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A Report on the Fiber Content of Eighty Industrial Talc Samples Obtained from and Using the Procedures of the Occupational Safety and Health Administration Prepared for Occupational Safety and Health Administration Department of Labor Washington D. C. 20212 20212 Prepared by the Staff of the Analytical Chemistry Division P. D. LaFleur Chief Institute for Materials Research National Bureau of Standards Washington D. C. 20234 May 1977 JNJH29W_000003721 U.S. DEPARTMENT OF LABOR Occupational Safety and Health Administration WASHINGTON D.C. 20210 Officoef the Assistant Secretary 20 20 MAY 1977 Enclosed is a copy of A Report of the Fiber Content Eighty Industrial Talc Samples Obtained from and Using the Procedures of the Occupational Safety and Health Administrtion OSHA The analysis discussed in the report was conducted by the National Bureau of Standards at the request OSHA The purpose of this study was to determine the fiber content of industrial talcs and thereby answer parties regulated by OSHA who challenged data of both OSHA and the National Institute for Occupational Safety and Health The enclosed final report was received by OSHA on May 10 1977. I hope you find that this report addresses your concerns and consider it as does OSHA a means to assure healthful working conditions for employees Sincerely Eula Bingham Bec Eula Bingham Assistant Secretary Occupational Safety and Health Enclosure ce ee eee peer ae ge to ee em geet em oe JNJH29W_000003722 TALC SAMPLE NUMBER 1 2 3 4 ' 5 6 7 39 40 COMPANY AND SAMPLE DESIGNATION Vanderbilt Talc Company Nytal 300 Vanderbilt Talc Company Nytal 400 Vanderbilt Talc Company 5X Vanderbilt Talc Company 325 Vanderbilt Talc Company X Vanderbilt Talc Company FT Vanderbilt Talc Company 3X Hitchcock Corporation Murphy N.C. Product Talc Windsor Minerals July 29 1975 Gassets 37 Windsor Minerals West Windsor Mineral Ray Grind Composite Windsor Minerals Ludlow 36 July 29-30 1976 Windsor Minerals Gassetts 36 July 28-30 1975 Vermont Talc Company - Bagging Bulk Sample 7/16/75 2nd shift | Vermont Talc Company -- Bagging Bulk Sample vertah XXXD 9/17/76 1st shift TH omens os gw eee Sewanee HP MTN Teen me ay tag) ra epee ow ree JNJH29W_000003723 JNJH29W_000003723 TALC SAMPLE NUMBER 41 42 43 44 45 46 47 48 49 50 51 52 53 COMPANY AND SAMPLE DESIGNATION Southern Talc Co. Cohutta Mill Chatsworth Ga Product Powder Sample Mine MESA I.D. 04-00493 Packer Station # Vanderbilt Mill 1 Gouverneur N. Y. 1st shift 11/4/75 FT Talc Packer Station 2 Vanderbilt Talc Mill 1 Gouverneur N. Y. Nytal 100 1st shift 11/4/75 Ceramitalc HDT Vanderbilt Talc Co. 1st shift 11/4/75 Bagging Station 3 Vanderbilt Talc Co. Mill 1 Gouverneur N. Y. 11/4/75 Nytal 200 Hitchcock Corp. 5 Mine MESA ID 3100222 Hitchcock Corp. 3 Mine MESA ID 3100683 Wrau Mine 3 mill Int Minerals and chemicals MESA ID 31-0008 Bagging Station Vanderbilt Talc Co. 2nd shift Mill 1 Gouverneur N. Y. Nytal 300 11/3/75 Bagging Station Vanderbilt Talc Co. shift 11/3/75 Nytal 200 2nd Southern Talc Co. Southern Mill Product Talc sample Chatsworth Ga Rock Cliff Mine MESA ID 0900492 9/3/74 Southern Talc Co. Southern Mill Chatsworth Ga ore from Rock Cliff MESA ID 90-00492 Southern Talc Co. Southern Mill Ore from Jude Hole Mine MESA ID 09-00492 JNJH29W_000003724 TALC SAMPLE NUMBER 54 55 56 57 58 59 60 61 62 63 64 -' COMPANY AND SAMPLE DESIGNATION Winterborg Mine & Mill Ore from American Talc Co. Alpine Ala Willowreek Mine MESA ID 01-00433 9/4/75 Thompson Co. Cartersville Plant Cartersville Ga 9/5/74 Ore from Brady Mine MESA ID 09-00224 Southern Talc Co. Cohutta Mill ChatswortGha 9/3/74 Ore from Ernest Mine MESA ID 09-00493 American Talc Co. Alpine Ga Winterboro Mine & Mill 9/5/75 MESA ID 01-00433 Final Prod Pioneer Talc Co. Inc. Garren Pit 6 Allamore Hudspeth Co. Texas MESA ID 41-00869 Prod Pioneer talc Co. Inc. Pit Product 4 Texas MESA ID 41-00869 Apache Pioneer Talc Co. Inc. 4 Texola Pit Product Texas MESA ID 41-00869 Southern Clay Products 2 Bottom Product Allamore Hudspeth Co. Texas 18 Milwhite Co. Inc. Van Horn Cumberson Co. Texas MESA ID Ground Calcined Product 41-01527 Milwhite Co. Inc. 11 Van Horn Culberson Co. Texas Eagle Hat Pit Crude MESA ID 41-01527 Pioneer Talc Co. Allamore Hudspeth Co. Texas 8 Garren Ceramic MESA ID 41-00869 Pane em nemo NL errr ge cman et erttntitettitate tS rH SOR ne RanRt ear Mpopuanane Soup " JNJH29W_000003725 TALC SAMPLE NUMBER _ 65 - 66 67 68 69 70 71 72 73 74 75 76 78 79 ep oe COMPANY AND SAMPLE DESIGNATION Milwhite Co. Inc. Van Horn 14 Tumble Down Pit Product MESA ID 41-01527 Texas 14 Eastern Magnesia Talc Emtal 42 Co. Vermont 8/28/75 Pfizer Barretts Mill Montana minus 12 Micron Pfizer Barretts Mill Montana minus 325 mesh Pfizer Barretts Mill Montana minus 20 microns Cyprus Industrial Minerals Three Forks Mill Montana minus 325 mesh " Cyprus Industrial Minerals Three Forks Mill Montana Mistron Vapor minus 10 micron Cyprus Industrial Minerals Three Forks Mill Montana Floor Sweepings Bagging Area Cyprus Industrial Minerals Yellowstone Mine Montana Drill Hole Southern Talc Southern Mill Ga 98 passing 200 mesh Southern Talc Southern Mill Ga 99 passing 325 mesh 1767 Southern Talc Cohutta Mill Ga 95 passing 325 mesh Milwhite Talc Co. Inc. Tex Finished CM4 product # Westex Talc Co. TDM Dark - Milwhite Inc. 231 Tex 000003726 TALC SAMPLE NUMBER 80 81 82 83 84 86 87 88 89 91 92 93 94 95 96 seme ee mani oem amen eens oe et meme tabs eae owom atin