ASBESTOS (bulk) by PLM various
MW: various
METHOD: 9002, Issue 2
CAS: 1332-21-4
EVALUATION: PARTIAL
EPA Standard (Bulk): 1%
9002 RTECS: C16475000 Issue 1: 15 May 1989 Issue 2: 15 August 1994
PROPERTIES: solid, fibrous, crystalline, anisotropic
SYNONYMS [CAS #]: actinolite [77536-66-4], or ferroactinolite [15669-07-5]; amosite [12172-73-5]; anthophyllite [77536-67-5]; chrysotile [12001-29-5]; serpentine [18786-24-8]; crocidolite [12001-28-4]; tremolite [77536-68-6]; amphibole.
SAMPLING
MEASUREMENT
BULK SAMPLE:
1 to 10 grams
TECHNIQUE:
MICROSCOPY, STEREO AND POLARIZED LIGHT, WITH DISPERSION STAINING
SHIPMENT:
seal securely to prevent escape of asbestos
ANALYTE:
actinolite asbestos, amosite, anthophyllite asbestos, chrysotile, crocidolite, tremolite asbestos
EQUIPMENT:
microscope, polarized light; 100-400X dispersion staining objective, stereo microscope: 10-45X
RANGE:
1% to 100% asbestos
ESTIMATED LOD:
<1% asbestos [1]
PRECISION:
not determined
SAMPLE STABILITY:
stable
BLANKS:
none required
ACCURACY RANGE STUDIED:
<1% to 100% asbestos
BIAS:
not determined
PRECISION:
not determined
ACCURACY:
not determined
APPLICABILITY: this method is useful for the qualitative identification of asbestos and the semi-quantitative determination of asbestos content of bulk samples. The method measures percent asbestos as perceived by the analyst in comparison to standard area projections, photos, and drawings, or trained experience. The method is not applicable to samples containing large amounts of fine fibers below the resolution of the light microscope
INTERFERENCES: Other fibers with optical properties similar to the asbestos minerals may give positive interferences. Optical properties of asbestos may be obscured by coating on the fibers. Fibers finer than the resolving power of the microscope (ca. 0.3 µm) will not be detected. Heat and acid treatment may alter the index of refraction of asbestos and change its color.
OTHER METHODS: This method (originally designated as method 7403) is designed for use with NIOSH Methods 7400 (phase contrast microscopy) and 7402 (electron microscopy/EDS). The method is similar to the EPA bulk asbestos method [1].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 2 of 9 REAGENTS:
EQUIPMENT:
1. Refractive index (RI) liquids for Dispersion Staining: high-dispersion (HD) series, 1.550, 1.605, 1.620. 2. Refractive index liquids: 1.670, 1.680, and 1.700. 3. Asbestos reference samples such as SRM
- 1866, available from the National Institute of
Standards and Technology.* 4. Distilled Water (optional). 5. Concentrated HCl: ACS reagent grade.
1. Sample containers: screw-top plastic vials of 10- to 50-mL capacity. 2. Microscope, polarized light, with polarizer, analyzer, port for retardation plate, 360E graduated rotating stage, substage condenser with iris, lamp, lamp iris, and: a. Objective lenses: 10X, 20X, and 40X or near equivalent. b. Ocular lense: 10X minimum. c. Eyepiece reticle: crosshair. d. Dispersion staining objective lens or equivalent. e. Compensator plate: ca. 550 nm± 20 nm, retardation: "first order red" compensator. 3. Microscope slides: 75 mm x 25 mm. 4. Cover slips. 5. Ventilated hood or negative-pressure glove box. 6. Mortar and pestle: agate or porcelain. 7. Stereomicroscope, ca. 10 to 45X. 8. Light source: incandescent or fluorescent. 9. Tweezers, dissecting needles, spatulas, probes, and scalpels. 10. Glassine paper or clean glass plate. 11. Low-speed hand drill with coarse burr bit (optional).
- See SPECIAL PRECAUTIONS
SPECIAL PRECAUTIONS: Asbestos, a human carcinogen, should be handled only in an exhaust hood (equipped with a HEPA filter) [2]. Precautions should be taken when collecting unknown samples, which may be asbestos, to preclude exposure to the person collecting the sample and minimize the disruption to the parent material [3]. Disposal of asbestos-containing materials should follow EPA Guidelines [4].
