Darnton's estimates would equate to a lifetime cumulative exposure of about 0.1f/ml (say twenty years at 0.005f/ml).

Without further explanation (which is what I'm looking for here), that would mean that during the period when people took absolutely no precautions whatsoever with asbestos, the average air concentration arising from this lack of any precaution (after the dust had settled) must have been no more than about 0.005f/ml, and this ties in well with the few air tests done close to that time (1982 is the earliest I've been able to find). Even with conserative estimates of re-entrainment to the air from settled dust, ten billion fibres is enough to contaminate a whole building and a hundred times this figure and that's just one drill hole, hence my confusion about where all the fibres went.

Any further help understanding this would be greatly appreciated.

RayRapp  
#4 Posted : 01 June 2017 09:21:33(UTC)
Rank: Super forum user
RayRapp

Not sure exactly what your'e asking as I'm not a scientist...asbestos fibres which get released could end up on clothing, footwear, tools, remain dormant in the building until disturbed by others, or given time escape to atmosphere.

aud  
#5 Posted : 01 June 2017 09:37:41(UTC)
Rank: Super forum user
aud

Hmm. Interesting question. Surely they all ended up in the ground, first as 'dust' then part of the soil, either via landfill as sweepings, building debris after demolition, or settling from the air to be integrated with the land by the actions of water, weather etc. As you say, there will have been an awful lot of fibres floating about over the years, so I too wonder as to the lack of evidence of widespread effects in those decades. Maybe people died of other things (smoking etc) before asbestosis had a chance to show, or medics didn't look for, or notice it with everything else in the air - smog, coal & cotton dust etc.

Once part of the soil, fibres are unlikely to refloat into the air where they would pose a risk, and so become part of the landscape; back to nature - from whence they came.

chris42  
#6 Posted : 01 June 2017 09:41:53(UTC)
Rank: Super forum user
chris42

If I understand your question correctly. Let’s say someone drills a hole in a ceiling, most of what comes out of the sheet where the hole now is, is drilling dust ( ie if it was wood it would be saw dust, if metal called it would be called swarf). This dust which is clumps of asbestos fibres will fall due to gravity onto the persons shoulder, their boots, the ladder they are on and if you are lucky a big plastic sheet on the floor. Only a small proportion of these very small fibres separate out into individual fibres or clumps so small as to be able to be suspended in air, hence the readings you suggest.

If the room is not sealed then yes, these fibres in the air will migrate with the natural flow of air around a house.

Take a step back from the microscopic and consider the very small amount of visible matter that has actually been taken from where the whole now is. Even the dust formed from drilling will not look that significant (although is).

So, my answer would be most of it falls due to gravity as it does not all break up into individual fibres, some will be suspended in air and some more later will make it into the air if the dust is allowed to kick up from the movement of people etc.

This is just my view can’t back it up in any way.

Chris

DanIsaacs  
#7 Posted : 01 June 2017 10:11:41(UTC)
Rank: Forum user
DanIsaacs

Thanks to all involved. I'm slightly concerned that there's no easy answer to this. Considering that in the event of a small asbestos incident or damaged ACM discovered, one might well be advised to spend hundreds, if not thousands of pounds to get it professionally sorted, I'd expect there to be some fairly clear demonstration of the risk that just leaving it would entail, but perhaps it's still out there somewhere.

To those suggesting it will simply end up on a ground, a little maths (only a little). Ten billion fibres  spread out over a floor space of 5x5m would give 40,000 fibres/cm2. Conversion factors (K factors), can be used to estimate re-entrainment from surface to the air. Most experiments concur on K factors for asbestos of 1e-5 (1 with five zeros in front of it). For our 40,000 fibres/cm2 this would give 0.4f/ml. Without any clearance (the dust is on the foor now so air clearance is negligable and apparently ordinary vacuum cleaners don't work on asbestos) that's 8f/ml.yr cumulative for someone living there for twenty yrs. This is higher than most pre-regulation industrial settings, just from one hole!

To those who suggest the fibres remain in clumps, that is exactly the explanation I presume must be true as I can't think of anything else, but that would have to come along with the rather controvertial fact that normal houshold cleaning methods (vacuum, duster, mop etc) are actually quite effective at removing asbestos as the small fibres which could theoretically make it through these processes don't really form a great proportion of the dust which is mostly made up of large clumps that the vacuum cleaner would both pick up and (largely) retain in it's bag. If we postulate that normal cleaning methods break up these clumps to dangerous small fibres, we're back to the problem again of where they all are in buildings which consistently show very low air fibre concentrations.

Postulating that normal cleaning gets rid of most of the fibres within a fairly short space of time (or even that some other natural methods such as air changes do) is, however, contrary to all advice on dealing with damaged or friable asbestos in the home (broadly, that it presents a risk high enough to be worth spending hundreds of pounds eliminating), hence my reluctance to accept this conclusion and my continued search for some other explanation.

ryangavin777  
#8 Posted : 01 June 2017 10:35:09(UTC)
Rank: Forum user
ryangavin777

An interesting question but I tend to agree with the majority of the answers above. I'm not qualified in the subject matter and neither can I back up my thoughts.

Would you not need to know how much asbestos is contained in each material? Presumably different materials contain different amounts of asbestos? Do you not also need to consider the compound in which the asbestos is mixed with?