COMPANY AND SAMPLE DESIGNATION - Milwhite Co. Inc. Tex Marshel mix - 92-200 mesh # Westex Talc Co. Milwhite Inc. White mine 93-200 mesh 24 Tex Southern Clay Products - Tex Garren Mine 2 5 Texas Talc Co. - TPI Mine Texas Pacific Tex # Texas Talc Co. Tex David Mine # Cyprus Industrial Minerals Loyce Fine Mine Tex 9 Co. Pioneer Talc Co. Texola Mine Inc. Tex 10 Pioneer Talc Dees Mine Co. Inc. Tex 11 Milwhite Co. Inc. Bryant Soapstone Mine Arkansas Laws Mill Micro talc from White Eagle Mine Standard Industrial Minerals Laws Mill Desert Talc Product Standard Industrial Minerals Laws Mill Holiday Talc Product Standard Industrial Minerals Keeler 076 Tecopa Mine 100 Panamint Cyprus Industrial Minerals Montana Keller HGO Blend 4 Panamint 3 Oasis 3 White Eagle Cyprus Industrial Minerals Montana Keeler Sierra Cloud Blend 4 Panamint 1 White Eagle Cyprus Industrial Minerals Montana JNJH29W_000003727 TALC SAMPLE NUMBER 97 98 99 100 101 102 103 104 105 106 107 108 109 BKK mmc 3-21-77 Retyped A re etre en see eee COMPANY AND SAMPLE DESIGNATION Keeler MSC Mistron Panamint + 0.5 stearite Cyprus Industrial Minerals Keeler Sierralite Talc City Frisco Cyprus Industrial Minerals Keeler Glacier 200 Talc City Tailings Cyprus Industrial Minerals Keeler USP Oasis Mine 100' Cyprus Industrial Minerals Keeler White Eagle Screenings Cyprus Industrial Minerals Keeler Suggar Mine Cyprus Industrial Minerals Pfizer Inc. Cal Talcron CP 44-31 Eclipse Bonnie Mongolian Pfizer Inc. Cal Cercron CF 96-38 Eclipse Acme Mongolian Pfizer Inc. Cal Cercron CF 96-36 White Eagle Mongolian Apex Cyprus Industrial Minerals Tecopa 100 Panamint LA Furnace Creek Cyprus Industrial Minerals Vanderbilt Co. crude Soft LB LA American Talc Alabama 84 Color Dark 200 Mesh Willow Creek Mine American Talc Alabama 92 Color 99 400 Mesh Willow Creek Mine " JNJH29W_000003728 JNJH29W_000003728 A REPORT ON THE FIBER CONTENT OF EIGHTY INDUSTRIAL TALC SAMPLES OBTAINED FROM AND USING THE PROCEDURES OF THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION Prepared for Administration Occupational Safety and Health . Department of Labor Washington D. C. 20212 Prepared by the Staff of the Analytical Chemistry Division P. D. LaFleur Chief Institute for Materials Research National Bureau of Standards Washington D. C. 20234 May 1977 or DEPARTME AMERCE BUREAU STANDA U.S. DEPARTMENT OF COMMERCE Juanita M. Kreps Secretary Dr. Betsy Johnson Assistant Secretary for Science and Technology NATIONAL BUREAU OF STANDARDS Ernest Ambler Acting Director JNJH29W_000003729 This document has been prepared for the Occupational Safety and Health Administration of the Department of Labor Responsibility for its use rests with that agency JNJH29W_000003730 I. INTRODUCTION A. Purposoef Study This report has been prepared in response to a request received by Dr. Institute for Materials John D. Hoffman Director of the Research of the National Bureau of Standards NBS in a letter dated September 1 1976 from Dr. Morton Corn Assistant Secretary of Labor Occupational Safety and Health Administration Dr. Corn stated that analysis of OSHA In that talc samples for letter their asbestos content was being performed by OSHA and the National Institute of Occupational Safety and Health NIOSH but that the methodology was being challenged by some of those regulated by OSHA Dr. Corn indicated that his request to NBS was composed of two tasks 1 to resolve the variability in the definition of 2 asbestos fibers in talc and to determine the asbestos content of some 80 talc samples to be provided by OSHA Copies of the letter containing this request correspondence between Drs Hoffman and Corn further background information are included as Appendix I. and the subsequent which provide in this report It was agreed by both parties that the first of these tasks i.e. resolving the variability of the definition of asbestos fibers would be a complex would require input from a number of term program which sources both in the private and public sectors In view of this it was agreed that the more limited task that of determining the asbestos content first of the As Dr. OSHA Corn talc samples would be addressed by NBS pointed out in his letter of October 8 1976 this was recognized not to be a research task but would involve an analysis performed according to the procedures given in 29 CFR 1910.1001 JNJH29W_000003731 29 CFR 1910.1001 39 FR 23502 June 27 1974 as amended in 41 FR 11505 March 19 1976 deals exclusively with airborne asbestos and does not describe procedures for nor make any reference to include the following two asbestos in talc It does however paragraphs which are pertinent to the work discussed in this report a Definitions For the purpose of this section 1 Asbestos includes chrysotile amosite crocidolite tremolite anthophyllite and actinolite fibers 2 longer Asbestos fibers means than 5 micrometers asbestos e Method of measurement All determinations of airborne concentrations of asbestos fibers shall be made by the membrane filter method at 400-450 X magnification 4 millimeter objective with phase contrast illumination These regulations do not however describe a measurement procedure but rather prescribe a method of measurement viz phase contrast microscopy A procedure contains a detailed listing of the sampling of the material the specific experimental steps to be performed during an analysis and often descriptions of the mathematical calculations to be performed and their associated of