Document b68XE260vmzrQxg6zBkqropO

C. R. F^0 K y EQUIPMENT AND PROCEDURES FOR MOUNTING MILLIPORE FILTERS AND COUNTING ASBESTOS FIBERS BY PHASE CONTRAST MICROSCOPY Stephen G. Bayer Ralph D. Zuitvalde Thomas A. Brown 4 Bureau of Occupational Safety and Health 1014 Broadway Cincinnati, Ohio 45202 JULY 1969 U. S DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE PuhMe U-cAJ; i>r Conout.icr Protection cm? T.i,virei.-\ istal Health Service Enviro-iuicrtal Control Ad; inistration txtiner RMC0086742 004226 TABLE OF CONTENTS INTRODUCTION EQUIPMENT'LIST ' LABORATORY SET-UP PRELIMINARY MICROSCOPE SET-UP MICROSCOPE SET UP AND THE PROCEDURE FOR OBTAINING KOHLER ILLUMINAIION DETAILED INSTRUCTIONS FOR BAUSCH AND LOUB BINOCULAR MICROSCOPES FILTER MOUNTING Set-up prior to mounting Mounting procedure MICROSCOPE PRECAUTIONS AND MAINTENANCE COUNTING PROCEDURE ' FIELD MONITOR DISCUSSION CALOULATUJN OK CONCENTRATION ADDRESSES 1 2 2 3 5 8 9 10 11 12 13 14 17 TXT1NER BMCQ086743 004221 FOREWORD To determine concentrations of asbestos dust in air for compari son with established hygiene limits, a simple reproducible method is required. A simple and inexpensive sampling method uses disposable (reloadable if desired) plastic membrane filter holders, pre-loaded with membrane filters. These membrane filters may be rendered transparent and * the asbestos fibers counted with a phase-contrast microscope at 430X (or 400X). This method has been used by the Asbestosis Research Council in Great Britain and the U. S. Public Health Service in the United States of America. It is specified in the proposed change for asbestos in the 1968 threshold limit values of the American Conference of Governmental Industrial Hygienists. Uniform procedures must be used for carrying out these counts if reproducible results are to be achieved. Detailed equipment and proce dures used by the U. S. Public Health Service are described here. txtiner RMC0088744 004228 \ - 1INTRODUCTION For several years, a set method for counting and .sizing airborne particulate matter, which has been deposited upon membrane filters, has been used. The filters used in this technique are 37 mm diameter cellu lose ester membrane filters manufactured by Millipore Corporation, (cat. 4 no. AAWP03700). The slide mounting technique refers only to these filters, and will not work for any others. The filters may be purchased premounted in convenient field monitor cases, and are ready for sampling. The filters are nearly 100% efficient for any asbestos dust, even for fibers with diameters much smaller than the 0.8 micron (p) pore size. Sample preparation for electron and optical examination are both relatively simple, S14de mounts of the filfnrp are semifcpermanent. The following procedures and recommendations will produce accurate results, if each step is performed exactly as indicated. TX TIMER RMC0088745 004229 - 2- EQUIPMENT L7ST 1. Tab1e 2. Adjustable chair 3. Phase contrast microscope 4. Ribbon filament illuminator or (built-in illuminator) 5. Eye piece reticle (Porton type) 6. Lens tissue 7. Small camels hair brush 8. Slides 9. Cover slips 10. Spatula 11. Tweezers 12. Scalpel 13. Wheaton Balsam bottle LABORATORY SET-UP It is important to provide a suitable counting area, for the room in which the counting is to be dene has a great bearing upon the mlcrosconlst. It should be out of the way of normal traffic, and be kept as free from dust and smoke as possible. The tables on which the microscopes are placed should be oe free from vibrations and shocks as possible. An adjustable chair will do much to add to the comfort of the counter. rMC0086748 004230 PRELIMINARY MICROSCOPE SET UP Before any dust sizing or counting can be done, proper equipment must be at hand. This section describes the required equipment. The illuminator should be small and reasonably compact. Ribbon filament illuminators are generally much easier to use. The illuminator must incorporate a condensing lens, so that the enlarged image of the lamp filament may be focused in the plane of the substage condenser diaphragm. The illumnator must also have an iris diaphragm located as near as possible to the condensing lens. The iris serves as a field diaphragm and is focused in the plane of the specimen. The microscope used must have a substage condenser fitted with an iris diaphragm. This iris serves as an aperture diaphragm. The microscope should have a calibrated reticle inside the non-adjustable eyepiece. The reticle should be small enough that all the counting field is in focus (if the flat field objective and eyepieces are used, essentially the entire field will be in focus). The microscopes must be equipped with phase contrast accessories. Using phase contrast, even objects with almost , the same_refractive index as the mounting media can be seen. Light waves which travel through such a specimen are retarded by a fraction of a wave length to produce a change in phase. The phase contrast optical system reveals these phase changes as light or dark contrast against the back ground. This procedure was written by a user of Bausch and Lca.b phaseequipped microscooes, so that microscope set:-up procedures correspond with TXTINER RMC0Q86747 004231 -4 - these. However, any good microscooe with phase contrast accessories will be satisfactory. For continual routine examination of filters, the binocular type microscooe is much more comfortable. The use of a first surface mirror is recommended, but not necessary. By utlizing a second surface mirror, multiple images of the illuminator field iris are formed which will detract from the crisoness of the final image. 4 As mentioned previously, the microscope must contain a reticle. Any reticle, such as the Porton or Patterson Clobe and Circle, which projects a constant counting area and has provision for sizing, will work. The Porton reticle which we use outlines a rectangle that fits easily within the periphery of focus. The rectangle is divided into two squares. The left square is divided into six rectangles which constitutes the counting area. Above and below the large rectangle are a series of circles in which every other circle doubles in diameter. Hence the third is twice the diameter of the first; the fourth is twice the size of the second, etc. The right half of the rectangle contains a scale for extending the size above the number nine circle. The formula D=L 2^ describes the circles sizes. The diameter D is found from L which is the unit of length, and N which represents the number of the circle. L is determined by cali bration with a stage micrometer. The entire length of the rectangle is 200 L units. By measuring the length and dividing by 200, L is obtained and the circle sires may be calculated. Whenever a microscope is disassembled or cleaned, the retie'e calibrat ion should be checked. Another fact to fair. TX TIMER RMC0086748 004232 - 5into consideration is that changing the interpupillary distance of the binocular will change the calibration, so the microscopist may want to check the calibration at both extremes of adjustment. The counting area on the reticle should be kept as clean as possible, as dirt on the reticle is in focus and may be counted. 4 MICROSCOPE SET-UP AND THE PROCEDURE FOR OBTAINING KOHLER ILLUMINATION By utilizing equipment that meets the requirements just mentioned, any counter may achieve comparable counts after some practice. This section will deal with setting the microscope up and obtaining Kohler illumination. It is extremely important that, every step be followed exactly as indicated. 1. Place the microscope on a flat, level surface at a height such that the eycoieces may be observed without strain or discomfort. 2. Place a moderate dust sample upon the stage. 