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Occupational Exposure to Asbestos in the Drywall Taping Process

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Occupational Exposure to Asbestos in the Drywall Taping Process Studies of airborne asbestos fiber concentrations associated with various operations of the drywall tapin process have been undortaken in the province of Alberta, Canada. The results show that mixing, sanding an~ sweeping created high levels of airborne asbestos dust. The measured concentrations were-frequently in exces of occupational health standards. Sanding in particular was assessed the most hazardous op.eration. The resu1/ are discussed in light of present and proposed Occupational Health Standards, and in terms of its implications f~~ other workers, household contacts, and cc:>nsumer's risk. Measures to reduce and control the health hazards associated with the process are described. Occupational exposure to asbestos in the drywall taping process 11 DAVE K. VERMA A and CHARLES G. MIDDLETON AOccupational Health Program, McMaster University, Hamilton, Ontario, Canada L8N 325; 80ccupational Health & Safety Division, Alberta Worker's Health Safety & Compensation, Edmonton, Alberta Canada T5K 2J6 PLAINTIFF'S i EXHIBIT l SoA 5'151 introduction Occupational exposure to asbestos is associated with a risk first study may not be indicative of typical occupational of asbestosis, mesothelioma, an excess risk of cancer of the exposure of the drywall taping process. 4 lung and possible cancers at other sitesY- ) These asbestos 5 related diseases have been found in mines and mills,( ) in Data is also lacking on the health status of this group of 6 manufacturing industries,( ) and in the use of asbestos workers exposed to asbestos. One published report of 7 products such as insulation in construction industries. ( ) The medical examinations conducted on a group of 69 tapers magnitude of the occupational health problem associated showed X-ray abnormalities characteristic of asbestos 1 with asbestos exposure is enormous. The relative risk of exposure in 37 out of 69 filmsY l Two thirds of this group lung cancer among asbestos workers has been demonstrated had an exposure of 10 years duration or longer, and 61 were 9 from epidemiological studies to range between 1.4 and 3.3 smokers or ex-smokers. A recent clinical report( ) on the for miners and millers, 1.0 to 13.7 for production and same group of drywall workers, but with an expanded manufacturing industry workers and 5.1 to 8.3 for cohort (114), showed radiological evidence for pulmonary 4 insulators. ( ) The risk due to cigarette smoking and asbestos asbestosis in 40.9% of the cases examined. This compares to 9 exposure has been recognized to be multiplicative rather 48.5% among insulators.( ) Consequently drywall tapers than additive so that an asbestos worker who smokes has an appear to have similar exposure as insulators. In light of this extremely high risk oflung cancers. An asbestos worker who it is interesting to note that tapers in Alberta are not under smokes has a 92 times greater risk than a wor.ker who neither medical surveillance whilst insulators, who are considered 3 smokes nor works with asbestos. ( ) asbestos workers, are. To our knowledge this lack of medical ~urveillance for tapers as asbestos workers exists in Very little has been reported in the literature about the potential occupational health risk to drywall taping other provinces of Canada and most parts of the U. S. workers. A review of the literature revealed only two Because of the above mentioned concerns we initiated, in independent studies dealing with the occupational exposure 1975, an investigation in the province of Alberta of the to asbestos in the taping process. In the first study results of drywall taping process. This operation was known to thirty-nine air samples taken at the various operations of the involye the use of an asbestos containing compound. process were discussed. (B) Generally high (mean values of 2.6 Specifically the aim of this study was to assess quantitatively to 47.2 fibers/cc for specific operations) airborne asbestos the occupational exposure· to asbestos in this group of levels were noted. This earlier report has recently been workers. Our findings are summarized in this report. 9 published in an expanded version.