Purely a fictitious scenario....If asbestos is mixed with a strong glue then wouldn't a normal vaccum be able to suitably lift it / filter it?

DanIsaacs  
#9 Posted : 01 June 2017 11:01:40(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: ryangavin777 Go to Quoted Post
Would you not need to know how much asbestos is contained in each material? Presumably different materials contain different amounts of asbestos? Do you not also need to consider the compound in which the asbestos is mixed with?

Yes, for anyone interested, in my calculations I'm using a solid asbestos density of 2000kg/m3, density of AIB as 700kg/m3 and consisting of 30% asbestos, this gives a conversion factor of about 0.11. With an average fibre size of 0.16 cubic microns we get about 6e11 fibres per cc of AIB. I've used figures from air tests in asbestos mines which show about 2% of all fibres in the "dangerous" range of sizes, hence about 1e10 (ten billion) "dangerous sized" fibres per cc.

I take your point about the binding material, but as per my post above that would only lead to the the conclusion that normal household cleaning activities are basically safe for small-scale exposures (by safe, I mean as safe as crossing the road, or driving to work), which is definately not the message we're getting from the experts so I remain confused.

David Bannister  
#10 Posted : 01 June 2017 11:55:36(UTC)
Rank: Super forum user
David Bannister

I think that the question is extremely thought-provoking and one that I have never before considered. Nor I suspect have many others in this profession. Looking at it from a purely numerical perspective, without our ingrained bias presents interesting scenarios and raised further questions in my mind.

I would really like to know what the answer is and do not have sufficient knowledge to offer any satisfactory answer.

My gut feeling is that they are largely incorporated in the dirt we collect and end up in landfill or swilled downstream in the rivers and sewers, as well as blowing in the wind, but that is purely guesswork on my part and nowhere near a good answer.

Hilti  
#11 Posted : 01 June 2017 12:07:42(UTC)
Rank: Forum user
Hilti

Interesting discussion

I suspect that after the initial disturbance, the fibres would settle and the airborne resuspension of fine particles/fibres from a surface is low thereafter, as small particles adhere to surfaces quite well.

Even if considering resuspension and associated resuspension factor (K). Typical K factors for walking on surfaces are around 10-5 (i.e. about 1 in 100,000 of the fibres would become airborne).

Regards

hilary  
#12 Posted : 01 June 2017 12:30:41(UTC)
Rank: Super forum user
hilary

I refer you to the Control of Asbestos Regulations.  All work on asbestos is done using hand tools which reduces the dust to begin with. All work must then be carried out with the workpiece damp so that the fibres produced clump together in a lump or lumps and do not become airborne.  Each person working has to have a disposable suit, mask, goggles, head covering, gloves, shoe coverings.   The area should be clear of other people and if the work is of any duration, air monitoring should be carried out. 

In the instance of the hole, the hole will be drilled by hand into pre-wetted asbestos which will continue to be wetted as the job progresses.  There will be extraction in the event of any airborne particulate.  The resulting mess will be cleaned up using a class H vacuum rather than sweeping so it does not encourage the particles to become airborne.  Damp rags will be used to clean all surfaces.  At the end of the job the contents of the vacuum, the rags, the suit, goggles, shoe coverings etc will all be put in a bag marked "asbestos waste" and sent to a specialist waste contractor for controlled disposal without the bag ever being opened.

So there should be no airborne fibres if work is carried out properly, hence the low concentration levels.

But then, perhaps I completely missed the point ....

DanIsaacs  
#13 Posted : 01 June 2017 12:59:40(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Hilti Go to Quoted Post
Even if considering resuspension and associated resuspension factor (K). Typical K factors for walking on surfaces are around 10-5 (i.e. about 1 in 100,000 of the fibres would become airborne).

Yes, those are the k factors I'm using, but extrapolating back from them to 0.0003f/ml gives 30 fibres/cm2 multiplied by a 10x10 office that gives 30,000,000 fibres in settled dust. Seeing as a single hole could contain 30,000,000,000 fibres, where have all the rest gone?

Originally Posted by: hilary Go to Quoted Post
But then, perhaps I completely missed the point ....

Yes, a bit, to be fair it is now abit buried in the post. I'm talking about the fibres that would have been created either in the 60s and 70s when no precautions were taken, or nowadays in situations where no-one involved is aware that the material is an ACM. In neither case do we find any evidence of greatly elevated air concentrations afetr a period of time, yet there doesn't seem to be any reconised means of fibre removal. So where did they go?

Hilti  
#14 Posted : 01 June 2017 14:56:37(UTC)
Rank: Forum user
Hilti

In real world tests where a 7 mm dia 1/4 inch drill bit was used to make a hole in AIB. This resulted in 0.35 f ml-1 to 0.9 f ml-1. This gave an average of 1,800 airborne e fibres during the activity. 36 fibres being in the dangerous range.  

johnmurray  
#15 Posted : 01 June 2017 16:14:21(UTC)
Rank: Super forum user
johnmurray

Interesting. I suspect that modelling exposure to ailment is complicated by the problem that many people can be exposed to asbestos, but wither they develop illness as a result is not forecastable. Many will not. Exposure as a child seems more problematical. Even more problems occur because asbestos is naturally occurring. There seems a considerable amount of published material. Most of which is barely legible! http://www.silc.org.uk/w...13/05/Paul-Nathanail.pdf However: http://www.iom-world.org/pubs/IOM_TM8814.pdf As long as "it" is in the soil it presents few problems. In the air, however...
Bigmac1  
#16 Posted : 01 June 2017 17:11:39(UTC)
Rank: Super forum user
Bigmac1

The sad fact is that asbestos fibres are around us all the time. In urban environments more so than rural. Fibres from industry, brake pads, building demolition etc. We havnt always been as careful over the decades as we are now. As long as it is below 0.01f/ml of aie (legal limit). But whether we like it or not everyone of us breathe it in daily, not in the quantities to cause harm but we do. 