3. Place the illuminator directly in front of the microscope. Sight across the two and be sure they are aligned. For coil filament _ bulbs the illuminator iris should be ten inches from the center of the microscope mirror. For ribbon filament bulbs, the front of the filter holder should be seven inches from the center of the plane side of the mirror. Never use the curved side. 4. Remove all diffusing filters from the system and insert a neutral density filter and a clear blue filter. Blue or grecu colored filters may be used at the discretion of the microscopist. txtiner RMC0086749 004233 -6NOTE: Where the microscope includes a built-in illuminator to give Kohler illumination, the above steps will not all be necessary, REVIEW A. Check microscope and illuminator alignment, B. Check the distance between the microscope and the illuminator. C. Be sure that you are using the flat side of the mirror. 0. Make sure that there are only two filters in the system. -v 5. By means of the focusing knob on the side of the substage con denser assembly, raise it until the upper lens nearly touches the botton of the slide. Remember that the free working distance of the condenser is in the order of 1.2 mm and that the slide is about 1 mm thick. 6. Turn on the illuminafcr. Using the tilt controls, direct the beam onto the center of the mirror. Then, by tilting the mirror , direct the beam upward into the condenser. ""'7.'" Close the substage iris completely. Open the illuminator iris _ all the wajy. 8. By means of the focusing controls on the side of the illuminator, focus the image of the filament on the botton of the substage iris. This may be done by leaning over the microscope and observing the subntflgc iris in the microscope mirror. (On such models ac the Bausch & Lor.'o PR-27, there is a fine focus knob at the rear of the illuminator). In that case, move the condensing lens all the way forward and trim the focus with the fine focus knob. TXTINER RMC0086750 004234 7 9. Open the substage iris about half way. REVIEW A. Check the distance between the slide and condenser. B. Be sure that the beam is striking the center of the mirror, and that it is being deflected upward into the condenser. C. PI esse repeat sten 7. D. Check step 8. If the image is not in focus now, correct it. Do not continue until the filament is correctly focused. E. Please repeat sten.9. 10. Put the 10X objective in place and focus on the sample. This is done as follows: First, looking from the side of the microscope, lower the objective until it gets very near to the bliue. Then, by looking through the eyepieces, focus up. Never focus down with coarse focus when looking through eyepieces. A word of caution; The objective lenses are very expensive, so be careful not to grind them through the slide. Always focus up. Nov; trim the focus with fine focus knob. Focus sharply on the sample. Secondly, close the field iris fully. If the condenser is nearly in focus, you should see a bright spot of light. By using the condenser focus knob, bring the field iris into- sharp focus. Now, both the field iris and the objective are in focus on the r.a:::?le. If there appear to he f.ultiple iwages of the field iris, it is because of the second sv.ifrcc mirror. Soir.o.of the light: waves are reflected from the first surface, resulting in secondary images. TXTINER RMC0086751 004235 - 812. If the image of the field iris is not centered, re-center it by tilting the mirror. If the color around the field iris is not uniform, recheck the tilting of the illuminator. REVIEW A. Check and be sure you are focused on the sample. 10X objectives have a relatively long focal length and it may possible^to focus on: (a) the top of the cover slip. (b) the sample, (c) the botton of the filter, (d) the top of the slide, (e) the bottom of the slide. (f) the top of the condenser. So be sure of the focal plane. B. Be sure that the field iris is focused in the sample plane. Check this often when examining samolas. As the sample focus changes, so does the condenser focus. C. Recheck the centering and tilt of the illuminator. DETAILED INSTRUCTIONS FOR BAUSCH AND LO!m BINOCULAR MICROSCOPES 1. Leave the microscope phase rind on 0. Insert the telescope that is supplied with the kit into the right eyepiece tube. Focus on the dark phase ring. Open and close the substage iris to be sure that it is centered in relation to the objective phase ring. If it is not in the center, loosen the set screw on the condenser mount and prcnerly seat the condenser. Then retighten the set screw. This should very seldom be necessary. Do not force anything and be careful and patient. When you are satisfied that the condenser is aligned, open it all the way. 2. Turn the ohr.se wheel to 10. This shows that the 10X phase 004236 TX TINER RMC0086752 * -9ring is in place. Look through the telescope again. By using the adjustment screws on the side of the condenser, move the rings until they are perfectly concentric. When changing phase rings, move them carefully, so as not to knock the condenser out of alignment. 3. Turn to the 43X objective. Carefully turn the wheel to the 43 phase ring. Align the two rings in the same manner as per formed in step 2. 4. Remove the telescope and replace the eyepieces. Again, check the condenser focus. You are now ready to examine the sample at 430X, assuming that you are using 10X eyepieces. FILTER MOUNTING Set-up Prior to Counting Have available at hand a quality scalpei and a supply of no. 10 curved blades, a pair of tweezers (fine pointed are preferred), a spatula or fire polished glass rod and a box of lens tissue. Slides (1" x 3" or 25 x 75mm) with frosted ends are best because one may label the slide with the date^ sample number, etc. It is advisable to use quality number 1-1/2 cover slips. Host dry objectives are corrected for this thickness cover glass. The mounting media should be kept in a Wheaton balsam bottle. The edge around the lid should be coated with stopcock grease to keep out the surrounding air. The mounting solution may no- be prepared. A one to one solution by volume of dimethyl phthalate and diethyl oxalate is poured into the balsam txtiner RMC0086753 004231 - 10 bottle. Then add 0.05 gram of filter material for each milliliter of solution. . The added filters increase the viscosity of the solution. Before using the solution, all of the filter material must be dissolved and the solution must be of uniform consistency. This may require a day or so with frequent stirring. Refrigeration may add to the shelf life of the solution. ' Mounting Procedure u Keep in mind that cleanliness is imoortant. First, lay down two pieces of lens tissue; one directly in front of you and the other to the left or right for the mounting tools. Next, wipe the scalpel, tweezers and glass rod or spatula with lens tissue. Holding a slide by the frosting, wipe it clean. Lay it down with the frosted end toward you. Even pre cleaned slides must be cleaned this way. Hold a cover slip by the edges between the index finger and the thumb, and clean it in the same manner as the slide. Place the cover slip so that one edge rests on the unfrosted end of the slide and the other edge rests on the lens tissue. Be sure that the lower surface does not come into contact with the lens tissue. Using the glass rod, or dropper, dispense a small drop of the mounting media onto the center of the slide. P*eplace the rod or dropper into the solution bottle and cover it. Using the spatula, spread the solution into a triangular shape. While the fluid is spreading, cut a wedge of corresponding size from the filter. Place it upon the mounting media, sample side ud. Pick up the cover slip and place it on top of the filter. Press lightly on the cover slip to be sure the mounting media has made contact with it. Label the slide before completing any other TXTWER RMC0086754 004238 11 - slide. Soraetine, after an hour or so, the filter may not have cleared. Usually, this can be cured by pressing lightly on the cover slip with a pencil eraser that has been wrapped with lens tissue. If the filter has been used to filter liquids