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(continued)

The self-certification must be sent via registered mail, to EPA Headquarters at the following address: Attn. Self-Certification Program, Field Programs Branch, Chemical Management Division (7404), Office of Pollution Prevention and Toxics, Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. A duplicate copy of the complete submission must also be sent to any States from which approval had been obtained.

The timely receipt of a complete self-certification by EPA and all approving States shall have the effect of extending approval under this MAP to the training courses offered by the submitting provider. If a self-certification is not received by the approving government bodies on or before the due date, the affected training course is not approved under this MAP. Such training providers must then reapply for approval of these training courses pursuant to the procedures outlined in Unit III.

C. Requirements applicable to Accredited Persons.

Persons accredited by a State with an accreditation program no less stringent than an earlier version of the MAP or by an EPA-approved training provider as of April 3, 1994, are accredited in accordance with the requirements of this MAP, and are not required to retake initial training. They must continue to comply with the requirements for annual refresher training in Unit I.D. of the revised MAP.

D. Requirements applicable to Non-Accredited Persons.

In order to perform work requiring accreditation under TSCA Title II, persons who are not accredited by a State with an accreditation program no less stringent than an earlier version of the MAP or by an EPA-approved training provider as of April 3, 1994, must comply with the upgraded training requirements of this MAP by no later than October 4, 1994. Non-accredited persons may obtain initial accreditation on a provisional basis by successfully completing any of the training programs approved under an earlier version of the MAP, and thereby perform work during the first 6 months after this MAP takes effect. However, by October 4, 1994, these persons must have successfully completed an upgraded training program that fully complies with the requirements of this MAP in order to continue to perform work requiring accreditation under section 206 of TSCA, 15 U.S.C. 2646.

[59 FR 5251, Feb. 3, 1994, as amended at 60 FR 31922, June 19, 1995; 70 FR 59889, Oct. 13, 2005]

Appendix D to Subpart E of Part 763—Transport and Disposal of Asbestos Waste
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For the purposes of this appendix, transport is defined as all activities from receipt of the containerized asbestos waste at the generation site until it has been unloaded at the disposal site. Current EPA regulations state that there must be no visible emissions to the outside air during waste transport. However, recognizing the potential hazards and subsequent liabilities associated with exposure, the following additional precautions are recommended.

Recordkeeping. Before accepting wastes, a transporter should determine if the waste is properly wetted and containerized. The transporter should then require a chain-of-custody form signed by the generator. A chain-of-custody form may include the name and address of the generator, the name and address of the pickup site, the estimated quantity of asbestos waste, types of containers used, and the destination of the waste. The chain-of-custody form should then be signed over to a disposal site operator to transfer responsibility for the asbestos waste. A copy of the form signed by the disposal site operator should be maintained by the transporter as evidence of receipt at the disposal site.

Waste handling. A transporter should ensure that the asbestos waste is properly contained in leak-tight containers with appropriate labels, and that the outside surfaces of the containers are not contaminated with asbestos debris adhering to the containers. If there is reason to believe that the condition of the asbestos waste may allow significant fiber release, the transporter should not accept the waste. Improper containerization of wastes is a violation of the NESHAPs regulation and should be reported to the appropriate EPA Regional Asbestos NESHAPs contact below:

Region I

Asbestos NESHAPs Contact, Air Management Division, USEPA, Region I, JFK Federal Building, Boston, MA 02203, (617) 223–3266.

Region II

Asbestos NESHAPs Contact, Air & Waste Management Division, USEPA, Region II, 26 Federal Plaza, New York, NY 10007, (212) 264–6770.

Region III

Asbestos NESHAPs Contact, Air Management Division, USEPA, Region III, 841 Chestnut Street, Philadelphia, PA 19107, (215) 597–9325.

Region IV

Asbestos NESHAPs Contact, Air, Pesticide & Toxic Management, USEPA, Region IV, 345 Courtland Street, NE., Atlanta, GA 30365, (404) 347–4298.

Region V

Asbestos NESHAPs Contact, Air Management Division, USEPA, Region V, 77 West Jackson Boulevard, Chicago, IL 60604, (312) 353–6793.

Region VI

Asbestos NESHAPs Contact, Air & Waste Management Division, USEPA, Region VI, 1445 Ross Avenue, Dallas, TX 75202, (214) 655–7229.

Region VII

Asbestos NESHAPs Contact, Air & Waste Management Division, USEPA, Region VII, 726 Minnesota Avenue, Kansas City, KS 66101, (913) 236–2896.

Region VIII

Asbestos NESHAPs Contact, Air & Waste Management Division, USEPA, Region VIII, 999 18th Street, Suite 500, Denver, CO 80202, (303) 293–1814.

Region IX

Asbestos NESHAPs Contact, Air Management Division, USEPA, Region IX, 215 Fremont Street, San Francisco, CA 94105, (415) 974–7633.

Region X

Asbestos NESHAPs Contact, Air & Toxics Management Division, USEPA, Region X, 1200 Sixth Avenue, Seattle, WA 98101, (206) 442–2724.