Ian Bell2  
#17 Posted : 01 June 2017 18:42:41(UTC)
Rank: Super forum user
Ian Bell2

Are your calculations and assumptions behind your statistical model comet?
Ian Bell2  
#18 Posted : 01 June 2017 18:46:39(UTC)
Rank: Super forum user
Ian Bell2

Comet !! Correct... big fingers, small keyboard! !
DanIsaacs  
#19 Posted : 02 June 2017 06:42:42(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Hilti Go to Quoted Post

In real world tests where a 7 mm dia 1/4 inch drill bit was used to make a hole in AIB. This resulted in 0.35 f ml-1 to 0.9 f ml-1. This gave an average of 1,800 airborne e fibres during the activity. 36 fibres being in the dangerous range.  

OK so presuming it takes only a matter of seconds to drill a hole, we can eliminate the effect of any of those fibres falling to the floor under gravity as that would take hours so a 7mm hole in 25mm board has removed almost exactly 1cc of board (0.35^2*3.14*2.5), about 30% of which is asbestos depending on the type of board. 1800 fibres were airborne which at 0.16cubic microns per fibres is about 300 cubic microns, so out of 1e11 cubic microns of material (1cc, adjusted because the material is not 100% dense) 300 of which are airbourne sized fibres, the rest must be either single fibres or clumps mixed in with the binding material too big to be airborne (otherwise they would appear in your air tests).

The fate of these fibres is what I'm interested in. Over time, they cannot create more than about 0.0003f/ml concentrations otherwise the air tests in public buildings would generally be much higher and many more non-occupational deaths would have occurred from the 60s and 70s.

Using k factors of 1e-5 this would allow a maximum of 3e6 fibres in a 10x10 office/classroom (any more than that and the air concentration would be higher than has ever been recorded).

But 1e11 cubic microns of asbestos can potentially yield 6e11 fibres. To get from this potential figure down to 3e6 by normal cleaning methods over a relatively short timescale would mean that normal cleaning methods would have to be 99.9995% effective at removing asbestos fibres (or potential fibres all clumped together), That would mean even if we were to say that this was the result of 1,000 such operations over time (about one per day for three years), each one would still be 99.5% effective, which is a conclusion that flies in the face of all the advice from experts so can't be right, but I'm still not seeing anything else to explain where all the (potential) fibres went.

And just to keep perspective, we're still just talking about a single drill hole, how many holes, cuts breakages, sandings and general damage must a standard school/office have suffered during the 60s and 70s when no-one paid any attention to the dangers of asbestos? Yet they've still all ended up with only 0.0003f/ml in the air (about 30f/cm2 settled).

Ian, no, I'm very much much unsure that my assumptions are correct (far more certain of my calculations, as this is my job) that's mainly why I'm posting here to see if anyone can correct me on them.

johnmurray  
#20 Posted : 02 June 2017 15:37:39(UTC)
Rank: Super forum user
johnmurray

And the point of this is what? Obviously, the released fibres have not magically departed to another dimension. They have not been cleaned? So they must still be somewhere! The obvious somewhere would seem to be the ground. It's no good going by the diseases-caused-by-asbestos route...many are missed/misdiagnosed/late diagnosed. And many are not registered on death certs...
Ron Hunter  
#21 Posted : 02 June 2017 16:04:08(UTC)
Rank: Super forum user
Ron Hunter

Dan,

You may be oversimplifying things. The ,methodology for analysys and determining fibre count is given in MDHS 39/4.

When you've digested that, can you come back and explain it? It's baffled me for Years!

DanIsaacs  
#22 Posted : 03 June 2017 06:52:14(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: johnmurray Go to Quoted Post
It's no good going by the diseases-caused-by-asbestos route...many are missed/misdiagnosed/late diagnosed. And many are not registered on death certs...

That's an interesting theory, but it doesn't actually resolve the problem of the low number of mesothelioma cases from non-occupational exposure. If we were to postulate that a large number of such cases were going undiagnosed for whatever reason (and it would have to be a large number to explain the discrepancy), even in 2014 (where my data comes from) when it's such a well known and important issue, then we must presume that underdiagnosis was an even more significant problem prior to 1920 when the condition was barely heard of. The trouble is, lack of mesothelioma cases prior to widespread use of asbestos is the only evidence we have that non-occupational cases must be caused by asbestos (i.e that we don not know of any significant number of spontaneous cases in the absence of asbestos). If you're suggesting that there might have been a large number of cases prior to the widespread use of asbestos, but they were just underdiagnosed, then the entire presumption of cause for non-occupational cases is on very shaky ground. Interesting though.