or is damp, it will require drying, for it will not clear unless completely dry. Use only enough solution to clear the filter. If too much solution is used the sample may spread and give an erroneous count per unit area. The filter should be counted as soon as possible because the solution may eventually form crystals that look like fibers and may be mistaken for part of the sample. After a little practice and experience, several samples may be mounted at the same time with excellent results. Remember to keep the area in which mounting is done as clean as possible to prevent contamination df the filter. MICROSCOPE PRECAUTIONS AND MAINTENANCE Quality lens tissue is a must. The microscopist should use it for any kind of lens cleaning. It should be as lint free as possible. It may be wrapped around the blunt end of a small camels hair brush and used to clean the eyepieces. Never wipe the inside of the microsocoe body. If it is necessary to remove dirt from the inside of the tubes, blow it out with an aspirator bulb, khenever you arc using immersion oil, be sure that you wipe all surfaces that were in contact with the oil. Generally, solvents should not be used when cleaning lenses. Alcohol, like moot solvents will dissolve the lens mounting cenent, which may ruin TX TIMER RMC0086755 004239 12 the lens system. Xylene should be used sparingly to remove immersion oil. Use a camels hair brush to clean first-surface mirrors and noncritical lens surfaces. Never wipe first-surface mirrors with lens tissue. Avoid touching a lens surface with fingers as the fingerprint has a tendency to etch into the lens surface. COUNTING PROCEDURE Place the sample on the stage and focus on it. Since the sample is retained in the top ten fifteen microns of the filter, be sure that you are focused in the proper plane. The reticle in the left eyepiece is used to define the counting area. The reticle should be calibrated prior to being used. The total fiber count (a fiber is anything three times as long as it is wide) should be at least iOO fibers, or twenty tie ids, whichever is less. It is advisable to made as large a count as practical to get an accurate average. If a fiber crosses the limits of the counting field, only those crossing either or both of two adjacent sides are counted. For example, a fiber crossing the top or right, or possibly both sides would be counted. The sides chosen are at the discretion of the counter, but any counter must always use the same sides. The fibers counted are estimated as to length,using the circles at the top of the reticle. Our practice has been to record all fibers seen, all fibers longer than five microns and all fibers longer than 10 microns, llovever, for comparison with the ACGIH TLV (1968), only the longer than 5>i fibers need be counted. TXTINER RMCOO86750 004240 4 J' - 13 - FIELD MONITOR DISCUSSION Membrane filters may be purchases pre-loaded in plastic holders (Aerosol Analysis Monitors). The Monitors consist of three sections. The filter is held between the middle and bottom sections. Between the I membrane filter and the bottom section lies a support pad. The calibrated i ! pump, designed to draw a known and constant supply of air, is always connected to the bottom of the field monitor case. When-many loaded cases are taken into one particular area for sampling, a blank or control filter (meaning a loaded field monitor case) should bs taken out to the area, brought back unused and counted. This will determine what degree of general I : contamination is present on the filters. We have found that banding the field monitor cases with cellulose bands greatly reduces the general i contamination of the filters. The bands may be purchase from Walter H. Jelly and Company, Inc. They are white, opaque, size 41 x 25 and come `4 packed in solution S-132. .Upon removal from the solution, the bands are !' j l slipped around the middle and bottom joints, or around all joints, depending upon whether the sample is going to be drawn through the top section plug hole, or the entire top section removed for "open" sampling. The latter procedure is recommended for asbestos dust sampling since it results in a more even sample distribution over the entire exposed filter surface. Convenient personal sm.'r.litig pui.ps, tudi as those distributed by Mine Safety Appliances Co., Willson Vi.-odv.etF Division or Union Industrial are excellent for short term, low i-te (around 2 lorn) sampling. A sampling pump is connected to a 3 foot length of non-collcpsable, one quarter inch, rubber tubing with a male Lcur slip adapter (stock number Lll/L, .available from Becton, Dickson and Co.) inserted into the other end. This enables one to TX TIMER RMC0086757 - 14 connect the hose directly to the case by simply inserting the adapter into the plug hole at the bottom of the case. Field monitor cases may easily be re-used. The plugs and all sections are separated and placed in warm detergent water. The parts should be scrubbed thoroughly and rinsed in tap water. However, if the filters are to receive any chemical analysis, the cases^ should also be rinsed in distilled water. The cases should be allowed to dry in a cleann area (a clean room is preferable), to reduce contamination. The clean area is equally imoortant when loading the filters into the cases. The filter pad (the thicker, fibrous disc) is placed in the bottom section. The filter is placed directly on the pad. The middle and top sections are added, the case is pressed tightly together, and the top plug is inserted. Replacement of the bottom plug is uot necessary. A cellulose band is then place around the case and after the band dries, the unit is ready for sampling. Sample code numbers, etc. may be written on the band or upon the filter case, first making sure the markings can be removed when and if it is necessary. Additional information concerning filters and field monitors may be obtained-from Killipore Corporation. CALCULATION OF CONCENTRATION Wien a sample is taken, pertinent infornration about the sample should be recorded at the sampling site. First, the sample number should be written on the field monitor case and the sample ticket. Next, enter a description of his operation in the appropriate space. If the sample is a general air sample and docs not pertain to any particular employee, TXTINER RMC0086758 004242 15 - write ''general air sample" In the employee's name space. Information about the `area may be written in the "description of operation" space. If you have several puraos which are identical in appearance, but have different flow rates, it would be a good idea to assign them instrument numbers. This enables you to keen accurate records of maintenance and califbration. When instrument numbers are kept it is not necessary to * enter the flow rate at the sampling site. It may be entered later from the record cards. Otherwise, enter the flow rate at the sampling site. When a number of filters are taken into a general area a control (or blank) is taken along. This should be assigned a number and entered in the blank number space. Do not assign blank filters duplicate numbers. When the sampling pump is turned on, enter the time in the "time on" e n flP- fk - esmnl a q u rnplrd nnf*oe c- i .....e..