Once the transporter is satisfied with the condition of the asbestos waste and agrees to handle it, the containers should be loaded into the transport vehicle in a careful manner to prevent breaking of the containers. Similarly, at the disposal site, the asbestos waste containers should be transferred carefully to avoid fiber release.

Waste transport. Although there are no regulatory specifications regarding the transport vehicle, it is recommended that vehicles used for transport of containerized asbestos waste have an enclosed carrying compartment or utilize a canvas covering sufficient to contain the transported waste, prevent damage to containers, and prevent fiber release. Transport of large quantities of asbestos waste is commonly conducted in a 20-cubic-yard “roll off” box, which should also be covered. Vehicles that use compactors to reduce waste volume should not be used because these will cause the waste containers to rupture. Vacuum trucks used to transport waste slurry must be inspected to ensure that water is not leaking from the truck.

Disposal involves the isolation of asbestos waste material in order to prevent fiber release to air or water. Landfilling is recommended as an environmentally sound isolation method because asbestos fibers are virtually immobile in soil. Other disposal techniques such as incineration or chemical treatment are not feasible due to the unique properties of asbestos. EPA has established asbestos disposal requirements for active and inactive disposal sites under NESHAPs (40 CFR Part 61, subpart M) and specifies general requirements for solid waste disposal under RCRA (40 CFR Part 257). Advance EPA notification of the intended disposal site is required by NESHAPs.

Selecting a disposal facility. An acceptable disposal facility for asbestos wastes must adhere to EPA's requirements of no visible emissions to the air during disposal, or minimizing emissions by covering the waste within 24 hours. The minimum required cover is 6 inches of nonasbestos material, normally soil, or a dust-suppressing chemical. In addition to these Federal requirements, many state or local government agencies require more stringent handling procedures. These agencies usually supply a list of “approved” or licensed asbestos disposal sites upon request. Solid waste control agencies are listed in local telephone directories under state, county, or city headings. A list of state solid waste agencies may be obtained by calling the RCRA hotline: 1–800–424–9346 (382–3000 in Washington, DC). Some landfill owners or operators place special requirements on asbestos waste, such as placing all bagged waste into 55-gallon metal drums. Therefore, asbestos removal contractors should contact the intended landfill before arriving with the waste.

Receiving asbestos waste. A landfill approved for receipt of asbestos waste should require notification by the waste hauler that the load contains asbestos. The landfill operator should inspect the loads to verify that asbestos waste is properly contained in leak-tight containers and labeled appropriately. The appropriate EPA Regional Asbestos NESHAPs Contact should be notified if the landfill operator believes that the asbestos waste is in a condition that may cause significant fiber release during disposal. In situations when the wastes are not properly containerized, the landfill operator should thoroughly soak the asbestos with a water spray prior to unloading, rinse out the truck, and immediately cover the wastes with nonasbestos material prior to compacting the waste in the landfill.

Waste deposition and covering. Recognizing the health dangers associated with asbestos exposure, the following procedures are recommended to augment current federal requirements:

• Designate a separate area for asbestos waste disposal. Provide a record for future landowners that asbestos waste has been buried there and that it would be hazardous to attempt to excavate that area. (Future regulations may require property deeds to identify the location of any asbestos wastes and warn against excavation.)

• Prepare a separate trench to receive asbestos wastes. The size of the trench will depend upon the quantity and frequency of asbestos waste delivered to the disposal site. The trenching technique allows application of soil cover without disturbing the asbestos waste containers. The trench should be ramped to allow the transport vehicle to back into it, and the trench should be as narrow as possible to reduce the amount of cover required. If possible, the trench should be aligned perpendicular to prevailing winds.

• Place the asbestos waste containers into the trench carefully to avoid breaking them. Be particularly careful with plastic bags because when they break under pressure asbestos particles can be emitted.

• Completely cover the containerized waste within 24 hours with a minimum of 6 inches of nonasbestos material. Improperly containerized waste is a violation of the NESHAPs and EPA should be notified.

However, if improperly containerized waste is received at the disposal site, it should be covered immediately after unloading. Only after the wastes, including properly containerized wastes, are completely covered, can the wastes be compacted or other heavy equipment run over it. During compacting, avoid exposing wastes to the air or tracking asbestos material away from the trench.

• For final closure of an area containing asbestos waste, cover with at least an additional 30 inches of compacted nonasbestos material to provide a 36-inch final cover. To control erosion of the final cover, it should be properly graded and vegetated. In areas of the United States where excessive soil erosion may occur or the frost line exceeds 3 feet, additional final cover is recommended. In desert areas where vegetation would be difficult to maintain, 3–6 inches of well graded crushed rock is recommended for placement on top of the final cover.