As to the point. There is a discrepancy in the numbers, that is pretty much without doubt, the fibres from a hole are no longer in the whole, no-one is disputing the size of relative density of asbestos (these are just physical facts) and literally hundreds (possibly thousands) of air tests have been carried out in buildings with ACMs in them showing no more than about 0.0003f/ml in the air, which is thousands of time fewer than we would expect if the fibres were still hanging around on the floor. There's no way I can see of disputing that discrepancy in numbers (nor has anyone yet pointed one out). So, one of three things must logically be wrong;

1. The levels of asbestos really are higher than measured (maybe they're all below the height of the sampler units, or none of the samples were carried out near disturbances) and the number of deaths from asbestos related diseases is under recorded, as you suggest (but this would lead to the problem mentioned above).

2. As above, the fibres are still there but the low number of non-occupational cases are because asbestos at these levels isn't actually as harmful as we thought.

3. The fibres have all gone because normal household cleaning whilst clearly unsuitable for industrial scale exposure is actually 99.9% efficient at clearing up minor domestic-scale incidents.

To my mind all three would have huge implications for asbestos abatement, management and public safety, so I think the point is very important, unless of course my numbers are wrong, which is why I'm here.

DanIsaacs  
#23 Posted : 03 June 2017 07:15:48(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Ron Hunter Go to Quoted Post
You may be oversimplifying things.

I've read the methodology, I've digested quite a lot of data in my research on this topic, I'm not quite sure what you might mean by linking the fibre counting methods to the possibility that I might have oversimplified things. If you are suggesting that most of the billions of fibres that could have been released are too small or too large to be counted, then yes, I had thought of that, but the numbers would be massive.

Take for example an acitvity which generates a measured air concentration of 50f/ml (countable fibres). In order to do that over a dispersal area of say 2x3x3, it would have to generate 3e7 fibres per minute (this is to fill the space and to keep it full despite the fact that fibres are settling to the ground at a rate of 0.3mm/sec), so fifteen nimutes of such activity would generate about 4e8 countable fibres. Cutting AIB with a power saw might be just such an activity, but cutting AIB with a power saw (presuming 8ft boards and a 1mm kerf) would generate 3e13 potential fibres (i.e of all sizes) per cut. 15 minutes of such cutting would produce at least ten times as many (I don't know exactly how many boards one could cut in fifteen minutes). This would mean that out of 3e14 potential fibres only 4e8 are of countable size, that's about 0.00001%. I've no reason not to belive that to be the case as I've no expertise on how asbestos breaks up (that's why I'm here), but if it were true that only about 0.00001% of any asbestos fibres released by damage are of countable size, then that would have serious implication for asbestos management as per my post above. Either these other sizes are not dangerous and so minor asbestos incidents really can't release enough dangerous fibres to be of any concern, or the premise on which non-occupational asbestos related mesothelioma is based has to be questioned.

Bigmac1  
#24 Posted : 03 June 2017 08:45:14(UTC)
Rank: Super forum user
Bigmac1

There is between 10 and 200 fibres in the 1m3 of air we breath depending where you live. Not enough to cause serious health problems for the public, hence the lack of non-work related cases. Its at the workface we still have the problem. Lets increase awareness of all lung disease, get behind the BOHS Breathe Freely campaign or IOSH' No Time To Lose campaign.Spread the word people too many people are dieing when they shouldnt be.

DanIsaacs  
#25 Posted : 03 June 2017 09:41:30(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Bigmac1 Go to Quoted Post

There is between 10 and 200 fibres in the 1m3 of air we breath depending where you live. Not enough to cause serious health problems for the public, hence the lack of non-work related cases. Its at the workface we still have the problem. Lets increase awareness of all lung disease, get behind the BOHS Breathe Freely campaign or IOSH' No Time To Lose campaign.Spread the word people too many people are dieing when they shouldnt be.

I agree with your sentiment entirely, but have you read the HSE report about why people are not heeding the message about the risks from asbestos, conflicting messages and a culture of not believing in the risks come out pretty much at the top and a "don't look too closely at the figures" kind of attitude at HSE is not going to help. If we really want to save the lives of the people at the coal face who really are at risk, there needs to be openess and honesty otherwise the message will just not be believed. Admittedly I'm a mahtemitician so I'm comfortable with the figures, but if I can calculate a huge dicrepancy, then I'm sure many builders, electricians etc can see it too, even if only intuitively. If one message coming out of the safety industry is clearly contradicted then people are much more likely to throw the whole lot out and just carry on as they were. That's one of the reasons I think it's so important to get it right, so that the people who need it can really believe in it.

Bigmac1  
#26 Posted : 03 June 2017 10:04:22(UTC)
Rank: Super forum user
Bigmac1

Good point well made Dan. I have seen the report. My concern is not just asbestos but all dusts and fibres. When you see people working in plumes of dust and they think is OK worries me as to where we are with perception and attitudes of both the employer and employee.

johnmurray  
#27 Posted : 03 June 2017 17:47:40(UTC)
Rank: Super forum user
johnmurray

