How is the deadly asbestos disposed of?

Assessing possible asbestos contamination of an apartment

• QUESTION: Thanks for offering this service. My wife (who is pregnant) and I live on the upper floor of an old house. The basement below, where the laundry is located and where we have been storing our bikes, a/c, books in boxes, seasonal clothes in plastic bins, etc. for some three years, was recently determined to have asbestos problems. The asbestos inspector I retained characterized the problem as "moderate", and noted relatively small areas of damaged pipe insulation and cracking/ disturbance of the material covering the boiler. There was also some pieces of presumed asbestos debris present under one or two areas of pipe and around the boiler (where it was obvious prior repairs/patching had occurred). The inspector assumed all of this material was asbestos based on his experience. My concern is that we have been bringing things up and down from our basement storage space into our apartment for awhile now (but mostly in the last year, when we put more things down there due to a space crunch upstairs). I just had someone come out to do microvacuum sampling in the basement around where our items are stored (not directly where the crumbling asbestos was visible) to see if we can safely get them out. I asked what analysis method the lab would use, and he replied that it was PLM. I had done a bit of reading about this beforehand, and thought that TEM was the standard for "asbestos in settled dust" testing (With an ASTM-approved analysis methodology behind it), while PLM was not nearly as sensitive. When I asked him, however, he replied that PLM was plenty sensitive for the type of asbestos we would expect to see in pipe insulation and boiler coverings, adding that TEM was mostly used to very small asbestos particles such as would likely be found in flooring tile or vermiculite insulation. So I have two questions: 1) Is PLM analysis of basement dust on out stored things accurate enough to give a sense of whether it is safe to remove them from there? 2) I also worry about having contaminated the upstairs living areas by moving things from storage--I was going to ask him to take a couple microvacuum samples in our apartment, but was not convinced that this would be worthwhile if PLM was not sensitive enough. Should I consider contacting someone else to perform dust sampling upstairs using TEM analayis according to ASTM protocols? If so, is there any benefit to microvacuuming versus wipe-sampling? Thanks for your time--I'm just trying to put my mind at ease after discovering the problem int he basement. ANSWER: TEM analysis of micro-vac samples is the standard practice in the asbestos consulting profession. This has a lot to do with a "best-practices" approach regarding the superior analytical capabilities of TEM, and also the fact that the ASTM protcol specifies TEM as the analytical method. If your consultant proposes using PLM, what method is he going to follow? How is he going to prep the sample? Better yet, how is he going to interpret the data? TEM and PLM report in completely different units of measure. You can't compare the 2, it's apples to oranges. For sample collection, a plastic cassette with a filter inside is used to vacuum surfaces and collect dust onto that filter. At the lab, the sample is prepped by a series of very complex and specific requirements unique to preparing it for TEM analysis. A "simplification" of this process is as follows: The filter with the dust is wetted with a water and alcohol mixture to suspend the dust particles in solution. This solution shaken and sonicated to achieve uniform distribution of asbestos fibers in the liquid. This liquid is then drawn across another filter so you now have an even deposit of particles at theoretically similar concentrations on the filter. This filter is then prepared for TEM analysis by mounting it on a wire mesh grid, which have a precise area between grid openings (think of it as a section of wire screen). This screen is then placed in a plasma asher to burn away interfering organic junk in the dust and what is left is the asbetos fibers suspended on this metal screen, which is then coated in carbon and then inserted into the TEM scope under 15,000 to 20,000x magnification. The analyst then views the contents of each grid square on the filter mesh, which is an INCREDIBLY small surface area (about 75 to 100 micrometers diameter for each square grid). At least 4 of these grids are analyzed per sample, and then there are HUGE statistical extrapolations that are made to correlate the concentration of asbestos fibers over this VERY small analyzed area, to the theoretical number of fibers there would be over the entire vacuumed surface. This is necessary since the microscope is looking at such as small area (due to very high magnification). It would take years to read an entire filter going micrometer by micrometer... so this extrapolation is necessary. Along with it though, comes some uncertaintly, which is why the minimum limit of detection for the method is so high (seemingly poor)... 1,000 asbestos structures per square centimeter. Sounds scary to say, you have 1,000 asbestos fibers per square centimeter on your floor in your house... but this is the MINIMUM analytical sensitivity of the method! Ok, so I'm getting very technical, but with a point. The ASTM method has a lot of peer-reviewed science behind it. There is a precise method to to analysis, and the reliability of the data extrapolated by it relies heavily on the procedures followed. Now lets take a look at PLM for comparison. There are few ways to do this by PLM. 1). Shake the dust out of the cassette, apply dispersion oil, and look at it optically at several hundred times magnification. You may see asbestos fibers, or you may not because of all the interfering junk that was also vacuumed up. There is no ashing procedure like in TEM to burn off this interfering junk. Let's say the analyst see asbestos fibers... now what? How are results reported? Typically, in asbestos bulk samples, a visual estimation of % asbestos in the sample is made by the analyst. So your result would be X% asbestos. Great. Now what do we compare this standard to? There is really nothing out there to compare it to. All of the referenced guidelines for data interpretation are presented in S/mm2 which is the manner in which TEM results are reported. Another way to analyze these samples is to then take a section of clear scotch tape, and press it onto the collected surface dust. Mount this tape onto a microscope slide, and look for asbestos fibers. Once again, reporting format is a problem. This is typically reported as simply positive/negative for asbestos content. Not a whole lot to be learned from this since there is no assessment as to the degree of contamination. Hopefully by now you can understand why TEM is the better choice. Although more expensive, it's really the only RIGHT way to do it. I have worked for consulting companies that advocated the surface dust tape-lift / PLM approach before... and I just hate it. I think the data is garbage in my opinion. Stick with a recognized acceptable method - go with ASTM D5755 and use TEM. Now, don't be surprised when your TEM microvac data comes back with seemingly scary high levels. There is a LOT of reading out there about interpreting TEM micro-vac sample results - there is a lot of controvesy on how to interpret the results and decide what is acceptable, and what is not. One set of guidelines I have seen used often in the industry are <1,000 S/mm2 (ie the limit of detection) means you are ok... concentrations are "low". Anything above 10,000 S/mm2 is considered above "background" - what you may find in normal surface dust in a urban home. Anything above 100,000 S/mm2 is a good indication of contamination and should be cleaned up with abatement methods such as HEPA-vacuuming and wet-wiping. I have used 10,000 S/mm2 as a clearance criteria for cleanup projects before where surface contamination was a concern. If I were called in on this project, I would take a couple TEM microvac samples in the basement and upstairs. If the results were all <10,000 S/mm2, then I would say just make the pipe repairs and do one round of wet-wiping beneath the areas where the insulation was deteriorated and be done with it. If I found concentrations greater than 10,000 S/mm2 in some areas, then I would include wet wiping and HEPA-vacuuming of these areas, including contents. You could follow up with another round of "clearance" TEM microvacs if you want peace of mind, but a good cleaning should really take care of things just fine. ---------- FOLLOW-UP ---------- QUESTION: Thanks so much for the quick and detailed reply. How would you suggest going about finding someone qualified to do the TEM testing according to ASTM D5755? I've called numerous local "experts" and none of them seem to do it in my area. Is there some professional organization I could contact?