*.. exhaust hoods, fans, window ventilation, etc. These notes should be entered in the "description of controls". The sampler should then sign his name or initials at the bottom of the sheet. After sufficient time has passed, the sampling instrument should be turned off and the time recorded in the "time off" space. The difference between~"time on" and'"time off" space. The "total air volume" may be found by multiplying the flow rate (expressed liters per minute) by the total time and recorded in the appropriate, space-. After the sample has been taken, brought back into the lab and mounted, the counting procedure is next. The microscope must be properly set up. Place the slide to be counted on the mechanical stage. Focus on the sample a short distance away TXTINER RMC0086758 004243 16 from the edge. Never count close to the edges of the filter because the filter will spread a little and lower the count. Now, enter the date, sample number, blank number and field area on the count sheet. The counter should initial the form in the "initial"soace. The sized fibers are entered from right to left across the form, first entering the >!0p fibers, then the >5p fibers and finally, all fibers seen, called the total. After 100 fibers or 20 fields are counted and recorded, all of the vertical columns are added up and the totals are entered under their corresponding columns. Divide the totals at the bottom by the number of fields counted to determine the average number of fibers per si2e range- per field. By using information on these two sheets the concentration in fibers per cubic milliliter may be calculated and entered in the "con." space on the count sheet. Concentration (Av. Fiber Cnt.) (filter area) (field area) ( Sample volume) (1000) Av. Fiber Count: Average fiber count per size range --------- - Filter area: 855 mm^ for 37 mm dia. membrane filters Counting area: Reticle calibrated in mra^ Sample volume: total time x flow rate, express in liters 1000: Converts liters to milliliters If blanks are ucc-d, subtract the average blank count of the sane 8izc range froru the average fiber count. TXTINER RMCOO8670O 004244 17 ADDRESSES Millipore Field Monitor Cases (complete) Cat. No. MAVP 037AO Millipore filter (W. Fads) Cat. No. AAWP03700 Millipore Filter Corporation Bedford. Massachusetts ort?1' Porton Reticle Cat. No. 30084 Patterson Globe & Circle Reticle Cat. No. 30083 Edmund Scientific Co. 701 Edscorp Building Barrington, New Jersey 08007 Wheaton Balsam Bottle Cat. No. 2244 Arthur H. Thomas Company Post Office Box 779 Philadelphia, Pennsylvania 19105 Adapters, hose end for 1/4" tubing to male leur slip Cat. No. LN/L Beeton, Dickinson and Company Rutherford, New Jersey White, opao4ue, cellulose bands, 41 x 25 No. 28 Walter H. Jelly & Co., Inc. '' ........ 2822 Birch Street Franklin Park, Illinois 60131 Personal Sampler Ml:. IT Willson-Products Division Reading, Pennsylvania Monitaire Sampler Mine Safety Apnliances Co. Pittsburgh, Pcnnr.ylv'nifa Unico Telematic Nodel C-110 Unico Environmental Industries, Inc. Fall River, Massachusetts TX TIMER RMCOO86701 004245 Oooori K:;-- J G OOOoooooo. PATTERSON GLOBE AND CIRCLE o O oooQOO c O O O ( ') C ') ( \ 'v PORTON RETICLE TXTINER RMC0086762 004246 1 I UJ (A < Z BLANK o> | FIELD AREA IN Il tALS FLOW RATE BLANK 1 uu.. o hi 2 H Ui lJ o> 2 z o H- )- < X UJ 0. HHo- <K ho- UJ < o o zz 2 o Ui 2 (/> UUJJ UJ _J g a1-. oa-1. U-1J hro o- ir aUJ o TX TIMER RMC0088783 004247 INST. PHASE CONTRAST MICROSCOPE 004248 TX TIMER RMC0088764 LAMP CONDENSER IMAGED IN SPECIMEN PLANE 4 KOEHLER ILLUMINATION 004249 TXTINER RMC0086765 VIII. APPENDIX I Air Sar.plJ.np, Methods 63 In the study of asbe3tosis conducted by Dreessen et al. midget tmpinger count data were used ae an estimate of dust exposure. All of the dust particles seen, both grains and fibers, were counted since too few fibers were seen to give an accurate measurement. The resulting count concentration was a measure of overall dust levels rather than a specific measurement of the asbestos concentration. This method was satisfactory at that time since exposures were massive and the control measures installed to reduce overall dust levels also reduced the asbestos dust levels. As dust levels were reduced, it became necessary to measure the biologically appropriate attribute of the dust cloud. At equal levels of overall dustiness, the concentration ox asbestos could vary considerably from textile manufacture (75-35%) to insulation (5-15%). Furthermore, "if the limit were lowered below the 5 mppcf used previously and dust counts taken by the implnger technique, it would be necessary to consider the effect of background dust, which could be as high as 1 mppcf. A number of methods for measurement of asbestos dust concentrations have been used in the-NIOSH epidemiological study of the asbestos product 73 7A 75 76 ..industry. * * ' Based on these data, the preferred index of asbestos exposure is the concentration of fibers longer than 5 )m counted on 71 72 membrane filters at 43QX with phase contrast illumination. * This index is utilized in the method adopted as the standard field sampling method by the Public Health Service. VIII-l 004250 TXTINER RMC0088766 longer than 5 jim in length are counted in preference to counting f-~- fibers seen in order to minimize observer/microscope resolving power variability. Furthermore, the British define a "fibre" as a particle, "<- length between 5 jim and 100 yn and having a length-to-breadth ratio of et least 3:1, observed by transmitted light by mean3 of a microscope 62 c\ t magnification of approximately 500X." Although the British have refrained from standardizing on a single of measurement, recent measurements have been performed by a rnt-irod essentially identical to the fiber-count method described in denn.i below, and the British hygiene standards for use with their 62 regulations are stated in these terms. Pr i r.-z foies of Sampling L dust sampling procedure must be designed so that samples of actual, dust concentrations are collected accurately and consistently. The results of the analysis of these samples will reflect, realistically , the c-:>ncentrations of dust at the place and time of sampling. I.r. order to collect a sample representative of airborne dust, which in li.c.eiy to enter the subject's respiratory system, it is necessary to jonl.tt.on a collection apparatus near the nose and mouth of the subject ,r In r.is "breathing zone". TTne concentration of dust in the air to which a worker is exposed 'll v'ury, depending upon the nature of the operation and upon the . ;)C mf work performed by the operator and the position of the operator Intv.ve to the source of the dust. The amount of dust inhaled by c. r'<er can vary daily, seasonally, and with the weather. In order to -irepresentative samples of workers' exposures, it is necessary coll.set samples under varying conditions of weather, on different VIII-2 TX TIMER RMCOOS6787 004251 days, and at different times during a shift. The percentage of working time spent on different tasks will affect the concentration of dust the worker inhales since the different tasks usually result in exposure to different concentrations. The percentage can be determined from work schedules and by observation of work routines. The daily average weighted exposure can be determined by using the following formula: (Hours X cone, task A) + (Hours X cone, task B) + etc. 8 Hduds (or actual hours worked) The concentration of any air contaminant resulting from an industrial operation also varies with time. Therefore, a longer sampling time will better approximate the actual average. * With the following recommended samoling procedure, it is possible to collect samples at the workers' breathing zones for periods from A to 8 hours, thus permitting the evaluation of average exposures for a half or full 8-hour shift--a desirable and recommended procedure. Furthermore, dust exposures of a more normal work pattern result from the use of personal samplers. In evaluating daily exposures, samples should be collected as near as possible to workers' breathing zones. Collecting Sample The method recommended in this report for taking samples and counting fibers is based on a modification of the membrane filter method described by Edwards and Lynch. VIII-3 txtiner RMC0086768 004252 The sample should be collected on a 37-millimeter Millipcre type AA* filter tr.ountcd in en open-face filter holder. The holder should be fastened to the worker's lapel and air drawn through the filter by means of a battery-powered personal sampler pump similar to those approved