Controlling public access. Under the current NESHAPs regulation, EPA does not require that a landfill used for asbestos disposal use warning signs or fencing if it meets the requirement to cover asbestos wastes. However, under RCRA, EPA requires that access be controlled to prevent exposure of the public to potential health and safety hazards at the disposal site. Therefore, for liability protection of operators of landfills that handle asbestos, fencing and warning signs are recommended to control public access when natural barriers do not exist. Access to a landfill should be limited to one or two entrances with gates that can be locked when left unattended. Fencing should be installed around the perimeter of the disposal site in a manner adequate to deter access by the general public. Chain-link fencing, 6-ft high and topped with a barbed wire guard, should be used. More specific fencing requirements may be specified by local regulations. Warning signs should be displayed at all entrances and at intervals of 330 feet or less along the property line of the landfill or perimeter of the sections where asbestos waste is deposited. The sign should read as follows:

ASBESTOS WASTE DISPOSAL SITE

BREATHING ASBESTOS DUST MAY CAUSE LUNG DISEASE AND CANCER

Recordkeeping. For protection from liability, and considering possible future requirements for notification on disposal site deeds, a landfill owner should maintain documentation of the specific location and quantity of the buried asbestos wastes. In addition, the estimated depth of the waste below the surface should be recorded whenever a landfill section is closed. As mentioned previously, such information should be recorded in the land deed or other record along with a notice warning against excavation of the area.

[52 FR 41897, Oct. 30, 1987, as amended at 62 FR 1834, Jan. 14, 1997]

Appendix E to Subpart E of Part 763—Interim Method of the Determination of Asbestos in Bulk Insulation Samples
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Section 1. Polarized Light Microscopy

1.1 Principle and Applicability

Bulk samples of building materials taken for asbestos identification are first examined for homogeneity and preliminary fiber identification at low magnification. Positive identification of suspect fibers is made by analysis of subsamples with the polarized light microscope.

The principles of optical mineralogy are well established. 1 2 A light microscope equipped with two polarizing filters is used to observe specific optical characteristics of a sample. The use of plane polarized light allows the determination of refractive indices along specific crystallographic axes. Morphology and color are also observed. A retardation plate is placed in the polarized light path for determination of the sign of elongation using orthoscopic illumination. Orientation of the two filters such that their vibration planes are perpendicular (crossed polars) allows observation of the birefringence and extinction characteristics of anisotropic particles.

Quantitative analysis involves the use of point counting. Point counting is a standard technique in petrography for determining the relative areas occupied by separate minerals in thin sections of rock. Background information on the use of point counting 2 and the interpretation of point count data 3 is available.

This method is applicable to all bulk samples of friable insulation materials submitted for identification and quantitation of asbestos components.

1.2 Range

The point counting method may be used for analysis of samples containing from 0 to 100 percent asbestos. The upper detection limit is 100 percent. The lower detection limit is less than 1 percent.

1.3 Interferences

Fibrous organic and inorganic constituents of bulk samples may interfere with the identification and quantitation of the asbestos mineral content. Spray-on binder materials may coat fibers and affect color or obscure optical characteristics to the extent of masking fiber identity. Fine particles of other materials may also adhere to fibers to an extent sufficient to cause confusion in identification. Procedures that may be used for the removal of interferences are presented in Section 1.7.2.2.

1.4 Precision and Accuracy

Adequate data for measuring the accuracy and precision of the method for samples with various matrices are not currently available. Data obtained for samples containing a single asbestos type in a simple matrix are available in the EPA report Bulk Sample Analysis for Asbestos Content: Evaluation of the Tentative Method. 4

1.5 Apparatus

1.5.1 Sample Analysis

A low-power binocular microscope, preferably stereoscopic, is used to examine the bulk insulation sample as received.

• Microscope: binocular, 10–45X (approximate).

• Light Source: incandescent or fluorescent.

• Forceps, Dissecting Needles, and Probes

• Glassine Paper or Clean Glass Plate

Compound microscope requirements: A polarized light microscope complete with polarizer, analyzer, port for wave retardation plate, 360° graduated rotating stage, substage condenser, lamp, and lamp iris.

• Polarized Light Microscope: described above.

• Objective Lenses: 10X, 20X, and 40X or near equivalent.

• Dispersion Staining Objective Lens (optional)

• Ocular Lens: 10X minimum.

• Eyepiece Reticle: cross hair or 25 point Chalkley Point Array.

• Compensator Plate: 550 millimicron retardation.

1.5.2 Sample Preparation

Sample preparation apparatus requirements will depend upon the type of insulation sample under consideration. Various physical and/or chemical means may be employed for an adequate sample assessment.

• Ventilated Hood or negative pressure glove box.

• Microscope Slides

• Coverslips

• Mortar and Pestle: agate or porcelain. (optional)

• Wylie Mill (optional)

• Beakers and Assorted Glassware (optional)

• Certrifuge (optional)

• Filtration apparatus (optional)

• Low temperature asher (optional)

1.6 Reagents

1.6.1 Sample Preparation

• Distilled Water (optional)

• Dilute CH3COOH: ACS reagent grade (optional)

• Dilute HCl: ACS reagent grade (optional)

• Sodium metaphosphate (NaPO3)6 (optional)

1.6.2 Analytical Reagents

Refractive Index Liquids: 1.490–1.570, 1.590–1.720 in increments of 0.002 or 0.004.

