Document vVO8w4MJJanYYXBO3xKpOMNQ6

RECEIVED M ' p "I i ' -i. hSMiscabm---' 17/ i ri! I \jeWQS'aP S0QJX3& O&M in the Drywall Industry. Business - Health - Life Part 2 Harrison B. Rhodes Technology Manager and Blair L. Ingalls Supervisor, Special Projects Union Carbide Corporation Metals Division Niagara Falls, New York Introduction In the last issue of the C.DCl Dry- wail Magazine, the current status of the OSMA regulations for asbes tos and for crystalline silica was described. This article completes the picture with field data on as bestos and silica exposure under normal operating conditions ob tained at eight job sites in four states. Sanding, wet-out of dry-mix materials, and cleanup were ex amined. Work procedures at the jobs tested are described so that the results can be related to simi lar operations in other locations. Abstract The highest airborne asbestos concentration found during sand ing was 3.5 fibers/cc longer than 5 micrometers. This is well below the allowable OSHA ceiling limit of 10 fibers/cc. The corresponding 8hour, time weighted average ex posures ranged from 0.2 to 0.9 fibers/cc. These levels are also well below the 5 fiber/cc limit now al lowed and the 2 fiber/cc limit scheduled to go into effect in mid 1976. Asbestos exposure during the wet-out of dry-mix materials ranged from 2.7 to 62 fibers/cc. It appears to be possible to hold the concent rat ion t < > acceptable lex els by c,ire ful handling of the bags but it is probably desirable to wear an ap proved respirator during this op eration. i_ \ I 1 I PLAINTIFF'S EXHIBIT ,7 v-! / The concentrations of respirable dust generated by three different dry sanding procedures varied by a factor of ten. The contractor has a great deal of control over dust levels on the job by his choice of work practices. exposure to airborne o.ua'tz was checked at five job sites and three were found to be near or above the Action Level proposed by NIOSH. The observed levels depended di rectly on the quartz content of the mud and on the severity of the sanding operation. Much higher levels are possible under adverse combinations of these two factors. The Choice for the Drywall liuluslry The inhumation presented here provides an excellent illustration of a broader question th.it is facing industry today, i.e., what is the best way to comply with the vari ous occupational safety, consumer safety, and environmental piotvction regulations that are being promulgated? These safety and health regulations are an estab lished trend of the times .md ap pear to be here to stay. By their very nature, these regulations af,rieralty increase the cost of each product and service involved. Al though these costs will ultimately be borne by the final user, it bene fits everyone to achieve the appro priate level of safety and health in the most efficient way possible and thus minimi/e the tiu remental i ost foi these important items. When a new regulation is piom- ulgaied covering a paila ul.it ma terial, the natural reaitinn is to put the entire burden on the sup plier arid demand that hi' replai e ASARCO ALV 00024-26 the regulated ingredient. In the 'ase of asbestos, which imparts .cry valuable performance char acteristics to the tape joint com pounds, the replacement is proving to be difficult. The asbestos-free muds so far available are more ex pensive. Also, they often do not trowel as well which adds to the cost of installation. Additional re formulation to reduce the quartz level could result in further loss in properties and increases in cost. It will be shown that the dust levels related to drywall finishing vary widely depending on how the contractor operates. This suggests that it may be to the contractor's advantage to make reasonable ad justments in operating procedures to use existing products in compli ance with regulations rather than demanding that the suppliers pro vide products that are completely safe under the most adverse jobsite conditions but are more ex pensive and do not perform as well. Collection of Dust Samples The photographs on the cover of the November-December issue of Drywall Magazine showed how the air samples were collected. Both personal samples and highvolume area samples were ob tained. For personal samples, a small battery-driven vacuum pump was hooked to the operator's belt. Acartridgc containing a filter