by NIOSH under the provisions of 30 CFR 74. The filters are contained in plastic filter holders and are supported on pads which ' also aid in controlling the distribution of air through the filter. To yield a more uniform sample deposit, the filter-holder face-caps should be removed. Sampling flow rates from 1.0 liter per minute (1pm) up to the maximum flow rate of the personal sampler pump (usually not over 2.5 1pm) and sampling time from 15 minutes to eight hours are acceptable provided the following restraints are considered: (a' In order to obtain en accurate estimate of the number of fibers the statistical error resulting from the random distribution of the fibers must be kept to an acceptably low level. Since fiber counts follow a Poisson distribu tion, a count of 100 fibers in a sample would have a standard deviation of 100 or 10 fibers or + 10%. Thus the 95% confidence limits would be approximately 2 standard deviations or + 20%. Since the 37 mm filter has an effective collecting area of 855 mm and the projected field ...... j area of the Porton reticle is 0.005 mm , each field representn 1/171000 of the sample. Based on this ratio the following number of fields must be counted to measure the variouc limits in various sampling tim.as: *Mention of commercial products does not constitute endorsement by the Public Health Service or U. S. Department of Health, Education and Welfare. TXTINER RMC0086769 Sampling Time Minutes 10 15 30 90 90 240 240 480 Flow Rate 1pm 2 2 2 1 2 1 2 1 Number of Fields for ICO Fibers 0.2 fibers/ml 2.0 fibers/nl 10 fibers/nl 4350 2860 1430 1000 500 260 180 180 435 286 143 100 50 26 18 18 91 58 29 20 10 7 4 4' % 00 Do not count a field containing over 20 fibers because in addition to the fibers being counted, there are also present a number of grains which interfere with the accuracy of the count. Based on these restraints, i.e., number of fields to be counted and maximum number of fibers per field, acceptable sampling parameters for the various limits are underlined in the above table. The following conclusions may be drawn from this analysis: (1) The short-term limit should be for a period of at least 15 minutes and preferably 30 minutes. (2) The 2.0 fiber/cc limit may be evaluated over periods of from 90 to 480 minutes. many fields as required to yield at least 100 fibers should be counted. In general the minimum number of fields should be 20 and the maximum 100. Mounting Sample TXT1NER , RMC0086770 The mounting medium used in this method is prepared by dissolving 0.05 g of membrane filter per ml of 1:1 solution of dimethyl phthalatc VIII-5 004254 and diethyl oxalate. The index of refraction of the medium thus prepared is ND - 1.47. To prepare a sample for microscopic examination, a drop of the mounting medium is placed on a freshly cleaned, standard (25 mm X 75 cm), microscopic slide. A wedge-shaped piece with arc length of about 1^cm i3 excised from the filter with a scalpel and forceps and placed dust-side-up on the drop of mounting solution. A No. 1-1/2 coversllp, carefully cleaned with lens tissue, is placed over the filter wedge. Slight, pressure on the coverslip achieves contact between it and the mounting medium. The sample may be examined as soon as the mount is transparent. The optical homogeneity of the resulting mount is nearly perfect, with only a slight background granularity under phase contrast, which disappears within one day. The sample should h* counted within two days after mounting. Evaluation The filter samples mounted in the manner previously described are evaluated in terms of the concentration of asbestos fibers greater than 5 )im in length. A microscope equipped with phase-contrast optics and a 4-mm "high-dry*1 achromatic objective is suitable for this deter mination. 10X eyepieces, one of which contains a Forton or other suitable reticle at the level of the field-limiting diaphragm, should be used. The left half of the Forton reticle field serves to define the counting area of the field. Twenty fields located at random on the sample are counted and total asbestos fibers longer than 5 >im are __ recorded. Any particle having an aspect ratio of three or greater is considered a fiber. ------------------------------------- VIII-6 < .. t*twer p^C008977i * 004255 The following formulae are used to determine the number of fibers/ml: (1) Filter area (mn^) Field area (mm4-) * K (2) Average net count X K = fibers/ml Air volume sampled (ml) For example, assume the following: area of the filter used was 855 rnm^t counting area of one field under the Porton reticle was 0.005 mirr; , average net count per field of 20 fields was 10 fibers; and sample was collected at 2 liters per minute for 90 minutes: Then: 855mm2. = 171,000 (K) 0.005 mn/ 10 fibers x 171,000 * 9.5 fibers/ml 2,000 ml/rain x 90 min Calibration of Personal Sampler The accuracy of an analysis can L.. :.o greater than the accuracy of the volume of air which is measured. Therefore, the accurate calibration of a sampling device is essential to the correct interpretation of an instru ment's indication. The frequency of calibration is 3omewhat dependent on the use, care, and handling to which the pump is subjected. Pumps should be calibrated if they have been subjected to misuse or if they have just been repaired er received from a manufacturer. If hard usage is given the instrument, more frequent calibration may be necessary. Ordinarily, pumps should be calibrated in the laboratory both before they are used in the field and after they have been used to collect a large number of field samples. The accuracy of calibration is dependent on the type of instrument used as a reference. The choice of calibra- tion instrument will depend largely upon where the calibration is to be __ performed. For laboratory testing, a 1-liter burette or wet-test meter should be used. ___________________ In the field, a rotameter is the most convenient RMC0086772 VIII-7 004256 instrument used. The actual set-up will be the same for all of these instruments. The calibration instrument will be connected in sequence to the filter unit which will be followed by the personal sampler pump. In this way, the calibration instrument will be at atmospheric pressure. Connections between units can be made using the same type of tubing used in the personal sampling unit. Each pump must be calibrated separately for each type of filter used, if, for example, it has been decided to use a filter with a different pore size. The burette should be set up so that the flow is toward the narrow end of the unit. Care must be exercised in the assembly procedure to insure adequate seals at the joints and that the length of connecting tubing be kept at a minimum. Calibration should be done under the same conditions of pressure, temperature and density us will be encountered. The rotameter should be U3ed only in the field as a check if the diaphragm or piston pumps are not equipped with pulsation dampeners. The pulsating flow resulting from these type pumps causes the rotameter to give results which are not as accurate as that obtained with a burette or wet-test meter. Calibration can be accomplished with any of the other standard calibrating instruments, such as spirometer, Marriott's bottle, or drygas meter. The burette and wet-test meter were selected because of their accuracy, availability, and ease of operation. VIII-8 txtiner BMQ0086773 004251 a" pT-<C*U.CC3 "i- -.jooo z*xt*.ld3n br?.^ lini^ ' -> " - -'-' ' act m.uilberad, roo :**.5T\>Un ( .j', - floor til-a 3, plastics H ;2 1 o r: COS cn: 111.:.'- in chem; food, drug, boor industries T7.ME 1-iAl-H, SYNONYMS Asbestos 9i'l ot asbestos held is of chrveatilvariety CK1N1ICAL FAMILY MANUFACTURER FORMULA Magnesium Calcium Silicate STRUCTURAL FORMULA IIOL. WT. HAZARL` C LAS SI FI CATION ( ) LZPLOSIV- ( ) POISON ( ) co mosi vu < ^ VJ * xr f .' "T TM LIQUID ( ) ox:?' IILLE LI. ULD ( ) li'l.