Document vVqanNa3qrLVNDB7eXJKDk1O6

This article was downloaded by: [Pickett, Mary] On: 3 November 2008 Access details: Access Details: Free Access Publisher Informa Healthcare Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London WIT 3JH, UK Inhalation Toxicology Publication details, including instructions for authors and subscription information: http Jtwww. informaworld.com/smpp/tltle~content=t713657711 Inhalation Toxicology Re-Creation of Historical Chrysotile-Containing Joint Compounds G. P. Brorby P. J. Sheehan *; D. W. Berman b; J. F. Greene c; S. E. Holm d * Exponent, Inc,, Oakland, California fc Aeolus, Inc., Albany, California : Exponent, Inc , Spokane. Washington 11 Georgia-Pacific, LLC, Atlanta, Georgia Online Publication Date: 01 September 2008 To cite this Article Brorby, G. P , Sheehan, P. J.r Berman, D, W., Greene. J. F. and Holm, S. E.(2008)'Re-Creation of Historical Chrysotile-Containing Joint Compounds'.lnhalation Toxicology.20 11,1043 -- 1053 To link to thi# Article: DOI: 10 1080/08958370302290595 URL: http://dx doi.org/10.1080/08958370802290595 PLEASE SCROLL DOWN FOR ARTICLE j Full terms and conditions of use: http://wMV.infornc1woxld.con/ta7iMK and condition*-of-access.pdf ' Tliiarticle may be used for research, teaching arid private study purposes. Any substantial or I systematic reproduction, re-distribution, re selling, loan or sub licensing, systematic supply or distribution in any form to anyone in expressly forbidden. j The publisher does not give any warranty express or implied or maxe any representation that the contents will be complete or accurate or up to date. The accuracy of any instruct ionsr formulae and drug doses should be independently verified with piimary sources. The publisher shall not be liable 01 any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. RE-CREATION OF HISTORICAL JOINT COMPOUNDS 1049 TABLE 3 Distribution of sizes of primary fibers and bundles in historical joint system cement and three samples of Grade 7 chrysolite <0.25 pm 0.25-0.4 gm >0.4 pm all widths <0.25 pm 0.25-0.4 pm >0.4 pm all widths <0.25 pm 0.25-0.4 pm >0.4 pm all widths <0.25 pm 0.25-0.4 pm >0.4 pm fill w idths Historical joint system cement primary fibers and bundles <5 pm 5-10 pm 10-40 pm 0.444 0.041 0.050 0.180 0.012 0.018 0.187 0.041 0.024 0.811 0.094 0.092 JM 7RF3 primary fibers and bundles <5 pm 5-10 pm 10-40 pm 0.476 0.040 0.020 0.162 0.004 0,005 0.268 0.013 0.010 0.906 0.057 0.035 JM 7R05 primary fillers and bundles <5 pm 5-10 pm 10-40 pm 0.345 0.026 0.005 0.125 0.008 0.002 0.465 0.015 0.008 0.935 0.049 0.016 Brazilian CB7RP primary fibers and bundles <5 pm 5-10 pm 10-40 pm 0.364 0.025 0.008 0.137 0.007 0.003 0.421 0.025 0.009 0.922 0.057 0.021 >40 pm 0.003 0.001 0.(XX) 0.004 >40 pm 0.001 0.001 0.001 0.002 >40 pm 0.000 0.000 0.000 0.001 >40 pm 0.000 0.000 0.000 0.001 all lengths 0.537 0.212 0.251 1 all lengths 0.536 0.172 0.292 1 all lengths 0.377 0.135 0.488 1 all lengths 0.397 0.146 0.456 1 A t* 3 9 -4 1 3 R o v m b t r ?08t D o w n lo a d 'd B y: variation between samples of the same material (i.c. historical material or the three Grade 7 samples) and the best estimate for each material. Figure la includes structures of all lengths. Fig ure I b excludes structures shorter than 5 gm. so that the relative contributions from other sizes can be belter observed. Circles in these figures represent the traction in each size category ob served in each of the three individual replicates analyzed for each material. The square represents the fraction in each size category observed based on the combined (pooled) mean across the replicates for each material (determined by maximum like lihood; Berman ct al,, in preparation). It can be seen clearly In these figures that, especially when variation is taken into ac count, the proportion of each size range of structures in the his torical material overlaps the proportion for every one of the cor responding size ranges in JM 7RF3, but not JM 7R05 or Brazilian CB7RP. Overall, the distribution of fiber sizes in the JM 7RF3 sample best overlaps the size distribution observed for tire chrysotiie in the historical joint system cement (Berman et a)., in prepa ration). It should be noted that the chemical characteristics of die historical material appear to interfere with preparation of' the polycarbonate tillers used for these analyses, such that some tibers and other particles are lost during preparation. The effect of this phenomenon, which was not observed among the Grade 7 chrysotiie samples, is being evaluated further using mixed cellu lose ester (MCE) filters ( Berman et atin preparation). However, this comparison w as not the only criterion relied upon for select ing the chrysotiie sample to be used in the re-crcatcd products. JM 7RF3 was also selected, because it clearly contains the great est fraction of the longest fibers among the materials tested, and substantial evidence suggests that it is the longest fibers that con tribute the most to asbestos-related cancer risk (Berman et al., 1995: Berman and Crump, 2003, 2008; ERG, 2003a. 2003b). Thus, using JM 7RF3 for the rc-created products represents a conservative choice (i.c. tending toward maximizing potential health