Round table of the SBB for the investigation of tar board waste for carcinogenic fibres on 6.12.2018 in Potsdam, Germany

On Invitation of the SBB Sonderabfallgesellschaft Brandenburg/Berlin mbH a 'Round Table' for the examination of tarboard waste for carcinogenic fibres took place on 6.12. at the house of the SBB in Potsdam.

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Associates had come together

  • the SBB, 
  • the Berliner Senatsverwaltung für Umwelt, Verkehr und Klimaschutz – Abfallbehörde
  • of the German Pollutant Remediation Association (Gesamtverband Schadstoffsanierung e.V.) (GVSS)
  • accredited testing laboratories performing tests on carcinogenic fibres - asbestos and synthetic mineral fibres

From CRB Dr. Gunnar Ries and Dr. Stefan Pierdzig took part in the meeting.

Goal of the meeting ...

... was information from the SBB on the background of the measures initiated as well as discussion and harmonisation of the methods for sampling and analysis of potentially contaminated tar board waste on the part of the laboratories.

was information from the SBB on the background of the measures initiated.

Background of the current 'roofing felt problem' ...

... is the fact that disposal companies, such as cement manufacturers, who use roofing felt in their rotary kilns as secondary fuels, understandably want to ensure that no asbestos is introduced into their products.
Therefore, the 0.1% limit of the GefStoffV is not an evaluation criterion for roofing felt with regard to carcinogenic fibres.


The participants agreed that sampling is the decisive factor in the entire process of assessing roofing felt with regard to its potential risk. Many roof coverings show a vertical, multi-layered structure and also show inhomogeneities in horizontal expansion, such as repair spots or wedges at the edges.  

The goal must be an in-situ sampling according to guidelines VDI/GVSS 6202 sheet 1 / LAGA PN 98 to avoid complex 'mixed samples' which are difficult or impossible to homogenize and analyze.
It was also pointed out that, in addition to the analysis report, a well-documented sampling protocol is required for the acceptance of roofing felt waste at the landfills.


From analytical view it was agreed on the pure qualitative investigation of the roofing felt after homogenization, ashing, suspension and filtration by means of a method with a detection sensitivity clearly smaller than 0.1 mass %.

This is according to the current state of standardization Annex B of VDI Guideline 3866, Sheet 5:2017-06, even if some laboratories have expressed concerns regarding the visibility of thin fibers at 1000x magnification and the high density of the filter preparations under the standard conditions of Annex B.

A quantitative examination according to BIA method 7487 is not necessary and in the opinion of a few (not all!) participants of the meeting can lead to false results, because at high magnifications of 2000x only a small area of the filter preparation is detected.

According to the findings of some laboratories, the acid treatment of the samples required by Annex B poses a problem, as thin, respirable artificial mineral fibres can be dissolved. An acid treatment of incinerated roofing felt should therefore only be carried out for a short time or not at all.

References of the CRB for the investigation of roofing felt and roofing felt waste

Roofing felt can have high asbestos and/or mineral fibre concentrations, sometimes in the 2-digit mass % range. For reasons of occupational safety during sample preparation in the laboratory, CRB Analyse Service GmbH investigates roofing felt and roofing felt waste as follows:

  • Preliminary investigation of the material after hot ashing at 450° as a litter preparation according to guideline VDI 3866, sheet 5:2017-06 with a detection sensitivity of 0.1 mass % asbestos/AMF - CRB-order no. 111
    If the result is positive, the examination is completed according to a cost-effective procedure, as asbestos has been detected.

  • Only in case of a negative result a follow-up examination according to VDI 3866, sheet 5:2017-06, Annex B with a detection sensitivity of 0.001 mass-% Asbestos/AMF - CRB-Best is performed Translated with www.DeepL.com/Translator