the format for errors A method reporting results of measurement is and defined by a very general statement of the type of measurement to be made from which a specific procedure is developed Since 29 CFR 1910.1001 stipulates only that the method of phase contrast microscopy is to be used for the determina- tion of asbestos NBS requested a detailed procedure from OSHA In response NBS was provided with a copy of the OSHA document Asbestos Fiber in Air - Method No. CAM 239 JNJH29W_000003732 issued March 30 1976 NBS was also informed that the determination of asbestos including asbestos in talc was performed at the OSHA Salt Lake City Utah laboratory OSHA using CAM 239. Method No. CAM 239 however deals only with the determinatioonf asbestos in air using phase contrast microscopy to examine membrane filters Since the determination of asbestos in talc is not described in the document NBS was told to contact Mr. Willard C. Dixon at OSHA to obtain an exact description of the procedure used on talc samples To become familiar with the asbestos in talc procedure an NBS scientist then visited the OSHA laboratory and obtained verbal and written descriptions of the procedure used He spent approximately one and half days at the laboratory observing the procedures and techniques used and discussing them with the OSHA employees At the conclusion of the visit he wrote a detailed report of what he had observed This report was submitted to Mr. Dixon for comment -- -- of the report is included as Appendix II to this document The portions of the report that are enclosed in boxes are the comments added by OSHA personnel NBS scientists also discussed the analysis of talc with a number of other persons Those contacted are listed in Appendix III to this report Prior to commencing the actual analysis of the 80 talc samples we were assured by OSHA personnel that 29 CFR 1910.1001 CAM 239 and the annotated NBS trip report were the only documents appropriate for documenting the analytical procedure to be employed and that the process followed by NBS in developing the detailed procedure was proper JNJH29W_000003733 The detailed procedure followed at NBS is given in Section II of this report however a brief description of the procedure and some comments are given below Phase contrast microscopy with a mounting medium having an index of refraction of 1.546 is used Both fibers a fiber being defined as having a minimum length of 5 ...ma maximum diameter of 5 ...mand a minimum length to diameter ratio of 1 and other particles are counted Early in the study we determined that the identification of asbestos with the procedure used was extremely difficult for the following reasons 1 Since phase contrast microscopy is only a contrast mechanism it does not indicate the degree of difference between the refractive index of the liquid and a particle or fiber For example if a specimen is mounted in a liquid which matches a refractive index of chrysotile then the particles and fibers counted would include all fibers which do not have that particular refractive index e.g. talc anthophyllite wollastonite fiber glass liquid used etc. The same would be true for any other , 2 Most mineral species have three refractive indices therefore correct orientation any for mineral fiber not lying in the the selected liquid will not match and would be visible and would be counted 3 The amphiboles are end members in solid solution refractive As a result there may be a large range of indices from one end member to another One example of such a series would be the actinolite solid solution 4 JNJH29W_000003734 4 In addition most common methods of talc formation are the hydrothermal alteration of ultrabasic rocks such as serpentine and tremolite and the thermal metamorphism of siliceous dolomites Therefore during the formation of talc in contact with other minerals there may be extensive interconversions between talc and the minerals serpentine tremolite and anthophyllite These interconversions may give rise to single particles which have a combination of the talc anthophyllite and serpentine mineral phases 5 There are many materials which may be present in talc which have overlapping refractive indices e.g. Mineral Wollastonite Tremolite Quartz Talc Chrysotile Refractive Index 1.63 - 1.599 1.637 1.55 ; 1.539 - 1.589 1.493 - 1.567 6 Even if the refractive indices were known positive identification of minerals could not be made since there may be interferences from other materials * Deer W. A. Howie R. A. and Zaussman J. Rock Forming Minerals Vol 3 Longmans Green and Co. Ltd London England 1967 pp 126-128 JNJH29W_000003735 In his first letter to NBS Dr. Corn requested a determination of the number of fibers per unit weight or unit volume Also the asbestos as content percent of total weight This was to be based upon the definition of asbestos to be resolved by NBS - Since the definition of asbestos is to be investigated as part of the longer study | reporting results obtained in these analyses in terms of - asbestos was not possible The procedure used by OSHA did not use weight or volume of total sample but instead used percent fibers as a function of total numbers of particles on a slide that convention was followed at NBS Thus all data given in this report are on the basis of numbers or percent of fibers per total number of entities particles plus fibers counted this is referred to as number percent | B. Goal of the Study In view of the