Document O3aNXkB75GweJv8dn69NkgEOp

iKnii'r:*7;,:, ; vc;irv.rv t:ik rt;Ti::.!V ~r: willaLero. Kcv 7t F.t:p;rt |.-.y 1-nlph /.i'TTr.,ji'Je Survey Date June 14-16, 1976 Pinal Report Cato Industry-Wide Studies r;rrh Pivis/tn of Surveillance, linnard rvalue tic-rir., and rield rtudioa K. Lior.;:l` Inetituto for Occupational .".atcty and Health Center for Oisoafte Contre1 Cincinnati, riiio 2^13 FQS-00-000000116<J Introduction The National Institute Cor Occupational Safety am'. Vvnlth (::;on:) has underway industry-wide studies to assess the chronic health hazards from occupational exposure to respirable fibers. These studies include cpidem.iological studies of exposed worker populations to determine health effects which way be attributed to the work environment, nodical studies to assess chronic health effects, and detailed industrial' hygiene studies to characterise the various agents to which them: workers have beer, exposed. Durir.g the week of June 14-16, 197G, Ralph Zunwaldc, Mar): Docnicer and Robert Wheeler (AZ.CSI1) conducted an industrial hygiene survey of the Inttrpece Corporation in Nillsboro, hew York. The purpose of the survey was to collect samples of airborne wollastonite, characterise its composition and evaluate worker exposures. Approximately 60 airborne samples were collected at various mining and milling operations. Of these 60 airborne samples, 45 were per sonal breathing zone samples with the remaining 15 samples being collected at stationary sites near processing operations. Airborne samples were collected for the determination of respirable and total dust and wollastonite fiber concentrations. All of the respirable and total dust samples were also analysed for free silica. In addition, all stationary samples were analyzed for trace metal (Cadmium, Chromium, Cobalt, Iren, Manganese, Nickel, and Zinc) content. Settled dust samples were collected at different processing operations and were analysed in the sane manner as the airborne. Some high noise levels were apparent di^e to mill processing operations; consequently, sound level measurements were taken at various locations within the mill. 2414 FQS-00-0000001170 -2- Tr.c following paragraphs describe the sar.pl i:m :.-.A analy'-ical r.rthcd; employed, sample results, conclusions er.l recommend.-itirns drawn ior workplace improvement.*; and worker safety. To help reduce duplication of information, a copy of the February 12, 2 76 Preliminary Industrial I'yeicne Purvey P.cport of the Intcrpace Ccporation facility is attached (Appendix 7). This report documents the mining and milling processes, medical, industrial hygiene and safety practices at the facility and disc\*.s*er the potential problems with the inhalation cf airborne wollautonitc. Survey Procedures The major portion of the survey van devoted to the collection of personal breathing tone samples for documenting employee exposures at various milling and mining processes. Personal air samples were collected on the employees to determine tine-weighted average (TWA) concentrations for respirable and total dust, vollastonite fibers, and free silica. Samples for airborne respirable and total dust were collected at a flow rate of 1.? liters car minute (1pm) on 27 rsa diameter pre-weighed MSA type FWS (polyvinyl chloride) filters. Total dust samples wore collected open faced with respirable dust samples collected for trace metal analysis using 37 nm diameter pre-weighed Millipore Type AA (cellulose ester) filters. To determine airborne vollastonite fiber concentra tions both personal and stationary air samples were collected on open faced 37 ra Millipore Type AA filter* (0.0 yra pore sice) at a flow rate of 1.7 lpn. All respirable, total dust and trace metal samples were collected during the majerit of the wash shift, whereas, vollastonite fiber samples were changed periodically during the work shift as needed to prevent particulate overloading on filters. 2*15 FOS-00-0000001171 -3Frce silica concentrations for air ar.d settled dur.t samples were '`.ctcminct! using >:-ray diffraction as specified in the l.'IOfll Crystalline filica Criteria Document.1 Trace mc-tal analyses for Cel, Cr, Co, Fc, *j., Ni and 7n wars detei~ir.cd by atomic absorption spocurorc<>[-y on r.tatirv..,ry air snrples :.nd settle.', dust. To determine an index of exposure to airborne wsllastomtc fiber all fiber samples were- analysed using the MO:'!! ashertrs orunting technique." These r.irplfts were analysed by phase contrast tticretcc.ny at <ld>: ragnificaticn with fibers (3:1 length to diameter aspect ratio) counted and sited into croups of less or creator than 5 micrometers (uta) in length. Tnesc same samples were further analysed by transmission electron miororeopy (Tit") using selected area electron diffraction end energy dispersive X-ray analysis to identify all fibrous .-articles. TKM was also used for determining fiber ::i::e (length and diameter) distributions using a sample preparation method developed by Ortis" and analysed on a JHOL# JEM 10C-D TE1'. at a r.agnificaticn of 10,001:'. A rrinirvin cf ICC fibers were analysed on each sample. Sound level measurements were tahen at various mining end milling operations for identifying potential excessive noise sources. Decibel measurements were made using a General Padio 1S6SA sound level meter on the A weighted scale. Sample Results Attached as Appendix II in a brief description of each job within the mill and also the mine, a description of sampling and analytical methods utilized. 