POLARIZED LIGHT MICROSCOPY

Polarized Light Microscopy (PLM) is the utmost accepted method by the EPA and internationally is the most accepted technique for initial analysis of bulk building materials for asbestos content. By utilizing the polarized light microscope, analysts determine the optical properties of the samples’ fibrous components and provide both the asbestos type and estimated percentages in the sample material. PLM is also employed by methods for soil, vermiculite-containing building materials, and other mineral assemblages (ex. talc in cosmetics).  

POLARIZED LIGHT MICROSCOPY POINT COUNT

Polarized Light Microscopy Point Count determines the type of asbestos present and point counts quantify the percentage of asbestos. This method is primarily used to supplement the original PLM calibrated visual estimate.

POLARIZED LIGHT MICROSCOPY GRAVIMETRIC POINT COUNT

Polarized Light Microscopy Gravimetric Point Count utilizes thermal and acid treatments to create residue that allows the lab to get a percentage of asbestos in the residue based on a point count technique.

Many regulatory recognized PLM standard methods are employed by EBET including USEPA 600 R93/116, USEPA 600 R-04-004, and other jurisdictional required methods (ex. NYSDOH ELAP, ISO22262-2, CARB435, USEPA Region I Asbestos in Soils, Sludges, and Sediments).

TRANSMISSION ELECTRON MICROSCOPY (TEM) “CHATFIELD”

This procedure originated from work published by Dr. Eric Chatfield decades ago, and has adopted by the USEPA 600 R93/116 as Sections 2.3 Gravimetry and 2.5 TEM Analysis. The method includes initial macroscopic and microscopic analysis before proceeding with this technique.  Here the bulk materials are gravimetrically reduced (mass measured at each step) through a series of thermal and acid treatments to create a residue that is examined by TEM.  The morphological, chemical (EDS) and crystal structure (SAED) of the mineral fibers within the residue provide results as a  derivative of the percentage of asbestos in the initial sub-sample. This method is approved by the EPA to confirm low-level concentrations of asbestos in non-friable organically bound and some limited friable bulk building materials.   Other bulk materials such as consumer products (ex. vehicle brake assemblies, gaskets) and cosmetics that are talc-based, require a combination of standard (ex. USP 901 and 1901) and proprietary methods. In some jurisdictions related methods are required such as ELAP 198.4 or sections of ISO22262-2.
 

TRANSMISSION ELECTRON MICROSCOPY AIR AHERA (Asbestos Hazard Emergency Response Act)

This method is primarily utilized for the final clearance of asbestos remediation area in public schools. It was developed and published by the EPA for clearance of air samples in schools. For the results to be effective, specific sample protocol consistent with AHERA must be followed. You can find these details on the EPA website. Other methods include the NIOSH 7402 method, the optional follow-up to PCM testing using NIOSH 7400 which provides qualitative analysis and an optically visible fraction (OVF) that can be applied to the initial PCM fiber concentrations.  The ISO10312 and related ISO13794 methods are mandated by many USEPA related projects. Other airborne methods include ASTM D7201 and ASTM D6281.  EBET can provide customers with information to assist investigators.  

TRANSMISSION ELECTRON MICROSCOPY DUST ANALYSIS

There are primary consensus standards from ASTM and the USEPA that are recognized by regulators and in legal settings. The intent of each method should be understood by investigators and building engineers before implementing sample collection. EBET can provide customers with materials and directions to assist project objectives. The methods include a micro-vacuum sample collection technique limited to surface dust particles that are easily re-entrained into the air, another method where the investigator employs a specific wipe material to collect the surface dust to understand historical deposition of suspect particles, a third method that employs destructive testing on small swatches of woven surface substrate (ex. fabric on furniture, clothes, carpets, etc.) that particles are separated and processed for TEM analysis. Results are reported in concentration of asbestos structures pert unit area of surface collected. The last method employs a statistical comparison of two environments using the methods listed here. There are various accepted method analytical sensitivity limits, ambient level concentrations that have been studied, as well as accepted clearance concentrations dependent on sample location. Methods include ASTM International’s D5755, D8480, D7390, and USEPA J-93/167.