-lXTA^T ( ) OXIDIZING ACL () TONICITY RATING SKIN 0 = None Acute Local 1 = Slight Chronic Local 2 - '"ocarata 3 - High Acute~ Systemic U =* Unltno^m Chronic Systemic Of 42 cases of mesotheliomas (rare cancer of pleura and petitoneum) one syr. period, all but 11 ctad. sene exposure to asbestos (10 worked in asbestos plant, 3 lived or worked close to asbestos plant, 3 were family members of asbestos workers, 10 had histcry of assomed exposure, 10 no known history of exposure) (5)Long-continued inhalation asbestosis (intestinal polncnary fibrosis) Disease is characterized by asbestos bodies in lungs and sputum. Based on x-rays can bo classified as minimal, moderate and advanced. It is a serious disease in some Histories but ::eru usually just disubliny unless some other serious disease sequences (3) Chief synptons of advanced asbestosis are variable cough, dysynea, substernal chest pains, cher. chest expansion, /amass, emaciation, clubbed fingertips and curved fingernails. A.ny appreciable dec. in am't otc jsbestns dust in breathing atnes. will cause dec. in incidence and severity of asbestosis. Cndi-'idual susceptibility varies (7, Hyg. Guide) TXTINER RMCOO80774 Neoplasms, such as pleural and peritioned mesothelioma, occur in excess even among ashes toe porks cs with little nir.o radiological evidence of asbestosis, suggesting that exposures ir.suf- tiucent to cause asbastosis may still produce neoplasia. (22,23) 004258 ;i7D chemical p: 'ER.TIEG See Mineralogies 1 Appendix of (36). Physical State-Masses, either compact or of Color white, greyish or greenish taor Vapor Density -(air = 1) Vapor Pressure (are Hg) Specific Gravity = 1) Melting Point Soiling Point Flash Point Auto - ignition tenp. Vicsocity Surface Tension Evaporation Rate long silky fibers, flax-like and readily sc uel pH pka Partition Coefficient Solubility Coefficient Solubility - luO lipids Stability Chenicau. Reactivity chem. inert and resists attach by most chere. Decomposition & Polynerization Products Materials Si Conditions to Avoid TX TINER RMC0088775 004259 Ingredients (H mixture or contains sis impurities) crocidolite (sodium iron silicacc) amo&ile (iron magnesian silicate) anthophyilite actinite FIRS & EXPLOSION HAZARD Fire - fighting Procedures Personnel Protection (Clothing, equipment, ventilation) Storage & handling Clean - up and Disposal TLV HEALTH HAZARDS LD._ (lethal dose 50) (approx, lethal dose) LC5Q (lethal cone. 50) LCca (approx, lethal cone.) (toxic dose) TXC (toxic cone.) TFX (toxic effects) TLV ppn Sampling period (1/10 t/12) Biol. half-time Ref AIC 5 fiber3/ml (longer than 5 ) 5MPFCF Spue feeling this is too high (See TLV documentation and 17) (12,11) (1, (13,14,15,1 (over) 004260 TX TINER RMCOO80776 Crir?ro i. for limiting shrysotile exposure assuming i.I of asbestos during oO yr. wo ruin'' a::ro; Just categor}' Chrysotile Cone. (av. of 3 hrs) fivers ip. Meglibibla Lew Median 0.5 0.5-2.0 limit of 100 fibers/ml yrs 2-10 10 5 mppcf would provide inadequate protection 2 might not be substantiated Types of Asbestos (21) Chrysotile - widely used in food processing industries (sugar, lard, beer), are bundles of fibrils, each 2C0-400A dia and 1000 A to several micrometers long pharmaceutical use as filter Crocidolite - gas mask and cigarett filters amosite arithophyllite tremolire Amount of asbestos in some samples of dwgs exceeded those in other e?av. circumstances (such as in (21)) These were drugs to be given on IV, IM in IP. Sources of Asbestoc incl. serpentine rock (chrysotile).. Industrial controls are necessary to provcnt air pollution, particularly in construction products, ship building and repair.(22) chrysotile occurs in serpentine rock Prod. (1962) 1000 tons 1700 Color white Composition (%) Si Mg Fe 40 38 2 Source Canada, S. Africa, S. Rhodesia, U.S.A* Italy, Cyprus Crocidolite occurs in banded iron, stone Amosite 132 75 blue brown 50 -- 40 50 -- 40 S. Africa (Cape) Australia S. Africa (Transuaal) Anthophyilite 11 white 58 29 6 Finland, Italy 004261 TX TIMER RMC0086777 Blood TLY Urine TLV Breath TLV Absorption Rata Execretory Rate Ain't of asbestos recovered from lungs of persons occupationally er.nosad has ranged from 0.6-0.901% of lung wt. (24), with chrsotile asbestos fiber lew and r.mphiboLa asbestos fiber generally high (25) Critical Site (Locus of Action) Inhalation, Alreolar membrane responds with production of chror.im interstitial pnemonitis (35) see also 24) Biotransformation Chrysotile asbestos tends to break down chem. and physically after pro longed bid. residence. Is chem. unstable every in distilled H^O, and ag'. solu < 0.3 pli. Some of its magnesium will be leached out (24,25,26). The bundle of fibrils breaks open and the individual unit fibrils are separated (27) (Not seen with amphibote asbestos) (often <0.5u) Susceptible Individuals Cone. X Time Response or Effect Species F.ef. Natural chrysotile 0.05-0.2u-lQ.5 mg + 14 mg 0.2-1 udia. 90% mortalilz in 18 raos. 100% mortalilz in 24 mos. 55 rals. 3 Synthetic chrysotile firbrous also macrophage reaction with minimal stromal participation did not collagenize 0.02-0.04 y dia. 14 mg + 45 mg. 22% mortalilz in 12 mos. 3 53% mortalilz in 24 mos. Talc (tremolite 0.1-0.2 y dia 25 mg to 50 rats injected intratracheally 40% mortality in 6 mos 0.2 y = high natural nickel content 44% mortality in 6 mos 0.1 y 3 low natural nickel content 3 Also polypoid proh teratiose inflammuration which in time become callogenous scaes deforming air ways amorphous magnesium silicate 75 mg intratrachally in 10 rats 10% mortality in 6 mos. Proliferative inflammation considered artificial 3 004262 TXTINER RMC0086778 sy:i?to'!S Acute Chronic Mesothelioma of the pleura occurred in 33 cases in S. Africa, all but one vith a probably exposure to crocidolite asbestos (ape Blue) (32) Pleural calcification from asbestos exposure nay occur. Appears usually bilaterally ir. pauetal pleura (x-ray) vith no clinical objective or subjective resp. symptons. (36) Diagnostic Procedures ^ characteristic finding in asbestosis is asbestos bodies in lung and sputum. The care of the body of an asbestos fiber is surrounded by protein deposits; un stained specimens are golden yellow or golden brown. They (in lung or sputum) are not stained by ordinary histological stories but may be demonstrated by Prussion blue staining pro cedure (8). See also (9). After death when lungs examined by naked eye they are large and densely fibrotic. Often the lung is completely adherent to chest wall and in advanced cases to diaphrogan with formation of a thick and extremely dense layer of fibrous tissue. 4 main compli cations and segutae of polmonary asbestosis are purulent bronchitis, bronchial pneumonia, pulmona l'B and emphysema (8) Treatment Removal from exposure. # Medical Surveillance Periodic clinical exams for signs and symptons of asbestosis, mil-examination of sputum for asbestos bodies and chest x-rays (hyg. Guide) In general the lapsed period between onset of asbestos air pollution and appearance of neoplasin is 20,30, 40, or more yrs (22). Possible variable parameters mid-intensity of exposure, fiber variety, size, competitive risk of asbestos, cofactors such as cigarette smoking, trace elements . . . (22) Latent period rarely less than 10-20 yrs (30). 