Originally Posted by: DanIsaacs Go to Quoted Post
Originally Posted by: johnmurray Go to Quoted Post
It's no good going by the diseases-caused-by-asbestos route...many are missed/misdiagnosed/late diagnosed. And many are not registered on death certs...
That's an interesting theory, but it doesn't actually resolve the problem of the low number of mesothelioma cases from non-occupational exposure. If we were to postulate that a large number of such cases were going undiagnosed for whatever reason (and it would have to be a large number to explain the discrepancy), even in 2014 (where my data comes from) when it's such a well known and important issue, then we must presume that underdiagnosis was an even more significant problem prior to 1920 when the condition was barely heard of. The trouble is, lack of mesothelioma cases prior to widespread use of asbestos is the only evidence we have that non-occupational cases must be caused by asbestos (i.e that we don not know of any significant number of spontaneous cases in the absence of asbestos). If you're suggesting that there might have been a large number of cases prior to the widespread use of asbestos, but they were just underdiagnosed, then the entire presumption of cause for non-occupational cases is on very shaky ground. Interesting though. As to the point. There is a discrepancy in the numbers, that is pretty much without doubt, the fibres from a hole are no longer in the whole, no-one is disputing the size of relative density of asbestos (these are just physical facts) and literally hundreds (possibly thousands) of air tests have been carried out in buildings with ACMs in them showing no more than about 0.0003f/ml in the air, which is thousands of time fewer than we would expect if the fibres were still hanging around on the floor. There's no way I can see of disputing that discrepancy in numbers (nor has anyone yet pointed one out). So, one of three things must logically be wrong; 1. The levels of asbestos really are higher than measured (maybe they're all below the height of the sampler units, or none of the samples were carried out near disturbances) and the number of deaths from asbestos related diseases is under recorded, as you suggest (but this would lead to the problem mentioned above). 2. As above, the fibres are still there but the low number of non-occupational cases are because asbestos at these levels isn't actually as harmful as we thought. 3. The fibres have all gone because normal household cleaning whilst clearly unsuitable for industrial scale exposure is actually 99.9% efficient at clearing up minor domestic-scale incidents. To my mind all three would have huge implications for asbestos abatement, management and public safety, so I think the point is very important, unless of course my numbers are wrong, which is why I'm here.
Maybe your discrepancy is caused by the differences between people. Some, with low exposure, develop disease. Others, with high exposure, develop no disease. Then again, development times vary quite dramatically. Some will develop mesothelioma, others with similar exposure levels, will develop different diseases. Some people will develop mesothelioma from exposure to clothes-borne fibres... It may well be that you are attempting to calculate the incalculable.
DanIsaacs  
#28 Posted : 05 June 2017 07:04:17(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: johnmurray Go to Quoted Post
Maybe your discrepancy is caused by the differences between people. Some, with low exposure, develop disease. Others, with high exposure, develop no disease. Then again, development times vary quite dramatically. Some will develop mesothelioma, others with similar exposure levels, will develop different diseases. Some people will develop mesothelioma from exposure to clothes-borne fibres... It may well be that you are attempting to calculate the incalculable.

Trying to calculate the incalculable is a fault of mine, but with asbestos being so ubiquitous, the trouble is someone's got to. From the HSE report I linked above it seems that the issue facing most workers at risk from asbestos nowadays is how to remain profitable in the face of the risk and that's all about drawing a line somewhere. The HSE etc. are no help saying all damage is unsafe no matter what the scale and requires specialist attention. Crossing the road is unsafe but we don't get specialists in to help every time we do it, we draw a line at a level of risk we're prepared to accept is inevitable in life and this is what workers will do with asbestos. The trouble is no-one's helping them draw that line because no-one's providing real world figures for small scale exposure, it's all just theory; small fibres could theoretically make it through an ordinary vac bag, fibres could theoretically remain in the building for years, exposure at such a level could theoretically cause disease etc.

It simply is not possible to get people to behave in a way which is so monumentally counter intuitive on the basis of a rough guess which doesn't even add up. All that's going to happen is workers are going to make their own guesses; some (the lucky ones) will get it right, other will guess too low and suffer ill health, others too high and loose their jobs to inefficiency. Since starting this post (which I thought would yield a fairly simple answer) I've become increasingly astonished at the complacency of the Occupational Health community that these figures, (sometimes thousands of times out) are simply taken for granted. Surveys of over 300 buildings with ACMs show air fibre concentrations of lower than 0.0003f/ml regardless of the condition of the material, and no-one seems to have considered this fact might warrant an explanation? The entire basis of asbestos surveys is still about the condition of the material. So what factors do have an effect? No-one knows because no-one's bothered to find out, just carried on presuming it's to do with friability and damage regardless of the overwhelming evidence that this factor does not have any long term effect on the exposure of the building occupants.

If there was a serious intention to help workers and occupants who might be exposed to asbestos, then there should have been tests carried out to measure the exposure that normal activities generates including the settled dust resulting, the fact that there have been none whatsoever in the 40 years since we've known this to be a problem is, frankly, shocking.

The facts that we have to explain are fairly indisputable, no buildings have yet to be recorded with air fibre levels above a few per litre regardless of the condition of the ACM, deaths from asbestos related diseases in 2014 for non-occupation exposures are lower than those from crossing the road despite the fact that 40 years ago (when these exposures would have taken place) absolutely no precautions whatsoever were taken with asbestos. From an industry that could potentially be advising people to spend into the thousands on remediation, I don't think it's too much to ask that there should be an explanation for this, but it would appear it is.

RayRapp  
#29 Posted : 05 June 2017 08:37:47(UTC)
Rank: Super forum user
RayRapp

Dan, I am not a number cruncher so I readily admit I do not fully appreciate the sums or hypotheses you are promulgating with regards to exposure from asbestos contaminated materials. However, I do understand the concept of risk, subjective though it is, I suspect others like yourself are not so familiar with this concept.