current limitations both in the definition of asbestos and in OSHA methods using the the ability to distinguish existing definition of minerals by the asbestos NBS established as the goal for this portion of the study to analyze the 80 talc samples supplied by OSHA to NBS and to report the number percent and if possible the limits of error of procedure fibers using the phase contrast discussed above and outlined in optical microscopy detail in Section II below JNJH29W_000003736 II Analysis Procedure 1 Equipment used by NBS a A Leitz Ortholux 1 microscope equipped with 10x and 40x phase contrast objectives and a phase contrast condenser b Cargille refractive index liquid mounting medium 25 C 1.546 C. Porton Reticle d 10x Periplan oculars 2 Specimen Mounting Procedure Two drops of the mounting medium were placed on a clean microscope slide The end of a new clean metal wire paper clip was dipped into the mounting medium on the slide and then into the sample which was contained in a bottle The material adhering to the wire was blended into the mounting medium on the slide A cover slip was then placed over the preparation Note No attempt was made to homogenize the contents of the sample bottle prior to drawing the specimen A vigorous blending or mixing could itself lead to mechanical breakdown of particles into fragments with fibrous appearance or the separation of one fiber into many fibers NBS did not attempt to homogenize * In order to describe materials and experimental procedures adequately it is occasionally necessary to identify the sources of commercial products by the manufacturer's name In no instance does such identification imply endorsement by the National Bureau of Standards nor does it imply that the particular product is necessarily the best available for that purpose JNJH29W_000003737 the samples as the OSHA procedure does not include homogenization 3 Sample Notation Upon receipt of the samples a scientist who was not involved in the analysis divided the samples and assigned internal NBS numbers This prevented the analysts from knowing which of the 80 samples they were dealing with and permitted blind replicate analyses Note In the original transfer of the samples from OSHA to NBS a list was inadver- tently included which gave the sample identi- fications As soon as this was discovered the list was sealed in an envelope and placed in the NBS Security Office safe until it was returned to OSHA The only person at NBS who saw the list did not participate in any any of the analytical work 4 Microscopy Techniques NBS Phase contrast microscopy was the method used by since it is the only technique specified both in 29 CFR 1910.1001 and in OSHA Method No. CAM 239. The detailed procedure steps which differ followed from the by NBS is described below Any OSHA procedure are noted the 1 Before the analysis of microscope illumination was a specimen was performed adjusted for Kohler illumin- ation the annular diaphragm and shifting elements were aligned and the Porton reticle was calibrated against a stage micrometer The configuration of a Porton reticle is showinn figure calibration and 1. use A detailed description of both the of this reticle is given in CAM 239 JNJH29W_000003738 2 The counting field was defined as the six rec- tangles on the left half of the Porton reticle 3 Fiber dimensions were determined by comparing the length on the and width to the Porton reticle diameters of the calibrated . circles 4 The unknown samples were mounted as described above in a Cargille liquid with a refractive index of 1.546 Note OSHA 25 C with n mounted their samples in . equal to 1.546 and 1.47 liquids The 1.546 index was used to identify quartz and chrysotile which appear blue in bright observation with their Zeiss contrast microscope while the background is light brown and most other materials are brown or black The 1.47 refractive index liquid is carried over from techniques for identifying airborne fibers collected on membrane filters as opposed to the 1.546 liquid used for talc analysis 5 Counting fields were selected by advancing the mechanical stage in a pattern of traverses of the slide in one axis and steps along the rectangular zag pattern other This axis resulting in a procedure was followed until the necessary number of fields was counted 6 NBS used the definition of asbestos fibers discussed above viz a fiber is greater than or equal to 5 ...m in length has a length to width ratio of at least 3 to 1 and has a maximum diameter of 5 ...m Any particle meeting these criteria was counted as a fiber JNJH29W_000003739 7 The samples were continuously viewed over the range of focal planes covering the sample thickness during the counting 8A attempt to preliminary find fibers scan of the slide in the specimen was performed to If a fiber was found the following counting procedure was performed on newly prepared slides Fibers were counted in as many fields as necessary to yield a total fiber count of 100 with the following exceptions a The analysts counted at least 20 fields even if they counted more than 100 fibers . ie and b they stopped at 100 fields even if they did not count 100 fibers 9 For fibers and particles that crossed either one or two sides of the counting field the following procedure was used to obtain a representative count The analysts counted all particles or any fibers of the correct dimensions which 1. Were entirely within the counting area or 2 Crossed the left