As a result of an instruction from UKAS published last April as UKASATB001 the testing of soils for asbestos has become the most regulated testing that laboratories provide to the contaminated land sector. All asbestos reports must be accredited and laboratories have invested significantly in training and the validation of soil methods.
A number of techniques are employed to generate both qualitative and quantitative data for reporting which have with them associated terminology, references and abbreviations that need to be appreciated. Of note is that although quantification of asbestos in Asbestos Containing Materials (ACM) is no longer permissible, in soils it is required for hazardous waste on human health risk assessment. As with many procedures the terms used may be laboratory or client specific so an overview is presented here.
ASBESTOS CONTAINING MATERIALS SCREEN IN SOILS Sample Preparation Technicians are trained to be vigilant for the presence of Asbestos Containing Materials (ACM), e.g. Asbestos Insulation Board (AIB) or other asbestos containing construction materials, in all soil samples arriving at the laboratory. This is in order to prevent fibre release from asbestos in samples being dried and ground in preparation for other tests.
If suspected ACM is found at this stage, or where a client’s initial study indicated the possibility of ACM on a site and asbestos screening was requested, visual assessment of the entire sample is conducted by a trained Technician using the soil screen for ACM method. Any probable ACM is removed from the sample for further investigation and the client is contacted with the following options as to how to proceed with their sample/s: 1. Leave the report showing the initial findings 2. Report ACM as Suspected or Not Found 3. Report Suspected or Not Found and conduct a bulk asbestos identification on the suspected ACM
Any other analysis originally scheduled continues, where possible, on an as received (wet) sample basis. Please note that a sample as received may be reported as Not Suitable for some tests, while for other tests proceeding on an as received basis may be beyond the scope of the appropriate accreditation and results will therefore appear on the report as non-accredited.
This method may also be employed when a soil asbestos screen is scheduled and then the whole sample is examined and not just the material that is trayed out for drying. When this data is reported the test must be accredited.
ASBESTOS FIBRE IN SOILS This method isolates and identifies asbestos fibres in the soil matrix, rather than distinct pieces of ACM. A representative sub-sample is obtained from a soil sample which must be between 200g and 1kg, by coning and quartering. Any fibres found are removed and mounted for Polarised Light Microscopy (PLM) according to the guidance in HSG248 Asbestos: The analysts guide for sampling, analysis and clearance procedures, HSE, 2005.
No limit of detection can be associated with this qualitative method, although by the detection of individual fibres it will be more sensitive than the method above.
ENVIRONMENT INDUSTRY MAGAZINE |81|
A NEW PERSPECTIVE ON ASBESTOS
By Phil Hellier, Project Director, CHEMTEST.
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