The HSE have provided much guidance on how asbestos should be managed to try and reduce the risks from exposure. There are many different types of ACMs, some are by definition low risk and some are high. The condition for each and every type of ACM needs to be assessed as well as the location and other factors. So, there are many variables which need to be taken into account when managing ACMs. Notwithstanding the risk element, there is also the matter of cost, which is no small matter.

Your premise that h&s practitioners are not properly managing the risk from ACMs I would challenge. We may not be able to quantify those risks in a scientific formula, we have many other non-asbestos related risks to manage with limited resources and budgets. There is no such thing as a risk free society - it is about managing those risks to as low as reasonably practicable.   

 

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jodieclark1510 on 05/06/2017(UTC)
DanIsaacs  
#30 Posted : 05 June 2017 11:39:20(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: RayRapp Go to Quoted Post

Dan, I am not a number cruncher so I readily admit I do not fully appreciate the sums or hypotheses you are promulgating with regards to exposure from asbestos contaminated materials. However, I do understand the concept of risk, subjective though it is, I suspect others like yourself are not so familiar with this concept.

The HSE have provided much guidance on how asbestos should be managed to try and reduce the risks from exposure. There are many different types of ACMs, some are by definition low risk and some are high. The condition for each and every type of ACM needs to be assessed as well as the location and other factors. So, there are many variables which need to be taken into account when managing ACMs. Notwithstanding the risk element, there is also the matter of cost, which is no small matter.

Your premise that h&s practitioners are not properly managing the risk from ACMs I would challenge. We may not be able to quantify those risks in a scientific formula, we have many other non-asbestos related risks to manage with limited resources and budgets. There is no such thing as a risk free society - it is about managing those risks to as low as reasonably practicable.   

 

I sympathise with the limited budget available to the HSE, but I do understand risk. Risk, in the mathematical sense, is what I do for a living. What I do not sympathise with is the poor use of dat and inconsitent approaches whic leave workers (and housholders alike) with very skewed idea of risk.

Risk of lung cancer from Radon at 200Bq/m3 - about 1:190; HSE advice - no action required (the action limit is 400Bq/m3.

Risk from radiation (X-rays) 10 years at 6mSv/yr about 1:200; HSE advice - no action required, advisary is above 6mSv

Risk from driving at work - 150 people killed every week in work related driving incidents; HSE advice - a leaflet reminding employers that they need to do a risk assessment.

I could go on.

Risk of mesothelioma from non-occupational exposure to asbestos with no special precautions taken - about 1:50,000 (according to 2014 figures), or alternatively, according to Hodgson and Darnton models risk of ten yrs at 0.0003f/ml (which remember is the average air concentration in building regardless of the condition of the ACM) 2:100,000; HSE response - If you suspect a material might be asbestos consult a specialist, if it is friable/damaged it should be encapsulated or removed regardless of the cost, any exposure incident should be treated by disposal of clothes, thourough washing, evacuation of the room (all with no limits on the scale of the exposure)

As far as I can tell, this is totally out of proportion to the risk and totally at odds with the approach taken with other risks such as Radon and X-rays, where a lower limit has been set, and the HSE's own guidance which states that acceptable risks are around 1:10,000 for the public and 1:1,000 at work. Out of the workplace, alchohol, processed meat, tiredness while driving, stress at work, all seem to have had lower limits set which bring risks down to around 1:1,000, lower if practicable, higher if the cost is really prohibitive. Yet with asbestos, there's no lower limit of practicability been set for the public, no square meterage of material that it's OK to leave no matter what condition it's in, no frequency of incidents below which no actions need be taken, nothing. I just find that really odd, that's all.

peter gotch  
#31 Posted : 05 June 2017 13:00:32(UTC)
Rank: Super forum user
peter gotch

Dan

Not sure what geographical area you are referring to as regards road traffic fatalities.

But latest stats to end March - 1780 in Great Britain + 68 in Northern Ireland equates to 35.5 deaths on the roads per week, so does not translate to 140 work related road traffic fatalities per week.

I've never seen an authoritative estimate of how many of these deaths are work-related.

In the past HSE has estimated 10%, RoSPA 25%, Devon and Cornwall Police 40% in their patch.

Partly the lack of clarity has been HSE's consistent position that we should be one of the few developed nations that do not require the reporting of work-related transport accidents (with very limited exceptions).

My guess is that perhaps half of those killed or seriously injured on the roads are work-related. But this would only mean 15-20 work-related road deaths per week. (It would seriously impact on the U.K.'s position on the EU league when looking at accident rates.)

As far back as the 1st Century, Pliny advised villa owners in Cyprus not to take on former quarry slaves as "they tend to die young". Cyprus did not stop quarrying asbestos until 1985.

Xavier123  
#32 Posted : 05 June 2017 13:28:04(UTC)
Rank: Super forum user
Xavier123

Hi Dan

I'm on board with your point and I like the cut of your gib Sir.  Relative risk and subsequent degree of control eschewed/proscribed is inconsistent across h&s hazards - let alone when you move beyond the scope of work related issues into alcohol etc.  I fear you step into the realm of political and social perceptions though - fields that continue to mock and defy rational explanation!