2416 FOS-00-0000001172 -4- results of nil individual samples, and p|iroiu'ucc summary statistic:. All job categories have been identified by a 4 (Unit job code. The first 2 digits represent the general work area while the last 2 digits correspond to specific jobs within these areas. Tabular nur.-.ar icc of tint--weighted average concentrations by job category for free silica and respire!ic ar.d total r.ars dust samples (wcllestonite) are given in Table 1. Presented in Table 2 is a suraary of the trace metal analyser cf settled dust samples collected at various locations within the mill. r.-.'A free silica concentrations calculated for each job category appear to he within accoptable limits as recommended by KICTiH.* Some individual respirable sampler did indicate free silica concentrations in excess of the UlCSi! reccraor..-.cd '*.'A standard of 0.050 mq/tt?. However, there is some questions as to the interpretation of those cor.centrations since the analysis for free silica on most of the samples was reported near the lower detection.limit of the analytical method (0.05 mg per filter). Trace metal (Co, Cr, Co, To, hn, ::i, Z~) analyses performed on collected airborne samples indicated levels near the lower detection limit of the analytical method, hence, air sample concentrations (cg/w^) for trace metals reported in /ppendix II reflect these low levels. The trace netal analysis of the settled dust ::a:.:p)c.>, a:, indicated in Table 2, substantiates the low levels found in the air samples. Iron was the only trace mutal found in any appreciable quantity (0.5 - 5.5*.). 2417 FOS-0-1173 5 As reported in Table 1 all T*A concentrations for respirable duct were below 5 r.g/m^, however, son* TVA concentrations for total dur.t exceeded 10 r.-a/n3. Since there is currently no specific occupational health standard for wollastonitc the standards for inert or nuisance rinser, are applicable, /.e present the Mine Enforcement and Safety Administration (::idust star-lard is 5 rr.g.'n^ respirable and 10 ir.n/r.^ total, whereon*, the Occupational Safety ar.ri Health Administration (CSHA) duct standard is S rg/rr.^ respirable ant'. 13 rg/r.3 total. bisted in Table 3 are airborne concentrations for wo 11 as tori to fibers at varieu:* operations within the mine and mill. These concentrations along with fiber sizing were performed by both optical phase contrast and electron r.icroccepy. It is apparent from the data that fiber concentrations, both total ar.d > S ::m, within the mine are much lower than those found in the mill. Also, sample concentrations in the mine for > 5 um fibers were sim ilar for both the optical ar.d electron microscopy analysis. However, those samples collected in the r.ill indicated higher > 5 um fiber concentrations when determined by optical microscopy. This difference could be attributed to the high fiber density per counting field which contributed to the difficulty in accurately sizing ar.d counting fibers. All reported fiber concontratior.s for both nine and mill substantiate these sample results previously reported in the February 12, 1C-7G Trclininary Industrial Hygiene Survey Report (Appendix I) . Sampler- evaluated by transmission electron microscopy vere also characterized fer other fibrous minerals by utilizing selected area electron diffraction end energy rtir.ret sive X-ray analysis at a magnification of 17,COOX.4 A few ehrysetilc ar.husr.os fibers were identified from the IS analyzed airborne sampler. 2418 FOS-00-0000001174 However, the.*.' few asbestos fiber;; could have le.-ulrod through contamination in handling and sample preparation methods. 7) Jus traced in figure 1 is * typical photemicrogrnph, selected area electron diffraction pattern, and rny speed urn of airborne vcllastonitc fibers fc.und in the rill. '.:i addition to determining fiber concentration: 'r.^airL-crny sw-C5 < rite distributions vert- also performed on observed fiber:; u;;ir.:; loth phase contrast and T.:\. Sampler. analysed by phase contrast microscopy, as illustrated in Tabic 4, indicated that S2-571 of the airborne fibers observed had diameters Its than J. :> urn, of which, PP*. had lenoths les3 than SO us. ".hose -.ar.e Scr.ples varc analysed by IT:', at 10,CC0X magnification. Arpioxirdto?y 1 ICC fibers were sissd from both nine and mill airborne samples for the determination cf length and diameter medians. As reported in Table 5 the count median v?s calculated ro be 0.01 tm for diameter:and 2.5 vm for lengths. This data closely compares with the fiber site data reported ir. the Preliminary Industrial hygiene Survey P.eFtrt As the TCH fiber size data indicates there are a considerable number of airborne fibers with snail diameters and short lengths which were not resolved by phase contract microscopy. Sound level mcr.surem.ents taken in the mine ranged from 104-112 dEA near the drilling operations to 70 c:3A on the loading doc): of the mill. All sound lev*] ncasvirom-.r.cs are reported in Appendix II. Discussion In d.