• Answer:

  Any knowledgable asbestos consultant should be able to COLLECT the sample. Make sure you are clear with them that you just want them to collect the TEM microvac and ship it out for analysis. Using the ASTMD-5755 reference may throw them off. Just call it "TEM surface microvac" and they should know what you are talking about. If they don't, run away. The procedure itself is very easy. Use a 25mm MCE 0.8um pore size filter cassette (standard TEM cassette). Attach a short length (1") of tygon tubing to the base of the cassette, and cut the other end of the tygon at a 45 degree angle to use as a suction nozzle. Connect the top side of the cassette to a vacuum pump at 2 liter of air per minute (2 LPM). Measure out a surface area of 100 cm2 and vacuum surface dust up onto the filter until there is no visible dust or particulates remaining on the measured area. Perform a minimum of two orthogonal passess on the surface within a minimum of 2 minutes of sampling time. At the end of sampling, invert the cassette so that nozzle inlet faces up before shutting off the power to the pump. Then plug the cassette with the end-plug. Ship it off to a lab indicating the suface area that was vacuumed. www.emsl.com is a good "cheap" lab I use often for this. Also statanalysis.com is good. Some good places to look for qualified people in your area are: http://abih.org/members/roster/rostersearch.cfm The CIH credential is hard to earn, shows you really know your stuff. Not specific to asbestos though, so make sure you find a CIH who has asbestos experience. CIH rates can be pricey, but quality is high. Here is a list of accredited labs with TEM scopes that should be able to handle the analysis: http://ts.nist.gov/standards/scopes/temtm.htm Also, some states maintain a roster of individuals within the state that re licensed to conduct asbestos sampling/testing/consulting services. If you tell me what state/area you live in I could show you where to find that information too. Another good way to go about it may be to call one of the labs listed in your area, and ask for a consultant/inspector referral. They should know who in the area turns in TEM microvac samples to them for analysis.