SAMPLING: 1. Place 1 to 10 g of the material to be analyzed in a sample container. NOTE: For large samples (i.e., whole ceiling tiles) that are fairly homogenous, a representative small portion should be submitted for analysis. Sample size should be adjusted to ensure that it is representative of the parent material. 2. Make sure that sample containers are taped so they will not open in transit. 3. Ship the samples in a rigid container with sufficient packing material to prevent damage or sample loss. SAMPLE PREPARATION: 4. Visually examine samples in the container and with a low-magnification stereomicroscope in a hood. (If necessary, a sample may be carefully removed from the container and placed on glassine transfer paper or clean glass plate for examination). Break off a portion of the sample and examine the edges for emergent fibers. Note the homogeneity of the sample. Some hard tiles can be broken, and the edges examined for emergent fibers. If fibers are found, make an estimate of the amount and type of fibers present, confirm fiber type (step 14) and quantify (step 15). 5. In a hood, open sample container and with tweezers remove small, representative portions of the sample. 1. If there are obvious separable layers, sample and analyze each layer separately. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 3 of 9 b.
If the sample appears to be slightly inhomogeneous, mix it in the sample container with tweezers or a spatula before taking the portion of analysis. Alternatively, take small representative portions of each type of material and place on a glass slide. c. On hard tiles that may have thin, inseparable layers, use a scalpel to cut through all the layers for a representative sample. Then cut it into smaller pieces after placing RI liquid on it before trying to reduce the thickness. Alternatively, use a low-speed hand drill equipped with a burr bit to remove material from hard tiles. Avoid excessive heating of the sample which may alter the optical properties of the material. NOTE: This type of sample often requires ashing or other specialized preparation, and may require transmission electron microscopy for detection of the short asbestos fibers which are characteristic of floor tiles. d. If the sample has large, hard particles, grind it in a mortar. Do not grind so fine that fiber characteristics are destroyed. e. If necessary, treat a portion of the sample in a hood with an appropriate solvent to remove binders, tars, and other interfering materials which may be present in the sample. Make corrections for the non-asbestos material removed by this process. NOTE: Other methods of sample preparation such as acid washing and sodium metaphosphate treatment and ashing may be necessary, especially to detect low concentrations of asbestos. If needed, use as described in Reference [1]. 6. After placing a few drops of RI liquid on the slide, put a small portion of sample in the liquid. Tease apart with a needle or smash small clumps with the flat end of a spatula or probe, producing a uniform thickness or particles so that better estimates of projected area percentages can be made. Mix the fibers and particles on the slide so that they are as homogeneous as possible. NOTE: An even dispersion of sample should cover the entire area under the cover slip. some practice will be necessary to judge the right amount of material to place on the slide. Too little sample may not give sufficient information and too much sample cannot be easily analyzed.
CALIBRATION AND QUALITY CONTROL: 7. Check for contamination each day of operation. Wipe microscope slides and cover slips with lens paper before using. Check refractive index liquids. Record results in a separate logbook. 8. Verify the refractive indices of the refractive index liquids used once per week of operation. Record these checks in a separate logbook. 9. Follow the manufacturer's instructions for illumination, condenser alignment and other microscope adjustments. Perform these adjustments prior to each sample set. 10. Determine percent of each identified asbestos species by comparison to standard projections (Figure 1) [1]. If no fibers are detected in a homogeneous sample, examine at least two additional preparations before concluding that no asbestos is present. 11. If it appears that the preparation technique might not be able to produce a homogeneous or representative sample on the slide, prepare a duplicate slide and average the results. Occasionally, when the duplicate results vary greatly, it will be necessary to prepare additional replicate slides and average all the replicate results. Prepare duplicate slides of at least 10% of the samples analyzed. Average the results for reporting. 12. Analyze about 5% blind samples of known asbestos content. 13. Laboratories performing this analytical method should participate in the National Voluntary Laboratory Accreditation Program [5] or a similar interlaboratory quality control program. Each analyst should have complete formal training in polarized light microscopy and its application to crystalline materials. In lieu of formal training, laboratory training in asbestos bulk analysis under the direction of a trained asbestos bulk analyst may be substituted. Owing to the subjective nature of the method, frequent practice is essential in order to remain proficient in estimating projected area percentages.