( ) In the second study, conducted on a similar sample size, much lower (mostly between 0.5 and 3.5 fibers/cc) exposure levels were reported. (IO) The latter authors inferred that the results of the the drywall taping process In the construction of a co'minercial building, wallboards are fixed to metal studs with screws, while in residential The opinions and suggestions contained In this report are the private views of the authors and are not to be construed as official or houses the gyp.sum wallboards are nailed onto the wooden representing the views of Alberta Worker's Health Safety and studs. The resulting joints, as well as screw and nail Compensation. indentations, are finished by taping. Copyright 1980, American Industrial Hygiene Assoolallon 264 Am. Ind. Hyg. Assoc. J, (41) April, 1980 of asbestos (chrysotile), in the past they have contained 'x/ng 9 e dry joint compound powder is normally contained in much higher proportions of asbestos. ( l Three types of joint er bags. The bag is slit open by a knife and the powder compounds are available: taping, topping, and all purpose, mped into a container. Water is then added according to all of which contain asbestos. Taping joint compound is manufacturer's directions and the compound mixed by applied in one or two coats and is designed for strength. The ns of a portable electric drill equipped with a mud and topping or finishing variety is generally applied in the final t mixer. Some joint compound is sold· as a paste coat and has better finishing qualities. The all purpose compound is a compromise formula that can be used for erred to as "premix") and only a small amount of water is both taping and finishing purposes. Asbestos is used in these uired. The prepared mixture in its putty like form after joint compounds because it serves several functions ting is referred to as mud. The time spent mixing in a including controlling shrinkage and cracking when the mud rking day is short. It usually takes 5 to 10 min. to mix a dries, and providing good workability in troweling and ch and in most instances 09e to three batches are sanding. uired daily. //cation materials and methods joint compound (mud) is placed on the bottom side ofa site description er tape and is applied to cover the joints between the During 1975 to 1977 several work-sites were visited sum boards and allowed to dry. Subsequently, this throughout the province and eight of them were evaluated pound is also applied on the front side of the tape and to by air sampling. Work schedules and the time spent at wand nail indentations. A major portion (65-70%) of various operations at worksites differed widely. In small working day is spent in this operation. companies, the owner often worked out of his home and undertook all the work himself. Companies with larger ding workforces of 15-20 employees had individual workers e joints and indentations are sanded between each performing specific tasks such as sanding on a full-time lication of mud, with the major amount of sanding being basis . .ried out after the final coat. Three to four coats of mud ·· usually applied. Sanding operations normally involve Following these initial surveys we conducted a more er hand sanding or pole sanding. Hand sanding is detailed study over a three-month period at a downtown site ried out with a hand-held, abrasive paper, covered in Edmonton where a multi-storied hotel was under ding block. In pole sanding, the sanding block is at the construction. This survey of a large commercial site was of a long pole. Generally speaking most of the sanding is begun in January, 1978. ded out by pole sanding, We estimate that 25-30% of Both the residential and commercial site studies al time is spent in this operation. concentrated on the evaluation of worker's exposure to airborne asbestos dust. The potentially hazardous effects of eeping and cleanup other components of dust such as nuisance particulates, debris and the dust accumulated on the floor resulting crystalline silica, chemicals, etc., were not examined in the m the mixing, application and sanding operations is same detail. It was felt that asbestos posed the most erally cleaned up by dry sweeping. In many instances, significant hazard and control measures applied for asbestos ecially in cases of commercial building and large exposure would be equally effective against other hazardous jects, this operation is carried out by general laborers. particulates. ever, it was generally found to be part of the work edule of employees of small companies working on methodology ential construction projects. 1. Airborne asbestos dust samples were taken by using open-face filter cassettes, loaded with 37 mm 0.8 omposition of joint compounds micron pore size Millipore, Type AA membrane composition of joint compounds varies from filters. Air was drawn through the filter papers by a nufacturer to manufacturer. During the study period portable pump at a flow rate of 2.0 liters/min. The st joint compounds were said to contain between 3 - 6% sampling period was guided by two factors - · chrysotile asbestos by weight. The remainder was concentrations expected and duration of posed of limestone or dolomite, talc, clay, mica, starch operations. Most sampling assemblies were · fungicide, A typical joint compound formulation, based attached to the worker's lapels. To obtain area or he information obtained from the manufacturers, was: location samples assemblies were attached to Limestone , , , , , ............. , .. , 80 - 85% portable stands. The pump was calibrated before · Clay, talc, mica ...... , ......... , . , S - 10% each use by a soap bubble meter.
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