paper about one and one-half inches in diameter was attached to the oper ator's shirt pocket and connected to the pump with plastic tubing. As the man went about his job in the normal manner, airfrom his breath ing zone was drawn through the filter paper by the vacuum pump so that the dust present in the air sample was deposited on the fil ter paper. The high-volume samplers oper-ed the same way but were larger .d pulled about five times as much air. They were mounted on poles adjacent to the sanding and were moved at regular intervals to stay close to the operator. There was one important differ ence in the samples collected for silica analysis. The proposed regu lations refer to the "respirable fraction"of thetotal dust. This fraction is made up of the smaller, lighter particles in the total dust which are considered most likely to be carried into the lungs during breathing. A small cyclone sepa rator was used ahead of the filter for these samples to remove the heavier dust particles and leave only the respirable dust. For the asbestos measurements, the filter paper was examined un der a microscope and the number of fibers longer than r, micrometers (fim) was counted. For silica, the total quantity of sample collected was weighed and the percent quartz was found by X-ray diffraction. All procedures used were in accord ance with OSHA regulations for asbestosor NIOSH recommendations for crystalline silica.' UBS-Enra iffU'ik.r..-**! ir.trea t31 " nri Hi- t til 1 IN (IT* 1* 4. !& 1f fi | it r#i & fr rj j i1 | ' ii 1 j (k ' i c* ' j E M i ii i au i [i ;; 1 bt>t:i::l il iif si 1t s 11 i.. i- - jail - - tr:. ill i i aLUD_ 1 -j u iliSji_ - Airborne AsbesloS Exposure in Drywall Finishing Sanding of Finished luints: Air borne asbestos fiber concentra tions during routine sanding opera tions were measured at six loca tions in four states. The results are shown in Figure 1 together with the data reported by Nicholson et al*. The range of fiber concen tration measured at each tocalion is given by the cross-hatched bars. The type of sanding, hand or pole, and the total number of personal samples taken at each job location are shown at the bottom of the Figure. It is immediately evident that the samples collected in this sur vey are much lower than those re ported by Nicholson. When this gross difference became evident, two filters each from three differ-^ ent locations were sent to inde pendent laboratories for check counts. The results are compared with those of the Union Carbide ! laboratory in the following table: Inlerlaboratory Comparison Asbestos Fiber Counts Airtxjrne AsU-stos Fiber Coni miration (fibers/cc longer than >^m) Sample Source BvUCC Bv lal* A B\ lab location 1 (Filter si) 0.4 location 1 (Fillet =2) 04 03 00 02 02 location II (Filter si) 1 3 location It (Filter *2) 13 10 10 1b Ob location III (Filter *11 Ob location III (Filter 2) 0.4 00 02 OV 02 Althoughthere is some variation, these are difficult samples to count and the agreement between labora tories is excellent. It is evident that the differences between this sur vey and that of Nicholson are not due to sample analysis. The sand ing procedures used to generate seem to be the most likelv cause. In any case, the Nicholson results do not appear to he typical of die concentrations encountered undei most job-site working conditions. 1 I lu* authors wish to express their tlumks to the NGC rnvirtinnieni.il Laboratories. Cold bond Building Products. Division of National Gvpsuni Company. Buffalo. New York, who provided the collection equip ment and analyzed the silk a samples Paper piesented by Dr. W. |. Nil Imlson at the Miami. Florida meeting ot the American Industrial Hygiene As sociation Conference. May I.1 17, 1974. 