• Refractive Index Liquids for Dispersion Staining: high-dispersion series, 1.550, 1.605, 1.630 (optional).

• UICC Asbestos Reference Sample Set: Available from: UICC MRC Pneumoconiosis Unit, Llandough Hospital, Penarth, Glamorgan CF6 1XW, UK, and commercial distributors.

• Tremolite-asbestos (source to be determined)

• Actinolite-asbestos (source to be determined)

1.7 Procedures

Note: Exposure to airborne asbestos fibers is a health hazard. Bulk samples submitted for analysis are usually friable and may release fibers during handling or matrix reduction steps. All sample and slide preparations should be carried out in a ventilated hood or glove box with continuous airflow (negative pressure). Handling of samples without these precautions may result in exposure of the analyst and contamination of samples by airborne fibers.

1.7.1 Sampling

Samples for analysis of asbestos content shall be taken in the manner prescribed in Reference 5 and information on design of sampling and analysis programs may be found in Reference 6. If there are any questions about the representative nature of the sample, another sample should be requested before proceeding with the analysis.

1.7.2 Analysis

1.7.2.1 Gross Examination

Bulk samples of building materials taken for the identification and quantitation of asbestos are first examined for homogeneity at low magnification with the aid of a stereomicroscope. The core sample may be examined in its container or carefully removed from the container onto a glassine transfer paper or clean glass plate. If possible, note is made of the top and bottom orientation. When discrete strata are identified, each is treated as a separate material so that fibers are first identified and quantified in that layer only, and then the results for each layer are combined to yield an estimate of asbestos content for the whole sample.

1.7.2.2 Sample Preparation

Bulk materials submitted for asbestos analysis involve a wide variety of matrix materials. Representative subsamples may not be readily obtainable by simple means in heterogeneous materials, and various steps may be required to alleviate the difficulties encountered. In most cases, however, the best preparation is made by using forceps to sample at several places from the bulk material. Forcep samples are immersed in a refractive index liquid on a microscope slide, teased apart, covered with a cover glass, and observed with the polarized light microscope.

Alternatively, attempts may be made to homogenize the sample or eliminate interferences before further characterization. The selection of appropriate procedures is dependent upon the samples encountered and personal preference. The following are presented as possible sample preparation steps.

A mortar and pestle can sometimes be used in the size reduction of soft or loosely bound materials though this may cause matting of some samples. Such samples may be reduced in a Wylie mill. Apparatus should be clean and extreme care exercised to avoid cross-contamination of samples. Periodic checks of the particle sizes should be made during the grinding operation so as to preserve any fiber bundles present in an identifiable form. These procedures are not recommended for samples that contain amphibole minerals or vermiculite. Grinding of amphiboles may result in the separation of fiber bundles or the production of cleavage fragments with aspect ratios greater than 3:1. Grinding of vermiculite may also produce fragments with aspect ratios greater than 3:1.

Acid treatment may occasionally be required to eliminate interferences. Calcium carbonate, gypsum, and bassanite (plaster) are frequently present in sprayed or trowelled insulations. These materials may be removed by treatment with warm dilute acetic acid. Warm dilute hydrochloric acid may also be used to remove the above materials. If acid treatment is required, wash the sample at least twice with distilled water, being careful not to lose the particulates during decanting steps. Centrifugation or filtration of the suspension will prevent significant fiber loss. The pore size of the filter should be 0.45 micron or less. Caution: prolonged acid contact with the sample may alter the optical characteristics of chrysotile fibers and should be avoided.

Coatings and binding materials adhering to fiber surfaces may also be removed by treatment with sodium metaphosphate. 7 Add 10 mL of 10g/L sodium metaphosphate solution to a small (0.1 to 0.5 mL) sample of bulk material in a 15-mL glass centrifuge tube. For approximately 15 seconds each, stir the mixture on a vortex mixer, place in an ultrasonic bath and then shake by hand. Repeat the series. Collect the dispersed solids by centrifugation at 1000 rpm for 5 minutes. Wash the sample three times by suspending in 10 mL distilled water and recentrifuging. After washing, resuspend the pellet in 5 mL distilled water, place a drop of the suspension on a microscope slide, and dry the slide at 110 °C.

In samples with a large portion of cellulosic or other organic fibers, it may be useful to ash part of the sample and view the residue. Ashing should be performed in a low temperature asher. Ashing may also be performed in a muffle furnace at temperatures of 500 °C or lower. Temperatures of 550 °C or higher will cause dehydroxylation of the asbestos minerals, resulting in changes of the refractive index and other key parameters. If a muffle furnace is to be used, the furnace thermostat should be checked and calibrated to ensure that samples will not be heated at temperatures greater than 550 °C.

Ashing and acid treatment of samples should not be used as standard procedures. In order to monitor possible changes in fiber characteristics, the material should be viewed microscopically before and after any sample preparation procedure. Use of these procedures on samples to be used for quantitation requires a correction for percent weight loss.