QUALITATIVE ASSESSMENT: 14. Scan the slide to identify any asbestos minerals using the optical properties of morphology, NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 4 of 9 refractive indices, color, pleochroism, birefringence, extinction characteristics, sign of elongation, and dispersion staining characteristics. NOTE: Identification of asbestos using polarized light microscopy is unlike most other analytical methods. The quality of the results is dependent on the skill and judgment of the analyst. This method does not lend itself easily to a step-wise approach. Various procedures devised by different analysts may yield equivalent results. The following step-wise procedure repeatedly utilizes the sample preparation procedure previously outlined. a. Prepare a slide using 1.550 HD RI liquid. Adjust the polarizing filter such that the polars are partially crossed, with ca. 15E offset. Scan the preparation, examining the morphology for the presence of fibers. If no fibers are found, scan the additional preparations. If no fibers are found in any of the preparations, report that the sample does not contain asbestos, and stop the analysis at this point. b. If fibers are found, adjust the polarizing filter such that the polars are fully crossed. If all of the fibers are isotropic (disappear at all angles of rotation) then those fibers are not asbestos. Fibrous glass and mineral wool, which are common components of suspect samples, are isotropic. If only isotropic fibers are found in the additional preparations, report no asbestos fibers detected, and stop the analysis. c. If anisotropic fibers are found, rotate the stage to determine the angle of extinction. Except for tremolite-actinolite asbestos which has oblique extinction at 10-20E, the other forms of asbestos exhibit parallel extinction (Table 1). Tremolite may show both parallel and oblique extinction. d. Insert the first order red compensator plate in the microscope and determine the sign of elongation. All forms of asbestos have a positive sign of elongation except for crocidolite. If the sign of elongation observed is negative, go to step "g." NOTE: To determine the direction of the sign of elongation on a particular microscope configuration, examine a known chrysotile sample and note the direction (NE-SW or NW-SE) of the blue coloration. Chrysotile has a positive sign of elongation. e. Remove the first-order red compensator and uncross the polarizer. Examine under plane polarized light for blue and gold-brown Becke colors at the fiber-oil interface (i.e., index of refraction match). Becke colors are not always evident. Examine fiber morphology for twisted, wavy bundles of fibers which are characteristic of chrysotile. Twisted, ribbon-like morphology with cellular internal features may indicate cellulose fibers. It may be necessary to cross the polars partially in order to see the fibers if the index of refraction is an exact match at 1.550. If the fibers appear to have higher index of refraction, go to step "h," otherwise continue. f. Identification of chrysotile. Insert the dispersion staining objective. Observation of dispersion staining colors of blue and blue-magenta confirms chrysotile. Cellulose, which is a common interfering fiber at the 1.550 index of refraction, will not exhibit these dispersion staining colors. If chrysotile is found, go to step 15 for quantitative estimation. g. Identification of crocidolite. Prepare a slide in 1.700 RI liquid. Examine under plane-polarized light (uncrossed polars); check for morphology of crocidolite. Fibers will be straight, with rigid appearance, and may appear blue or purple-blue. Crocidolite is pleochroic, i.e., it will appear to change its color (blue or gray) as it is rotated through plane polarized light. Insert the dispersion staining objective. The central stop dispersion staining color are red magenta and blue magenta, however, these colors are sometimes difficult to impossible to see because of the opacity of the dark blue fibers. If observations above indicate crocidolite, go to step 15 for quantitative estimation. h. Identification of amosite. Prepare a slide in 1.680 RI liquid. Observed the fiber morphology for amosite characteristics: straight fibers and fiber bundles with broom-like or splayed ends. If the morphology matches amosite, examine the fibers using the dispersion staining objective. Blue and pale blue colors indicate the cummingtonite form of amosite, and gold and blue colors indicate the grunerite form of amosite. If amosite is confirmed by this test, go to step 15 for quantitative estimation, otherwise continue.
i.