or bottom sides or 3 Crossed the upper or lower left corner or 4 Crossed both the top and bottom sides Any other fibers and particles were not counted 10 When particle agglomerates covered a large portion of the field of view the field was rejected and replaced by a new one 11 The measurements at NBS were performed @ 500x magnification OSHA measurements were done @ 400x to 450x magnification but NBS could not duplicate that magnification with the equipment available Calculations performed indicate that result in any the differences in magnification would not significant changes in the number of fibers and particles identified 10 JNJH29W_000003740 was 12 0.65 The numerical aperture NA of the OSHA specifies a NA range of 0.65 NBS objective to 0.75 With an objective having NA = 0.65 and at a total system magnification of 500x the smallest diameter of a suspected fiber which could be seen was approximately 0.4 m Hence any fiber 5 ...m long but having a diameter less than 0.4 ...m could never be found unambiguously The class of particles defined as fibers and visible by the procedure is depicted as the cross hatched portion shown in figure 2 Note The OSHA Laboratory in addition to contrast microscopy sometimes uses polarized light microscopy with a retardation plate to distinguish tale plates oriented asbestos fibers on end and from from other asbestos fibers such as glass or organic fibers which may have been present in the samples Since these of the contrast used at NBS techniques are not part method they were not NBS used two analysts working independently and following the procedure given above in obtaining the results on the supplied talc samples While the analysts did not have prior to this study an extended period of experience with the specific methodology employed they have had extensive experience in a wide range of particle characterization techniques including general optical microscopy 11 JNJH29W_000003741 III Preliminary Investigations of Samples Macroscopic A. Description of Samples _ A qualitative description of the 80 samples supplied to NBS by OSHA is given in table 1. The sample numbers are those assigned by OSHA The number after the description refers to the number of the color chip in the Society Color Council Color Name Chart Supplement to NBS Circular 553 B. Scanning of Samples _ Specimenosf the 80 talc samples were mounted on slides by each analyst independently using the dip method described in Section II.2 above These specimens each containing 1000 particles were then scanned rapidly i.e. only the presence or absence of fibers was noted and Fiber counts were not made at this time As a result of these scans specimens taken from 31 samples were identified by both analysts as containing at least one fiber specimens taken from an additional 21 samples were identified as containing at least one fiber by one analyst but no fiber was seen by the other analysantd either analyst for specimens taken no fiber from the was seen by remaining 28 samples IV Countin angd Analysis of Samples A. Samples Noted by Both Analysts as Containing Fibers , analysts As noted above 31 samples as containing fibers during were identifiebdy both scanning Data for these samples are given in table 2. The observed counts for each specimen by each of the two analysts listed as P i.e. fibers divided by fibrous particles + fibers are shown In addition the estimated percent of fibers p and the lower L and upper U limits of a 95 percent confidence interval for the true value of p for the slide on which the 12 JNJH29W_000003742 count was made are given It should be noted that the confidence interval refers only to the portion of fibers on the slide on which the count was made and not necessarily to the true average of fibers in the entire sample Estima- tions of the latter would require that the slide constitute a random sample of a homogeneous material under examination the It is seen that for eight of confidence intervals for replicate these 31 materials slides failed to overlap indicating a lack of statistical compatibility between these replicate determinations To study in more detail the consistency or lack thereof of the results from replicate slides a more exact statistical analysis was performed by considering the actual fiber and particle counts for each material as the elements of a contingency * The calculation of confidence limits and other statis- cal analyses in this report are valid under the assumptions i that the among the particles on a fibers slide are and randomly located ii that the stopping rule of Section II.4 above introduces negligible bias The confidence interval is based on the relation Prob at most c occurrences of event E in N trials = = Prob n F ] 2 ] > a where P is the probability of an event E F is the F statistic with and ,< , degrees of freedom and = ,< c n2 = N This relation is cited in Fisher R. A. and Yates F. Statistical Tables Hafner Publishing Company N. Y. 1963 p 3 13 JNJH29W_000003743 table and calculating the corresponding square value A significant value for square at the 5 percent level of significance was taken to indicate statistical incompati- bility between the replicate slides The samples for which significance at the 5 percent level was thus determined are identified by an asterisk in table 2. Of the 31 materials 17 showed incompatibility between replicate slides at the 5 percent level of significance The fact that over 50 percent of the