1.7.2.3 Fiber Identification

Positive identification of asbestos requires the determination of the following optical properties.

• Morphology

• Color and pleochroism

• Refractive indices

• Birefringence

• Extinction characteristics

• Sign of elongation

Table 1–1 lists the above properties for commercial asbestos fibers. Figure 1–1 presents a flow diagram of the examination procedure. Natural variations in the conditions under which deposits of asbestiform minerals are formed will occasionally produce exceptions to the published values and differences from the UICC standards. The sign of elongation is determined by use of the compensator plate and crossed polars. Refractive indices may be determined by the Becke line test. Alternatively, dispersion staining may be used. Inexperienced operators may find that the dispersion staining technique is more easily learned, and should consult Reference 9 for guidance. Central stop dispersion staining colors are presented in Table 1–2. Available high-dispersion (HD) liquids should be used.


Table 1-1_Optical Properties of Asbestoc Fibers
----------------------------------------------------------------------------------------------------------------
Refrac- tive indices \b\
Mineral Morphology, color ----------------------------- Birefring- Extinction Sign of
\a\ a ? ence elonation
----------------------------------------------------------------------------------------------------------------
Chrysotile Wavy fibers. Fiber 1.493-1.560 1.517-1.562\f\ .008 [verbar] to +
(asbestiform bundles have (normally fiber length. (length
serpentine). splayed ends and 1.556). slow)
``kinks''. Aspect
ratio typically
>10:1. Colorless
\3\, nonpleochroic.
Amosite Straight, rigid 1.635-1.696 1.655-1.729 .020-.033 [verbar] to +
(asbestiform fibers. Aspect \f\ (normally fiber length. (length
grunerite). ratio typically 1.696-1.710. slow)
>10:1. Colorless
to brown,
nonpleochroic or
weakly so. Opaque
inclusions may be
present.
Crocidolite Straight, rigid 1.654-1.701 1.668- .014-.016 [verbar] to -
(asbestiform fibers. Thick 1.717\3e\ fiber length. (length
Riebeckite). fibers and bundles (normally fast)
common, blue to close to
purple-blue in 1.700).
color. Pleochroic.
Birefringence is
generally masked by
blue color.
Anthophyllite- Straight fibers and 1.596-1.652 1.615-1.676 .019-.024 [verbar] to +
asbestos. acicular cleavage \f\. fiber length. (length
fragments.\d\ Some slow)
composite fibers.
Aspect ratio
<10:1. Colorless
to light brown.
Tremolite- Normally present as 1.599-1.668 1.622-1.688 .023-.020 Oblique +
actinolite- acicular or \f\. extinction, (length
asbestos. prismatic cleavage 10-20° slow)
fragments.\d\ for
Single crystals fragments.
predominate, aspect Composite
ratio <10:1. fibers show
Colorless to pale [verbar]
green. extinction.
----------------------------------------------------------------------------------------------------------------
\a\ From reference 5; colors cited are seen by observation with plane polarized light.
\b\ From references 5 and 8.
\c\ Fibers subjected to heating may be brownish.
\d\ Fibers defined as having aspect ratio >3:1.
\e\ to fiber length.
\f\ [verbar]To fiber length.




View or download PDF



Table 1-2_Central Stop Dispersion Staining Colors \a\
----------------------------------------------------------------------------------------------------------------
Mineral RI Liquid ? ?[verbar]
----------------------------------------------------------------------------------------------------------------
Chrysotile............................... 1.550 \HD\ Blue....................... Blue-magenta
Amosite.................................. 1.680 Blue-magenta to pale blue.. Golden-yellow
1.550\HD\ Yellow to white............ Yellow to white
Crocidolite \b\.......................... 1.700 Red magenta................ Blue-magenta
1.550\HD\ Yellow to white............ Yellow to white
Anthophyllite............................ 1.605\HD\ Blue....................... Gold to gold-magenta
Tremolite................................ 1.605\HD c\ Pale blue.................. Gold
Actinolite............................... 1.605\HD\ Gold-magenta to blue....... Gold
1.630\HD c\ Magenta.................... Golden-yellow
----------------------------------------------------------------------------------------------------------------
\a\ From reference 9.
\b\ Blue absorption color.
\c\ Oblique extinction view.


1.7.2.4 Quantitation of Asbestos Content

Asbestos quantitation is performed by a point-counting procedure or an equivalent estimation method. An ocular reticle (cross-hair or point array) is used to visually superimpose a point or points on the microscope field of view. Record the number of points positioned directly above each kind of particle or fiber of interest. Score only points directly over asbestos fibers or nonasbestos matrix material. Do not score empty points for the closest particle. If an asbestos fiber and a matrix particle overlap so that a point is superimposed on their visual intersection, a point is scored for both categories. Point counting provides a determination of the area percent asbestos. Reliable conversion of area percent to percent of dry weight is not currently feasible unless the specific gravities and relative volumes of the materials are known.