Identification of anthophyllite-tremolite-actinolite. Prepare a slide in 1.605 HD RI liquid. Examine morphology for comparison to anthophyllite-tremolite-actinolite asbestos. The refractive indices for these forms of asbestos vary naturally within the species. Anthophyllite can be distinguished from actinolite and tremolite by its nearly parallel extinction. Actinolite has a light to dark green color under plane-polarized light and exhibits some pleochroism. For all NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 5 of 9
j.
three, fibers will be straight, single fibers possibly with some larger composite fibers. Cleavage fragments may also be present. Examine using the central stop dispersion staining objective. Anthophyllite will exhibit central stop colors of blue and gold/gold-magenta; tremolite will exhibit pale blue and yellow; and actinolite will exhibit magenta and golden-yellow colors. NOTE: In this refractive index range, wollastonite is a common interfering mineral with similar morphology including the presence of cleavage fragments. It has both positive and negative sign of elongation, parallel extinction, and central stop dispersion staining colors of pale yellow and pale yellow to magenta. If further confirmation of wollastonite versus anthophyllite is needed, go to step "j". If any of the above forms of asbestos were confirmed above, go to step 15 for quantitative estimation. If none of the tests above confirmed asbestos fibers, examine the additional preparations and if the same result occurs, report the absence of asbestos in this sample. Wash a small portion of the sample in a drop of concentrated hydrochloric acid on a slide. Place the slide, with cover slip in place, on a warm hot plate until dry. By capillary action, place 1.620 RI liquid under the cover clip and examine the slide. Wollastonite fibers will have a "cross-hatched" appearance across the length of the fibers and will not show central stop dispersion colors. Anthophyllite and tremolite will still show their original dispersion colors. NOTE: There are alternative analysis procedures to the step-wise approach outlined above which will yield equivalent results. Some of these alternatives are: i. Perform the initial scan for the presence of asbestos using crossed polars as well as the first-order red compensator. This allows for simultaneous viewing of birefringent and amorphous materials as well as determine their sign of elongation. Some fibers which are covered with mortar may best be observed using this configuration. ii. Some analysts prefer to mount their first preparation in a RI liquid different than any asbestos materials and conduct their initial examination under plane-polarized light. iii. If alternative RI liquids are used from those specified, dispersion staining colors observed will also change. Refer to an appropriate reference for the specific colors associated with asbestos in the RI liquids actually used.
QUANTITATIVE ASSESSMENT: 15. Estimate the content of the asbestos type present in the sample using the 1.550 RI preparation. Express the estimate as an area percent of all material present, taking into account the loading and distribution of all sample material on the slide. Use Figure 1 as an aid in arriving at your estimate. If additional unidentified fibers are present in the sample, continue with the qualitative measurement (step 14). NOTE: Point-counting techniques to determine percentages of the asbestos minerals are not generally recommended. The point-counting method only produces accurate quantitative data when the material on the slide is homogeneous and has a uniform thickness, which is difficult to obtain [6]. The point-counting technique is, recommended by the EPA to determine the amount of asbestos in bulk [1]; however, in the more recent Asbestos Hazard Emergency Response Act (AHERA) regulations, asbestos quantification may be performed by a point-counting or equivalent estimation method [7]. 16. Make a quantitative estimate of the asbestos content of the sample from the appropriate combination of the estimates from both the gross and microscopic examinations. If asbestos fibers are identified, report the material as "asbestos-containing". Asbestos content should be reported as a range of percent content. The range reported should be indicative of the analyst's precision in estimating asbestos content. For greater quantities use Figure 1 in arriving at your estimate.
EVALUATION OF METHOD: The method is compiled from standard techniques used in mineralogy [8-13], and from standard laboratory procedures for bulk asbestos analysis which have been utilized for several years. These NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 6 of 9 techniques have been successfully applied to the analysis of EPA Bulk Sample Analysis Quality Assurance Program samples since 1982 [1,5]. However, no formal evaluation of this method, as written, has been performed.
REFERENCES: [1] Perkins, R.L. and B.W. Harvey, U.S. Environmental Protection Agency. Test Method for the Determination of Asbestos in Bulk Building Materials. EPA/600/R-93/116 (June. 1993). [2] Criteria for a Recommended Standard...Occupational Exposure to Asbestos (Revised), U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-169 (1976), AS AMENDED IN NIOSH Statement at OSHA Public Hearing, (June 21, 1984). [3] Jankovic, J.T. Asbestos Bulk Sampling Procedure, Amer. Ind. Hyg. Assoc. J., B-8 to B-10, (February, 1985). [4] U.S. Environmental Protection Agency, "Asbestos Waste Management Guidance" EPA/530-SW-85007, (May, 1985). [5] National Voluntary Laboratory Accreditation Program, National Institute of Standards and Technology, Bldg 101, Room A-807 Gaithersburg, MD. 20899. [6] Jankovic, J.T., J.L. Clere, W. Sanderson, and L. Piacitelli. Estimating Quantities of Asbestos in Building Materials. National Asbestos Council Journal, (Fall, 1988). [7] Title 40, Code of Federal Regulations, Part 763. Appendix A to Subpart F. Interim Method of the Determination of Asbestos in Bulk Insulation Samples, (April 15, 1988). [8] Bloss, F. Donald, Introduction to the Methods of Optical Crystallography, Holt, Rinehart, & Winston, (1961). [9] Kerr, Paul F., Optical Mineralogy, 4th Ed., New York, McGraw-Hill, (1977). [10] Shelley, David, Optical Mineralogy, 2nd Ed., New York, Elsevier, (1985). [11] Phillips, W.R. and D.T. Griffen, Optical Mineralogy, W. H. Freeman and Co., (1981). [12] McCrone, Walter, The Asbestos Particle Atlas, Ann Arbor Science, Michigan, (1980). [13] "Selected Silicate Minerals and their Asbestiform Varieties," Bureau of Mines Information Circular IC 8751, (1977).