The problem you've got in looking for a good evidenced answer to a complicated and technical question on this forum is that the vast majority are general practitioners.  We'll all have our specialist subjects of which we know more than many others but, by and large for our non-specialist subjects, we'll go with the HSE, HSL and various industry guidance on the basis that the underlying science will have been scrutinised.  Not that we're unthinking drones but these organisations aren't known for their willfull foolishness!  I would have thought that the better people to ask would be ATAC and ARCA - the relevant testing and removal associations.

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nic168 on 08/06/2017(UTC)
DanIsaacs  
#33 Posted : 05 June 2017 15:20:50(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: peter gotch Go to Quoted Post
My guess is that perhaps half of those killed or seriously injured on the roads are work-related. But this would only mean 15-20 work-related road deaths per week.

Yes, should have read 15, a stray zero, unforgivable for a matehmatician, I hope my clients aren't reading this! Point still stands though even at 15.

Originally Posted by: Xavier123 Go to Quoted Post
I would have thought that the better people to ask would be ATAC and ARCA - the relevant testing and removal associations.

Yes, you'd have thought so wouldn't you. I've written to ARCA, HSE, HSL, PHE, the occupational health units at several universities, and the IOM. No response at all from any of them except HSL, who wrote back simply confirming what I had speculated, namely that the average fibre concentration in ACM containing building was indeed 0.0003f/ml and that no, no-one had ever tested the fibre release from small scale domestic exposures, including settled dust nor the effect of household cleaning activities. Did they have any intention of doing anything about this gap in the evidence base? No.

Bruce Sutherland  
#34 Posted : 05 June 2017 15:21:02(UTC)
Rank: Forum user
Bruce Sutherland

Hi Dan

Good thread. Suggest on OP 2 and 3 are most likely. There is an aweful lot of fresh air and then likely to be fixed in soil etc. And yes I think a lot of your RA are probably empirically correct, but ignore human factors and emotions. A good example is the asbestos medical. Probably a complete waste of time and money with regard to detecting disease, but quite useful in relation to fitness to work. But imagine the uproar if asbestos medicals were withdrawn? 

Kind regards

Bruce

DanIsaacs  
#35 Posted : 06 June 2017 06:49:26(UTC)
Rank: Forum user
DanIsaacs

Just another thought on the same topic for anyone interested. Air tests showing that buildings have below 0.0003f/ml regardless of the condition of the ACM are not being taken as indicators that the building is safe, the advice on survey and management is still to remove or encapsulate damaged ACMs regardless of of the cost (i.e. not cost benefit analysis is carried out), or scale (there is no maximum size of material that can reasonably be left untreated. This implies air tests are not being considered as indicators of the safety of the building. Where does that leave the reassurance test which only proves the air is below 0.01f/ml, if proving that the air is below 0.0003f/ml isn't enough?

Basically, how is it being justified to advise building owners to remove damaged ACMs when all the evidence we have would seem to indicate that leaving them in place causes no more than 0.0003f/ml whereas the best that a removal operation can promise is less than 0.01f/ml. Surely for small-scale asbestos these figures present an argument for leaving it in place even if it is damaged and even if it can't be encapsulated? What evidence does anyone have that removing small pieces of damaged asbestos that can't be encapsulated releases fewer airborne fibres than normal occupation activities with it still in place? If no tests have been carried out on small scale domestic interactions with asbestos, and no air tests in buildings with damaged ACMs have shown any elevated levels then there's absolutely no evidence that the removal of such items is actually safer for the public than leaving them where they are.

Xavier123  
#36 Posted : 06 June 2017 07:53:35(UTC)
Rank: Super forum user
Xavier123

I have two additional thoughts/theories for the mix.

1. Asbestosis and related illnesses are currently still on the rise. Political will to make any lessening of control measures would be virtually unthinkable.  Any scientist knows that policy does not necessarily follow the science.

2. Exposure to asbestos fibres has no 'safe' level.  I recall there is a dose response curve but there is no WEL. Yes, fibres levels are demonstrated as being low despite historical damage to ACMs etc. but they ARE still found.  You've either got to declare a WEL (which they haven't got the empirical data to do as far as I know other than through circumstance) or prescribe more demanding controls. 

DanIsaacs  
#37 Posted : 06 June 2017 09:11:26(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Xavier123 Go to Quoted Post

I have two additional thoughts/theories for the mix.

1. Asbestosis and related illnesses are currently still on the rise. Political will to make any lessening of control measures would be virtually unthinkable.  Any scientist knows that policy does not necessarily follow the science.

2. Exposure to asbestos fibres has no 'safe' level.  I recall there is a dose response curve but there is no WEL. Yes, fibres levels are demonstrated as being low despite historical damage to ACMs etc. but they ARE still found.  You've either got to declare a WEL (which they haven't got the empirical data to do as far as I know other than through circumstance) or prescribe more demanding controls. 

1. That's true, but asbestos related diseases at the scale of exposure we're talking about are all cancers and the rate of all cancers is on the rise. In fact the rate of asbestos related cancers is rising slower than the rate of many other cancers so in order to ascertain what this means we must control for whatever factors are causing all cancers to rise (mostly an ageing population). If we do this, we find (depending on the statistical model we use) that rates of asbestos related cancers are falling relatively. Another way of doing it is to look at rates in younger (but still adult) age categories, which again are falling on average. So the continued rise is not so much related to absestos exposure post-regulation, but simply the fact that people are living longer.