For the purpose of this method, “asbestos fibers” are defined as having an aspect ratio greater than 3:1 and being positively identified as one of the minerals in Table 1–1.

A total of 400 points superimposed on either asbestos fibers or nonasbestos matrix material must be counted over at least eight different preparations of representative subsamples. Take eight forcep samples and mount each separately with the appropriate refractive index liquid. The preparation should not be heavily loaded. The sample should be uniformly dispersed to avoid overlapping particles and allow 25–50 percent empty area within the fields of view. Count 50 nonempty points on each preparation, using either

• A cross-hair reticle and mechanical stage; or

• A reticle with 25 points (Chalkley Point Array) and counting at least 2 randomly selected fields.

For samples with mixtures of isotropic and anisotropic materials present, viewing the sample with slightly uncrossed polars or the addition of the compensator plate to the polarized light path will allow simultaneous discrimination of both particle types. Quantitation should be performed at 100X or at the lowest magnification of the polarized light microscope that can effectively distinguish the sample components. Confirmation of the quantitation result by a second analyst on some percentage of analyzed samples should be used as standard quality control procedure.

The percent asbestos is calculated as follows:

% asbestos=(a/n) 100%

where

a=number of asbestos counts,

n=number of nonempty points counted (400).

If a=0, report “No asbestos detected.” If 0< a=3, report “<1% asbestos”.

The value reported should be rounded to the nearest percent.

1.8 References

1. Paul F. Kerr, Optical Mineralogy, 4th ed., New York, McGraw-Hill, 1977.

2. E. M. Chamot and C. W. Mason, Handbook of Chemical Microscopy, Volume One, 3rd ed., New York: John Wiley & Sons, 1958.

3. F. Chayes, Petrographic Modal Analysis: An Elementary Statistical Appraisal, New York: John Wiley & Sons, 1956.

4. E. P. Brantly, Jr., K. W. Gold, L. E. Myers, and D. E. Lentzen, Bulk Sample Analysis for Asbestos Content: Evaluation of the Tentative Method, U.S. Environmental Protection Agency, October 1981.

5. U.S. Environmental Protection Agency, Asbestos-Containing Materials in School Buildings: A Guidance Document, Parts 1 and 2, EPA/OPPT No. C00090, March 1979.

6. D. Lucas, T. Hartwell, and A. V. Rao, Asbestos-Containing Materials in School Buildings: Guidance for Asbestos Analytical Programs, EPA 560/13–80–017A, U.S. Environmental Protection Agency, December 1980, 96 pp.

7. D. H. Taylor and J. S. Bloom, Hexametaphosphate pretreatment of insulation samples for identification of fibrous constituents, Microscope, 28, 1980.

8. W. J. Campbell, R. L. Blake, L. L. Brown, E. E. Cather, and J. J. Sjoberg. Selected Silicate Minerals and Their Asbestiform Varieties: Mineralogical Definitions and Identification-Characterization, U.S. Bureau of Mines Information Circular 8751, 1977.

9. Walter C. McCrone, Asbestos Particle Atlas, Ann Arbor: Ann Arbor Science Publishers, June 1980.

Section 2. X-Ray Powder Diffraction

2.1 Principle and Applicability

The principle of X-ray powder diffraction (XRD) analysis is well established. 1 2 Any solid, crystalline material will diffract an impingent beam of parallel, monochromatic X-rays whenever Bragg's Law,

? = 2d sin T,

is satisfied for a particular set of planes in the crystal lattice, where

? = the X-ray wavelength, A ;

d = the interplanar spacing of the set of reflecting lattice planes, A ; and

T = the angle of incidence between the X-ray beam and the reflecting lattice planes.

By appropriate orientation of a sample relative to the incident X-ray beam, a diffraction pattern can be generated that, in most cases, will be uniquely characteristic of both the chemical composition and structure of the crystalline phases present.

Unlike optical methods of analysis, however, XRD cannot determine crystal morphology. Therefore, in asbestos analysis, XRD does not distinguish between fibrous and nonfibrous forms of the serpentine and amphibole minerals (Table 2–1). However, when used in conjunction with optical methods such as polarized light microscopy (PLM), XRD techniques can provide a reliable analytical method for the identification and characterization of asbestiform minerals in bulk materials.

For qualitative analysis by XRD methods, samples are initially scanned over limited diagnostic peak regions for the serpentine (~7.4 A ) and amphibole (8.2–8.5 A ) minerals (Table 2–2). Standard slow-scanning methods for bulk sample analysis may be used for materials shown by PLM to contain significant amounts of asbestos (>5–10 percent). Detection of minor or trace amounts of asbestos may require special sample preparation and step-scanning analysis. All samples that exhibit diffraction peaks in the diagnostic regions for asbestiform minerals are submitted to a full (5°–60° 2T; 1° 2T/min) qualitative XRD scan, and their diffraction patterns are compared with standard reference powder diffraction patterns 3 to verify initial peak assignments and to identify possible matrix interferences when subsequent quantitative analysis will be performed.