results of these 31 samples were incompatible suggests problems either of inhomogeneity or of difficulty in the determination of _ fiber morphology or both If the sample is inhomogeneous| the reason for the statistical incompatibility is obvious The problem of very difficult determining as there is fiber often or particle morphology is a great deal of subjectivity in deciding whether or not a particle meets the criteria to be classed as a fiber Photomicrographic examples of 1 a specimen containing unambiguous fibers 2 a specimen in which no fiber can be discerned and 3 a specimen which| required a great deal of judgment are shown in figure 3 a b and c respectively In figure 3 six different fields of view are shown for each specimen three using an optical microscope and three using a scanning electron microscope SEM The SEM fields do not correspond to the optical fields but were chosen randomly In the case of talc samples one must also judge which edge of the It is apparent possible fibers are talc platelets seen on to roll over some of these platelets by moving the cover plate slightly but while doing so one also may roll another platelet into a position where it would subsequently be viewed from the edge * Snedecor G. W. and Cochran W. G. Statistical Methods 6th Ed The Iowa State University Press Ames Iowa 1967 Eqn 8.10.3 p 217 14 JNJH29W_000003744 B. Samples Noted Initially by Both Analysts as not Containing Fibers Because of our concern over the incompatibility of results in the 31 samples in which both analysts agreed there were fibers we decided to reexaminea portion of the group of 28 samples originally classed by both analysts as not containing fibers Ten samples were selected at random from the pool of 28 samples and were scanned a second time Before discussing the results of additional scanning and counting in this group of samples it is useful to calculate the probability of seeing no fibers in a count of N objects particles or fibers The probability is a function of the true fiber content of the material from which the slide is prepared The calculation is based on the assumption that the specimen i.e. the portion of slide is a random sample from the the material on the material being measured According to zero fibers and p is the the binominal distribution in count of N equals N number percent fiber content the probability where 0 of the material Table 3 lists values of this probability for various values of p for 200 500 1000 and 2000. It is evident that the probability of seeing no fibers in two slides of 1000 counts each 2000 is extremely small unless the true fiber content of the material is less than 0.25 percent Even for 200 the probability of seeing no fibers is very small unless the fiber content of the material is less than 2.5 percent One would therefore expect the materials in this group to have fiber contents not greater than 0.25 percent It is also interesting to note that for materials with very low fiber content say 0.01 percent there is only an 18 percent probability of finding at least one fiber in a count of 2000. In order to reach a probability of 95 * Ibid Chapter 8 15 JNJH29W_000003745 percent of finding at least one fiber in such a material one would have to examine at least 30,000 particles For material with a 0.1 percent fiber content the number of particles required to find at least one fiber with 95 percent . probability is 3000. As a result of the second scan on newly prepared slides four samples were still but fibers were observed in the identified as remaining six fiber samples The results are given in table 4 Four samples showed fiber contents larger than 0.25 percent by both analysts Furthermore for two of these samples the two new slides gave incompatible results as shown by the square test These are indicated by an asterisk in table 4 The results obtained from this reexamination of the materials in the group of initial negative scans thus support the interpretations given by the analysis of the samples in the first group inhomogeneity and subjectivity in deciding fiber morphology C. Samples Noted as Containing Fibers by Only one Analyst During the Initial Scan The remaining pool of 21 samples which were noted as containing fibers by only one of the analysts during the initial scan was then examined In all of these cases the percent of fibers given above about was the estimated to be low and the arguments probability of finding fibers as a function of total number of particles are equally valid In this case eight samples were selected for fiber counts Of the eight samples selected seven provided incompatible replicates given further support to the interpretation made on the basis of the other two groups of samples These data are given in table 5. Again incompatible results are indicated with an asterix ] i 16 JNJH29W_000003746 v Conclusions In this report the results of the determination of the fiber content of 80 supplied samples of talc are presented along with a statistical interpretation of these results Of the 45 samples on which fiber counts were made the results for replicate analyses on 26 of the samples were statistically incompatible This incompatibility was not confined to any particular concentration range of fibers As a result NBS deemed it inadvisable to report uncertainty limits for the fiber content determinations obtained on the samples measured Fiber counts could be made using the present procedure on the 35 