Monday, October 28, 2013

Metro-NY AIHA Meeting on Vermiculite, Part 2.

As we discussed in our previous post we attended the Metro New York (Metro-NY) American Industrial Hygiene Association (AIHA) chapter meeting on September 9, 2013.  This meeting was on the "New York State Asbestos & Vermiculite Analysis Guidance Update" it was presented in two parts, part one by Robert J. DeMalo, Senior Vice President of Lab. Services & Business Development and part two by Edward Cahill, Vice President of Asbesto, both from EMSL Analytical, Inc.  For pictures from the event visit Metro NY AIHA web album and for copies of EMSL's powerpoint presentation visit Metro-NY AIHA Meetings website for the Part 1 Handout and the Part 2 Handout.  Our previous post discussed part one of the presentation.  This post we will discuss part two, which was on the "Analytical Challenges of Vermiculite Containing Materials".

The second part of the presentation was significantly more complicated than the first part.  This does not mean the first part was not valuable, we are trying to indicate the second part really got into some of the details of analyzing the minerals utilizing polarized light microscopes, the quantitation of the samples, and additional methods of analysis including advantages and disadvantages (enough big words for everyone).

The second presentation started with a discussion of the new NYS DOH Guidance letter regarding the analysis of vermiculite containing materials (VCM).  We discussed this issue in our Blog on 7/21/13.  The big issue is the disclaimer being placed on the results and what is the best course of action for results that indicate greater than 10% vermiculite and less than or equal to 1% asbestos with the disclaimer.  

To understand the problems with analysis Mr. Cahill’s presentation showed us that vermiculite comes in three types – large (light), medium, & fine (dark).  See figure below:

As you can see the material is varying levels of “chunkiness”.  According to EMSL, when picking through the sample rice grain sized asbestos chunks can sometimes be detected visually.  However, the absence of these chunks does not mean the sample is asbestos free.  The polarized light microscope (PLM) methodology is strong for identification, while quantification is weak.  The PLM analysis is only as good as the prep (especially for point counting).  The sample must be uniform, random, & a monolayer (the height of a particle size prevents a nice monolayer).   Based on this information the problems regarding vermiculite analysis are:

  • Particle size prohibits making a proper slide mount.
  • Asbestos not always homogeneous within the sample
  • Asbestos can be locked between plates & therefore not easily detected
  • Non-regulated Libby Amphiboles are present.
The discussion then turned to other methods of analysis, noting that monokote fireproofing has removable matrix.  Methods with matrix removal include:

·         EPA (600) PLM NOB
·         EPA (600) TEM NOB
·         NYS ELAP 198.6 (PLM)
·         NYS ELAP 198.4 (TEM)
·         Chatfield SOP (TEM)

At this point, the preferred NYS ELAP method is 198.6, but that means you get the disclaimer on your results.  EMSL’s presentation discussed 4 different approaches of what to do regarding VCM, these approaches are:

  1. Cancel or delay asbestos surveys if possible until final regulations are in place.
  2. If initial analysis determines vermiculite content >10% they are stopping.  The material is treated as ACM.
  3. If 198.1 analysis determines vermiculite content >10% proceed to 198.6 to determine the asbestos percentage.  Materials are classified as ACM or non-ACM accordingly, disclaimer is tolerated.
  4. Approach 2 or 3 are followed for regulatory compliance and then various additional prep and analysis steps are requested.  Transmission Electron Microscopy (TEM) analysis is typically a part of this process to demonstrate “Best Available Technology”.
Options available for Approach 4 are:

  • Cincinnati Method – vermiculite separated into fractions, floating, sinks, & suspended fractions.  Analysis is by a combination PLM/TEM
  • CARB (CA Air Resource Board) 435 Method – Sample is milled, followed by a PLM point count
  • EPA 600 Milling followed by PLM/EPA 600 Milling followed by TEM analysis – Can break out of mass percent with & without the contribution of Libby amphiboles
  • ASTM TEM Qualitative Method – excellent fiber ID but no quantification
  • Addison Davies Method – remove vermiculite prior analysis

We learned a lot in this seminar regarding different methodologies and the problems involved with analyzing vermiculite and VCM.  It will be interesting moving forward to see which direction the analysis of these materials goes.   Based on the presentation, the EPA 600 milling followed by TEM analysis sounds interesting and promising.  However, NYS ELAP or EPA will be making that decision and only time will tell.
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