Table 2-1_The Asbestos Minerals and Their Nonasbestiform Analogs
------------------------------------------------------------------------
Asbestiform Nonasbestiform
------------------------------------------------------------------------
SERPENTINE
Chrysotile Antigorite, lizardite
AMPHIBOLE
Anthophyllite asbestos Anthophyllite
Cummingtonite-grunerite asbestos Cummingtonite-grunerite
(``Amosite'')
Crocidolite Riebeckite
Tremolite asbestos Tremolite
Actinolite asbestos Actinolite
------------------------------------------------------------------------




Table 2-2_Principal Lattice Spacings of Asbestiform Minerals a
----------------------------------------------------------------------------------------------------------------
Principal d-spacings (A) and relative
intensities JCPDS Powder diffraction file
Minerals ---------------------------------------- \3\ number

----------------------------------------------------------------------------------------------------------------
Chrysotile............................... 7.37100 3.6570 4.5750 21-543b
7.36100 3.6680 2.4565 25-645
7.10100 2.3380 3.5570 22-1162 (theoretical)
``Amosite''.............................. 8.33100 3.0670 2.75670 17-745 (nonfibrous)
8.22100 3.06085 3.2570 27-1170 (UICC)
Anthophyllite............................ 3.05100 3.2460 8.2655 9-455
3.06100 8.3370 3.2350 16-401 (synthetic)
Anthophyllite............................ 2.72100 2.54100 3.48080 25-157
Crocidolite.............................. 8.35100 3.1055 2.72035 27-1415 (UICC)
Tremolite................................ 8.38100 3.12100 2.70590 13-437b
2.706100 3.1495 8.4340 20-1310b (synthetic)
3.13100 2.70660 8.4440 23-666 (synthetic mixture
with richterite)
----------------------------------------------------------------------------------------------------------------
a This information is intended as a guide, only. Complete powder diffraction data, including mineral type and
source, should be referred to, to ensure comparability of sample and reference materials where possible.
Additional precision XRD data on amosite, crocidolite, tremolite, and chrysotile are available from the U.S.
Bureaus of Mines.\4\
b Fibrosity questionable.


Accurate quantitative analysis of asbestos in bulk samples by XRD is critically dependent on particle size distribution, crystallite size, preferred orientation and matrix absorption effects, and comparability of standard reference and sample materials. The most intense diffraction peak that has been shown to be free from interference by prior qualitative XRD analysis is selected for quantitation of each asbestiform mineral. A “thin-layer” method of analysis 5 6 is recommended in which, subsequent to comminution of the bulk material to ~10 µm by suitable cryogenic milling techniques, an accurately known amount of the sample is deposited on a silver membrane filter. The mass of asbestiform material is determined by measuring the integrated area of the selected diffraction peak using a step-scanning mode, correcting for matrix absorption effects, and comparing with suitable calibration standards. Alternative “thick-layer” or bulk methods, 7 8 may be used for semiquantitative analysis.

This XRD method is applicable as a confirmatory method for identification and quantitation of asbestos in bulk material samples that have undergone prior analysis by PLM or other optical methods.

2.2 Range and Sensitivity

The range of the method has not been determined.

The sensitivity of the method has not been determined. It will be variable and dependent upon many factors, including matrix effects (absoprtion and interferences), diagnostic reflections selected, and their relative intensities.

2.3 Limitations

2.3.1 Interferences

Since the fibrous and nonfibrous forms of the serpentine and amphibole minerals (Table 2–1) are indistinguishable by XRD techniques unless special sample preparation techniques and instrumentation are used, 9 the presence of nonasbestiform serpentines and amphiboles in a sample will pose severe interference problems in the identification and quantitative analysis of their asbestiform analogs.

The use of XRD for identification and quantitation of asbestiform minerals in bulk samples may also be limited by the presence of other interfering materials in the sample. For naturally occurring materials the commonly associated asbestos-related mineral interferences can usually be anticipated. However, for fabricated materials the nature of the interferences may vary greatly (Table 2–3) and present more serious problems in identification and quantitation. 10 Potential interferences are summarized in Table 2–4 and include the following:

• Chlorite has major peaks at 7.19 A and 3.58 A That interfere with both the primary (7.36 A ) and secondary (3.66 A ) peaks for chrysotile. Resolution of the primary peak to give good quantitative results may be possible when a step-scanning mode of operation is employed.

• Halloysite has a peak at 3.63 A that interferes with the secondary (3.66 A ) peak for chrysotile.

• Kaolinite has a major peak at 7.15 A that may interfere with the primary peak of chrysotile at 7.36 A when present at concentrations of >10 percent. However, the secondary chrysotile peak at 3.66 A may be used for quantitation.

• Gypsum has a major peak at 7.5 A that overlaps the 7.36 A peak of chrysotile when present as a major sample constituent. This may be removed by careful washing with distilled water, or be heating to 300 °C to convert gypsum to plaster of paris.