Following on from what you said about political will, I came across this poster during my research from BOHS which shows a shoking level of statistical ineptitude. It states "Fact: Asbestos kills around 5000 workers each year", "Fact:Asbestos is still a problem today - it can be present in buildings [constructed] up to the year 2000" and "There is a need for qualified professionals to minimise the risk". Whilst I don't doubt the final conclusion, it just plays directly into the hands of people wishing to play down the threat if they're going to use such blatantly false scaremongering to get their message across. To link the first two facts is appalingly bad science, they are totally unrelated, as we have established in this discussion, there is at present no evidence to prove that any of the 5000 deaths are related to there being asbestos in buildings at the levels currently experienced. If organisations like BOHS want to get people on board with being more aware of the risks from asbestos to people nowadays then they need to be campaining for some research to be done into that risk, which we currently seem to know nothing about, not the one that was present 50 years ago which is completely different from that which we have now. Personally I can't see anyone looking at that poster and not just thinking, well it doesn't apply to me, all those 5000 people were exposed years ago and things are different now.

2. This is true (if, and only if, you accept what's caled a linear no-threshold model for exposure, which even the authors of the model admit is a complete guess with no evidence to back it up), but this is also true of all genotoxic carcinogens, it's to do with the presumed mechanism of carcinogenisis. The issue I have is that someone's got to set a safe level, we can't all wear facemasks permanently because of the ambient level in the air. If the experts don't set a level based on the best data they have and weighed against the cost, then all that's going to happen is people are going to that calculation themselves with what limited and narrow data they happen to have. That's the sort of behaviour that puts people at risk.

Xavier123  
#38 Posted : 06 June 2017 09:32:13(UTC)
Rank: Super forum user
Xavier123

Well, this has moved on from your original post....!

It's a reasonable drum you're beating but one that requires significant understanding of the question marks surrounding the genuine level of risk...which in turn sounds like it requires more directed research that might rail against the current direction of travel for the issue.  I think you've made some really good points about the evidence base here and got people thinking.

With regard your point about people taking more risk because they can't equate the facts you highlight with the legislative requirements, I'm less convinced.  The legislation has been around a substantial time now and is well understood, regardless of opinion concerning its necessity/depth.  In my experience, those who breach it do so through ignorance or recklessness, not out of reasoned calculation concerning relative risk levels. I would wager that the group you're concerned about there is pretty darn small.

DanIsaacs  
#39 Posted : 06 June 2017 10:42:30(UTC)
Rank: Forum user
DanIsaacs

Originally Posted by: Xavier123 Go to Quoted Post

Well, this has moved on from your original post....!

It's a reasonable drum you're beating but one that requires significant understanding of the question marks surrounding the genuine level of risk...which in turn sounds like it requires more directed research that might rail against the current direction of travel for the issue.  I think you've made some really good points about the evidence base here and got people thinking.

With regard your point about people taking more risk because they can't equate the facts you highlight with the legislative requirements, I'm less convinced.  The legislation has been around a substantial time now and is well understood, regardless of opinion concerning its necessity/depth.  In my experience, those who breach it do so through ignorance or recklessness, not out of reasoned calculation concerning relative risk levels. I would wager that the group you're concerned about there is pretty darn small.

Yes we do seem strayed off topic. All I can say is I hope you're right on both counts, but I can't in my experience justify that hope. There seems literally no interest in modelling the risk that we have nowadays from asbestos in buildings and part of my job is communicating risk to people and all that my years of doing so has taught me is that people do no understand risk at all and if you want them to take certain precautions you have to spell it out in detail. With asbestos, the HSE certainly seem to have identified what they think is a problem with people not treating asbestos with appropriate precautions and who hasn't heard that asbestos is dangerous? No-one I should think. That means that all the inappropriate activities the HSE have identified as a problem are being carried out because people are making their own guesses as to how dangerous. Even though I didn't have any involvemnt in the issue at the time, I still remeber the "one fibre can kill you" message (despite the fact that virtually everyone has a million fibres in every gram of lung tissue). People are not automatons and will not simply do as they're told without question. How many people still use machinery without the appropriate protection, or carry weights badly, even cross the road when the lights are still red? And we actually have current indisputable facts to prove these activities are harmful. To try and change people's approach based on some speculative guesswork from exposures in a completely different environmnet 50 years ago is ambitious to say least.

johnmurray  
#40 Posted : 06 June 2017 13:24:19(UTC)
Rank: Super forum user
johnmurray

All I can say is: you need to get out [in industry] more! I'm old enough to remember the posters about benzene plastered on engineering shop walls, people still cleaned their hands in the stuff. WAH regulations can be considered as almost routinely ignored... Only a month ago I had to point-out that the "wet cutting discs" we're actually not wet, and that the school may want to get the workers to think of the children while generating clouds of dust at a building site in the school grounds. Not to mention their lack of interest in the "no hard hat, no job" signs... I could continue in the same vein for a long time....workers prefer an easy life. Some may say a hard death as well. I fail to see what you are getting at, but then you are approaching a known problem from an unknown direction... The decades-long disease development time may make peopke assume they will have expired from other causes before the asbestos gets them....maybe watching someone die from mesothelioma will change their minds? Sadly, for most, watching themselves die will happen first. I was reminded of a published news article of the same name.... http://www.newstatesman....tos-still-killing-people Read and contemplate the lengths that industry has gone to, and is still going to, to get rich over the bodies of its workers....
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