risks) for generating materials for future exposure and toxicity studies. Evaluation of Product Specification Testing Product specifications for each formulation and the results from testing the re created materials are listed in Tabic 4. The re-created joint system cement and ready mix generally con formed to the product specifications. Specifically, the re-created joint system cement conformed to the specifications for work ing consistency, alkalinity, working properties, crack resistance, and color. Viscosity is not specified in the joint system cement formulation: however, die viscosity of the re-created joint sys tem cement conforms to the specification for the ready-mix. The degree of bonding was better than current-day products but less than the product specification. The re-created ready-mix RE-CREATION OF HISTORICAL JOINT COMPOUNDS 1051 TABLE 4 Results rtf performance testing of re-created products Joint System Cement Ready-Mix Test Specified Measured Specified Measured Working consistency (estimated amount of water as a percentage of dry ingredients) Alkalinity Working properties 63 -67 65 8.8--9.2 Plastic, buttery working and free of grit or coarse panicles 9.1 Smooth, plastic. buttery, no grit or particles, feathers well, sheers well Bonding properties Crack resistance Color Viscosity (BLI) After compound has dried, tape shall delaminate when peeled back At most, only a couple of small cracks in the wedge Minimal delamination. approximately 5%--10% No cracks Neutral NS Off-white 565 53-56 60 NS (M-971) Filler shall be very heavily bodied and possess fair plasticity. It shall be free of any coarse, gritty or undispersed particles. (M971/974) Compound shall be. plastic. buttery working and free of any coarse, gritty or undispersed particles Tape shall show at least 75% fiber tear when delaminated 8.9 Heavy bodied witJi fair plasticity Very smooth, plastic. buttery, little grit or particles, feathers well Minimal delamination, approximately 5%--10% There shall be no large fissure cracks in the wedge, and no cracks in die thin section White 580 20 One deep fissure in wedge, no cracks in thin section While 580 Mole. NS = not specified. BU = Brabender units. fct , * v | I k t * 1 9 H * ' Nov*nhrt" d o w n lo a d e d ; : conformed to specifications for working properties, color, and viscosity, and essentially conformed to the specifications for working consistency and crack resistance. Alkalinity is not spec ified in the formulation, butthe alkalinity ofthcjc-creatcd readymix conforms to the specification for the joint system cement. As with the joint system cement, the degree of bonding observed for the ready-mix was better than current-day products, but less than the product specification. DISCUSSION AND CONCLUSIONS The goal in re creating two historical chrysotile-containing joint compounds was to generate joint compounds that were representative of the original formulations with regard to the nature of the ehrysotile fibers contained in the materials and the behavior of the products during normal use. To be conser vative, the percentage of ehrysotile in the recreated products was at the upper end of the range of percentage clirysotile used in the entire GP product line. The majority of the ingredients used to produce the joint system cement and rcady-inlx were the same as those specified in die original formulations from the late l%0s. and many of these ingredients were obtained from the same suppliers. The replacement of the fungicide in both for mulations. and the elimination of the anti-foaming agent from the joint system cement are not expected to have an impact on the performance of the re-created materials. Several polyvinyl acetate emulsions (i.e. glue) from multiple manufacturers were evaluated as a replacement for the originally specified material in the ready-mix. Small batches of ready-mix were formulated without ehrysotile to allow for evaluation of the working prop erties and viscosity of the various batches. The majority of these initial batches (without ehrysotile) were too wet and too thin. These batches were formulated with glues that had lower per centage solids than the glue specified in the original formulation. 1052 G. P. BRORBYET AL. Movetube i Once a glue wilh ihe appropriate percentage of solids was identi REFERENCES fied, Lite test batches exhibited improved working properties and Addison, J.. and Davies. L. S. T. 1990. Analysis of amphibole as viscosity. bestos in chrysotile and other minerals. Ann. Orcup. Hyg. 34:159 Re-creating the joint system cement was straightforward, and initial test batches met the majority of the product spec ifications. Rc-creating the ready-mix was more complicated, especially with regard to the blending of the dry and wet in gredients. Small test batches, this time including chrysolite, were produced to evaluate working properties and viscosity. These initial test batches (with chrysotile) were consistently too thick, even at the upper end of the specified range of water 175. ATSDR. 