• Cellulose has a broad peak that partially overlaps the secondary (3.66 A ) chrysotile peak. 8

• Overlap of major diagnostic peaks of the amphibole asbestos minerals, amosite, anthophyllite, crocidolite, and tremolite, at approximately 8.3 A and 3.1 A causes mutual interference when these minerals occur in the presence of one another. In some instances, adquate resolution may be attained by using step-scanning methods and/or by decreasing the collimator slit width at the X-ray port.

Table 2–3—Common Constituents in Insulation and Wall Materials

A. Insulation materials

Chrysotile

“Amosite”

Crocidolite

*Rock wool

*Slag wool

*Fiber glass

Gypsum (CaSO4 · 2H2O)

Vermiculite (micas)

*Perlite

Clays (kaolin)

*Wood pulp

*Paper fibers (talc, clay, carbonate fillers)

Calcium silicates (synthetic)

Opaques (chromite, magnetite inclusions in serpentine)

Hematite (inclusions in “amosite”)

Magnesite

*Diatomaceous earth

B. Spray finishes or paints

Bassanite

Carbonate minerals (calcite, dolomite, vaterite)

Talc

Tremolite

Anthophyllite

Serpentine (including chrysotile)

Amosite

Crocidolite

*Mineral wool

*Rock wool

*Slag wool

*Fiber glass

Clays (kaolin)

Micas

Chlorite

Gypsum (CaSO4 · 2H2O)

Quartz

*Organic binders and thickeners

Hyrdomagnesite

Wollastonite

Opaques (chromite, magnetite inclusions in serpentine)

Hematite (inclusions in “amosite”)

*Amorphous materials__contribute only to overall scattered radiation and increased background radiation.


Table 2-4_Interferences in XRD Analysis Asbestiform Minerals
------------------------------------------------------------------------
Primary
diagnostic
peaks
Asbestiform mineral (approximate Interference
d-spacings,
in A)
------------------------------------------------------------------------
Serpentine
Chrysotile 7.4 Nonasbestiform
serpentines
(antigorite,
lizardite)
Chlorite
Kaolinite
Gypsum
3.7 Chlorite
Halloysite
Cellulose
Amphibole
``Amosite'' 3.1 Nonasbestiform
Anthophyllite [rcub3] amphiboles
Crocidolite (cummingtonite-
Tremolite grunerite,
anthophyllite,
riebeckite,
tremolite)
Mutual interferences
Carbonates
Talc
8.3 Mutual interferences
------------------------------------------------------------------------


• Carbonates may also interfere with quantitative analysis of the amphibole asbestos minerals, amosite, anthophyllite, crocidolite, and tremolite. Calcium carbonate (CaCO3) has a peak at 3.035 A that overlaps major amphibole peaks at approximately 3.1 A when present in concentrations of >5 percent. Removal of carbonates with a dilute acid wash is possible; however, if present, chrysotile may be partially dissolved by this treatment. 11

• A major talc peak at 3.12 A interferes with the primary tremolite peak at this same position and with secondary peaks of crocidolite (3.10 A ), amosite (3.06 A ), and anthophyllite (3.05 A ). In the presence of talc, the major diagnostic peak at approximately 8.3 A should be used for quantitation of these asbestiform minerals.

The problem of intraspecies and matrix interferences is further aggravated by the variability of the silicate mineral powder diffraction patterns themselves, which often makes definitive identification of the asbestos minerals by comparison with standard reference diffraction patterns difficult. This variability results from alterations in the crystal lattice associated with differences in isomorphous substitution and degree of crystallinity. This is especially true for the amphiboles. These minerals exhibit a wide variety of very similar chemical compositions, with the result being that their diffraction patterns are chracterized by having major (110) reflections of the monoclinic amphiboles and (210) reflections of the orthorhombic anthophyllite separated by less than 0.2 A . 12

2.3.2 Matrix Effects

If a copper X-ray source is used, the presence of iron at high concentrations in a sample will result in significant X-ray fluorescence, leading to loss of peak intensity along with increased background intensity and an overall decrease in sensitivity. This situation may be corrected by choosing an X-ray source other than copper; however, this is often accompanied both by loss of intensity and by decreased resolution of closely spaced reflections. Alternatively, use of a diffracted beam monochromator will reduce background fluorescent raditation, enabling weaker diffraction peaks to be detected.

X-ray absorption by the sample matrix will result in overall attenuation of the diffracted beam and may seriously interfere with quantitative analysis. Absorption effects may be minimized by using sufficiently “thin” samples for analysis. 5 13 14 However, unless absorption effects are known to be the same for both samples and standards, appropriate corrections should be made by referencing diagnostic peak areas to an internal standard 7 8 or filter substrate (Ag) peak. 5 6

2.3.3 Particle Size Dependence

Because the intensity of diffracted X-radiation is particle-size dependent, it is essential for accurate quantitative analysis that both sample and standard reference materials have similar particle size distributions. The optimum particle size range for quantitative analysis of asbestos by XRD has been reported to be 1 to 10 µm. 15 Comparability of sample and standard reference material particle size distributions should be verified by optical microscopy (or another suitable method) prior to analysis. (continued)