samples which were not counted but it is doubtful that any useful additional information would be obtained The variability of these results raises several questions regarding the OSHA procedure particularly sampling technique sample homogeneit anyd determining fiber morphology It is NBS that the opinion ae e.g. a homogeneous at even under favorable e.g. homogeneous samples easily identified circumstances fibers etc. the existing OSHA procedure is useful for determining fiber content and not asbestos content Although careful manipulation of the mounting medium might make it possible to identify some of the fibers as asbestos the problem of the definition of asbestos still remains NBS believes that the resolution of the measurement problem including the definition and identification of asbestos will be accomplished only by significant changes in the procedure and probably the method as well In order to complete the tasks requested by Dr. Corn in his letter of September 1 1976 it will be necessary to j arrive at an acceptable definition of asbestos and to develop the necessary measurement techniques and standards ' Once that has been achieved a more meaningful analysis of the 80 supplied talc samples can be accomplished 17 JNJH29W_000003747 Sample 34 35 36 37 38 39 40 41 42 43 44 Table 1 Description of bulk material Description fine white powder 263 fine white powder 263 fine white powder 263 fine white powder 263 fine white powder 263 fine white powder 263 fine white powder 263 fine white powder 263 coarse grains like 92 inhomogeneous fine white powder 93 beige grained nonhomogeneous some dark material some light 93 beige grained nonhomogeneous some dark material some material 93 light white powder 92 fine very light grey powder 92 fine light grey powder 264 fine white powder 263 fine white powder 263 fine white powder 263 18 JNJH29W_000003748 Sample 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Table 1 continued Description fine white powder 263 fine white powder 263 fine white powder 263 light brown powder 264 white powder clumps together in small aggregates 263 white powder clumps together in small aggregates 263 light grey powder 154 grey granular material non- homogeneous 155 light grey powder fine 154 fine white powder 263 fine white powder 92 grey granular material nonhomogeneous 154 fine white powder some aggregation 263 fine white powder 263 white powder clumps together in small aggregates 92 white powder clumps together in small aggregates 263 dark grey granular fragments 265 some small fine white powder 263 fine white powder 9 19 JNJH29W_000003749 Sample 64 65 66 67 68 69 70 71 72 73 74 75 76 78 79 80 81 82 Table 1 continued Description fine brown powder 264 _ fine grey powder 265 fine white powder 264 white powder some aggregation 263 fine white powder 263 white powder gation 263 some aggre- fine white powder 92 white powder some aggregation 263 white powder some aggregation 92 small light grey pebbles and powder inhomogeneous 264 fine light grey powder 264 fine white powder 264 fine grey powder 154 light grey to brown powder 264 dark grey rock fragments but grains 265 some large mostly small fine grey powder 264 white powder fine 9 dark grey rock mostly large fragments with some granular material 265 20 JNJH29W_000003750 Sample 83 84 86 87 88 89 91 92 93 94 95 96 97 98 99 100 101 Table 1 continued Description dark grey rock mostly large fragments with some granular and powdered material 265 dark grey rock almost all large fragments very little granular or powdered material 266 dark grey granular material with some large fragments 265 white and pink rocks very little granular or powdered material 9 coarse granular light brown several large fragments with some powder 93 brown granular geneous 93 inhomo- fine white powder 263 white rock with powder 263 grey and brown rocks 93 fine white powder 263 white powder gation 263 some aggre- fine white powder 263 fine white powder 263 fine fine white powder 92 . beige powder 153 fine white powder 263 white to light grey rocks with a fairly large amount of powder 92 21 JNJH29W_000003751 Sample 102 103 104 105 106 107 108 109 Table1 continued Description large grey rocks with white powder @ the bottom 153 fine white powder 263 white powder 263 fine white powder 263 fine white powder 263 large grey and light brown rocks some powder in the bottom very inhomogeneous 92 fine white powder 263 white powder extensive aggregation 263 22 JNJH29W_000003752 Table 2 Results of the 31 by Both Samples Identified as Containing Analysts on the Initial Scan Fibers Sample No. 1 * 3 4 5 6 * 34 38 41 42 43 45 46 47 49 50 Analyst 1 95 Confidence Intervals Count 2010 LU P * % * 102/760 135/809 13.4 11.1 16.0 16.7 14.2 19.4 100/480 20.8 17.3 24.7 105/660 15.9 13.2 18.9 100/711 14.1 11.6 16.8 158/1606 9.8 8.4 11.4 102/852 12.0 9.9 14.3 101/696 14.5 12.0 17.3 45/652 6.9 5.1 9.1 100/991 | 105/593 10.1 17.7 8.3 14.7 12.1 21.0 103/885 11.6 9.6 13.9 106/682 15.5 12.9 18.5 104/1163 8.9 7.3 10.7 104/543 19.2 15.9 22.7 142/1263 11.2 9.6 13.1 124/659 100/848 18.8 11.8 15.9 9.7 22.0 14.2 Analyst 2 95 Confidence Intervals Count F P * L % U % 125/833 15.0 12.7 17.6 142/1138 12.5 10.6 14.5 103/445 23.1 19.3 27.3 109/670 16.3 13.6 19.3 109/720 15.1 12.6 18.0 83/714 102/586 11.6 17.4 9.4 14.4 14.2 20.7 105/1028 10.2 8.4 12.2 17/451 3.8 2.2 6.0 70/501 106/492 14.0 11.1 17.3 21.5 18.0 25.4 102/829 12.3 10.2 14.7 86/627 13.7 11.1 16.6 103/1155 8.9 7.3 10.7 136/817 16.6 14.2 19.4 102/393 127/600 76/866 26.0 21.7 30.6 21.2 8.8 18.0 7.0 24.6 10.9 * Incompatible replicates 23 JNJH29W_000003753 Table 2 continued Analyst 1 Analyst 2 | 95 Confidence , Intervals 95 Confidence Intervals | Sample Count L U No. F % * * Count -- | F * * % 52 100/919 10.9 8.9 13.1 54/767 7.0 5.3 9.1 56 72/900 8.0 6.3 10.0 54/581 9.3 7.1 11.9 | 58 60 48/1863 100/1285 2.6 7.8 1.9 6.4 3.4 9.4 29/503 5.8 3.9 8.2 B 60/1190 5.0 3.9 6.4 68 75 76 87 92 94 95 96 104 - 109 ae 67/1901 87/2237 111/1474 105/1245 3.5 3.9 7.5 8.4 2.7 3.1 4.4 4.8 6.2 7.0 9.0 10.1 100/759 48/471 101/329 35/3276 13.2 10.2 30.7 1.1 10.8 15.8 7.6 13.3 25.8 36.0 0.7 1.5 43/1947 2.2 55/1571 3.5 69/959 7.2 111/2674 4.2 1.6 2.6 5.6 3.4 3.0 4.5 9.0 5.0 79/1685 . 