Here are internal notes produced by our asbestos team leader after discussion with our technical assessor during our recent UKAS annual accreditation visit and extension to scope.
"Concerning the EA guidance awaiting release, we believe this may take some time. After discussion with a member from HSL who has been directly involved with this work, we have been informed that the EA team working on this no longer exists.
As for the limit of detection of asbestos analysis; all identification should be in accordance with the method detailed in HSG248 (ANALYST GUIDE 2005)free download available from www.hse.gov.uk"
Also attached is a portion of UKAS asbestos technical bulletin issue 1 covering the legalities involved in providing results and required accreditation.
"As the term of a visual inspection giving a LOD of 0.1% is more than a little concerning, standard soil analysis should give a LOD of 0.001%. It is also possible to quantify asbestos to this level. For a risk based result: the potential respirable fibre content of a sample should be quantified."
Potentially respirable fibres are those fibres present within the sample which, if they became airborne, would be respirable, i.e. a fibre which, due to its shape and size is capable of penetrating the deepest parts of the lung, and therefore cause asbestos-related diseases. More specifically, a respirable fibre is defined by the HSE in HSG248 (The Analysts Guide) as a fibre which is >5um long, narrower than 3um, and has a 3:1 or greater length: width ratio.
Over time larger clumps of asbestos or asbestos containing materials will breakdown to the point where they become respirable, increasing the risk presented by the site, without increasing the mass of asbestos present.
Very low levels of asbestos (below 0.001% by mass) may still contain fine asbestos fibres, and therefore still present a risk to health. In fact, the detection of only one fibre, which translates as a mass % asbestos of as low as 0.00001%, can contain approximately 40000 potentially respirable fibres per gram of sample.
Thus, for site risk assessment the potential respirable fibre content per gram of soil analysed provides a more direct assessment of risk than quantification of asbestos by mass alone.
Regards
Mike Hopgood
Technical Manager
Derwentside Environmental Testing Services
Unit 2
Park Road Ind Est
Consett
Co Durham
DH8 5PY
Tel: 01207 582333
Fax: 01207 582444
Email: [log in to unmask]
Website: www.dets.co.uk
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-----Original Message-----
From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Aamer Raza
Sent: 19 July 2010 12:49
To: [log in to unmask]
Subject: Re: Asbestos in Soil
Hello Andy,
I've done a reasonable amount of work in this area. In our case, we had to assess a situation where a building with known ACM in the fabric was demolished, crushed, and used as fill. The risk with asbestos exposure is primarily related to inhalation, as we know, (though oral exposure may also have deleterious effects, this is minimal compared with inhalation). As such, the basic risk assessment approach that we followed was that of Berman and Crump (protocol attached). In this approach, it is critical to speciate the asbestos fibres, and quantify the asbestos content in fibres/g soil, rather than % volume. This data is then applied to models and calculations of soil entrainment in air, and an air exposure point concentration derived. The attached data also reviews dose response data for asbestos inhalation exposure, which can then be used to assess inhalation risk.
Relative to this methodology, I would advise that the sampling and measurement process, for processing the field samples, and the TEM identification for specific fibres, is not trivial, and requires considerable expertise, and accurate sample processing in the field and the laboratory, well trained technicians, and experienced risk assessors. As such, this level of examination, in my view should be reserved for sites where there is a known and substantial problem with asbestos in soil, such as asbestos mining wastes, or significant discharge from known industrial operations. This type of approach, for example was used for risk assessment at the Libby Superfund site.
We had good success with the methods - however, it was not cheap, and we were aided by the fact that Wayne Berman, the co-author of the protocol, was on-board as a direct consultant to our team.
Hope this is of interest - somewhat of diversion from your direct question - but hopefully of interest.
Best Regards
Aamer
Aamer Raza
Associate Director
Harrison Group Environmental
Kimberley Street,
Norwich, Norfolk, NR2 2RJ
Phone: 01603-613-111
Email [log in to unmask]
-----Original Message-----
From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Russell Corbyn
Sent: 19 July 2010 11:29
To: [log in to unmask]
Subject: Re: Asbestos in Soil
Morning
What from of asbestos are we discussing here?
Some are much more hazardous than others, such as Amosite or Crocidolite.
Regards
Russell
-----Original Message-----
From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Andy O'Dea
Sent: 19 July 2010 11:26
To: [log in to unmask]
Subject: Asbestos in Soil
Morning All
There have been several postings in the past on this forum about acceptable levels of asbestos in topsoil. These range from 0.001% (ICRCL quoted value) to 0.01% (cut-off for haz waste classification for carcinogenic material). In our experience, as there is no definitive guidance on the issue, we find that early and hopefully , pragmatic discussions with CLOs is often the best way forward.
My question; is anyone aware of any new, definitive, updated guidance on this issue. I know that an asbestos SGV was muted some time back.
Regards
Andy O'Dea
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