TRANSMISSION ELECTRON MICROSCOPY WATER ANALYSIS

There are primary methods from USEPA 100.1 and 100.2 that are required throughout the US and recognized by most of the international market.  The intent of each method is closely related.  EBET can provide customers with guidance on understanding the methods and sample collection and shipping requirements.  Often sample treatments are required by the methods to prevent biologic and organic interferences (ex. UV and Ozone).  TEM results are given in Million Fibers per Liter (MFL) of asbestos, and depending on the USEPA method version, the concentrations can be delineated by fiber size populations.  

TRANSMISSION ELECTRON MICROSCOPY SOIL ANALYSIS

A host of methods can be utilized for soil that all require initial macroscopic and microscopic screening by PLM.  The intent of each method is not always intuitive.  EBET can provide customers with guidance on understanding the methods and sample collection and shipping requirements.  Often sample treatments and preparation steps vary as required by the methods to help concentrate or separate asbestos from soil matrix interferences.   The ASTM D7521 method employs gross examination screening by PLM (including identifiable bulk building material in soil) and fractional size sieving to assist the investigator in identifying populations including the finest respirable fraction (<100um) by TEM.  The CARB435 method requires PLM analysis of two size fractions after milling and an optional TEM analysis of any negative fine fraction particles.  The USEPA R04-004 method for vermiculite requires a five-tiered process with initial PLM fractions and final TEM of the ‘sinks’ and ‘suspension’ fractions.  The USEPA Region I Method for Asbestos in Soil, Sludge, and Sediment likewise requires mandatory PLM and optional TEM analysis.  

PHASE CONTRAST MICROSCOPY (PCM)

Phase Contrast Microscopy (PCM) is performed on air filter samples that have been collected to monitor asbestos conditions prior to, during, and after asbestos remediation. This includes samples following NIOSH 7400 specifications for OSHA mandated personal monitoring.  THE PCM analyst counts fibers that are present on the filters with fiber density and fiber concentrations available. In additional, optional results can be derived in order to give a time-weighted average of the concentration of those fibers for the volume of air sampled normalized to 8 hours. PCM results are fiber concentrations and do not distinguish between asbestos and non-asbestos fibers by NIOSH 7400. See above TEM NIOSH 7402 method for more information  In some cases the use of B rules for specialized PCM samples where refractory ceramic fibers are suspected are available at select EBET locations.

When Asbestos Containing Material (ACM) is disturbed, asbestos fibers are released into the air, thereby creating a potential health hazard. Air monitoring is an essential component of any asbestos abatement project, and final clearance is determined by air sampling. Eurofins Built Environment Testing analyzes air samples by Transmission Electron Microscopy (TEM) and Phase Contrast Microscopy (PCM).

Although asbestos has traditionally been associated with insulation, Asbestos Containing Material (ACM) has also been used in other construction components, such as wall plaster, floor and ceiling tiles, and roofing materials. Accurate identification of ACMs through sampling of "bulk" materials is critical to building owners, actual or prospective, as well as lenders, contractors, and other concerned parties. Eurofins Built Environment Testing analyzes bulk samples by Transmission Electron Microscopy (TEM) and Polarized Light Microscopy (PLM).

While asbestos can be a natural contaminant from water sources (lakes, rivers, reservoirs) asbestos containing concrete pipe has often been employed to transport drinking water. As these pipes age, asbestos fibers can be released and find their way into drinking water. Disposal of asbestos contaminated wastewater generated in asbestos abatement projects can also be a problem. Eurofins Built Environment Testing analyzes water samples by Transmission Electron Microscopy (TEM) to quantify the level of asbestos contamination. TEM provides detailed information on fiber morphology with elemental composition determined using an energy dispersive Energy Dispersive X-Ray Analysis (EDX) system.