9 ASARCO ALV 0002427 The ceiling limil allowed under the present OSIIA asbestos mutila tions is also indicated in Figure 1. This limit is the highest level to which a worker may be exposed at any time without protective equipment. It is evident that the asbestosconcenlrationin the seven jobs checked in this survey were all well below the 10 fibers/cc limit. The OSHA regulations also spe cify a maximum allowable timeweighted average exposure of 5 fibers/cc now arid a reduced level of 2 fibers/cc in July 1976. The Time-Weighted Average (TWA) is a measure of the workers' average cxposure during the entire 8-hour workday. This concept is particu larly important to the tape joint industry where asbestos exposures generally occur only during a mod erate port ion of some working days. As an example of Time-Weighted Average, a man might sand for two hours at an exposure level of 4 fibers/ccand work at someolherjob for the rest of the shift at another location where there is no asbes tos present so the exposure would be essentially zero. In this case, his Time-Weighted Average would be calculated as: 4 tdvfvCC! X f- Wuf'i + (0 hlhft/Ct) X (6 hours) ,'hu'jis. + hour*) *4) X () i0> X <6] 6 4 0 ---- = i (d*f/ce. btl Time-Weighted Average expo sures have been estimated in the manner shown above for the seven job operations in Figure 1. The re sults are listed in the following table: Sunimiry of Anbnme Ailn-flOf fiber Cvn^enttuduns During Dry h j/1 Sanding it* atHM tvi*<vuf 1h*m> (Minuted Ceding Ouftftg R Hour ViixJ>ti|i fWA | \|Korr ff ilrv >',tim) ,f r KM<u-w', rh Hli.l C>. M AOH rrUlf. U OUnrl) D-rllov U It I J.nleiilnl*. fl | K.jg.u.i I ,ll\ N1 U(04 1\ 1t 18 l4 )fe 80 01 40 04 8100 0019 05 01 0J 61 0026 The estimated TWA values range from 0.9 fiber/ec down to 0.1 fiber/cc. They are all well below the current 5 fiber limit and the July 1976 2 fiber/cc limit. While it is retogni/ed that this is only a small sample from the hun dreds of locations throughout the country where tape joints arc sanded, the sanding procedures used were typical of most commer cial situations. The results pro vide good evidence that the as bestos concentrations during sand ing at most locations are generally below the allowable OSHA limits. Wet-Out of Dry-Mix Materials: In some parts of the country, drymix tape joint compounds and tex ture sprays containing asbestos are widely used. When these are mixed into water at the job site, as bestos exposure can result. Spray texture paints may contain about the same level of chrysotile asbes tos as tape joint compounds. Asbestos exposure during the wet-cut of wall and ceiling spray texture was measured at two loca tions. In Figure 2 the results are compared w ith those of Nicholson for the wet-out of tape joint com pounds. Since these are short-term occasional exposures, the ceiling limit of 10 fibers/cc is most perti nent and is also shown on the Fig ure. vary widely and arc also frequently well above the 10 fiber/cc limit. In the San Jose test where the hags were emptied slowly .and carefully, the levels were low. At the other local ion w here the hags were emp tied rapidly and shaken in a closed truck (lie fiber concentrations were in the same range as the high levels reported by Nicholson. On the basis of this data, it is prudent to wear a respirator while wetting out dry-mix and the bags should also he handled with care. Cleanup After lob Completion: Asbestos exposure may also occur during the cleanup after a drywall finishing job is completed. Limited data on this operation are shown in Figure 3, together with the re sults reported by Nicholson. In the left-hand portion of the Figure are data obtained in a test at a Florida condominium. Both the walls and ceilings had been sanded lightly and then sprayed with tex ture paint. The texturing overspray had hardened on the floor. The normal cleanup procedure was to wet the floor lightly with water from a hand sprayer and then re move all excess material from the floor with a long-handled x< raper. As might be expected, tins damp operation gave a very low airborne fiber concentration ot 0 1 tiber/ec. In order to get a dire, t < <>mparison with other cleanup methods. a number of apartments m tin- m'iil' building were swept with a stiff broom, both with and v. 'ut the addition of ordm.tw i-ping compound. Itwasd.Mi. ulttuhnnk loose the hardened os.'