-terrining any possible chronic respiratory health effects resulting from wolLar.tcn;tit fibers, it is necessary to determine what j.-ort-.ion of the 2419 FOS-00-0000001175 airborne fibers actually reach the lung alveolar regions. The respir.-.hrliry of fiber* is not clearly understood at the prefer.'. Ar: ..as discuscrt ir. the Preliminary Industrial Hygiene Survey i.upcit, vu-:;e*reh performed ty some ir.vcsti9r.t0rs have suggested tliat the physical parameters of the air borne fibers (e.g. size and morphology) dictate its renpirrhility :.d potential rr for producing tumorigonic cifeets. ' In a study to rtetcrmiu.- t!>e airh.-ine be havior of fibrous particles, Timbrell7 reviewed the mechanises by which particles deposit ir. the respiratory system, and rddrcssc-l airir..) ly *. r.c pro! Ion of fiber deposition. His study identified settling, incrtil impaction, and brownian diffusion as deposition mechanisms which operate for both co:-paet particles and fibers. In addition, he identified a fourth mechanism, direct interception, which is of little significance for compact particles but which pay be cf importance for fibers. Using or. aerosol spectrometer he found that the terminal settling velocity cf fibers is mainly a function of fiber diameter, with length being of secondary importance and that fibers with diameters less than 3.5 urn could escape upper respiratory deposition by settling and inertial deposition and penetrate deeply into the pulmonary spaces. Timbre11's work was substantiated in a later mathematical model study performed by Karris et al.8 in which os estimation of lung deposition of fibers was derived based on the aerodynamic behavior of thin straight rods. These Aforementioned studies, in addition to postmortem studies of the lungs of animals and asbestos workers5*'10'11, suggest that the majority of fibers which can penetrate into the alveolar regions are within a size range of less than 3.5 un in diameter and*less than 50 cm in length. The fiber size data which has m been presented in this report demonstrates that most (22t-97't) of the airborne wollAstcr.itc fibers found in tho mine and mill arc potentially respirable. In 2420 FQS-" 1 1^6 0 view of this, it would appear prudent that exposures be kept at tn absolute ninimun by the use of good engineering control r. ;:nd work practice:;. In additic: perrons working with wollastonite also should receive vei / clone redic.il surveillance ana be advised of the associated potential health hazards. It is difficult tc interpret the free silica results of the nirr.erre s.-.-plcs since the analysis for free silica was determine:', at the soc-no try ,':- r:.y diffraction quart: peak. It appears that wollastonite has a sigr.ifict.-.t interference at the primary quartz peak and a lers intcr.sa interference reflection at tho secondary' peak, making is somewhat subjective in quantifying the amount of quartz. However, the sample data shows that some areas within the aill had total dust concentrations that exeoetied 10 nc/n3. /-.nd, with a moderate free silica content (IV to 3t) associated with these high dust levels, tnc potential for inducing respiratory health problems is enhanced. It was noted during the survey that improvements had been made with the * exhaust ventilation around the bagging operations. These i::.pmovement:, since our preliminary industrial hygiene survey, have help to reduce total dur.t exposure throughout the mill. Additional measures to reduce spills, improve clcon-up procedures, and maxiniaa existing exhaust ventilation systems still appears warranted. Drilling operations in the mine and areas .around the ore crushing operations ir. the mill often had `sound level nea.vurements exceeding 90 dHA. It was observed, however, that most employees working in those areas wore hearing protection. C-rher areas throughout.the mill often had sound level mcat.urcar.<.;'.ts between 70 and S? ciliA. It has teen documented in the tlZOSH Hoiue Criteria Dccur.cnt^* 2421 FtlS-00-0000001177 that 8 to 1C hour tiitc-weiohtcd average exposures to round levels between 05 and 90 dL-A can induce hearing inpairr.erit.-,. Therefore;, it is reuostrer.ded th.tt employees exj.-osed to these levels be requested to wear hearing protection. It is also suggested that employees be nade aware of areas which have ex cessive raise levels. I'Ocause of the range of sound levels found throughout the p.ir.e arc mill it would be advisable to initiate a hearing conservation program with periodic hearing cncutinationa. 2422 FOS-00-001l7S Table 1. In tc rp a c c C o rp o ra tio n C o n c e rtra tio n s f.jrx-.-.iry o f T in e -W e ig h te d A v e ra g e (TWA) A irb o rn e C o n c e n tra tio n * by Job T itle Jit)TE: ( * ) R cprar-ents one ram plc ( -- ) No sar.plo c o lle c te d <A * .j .* -- 1 r *: n -j u c: < C.' 41 f- U*. "j V oX oW w 'J Wl ru 9 'J C ci W uJ O Cl *d o Cl T.1 'J (M 1- o * Mc o Cl c. u 41 >s u Uo a CX u CI IA 4i <0 w* 0 o co Cl ;> *4 3c w V Ci X w ci "9 *T5 PJ 9S u Cl 9 9 h >cr C o w Cl oi u O fi V* e l O u 0 CO M l f? oE <X i*, p: v< r: 9 t 4J w U w Tl Cl c. n n 4i *4 n Cl W4 Cl ./ U u i3 'J r: u fix r.o M 4 u '4 A i; c i< w iO t> O w Im o V FOS-0C-0000117<J 2423