2001. Toxicological profile for asbestos. US Department of Health and Human Services (DHHS), Public Health Service, Agency for toxic Substances and Disease Registry, Atlanta, GA. Berman, D. W., Crump, K. S., Ohatfield, E. J., Davis,). M., and Jones. A. D. 1995. The sizes, shapes, and mineralogy of asbestos structures that induce lung tumors or mesothelioma in AF/HAN rats follow ing inhalation. Risk Anal. 15:181-195. Erratum in Risk Anal. 15: 541. as a percentage of dry ingredients (i.e. 53% to 56%). Subse Berman, D W., and Kolk, A. J. 2000. Modified elutriator method for quent test batches indicated that a ratio of approximately 60% the determination of asbestos in soils and hulk materials. Revision water to dry ingredients (wt/wt) resulted in material that was I. Prepared for the l;S Environmental Protection Agency. Region 8. of the right viscosity. One possible explanation for this dif ference is that the original formulation was intended for GP's manufacturing facility in Marietta, Georgia, which has higher average humidity than our research facility in Hayward, Cal ifornia. Furthermore, addition of the waLer was best accom plished in increments rather than all al once. Approximately 90% of the water was added initially, and the remaining wa ter was added in increments until the appropriate viscosity was May 23. Berman, D. W., and Crump. K. S. 2003. Technical support docu ment for a protocol to assess asbestos-related risk. Prepared for Mark Foltcnsbce, Syracuse Research Corporation, Syracuse. New York, and the Office of Solid Waste and Emergency Response. US Environmental Protection Agency, Washington, DC. EPA #9345 4-Gib. Berman. D. W, and Crump, K. S. 2008. A rneta-analysis of asbestosrelated cancer risk that addresses liber size and mineral type. Cril achieved. Rev. Toxicol 38(S1 ):49-73. Characterization of the asbestos siructurcs in the histori Berman. D. W,, Brorby. G. P.. and Van Landingham. C. V. 2008. Charac cal joint system cement, which is believed to contain grade terization of asbestos structure sizes, shapes, and types among three 7RF9 chrysotile, and die three commercially available Grade commercial Grade 7 fiber products and a sample of historical joint 7 chrysotile, indicate that L) ail of the observed structures are compound. (In preparation) chrysotile. mid 2) Ihe majority of the chrysotile structures in Bernstein, D. M-, Donaldson, K., Decker. U.. Gacring. S., Kunzendorf, all four materials arc less titan 5 pm in length, with relatively P Chevalier. J.. and Holm. S. E. 2008. A biopersistence study fol lowing exposure io chrysotile asbestos alone or in combination with V ii few structures greater than 40 /rut in length. The observed per fine particles. Inhal. Tax. 20 (11): 1009-1028. centage of chrysotile structures in specific size categories varied Butler, M. A. 1980. The physical and chemical characteristics of ser across replicates for individual materials, although the degree pentine rocks and minerals. Ph.D. Thesis. Department of Mineral 4? of variability was larger in some eases than in others (e.g. the Exploration. University College, Cardiff, 1980. C percentage of structures less titan 5 m in length ranged from Cox, D R.. and Hinklcy, D. V. 1974. Theoretical statistics. London: 1 approximately 50% to 80% for the JM 7RF3, as compared to Chapman and Hall. s approximately 92% to 93% for the Brazilian CB7RP). The per ERG (Hastern Research Group). 2003a Report on thepeer consultation centage of chrysotile structures in any particular size category also varied across the four materials, although in most cases the ranges of values overlap. These results indicate that, of the three Grade 7 samples evaluated. JM 7RF3 is the best substttutc for the 7RF9 specified in the original formulations and fur ther suggest (at a minimum) that JM 7RF3 represents the most conservative option (in terms of health considerations) for re creating tire original formulations, because it contains the great est fraction of long structures among the available fiber products workshop to discuss a proposed protocol to assess asbestos-related risk. Prepared for the U S. Environmental Protection Agency. Office of Solid Waste and Emergency Response, Lexington. MA. ERG (Eastern Research Group). 2003b. Report on the expert pane! on health effects of asbestos and synthetic \itreous fibers: The in fluence of fiber length Prepared for the Agency for Toxic Sub stances and Disease Registry, Division of Health Assessment and Consultation, 1 .exington, MA. Fischbcin, A.. Rohl, A. N.. I.anger. A. M.. and Seltkoff, I. J. 1979. Drywall construction and asbestos exposure. Am hid Hyg. Assoc. tested. J. 40:402-407. The re-created materials were tested according to the original Gunter, M. E,, Sanchez, M, S., and Williams, T. J. 2007, Character product specifications (e.g. viscosity, workability, crack resis tance). Both materials generally conformed to product specifica tions. indicating that lire performance of tire re-created products during normal use would be representative of Lbe performance of the original material. ization of chrysotile Samples for the presence of amphiboles: The Carey Canadian deposit. Southeastern Quebec, Canada. Can. Min eral. 45:263-280. ISO. 1995. Ambient air-determination of asbestos fibers- Directtransfer transmission electron microscopy method. ISO 10312 In ternational Organization for Standardization. Geneva. Switzerland.