004263 TXTINER RMCOO80779 Detection of Odor Environmental Concentrations (including by-products) Operations Being Used Plants Being Used: Potential Hazard O.K. if Range of Cone. Average Cone. + -V n-i TLV Analytical Procedures 1. Qual. Analysis of Minerals by Solid Infrared Spectroscopy for mineral identification supple ments used instead of X-ray diffraction. Qualitative infrared spectra for anoaite, crocidoiite, trenioiite, serpentine, chrysotile. (4) Procedure for X-ray diffraction fo chrysotile, crocidolite and amosite and applicable to quantitative determination in 1-8 mg range latte 2 and 1-10 mg range for chrysoh6 (37) (39,40) 2. Dust may be sampled with electrostatic precipitation or by impinges method using alcohol or alcohol and water as collecting medium (1,8) The index of refraction of chrysolite is only slightly greater than Canada balsam, so relief is low. Other forms of asbestos have higher indices of refraction. Extinction is parallel except in case of tremolite which has oblique axtinction. Bizefungence of chrysotile is moderate nv - net = 0.03. Max interferences color is yellow of the 1st order. (8, see 10). TLV is bored on impinger sampling procedure. Environmental Monitoring TLV is based on fiber count, but LM observations that ivould be counted as a article, by the EM is seen as numerous fibers (fibrils) attached to the surface of particles. In such circumstances any biol. effect of the fibers could be incorrectly attributed to particles (22). Each asbestos fiber variety is quite different. Chrysotile fiber for ex. is not a unit whole but is composed of a number of 300-400 A fibrils. In industrial situations one has some idea of the ratio of optically visible fibers/total chrysotile pop. Not so in ambient air. Probably region EM to get this ratio and then use dp U in occupational setting. Ambient air reguines EM with magnification of at least 20,000 and probably over 40,000 x (22) What is seen by light microscopic methods often differs from EM observations (or 1/100 fibers present in air could be seen with LM as compared to EM) and that resp. size frac tions need not have some size and ist or properties as those in gross overall sample (24, 28) (over) 004264 TX TIMER RMC0086780 3. Gravimetric method usin" Kerlet sampler (31) Rayso 'Electronic Counter - continous series of dust .not of predetermined slue (31) c i * t. V TXTINER RMC0086781 004265 Aralytical Methods (38) reports a procedure for separating respirable dust fraction (< lOy) from settled dust, dust collected with hi-vol and electrostatic pracipitatas sam plers. The chem. and physical natures of the respirable fraction can then be analyzed. This method has been applied to asbestos and has shown that the chemical composition of the fraction < lGy may be quite different from the parent material. The results of our surveys of 9 asbestos textile plants reveal that dust cone, as measured by impinger are generally below TLV. Estimates of relative dusti ness from membrane filter samples were in good agreement with those made from impinger samples by either cone, or body burden methods of graying. Both show approx, some variance. A gross airborne mass cone, of asbestos equiva lent to 5 mppet would be on the order of 1 rag/n^, and respirable mass cone, as determined by elutriator and cyclone, would be in the order of 0.5-0.6 mg/ra^ and 0.3-0.4 mg/nr respectively. The impinger is as convenient as any other method of sampling and no less accurate. However the hygiene criteria is based on largely grain counts while the fibers are thought to be the cause of disease. For this reason the counting of fibers on membrane filters appears to have an advantage, esp. in industries where asbestos is only a small fraction of the aribaine dust. (41) Sampling The impinger method is not adequate for obtaining a statistically useful in dex of auharne fiber cone, i.e., that part which is most relevant to dis ease-causing mechanism. The impinger has a collection eff. related to aerodynomic size of particles and is not efficient for particles with falling speeds < 1 y unit density spheres. Further the lOx objective, light field, counting technique used does not resolve particles much smaller than 1 y. It is est. that ^l/lOO fibers in the air as seen in EM was seen in im pinger samples. Impinger counts are based to large extent on grain counts. But the falling speed of fibers dependent on dia only when aspect ratios 710; It is possible for much larger and heavier objects to penetrate deep into the lung if shaped as fibers than in the shape of grains. Using membrane filters pare sizes of 0.8 y/ almost 100% efficiency is ob tained for fibers down to several hundreds of a micron. The fibers are rendered transparent witn 1:1 dipthyloxalate and dimethyIphthlate I counted with 4 mm objective (430x) under phase contract illumination. When impinger samples give cone, of a 5 mppcf, membrane filters cone, are as follows: total fibers = 50 fibers/cc. fibers longer than 5 y = 30 " " fibers longer than 10 y =15 " " A goal of 4 fibers longer than 5 y/cc has been mentioned for English asbestos textile mills, approx, equivalent to 1 mppcf by impinger count TXTINER RMC0086782 004266 which is vary near the lower practical Unit of sensitivity for the impingar. Wt. method of analysis suffers from some defect as impingar. Chrysotile asbestos fibers are commonly found in lungs of urban dwellers with no occupational exposure to asbestos (22). Asbestotic pleural calcifiation has been associated with use of rock with high asbestos (anchophyllite) con tent in various parts of world (Bulguin, Finland, Czechoslavakia?) Ref. 1522. Recovery of chrysotile asbestos from lung tissue always low; recovery of amphibole asbestos generally high in human lungs (25). Asbestos insulation workers have comparatively light asbestos exposures as asbestos trades go. Many of the material they use contain little or no as bestos and others 5-15%. What few dues exposure surveys have been done have generally been within the 5 mppcf TLV. When exposure is reduced, eearly death from asbestosis decreases, and lung cancer becomes more common. Light exposure may come from industrial exposure and/or community asbestos air pollution. In this study it was shown that there is an extraordinary risk of developing and dying from lung cancer for asbestos workers who smoke cigarettes regularly. In the group studied, the combination of asbestos ex posure and cigarette smoking ^ 90x compared with men who neither work with asbestos nor smoke.(29). TX TINER RMC0086783 004261 SYMPTOMS - Asbestosis: Chest x-rays disclose abnormalities in only 10% of those exposed <10 years and in 44% with exposures 10-19 years. These abnormaliteis tended to be minimal. 72% abnormalities of exposures 20-29 years and >90% of 730 years exposure. Asbestos rearely provokes an acute inflammatory reaction, but usually slowly progressive fibrosis (that is apparently irrversible). The fibrosis is of the diffuse interstitial type which may not be readily apparent on x-rays and sometimes not extensive. The cardinal clinical finding is dyspnea, but these are not early, find ings (<10 years exposure, ]% dyspnea, 10-19 years - 28/379 dyspnea, 40 years exposure, 1/2 had dyspnea, usually moderate to severe) Finger clubbing, cyanosis and extensive fine basal rales all tend to develop very late. The pulmonary physiol, difert in asbestosis is a pattern characteristic of alveolar - capillary block syndrome with red. VC, fairly well preserved max breathing capacity, dyperventilation at rest and particularly on exercise, dec. diffusing capacity of lung, impaired oxygenation of arterial blood and red pulmonary compliance. These also appear late in the disease, even the V.C. is the most sensitive index of disease progression. (30) Lung Cancer: '1/5 of every asbestos insulation workers likely to die of bronchlogenic carcinoma. Risk of lung cancer 6 - lOx in asbestos workers expected rate. Latent period - long 13-32 years usually >20 years. Latent period not necessarily same for fibrosis and cancer. Fibrosis varies v/ith intensity and duration of exposure (lung cancer too to some extent). Inc. exposure may result in less lung cancer. Mesothelioma: neoplasms of plernal and peritoneal cavities shows striking association v/ith asbestos exposure. Latent period >20 years, generally >30 years. No regular correlation between severity of asbestosis and occurrence of mesothelioma (often occurs with no x-ray evidence of asbestosis.) Other Neoplasms - cancers of stomach and colon may be inc.; latent period lung cancer and mesothelioma. Pleural Calcification: 720 years latent