METHOD WRITTEN BY: Patricia A. Klinger, CIHT, and Keith R. Nicholson, CIH, DataChem Laboratories, Inc., Salt Lake City, Utah, under NIOSH Contract 200-84-2608, and Frank J. Hearl, PE, NIOSH/DRDS and John T. Jankovic, CIH.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 7 of 9
Figure 1. Percent estimate comparator NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 8 of 9
Table 1. Optical Properties of Asbestos Fibers Refractive Index (Approximate Values)
- to
Elongation
5 to Elongation
Mineral
Morphology and Color
Chrysotile
Wavy fibers with kinks. Splayed ends on larger bundles. Colorless to light brown upon being heated. Nonpleochroic. Aspect ratio typically >10:1.
1.54
1.55
0.002 - 0.014
CummingtoniteGrunerite (Amosite)
Straight fibers and fiber bundles. Bundle ends appear broom-like or splayed. Colorless to brown upon heating. May be weakly pleochroic. Aspect ratio typically >10:1.
1.67
1.70
0.02 - 0.03
Crocidolite (Riebeckite)
Straight fibers and fiber bundles. Longer fibers show curvature. Splayed ends on bundles. Characteristic blue color. Pleochroic. Aspect ratio typically >10:1.
1.71
1.70
0.014 - 0.016 Interference colors may be masked by blue color.
Anthophyllite
Straight fibers and fiber bundles. Cleavage fragments may be present. Colorless to light brown. Nonpleochroic to weakly pleochroic. Aspect ratio generally <10:1.
1.61
1.63
0.019 - 0.024
TremoliteActinolite
Straight and curved fibers. Cleavage fragments common. Large fiber bundles show splayed ends. Tremolite is colorless. Actinolite is green and weakly to moderately pleochroic. Aspect ratio generally <10:1.
1.60 - 1.62 (tremolite)
1.62 - 1.64 (tremolite)
0.02 - 0.03
1.62 - 1.67 (actinolite)
1.64 - 1.68 (actinolite)
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
Birefringence ASBESTOS (bulk): METHOD 9002, Issue 2, dated 15 August 1994 - Page 9 of 9 Table 1. Optical Properties of Asbestos Fibers (Continued) Central Stop Dispersion Staining Colors
Parallel to fiber length
+ (length slow)
1.550 HD
Blue
Blue-magenta
Parallel to fiber length
+ (length slow)
1.670
Red magenta to blue
Yellow
Fibers subjected to high temperatures will not dispersionstain. 1.680 1.680
pale blue blue
blue gold
1.700
Red magenta
Blue-magenta
yellow
pale yellow
Blue
Gold to goldmagenta
Blue-green
Golden-yellow
Pale blue (tremolite)
Yellow (tremolite)
Yellow (actinolite)
Pale yellow (actinolite)
Chrysotile CummingtoniteGrunerite (Amosite)
Cummingtonite Grunerite Parallel to fiber length
- (length fast)
1.680 Anthophyllite
Parallel to fiber length
+ (length slow)
1.605
HD
1.620 HD TremoliteActinolite
5 to Vibration
RI Liquid
Extinction
Crocidolite (Riebeckite)
- to
Vibration
Sign of Elongation
Mineral
Oblique - 10 to 20E for fragments. Some composite fibers show 5 extinction.
+ (length slow)
1.605
HD
HD = high-dispersion RI liquid series.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94