-pray so the broom work was t.ia \ irons. In spite of this, the highest level in ASARCO ALV 0002428 found was a coiling concentration of 5.5 fibors/cc produced by the dry sweeping. Use of the sweep ing compound reduced this to 1.8 fibers/cc. These data illustrate that moist scraping, which is now in regular commercial use in some parts of the country, is a good cleanup method to control dust. These data do not mean there is no asbestos dust problem during cleanup since jobs where the walls have been sanded heavily present more po tential for dust generation than the light sanding case tested. This point is emphasized by the data of Nicholson in Figure 3 which gave levels of 26 and 43 fibers/cc during sweeping after heavy sanding. While it seems doubtful that levels this high would be encountered in most typical job cleanup situa tions, exposures above the ceiling limit appear quite possible. More information is needed to define better the levels to be expected under routine field conditions. Airborne Respirable Dust Exposure in Drywall Sanding It was noted in the first article that there is an OSHA standard which sets the maximum allowable exposure level to the respirable fraction of nuisance dust at 5 milli grams per cubic meter (mg/M') of air. In simplest terms, a nuisance dust is a dust which does not have the exposure level controlled by any of the other standards for spe cific materials. Even if a dust con taining asbestos and/or crystalline silica is in compliance with the standards for these materials, it w'ould still be in violation if the respirable dust level exceeds 5 mg/M1. The concentration of respirable dust during sanding was measured at five of the job sites in three states. These levels, expressed as milligrams of respirable dust per cubic meter of air. .lie shown in Figure 4. The crosshatched bars give the range of concentrations found at each job with the respec tive average concentrations shown by the dark line in the- central por tion of each bar. Sanding condi tions for each site are also noted. At the New York location, two courses of general-purpose, readymix mud had been applied with hand tools. The building was a high-rise apartment with the win dows open and a light breeze blow ing. A five-man crew of tapers was spot sanding lightly by hand or with a pole sander as needed and touching up with a finish coat of general-purpose, ready-mix. Usu ally only one man was working in each room. Respirable dust levels from personal samplers ranged frorp 0.2 to 1 milligram per cubic meterand averaged a very low 0.55 mg/M'. The Michigan test took place at a multilevel dwellmg (approximate ly 2.300 square feet floor area) fin ished with a dry-mix topping com pound. The windows were closed and there was np ventilation. A laborer, who normally spends most of his time sanding, went over the walls and ceiling in about lour hours with a pole sander. Respir able dust ranged from 1.55 to 5.34 mg/M1 and averaged 3.02 mg/M1. The tests at Minnesota Site 1 and Site 3 were quite similar to that in Michigan. Both were residential dwellings of 2500 and 1500 square feet, respectively, finished by hand tools with asbestos-free dry-mix topping compound and pole sanded in about four hours by a laborer who did this as a full-time job. The windows were in and there was little ventilation. At the small er house. Site 3, only the walls were sanded. Respirable dust at Site 1 ranged from 0.15 to 3 23 mg/M' and averaged 1.43 mg/M1. At Site 3 the range was nairower at 1.59to2.62mg/M' but averaged about the same at 2.10 mg/M1. Minnesota Site 2 was a four- story apartment building with an asbestos-tree dry-mix lopping com pound finished with hand tools. There was very limited ventilation while three men sanded together in each apartment unit until it was finished and then moved on to the next unit. Here the range fell in the much higher level of 4.06 to 7.95 mg/M1 and the average was 5.76 mg/M'. This was the only lo cation where the respirable dust level consistently exceeded the OSHA limit. These data show clearlv that there can be a very wide, tenfold, difference in the average respirable dust levels for the different sever ities of sanding. Light, touch-up sanding with good ventilation gave about 0.5 mg/M*. The three tests with one man sanding steadily with little ventilation ranged from 1.5 to 3 mg/M' and averaged 2.1 mg/M3; about four times that for touch-up. Three men sanding to gether increased the average level to about 2.5 times that of one man sanding alone and 10 times that of touch-up. It is very clear that the dust level at the job site can be changed widely by the work prac tices employed. Airborne Crystalline Silica (Quartz) Exposure in Drywall Sanding The aiihorne quartz loiuentration in the dust generated doling, the sanding of tape joint i < unpi mod was measured at five job Mtrs in throe states. The concentrations (Continued on page 30 ) 11 ASARCO ALV 0002429