4.7 3.7 5.8 | | 109/686 . 15.9 -13.2 : 18.8 . . 100/522 19.2 15.9 22.8 5 55/527 10.4 8.0 13.4 111/314 35.4 30.1 40.9 a 105/906 11.6 9.6 13.8 72/1674 4.3 3.4 5.4 | 37/2820 1.3 0.9 1.8 36/625 5.8 4.1 7.9 | 101/773 13.1 15.6 104/1890 5.5 4.5 6.6 z * Incompatible replicates NOTE Confidence limits were calculated formula and a few may be in error in the last place using an approximate by one or two units 24 JNJH29W_000003754 Table 3 Probability of Finding No Fibers in Counts of Size N True Fiber Content in Percent - 0.01 0.05 0.10 | 0.15 0.20 0.25 | 0.30 0.40 0.50 0.60 0.80 1.00 1.50 | 2.00 2.50 200 0.98 0.90 0.82 0.74 0.67 0.60 0.55 0.45 0.37 0.30 0.20 0.13 0.05 0.02 0.01 Coou f n Cout nt 500 1000 0.95 0.90 0.78 0.61 0.47 0.61 0.37 0.22 0.37 0.14 0.29 0.22 0.08 0.05 0.13 0.02 0.08 0.01 0.05 0.01 0.02 0.01 0.01 2000 0.82 0.37 0.14 0.05 0.02 0.01 0.01 25 JNJH29W_000003755 | Table 4 | Results of the 28 Samples Identified by Both Analysts as | Not Containing Fiberosn the Initial Scan | , Analyst 1 . _ | Analyst 2 | Sample No. . Count |P 95 Confidence Intervals P L ( %( . | | 9.5 Confidence Intervals | Count P U F 8%% a 36 | not counted 37 54 55 ~~. + not counted 22/828 2.7 : not counted . 1.7 ~~ 4.0 a a 8 5/899 0.6 0.2 | 1.3 61 not counted a +62 +63 4/1395 0.3 0.1 0.7 0/1410 0.0 0.0 0.2 | no fibers observed on second scan +65 +66 70 8 no fibers observed on second scan 18/1545 | 1.2 0.7 1.8 10/1598 0.6 0.3 1.1 | | not counted | 71 not counted | a 72 not counted | 73 not counted 78 not counted 80 not counted a 81 not counted | * Incompatible replicates Samples selected for second scan . 26 | a JNJH29W_000003756 Table 4 continued Sample No. +82 84 86 +88 89 91 93 +98 +101 102 107 \ 108 Analyst 1 95 Confidence Intervals Analyst 2 95 Confidence Intervals Count 0100 L U F 0100 % % Count F] P * L % U ( no fibers observed on second scan not counted not counted no fibers observed on second scan not counted not counted not counted 18/746 2.4 2/200 1.0 not counted 1.4 0.1 3.8 3.6 9/522 6/230 not counted 56/833 6.7 5.1 8.6 18/1165 1.5 0.9 2.4 * Incompatible replicates + Samples selected for second scan 27 JNJH29W_000003757 | Table 5 a a Results the 21 Samples Identified as Containing by Only One Analyst on the Initial Scan Fibers __. Analyst 1 | -_ Analyst 2 a 95 Confidence Intervals 95 Confidence Intervals | Sample Count p L U Count P U No. P( %# F (%% | | 35 not counted B .39 29/813 3.6 2.4 5.1 9/550 1.6 0.7 3.1 ' 40 not counted | 44 100/905 11.0 9.1 13.3 -. 81/418 19.4 15.7 23.5 48 not counted | | 51 45/833 ry 53 5.4 4.0 7.2 - 50/1091 4.6 3.4 6.0 39/1354 42/1771 2.9 2.4 3.9 1.7 3.2 57 not counted 8 59 not counted | 64 not counted | 67 not counted a 69 not - counted 74 79 83 not counted' not counted 18/430 4.2 2.5 6.5 | . 3/630 0.5 | 97 99 36/1861 30/1212 1.9 2.5 1.4 1.7 2.7 3.5 18/1693 1.1 0.6 1.7 a 1/739 0.1 0.0 0.8 | * Incompatible Incompatible replicates 28 JNJH29W_000003758 Table 5 continued Analyst Analyst 1 95 Confidence Intervals Sample : No. 100 Count : F p L 8% not counted U $ 103 | not counted 105 86/1498 5.7 7.0 106 not counted 2 Analyst 95 Confidence Intervals P P L U .. % % % 2.3 5.0 * Incompatible replicates 29 JNJH29W_000003759 we N 1234567890 1234567890 Be 2N 1234567890 1234567890 246 108 11 Figure 1. Porton Reticle 30 JNJH29W_000003760 MAXIMUM LENGTH NOT SPECIFIED Zz 30 j= 28 + 26 24 m m 22 LENGTH LENGTH LENGTH 20 LENGTH LENGTH PARTICLE 18 - PARTICLE PARTICLE PARTICLE 16 PARTICLE 14 12 FIBER 7 MAXIMUM DIAMETER ' 5.0 ...m : . 10 8 6 4 2 0 0 \\ \ , LENGTH 3 OR GREATER MINIMUM LENGTH 5.0 ... RESOLUTION LIMIT OF MICROSCOPE 0.4 ...m 1 1 LL 1 1 1 2 3 4 5 PARTICLE WIDTH ...m | . j 6 Figure 2 Fiber dimensions that would be observed as per OSHA definitions and resolution limit of microscope 31 JNJH29W_000003761 Sample 92 Light Microscope Scanning Electron Microscope y+ aes ' od . ve ow . 1 > sy & Net . id oc. 20...m ry \ we C ve s New . sa & 4 =? 4 a 2 wae ~ s < . | ... SS / . i N * " tee . Lay. ee Ay Yo, . a. EN v * > ~ 3, . % - Oo .- . te, oe + al N he a4 8 Bu 5 Te mm oe . . | oy ~ aol. , Shoat, fy Yes ys ae a oY Sy NN an ae PONS 20...m 20...m 20...m Lr 4 : rw ry ie i | eee] y & < A oY P Figure 3a JNJH29W_000003762 - Light Microscope Sample 81 Scanning Electron Microscope e & a a *~ > Qo: tos : . o * bd ad *, . . . . a. \ e ^' aS Pa < o a e & . ^' i . a < - @ st ae 48 Or % : fe 4 > . Q oo . . n oe % : e ^' t - & vs. . |A, ey . es i a io : e s , . ~ Fars Figure 3b JNJH29W_000003763 . : Light Microscope Sample 108 Scanning Electron Microscope ~~. z . 6 4. # a * f set ~& ( hy \ . ., rod a wy , v . wy oe 48 wn . ee NN < 14 14 NY ' \ : 20... a 20... j . & . 3 ) * ~ 48 < M4, ro a ... ! : s . bs. fo" a * od ees ee a th MC Figure 3c JNJH29W_000003764