period; 7 1/2 of men with >40 years exposure. It should be noted that pleural calcification of limited extent and radiosensitivity is usually not visible in the x-ray film. It appears probable that the asbestos fibers inhaled largely remain in place with the result that tissue reaction to the retained fiber goes on even in the absence of continued exposure. The effect is cumulative over the expo sure years. Thus, a workman continually exposed for 25 years has a body bur den of 25 years, which removal from exposure cannot effect. TXTINER RMC0086784 (30) There is some evidence that if exposure ceases at an early stage progression may be slow or even arrested. (31) 004268 Occupational history is essential for diagnosis, particularly in instances of (1) interstitial pulmonary fibrosis of undet. origin 2) pleural calcification 3) masothelicnia 4) alveolar - capillary block syndrome, 5) iu nn cancer and 6) fibrotic pleural plaques. History of most interests iw work 20-30 years be fore. (30) Asbestosis - Clinical and x-ray findings. Couch and breathlessness are early findings. Cyanosis common, clubbing prominent. Fine basal roles are characteristic. Sputum is un in ur?com plicated cases. Asbestos bodies in sputum are sign of exposure - not asbestosis. Pulmonary function - lew total lung capacity, low vital capacity without evidence of airway obstruction, red. pulmonary compliance and diffusing capacity; reduced FVC with normal or inc. FEV/FVC ratios. X-ray in advanced cases loss of definition between lung and pleura and pericardium Early signs? - pleural thickening, linear markings in periphery of lung filds, not in line of vascular shadows; Bronchial Carcinoma - appro. 1/2 of patients certified as having asbestosis die of bronchial carcinoma which more often arises in lower than upper lobes of lungs. Mesothelioma - tumors which affect both pleura and peritonerm, spreading rapidly over serosal membrane, infiltrate adjacent tissue and metalize to regional lymph nodes and less often to distant sites. Aug. latent period 30-35 years Onset often with acute dyspnea due to rapid accumulation of a pleural effu sion. Pain often severe. Tumor may infiltrate chest wall. In peritoneal tumors symptoms more varied - dysuria with pain on defaecation; upper abdominal pain is common and ascites always present terminally. Course of disease rapid (approx. 2 years from onset to death) So far no effective treatment. (31) The most freq. complication of asbestosis of the lungs are, besides thickening of pleura and compensatory emphysend, the non-specific inflaminatious of the peribronchial, peribronchiectatic and bronchopneumonia type. Esp. the latter must be differentiated from lung cancer in asbestosis. An active pulmonary T3 as accompanying disease of asbestosis been found in 4.4% of 343 cases, which is higher than general pop. in Germany. Lung cancer in asbestos workers not more freq. than bronchrogemic carcinoma in^total pop. It can be distinguished (by x-ray) from bronchiogenic carcinoma of other genesis only by relatively more freq. occurence in lower lobe. (33) Asbestos and Maenophages - RMC0086785 004269 Two features distinguish the macrophage response to fibrous asbestos from the reaction to crystalline silica - giant call transformation and forma tion of iron-encrusted asbestos bodies. In lung organ cultures, alveolar macrophages take up dust particles with marked inc. dyi exposures. Within 2 hrs. some asbestos had escaped frofr, phagosomes and lay free in the gytoplasm; subsequently the lysosomal membranes collapsed and contracted around the dust par sides tor:,: ing dense bodies which also contained lamellar derivatives of cyto. membranes. Mu Itinucleate gianc cells seen at 24 hrs. and persisted unchanged through out 10 dap exp't. Some of the macrophages appeared to differentiate into fibroblasts, the r acid destruction of phagorytes chat characterizes response to silica not ooserved. The golden-brown bodies found in pulmonary asbestos!s thought to consist of asbestos fibers coated by orotein and iron. Thought to form within macrophages by deposition of ferritin molecules around phagocytized material. Crysotaile asbestos instilled in hamster lungs was rapidly taken up and segregated in macrophagic phogosomes; 16 days later hemosiderin granules appeared, each surrounded by a limiting membrane and scattered uniformly throughout cyto. By continuing migration and secretion of iron micelles the asbestos phagosomes were converted into asbestos bodies, a process that may serve to neutralize toxic effects of asbestos oarticle (34). Chemical Analysis of Crocidolite and Amosits (Cape 31ue Asbestos) from S. Africa (32) Crocidolite Anosite Si02 51.94 ' 49.47 Al23 Fa203 0.20 18.64 0.63 4.15 FeO 19.39 35.63 MgO 1.37 6.57 CaD 0.19 0.52 Na2<3 6.07 0.02 0 CM 1 0.04 0.20 h2o 0.31 0.07 h2o + 2.58 2.33 Ti02 0.25 MnO 0.61 F 0.01 Total 100.73 100.46 TXTINER RMC0086788 004210 Organic Contaminants in Asbestos - The organic content of coir,merci ally in i 11 a cl Canadian chrysotile ranged from 0.5 - 20 mg/100 gm. The contamination mostly occurred in the mining and milling process with field specimens (0.1 - 5 mg/100 gm) relatively free of organic matter. Extraction with benzene revealed 81.94- - 36.03% C, 11.47 - 13.143 H and monor amounts of other elements. IR and GC confirmed m-alkanes as the major con stituents; low cone, of polycyclic HC with some of these compounds (fluoranthene, pyrene) at cone. 1/1000 of levels found in Montreal 1970 Smoke sample. A moncmolecular layer of a hydrophobic compound such as an n-alkane on fibers or particles may influence solubility, their removal, or the biol. response to them. Compounds which are meakly absorbed by activated alumina (predominantly straight chain alphatic and alkyl aromatic HC) can act as accelerators of carcinogenesis (accelerators ir.c. sharply as chain length of n-parraffirn inc. from 8 to 10 C atmos.) (42) Metal Content Chrysotile A 2% 10 (ground) 30% 10 Chrysotile B 6% 10 (ground) 41% 10 Crocidolite 12% 10 (ground) 87% 10 Amosite 12% 10 (ground) 90% 10 Anthophyllite 12% 10 (ground) 90% 10 uq/q Ni Cr 1844 1488 1290 1050 1508 '999 665 288 139 239 30 34 105 178 79 65 414 341 397 407 mq/q % fr/Metals recovered in serum Co Mn Fe SiOp Ni Cr Co Hn as 0 OO C\J C\J 1 11 11 ** OO r-s. 53 714 19 .08 13% 33 245 7.1 .04 60 660 16.2 .10 17% 23 277 5.4 .63 i1 1 1 1 1 -4 10 2324 158.8 2.88 33% 11 800 144.8 1.60 7 14440 131.4 4.2 25% 3% 8 12650 158.1 1.5 27 364 17.0 .09 8% ............... 5% 18 752 14.2 1.12 (43) TX TIMER RMC0086787 004271 Asbestos 1. Lrersan, W. C. et.al. P.H. Bull 424 Washington, D.C. (1938). 2. Arch. Ip.d. Health 16.: 261 (1957). 3. Gross, P. at al. AIILAJ. 31.: 125-32 (1970) Polmonary Response to Fibrous Dusts of Dinece Composition. 4. D. G. Taylar et. al. AIHAJ 3_1: 100-8 (1970) Infrared Spectra for Mineral Identification. 5. J. Liehen and H. Pistawka Arch. Env. Health 14: 559-63 (1967). Mesothelium and Asbestos Exposure 6. Cartier, P. Arch. Ind. Health 11: 204 (1955). 7. S. B. McPhaebers, J. Ind. Hyg. Tox. 229 (1936). 8. Fairhall Industrial Toxicology 9. Noro, L. Acta pathal nicrobial. scandinav 2^: 53 (1946) Histolign of Asbestosis. 10. Fehnel, J. W. ind. Med. 9.: Ind. Hyg. Sect. 1: 5 (1940) Air Sampling of asbestos Dust: comparison of impinger and electrostatic precipitation methods. 11. Lynch, K. M. Arch Ind. Health 11: 135 (1955). 12. Smith, K. W. Arch. Ind. Health 12: 198 (1955). 13. Vorwald, A. J. et al. Arch Ind. Hgy. Occup. Med. 3.: (1951). 14. King, E. J. et al. Thorax I p. 188 (1946). 15. Wood, W. B., Glayne, S. R. Lancet p. 1383-5 *1934). 16. Donelly, J. J. Ind. Hyg. Tox. 18: 222 (1936). 17. Whipple, H. E. (ed) Ann. N.Y. Acad. Sci. 132(1) (1965) Biologic Effects of Asbestos. 18. Dalzar, J. L. and W. C. Cooper Ind. Hyg. News Report (Dec. 1967). 19. Ayer, H. E. et al. AIHAJ (1970-2). 20. Williams, H. L., E. J. Baier, and A. W. 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