Document vVaOpqL11jgLegOdpdmZEEM86

FILE NAME: Ford (FD) DATE: 2010 Dec 28 DOC#: FD238 DOCUMENT DESCRIPTION: Letter to Ford from ChemRisk RE Ford Billing Rates ChemRisk'" IT December 28, 2010 Dolores Nunez Studier Ford Motor Company One American Road Suite 410-A2 Dearborn, M I 48126 Re: Ford Rilling Rates - Proposal from C hem R isk for 2011 Dear Dolores: When we met in July in your office in Detroit, and again when I met with Craig and others in September, I asked if we could revisit our billing arrangements. You indicated in July and Craig indicated in the September meeting that we should set up a time to meet before the end o f the year to address this matter. Alas, we began to try to get on your calendar beginning in mid-November and hare been told that you were not available until mid-January. This was unfortunate as I had hoped to begin the rate change effective Jan. I, 2011, which would be plausible if we can reach agreement before we send our January invoices (usually issued by us around Feb, 12), Hopefully, Pam Chapman or 1will have secured a time on your calendar this week. As you are well aware, ChemRisk has had a long standing relationship with Ford. I have expres sed to you on numerous occasions that we are hugely appreciative o f your support. Based on what you have indicated to me, you have been generally pleased with our performance on behalf o f Ford. Over the past 8 or more years, Brent Finley and 1have worke d closely with Darrell, John and others to understand and further the science o f asbestos while providing sound technical expertise both in and out o f the courtroom. Our Problem As you are aware, our history goes back to 2002 when 1was originally approached by Darrell As we discussed in July and then later in September with Craig, we are currently working under the 2004 billing rate structure for Ford. While the auto industry was in financial turmoil, it made sense for us to accommodate the needs o f each firm to control costs. As 1went over with Craig, in some detail, the internal problems generated for our firm have been difficult, but some nuances have now moved to the near ridiculous. I know Jill is aware o f some o f the issues. Stmt at it e r Squat Suite 1800 " San Francisco, CA 94105 415-89&2400 415-896-2444 Fax m m n d ie n :n < k .a v December 28, 2010 Page 2 Not only are our biffing rate, nearly 7 year, " out of date", our W ^ o r d rate, are not consistent with current job titles for our employees For ^ ,IS 0, M cKinley had a Senior Associate Health Scientist title and a $145 homi: M Imm-irv 1st she is a Senior Health Scientist with an hourly bill rate ol $220, ye s " locked' ' at the 2004, $145 bill rate on all Ford cases. She, like many other early to m career scientists thave seen *a m50oA/ npnavy mmiissee dduurriinneg tmhaa,t time p1eriod so, our profit markgiirniR or, her work for you is virtually zero. This is true for many staff who hat e to n work, 0 on your projects. For those persons who do work on Ford cases and who are locked into the 2004 rates, our muMple (base salary and bonus vs. their hourly Ford billing rate) does not equal 2.1 Th U ? government contracts " start" at multiples of 2.8 because they assume n ts no. possible to stay m business below this level in the professional services industry. Personally I am wildly happy with the fantastic turn around in Ford' s profitability, its q - t y of Its products. It is a tribute to i-- -JJ *-* disci olire The recent article in the Economist must make eveiyone at bo ^ y PPV 1 am asking that since we have done our share in helping you control costs tor the pa " t ^ r k lp u s o u ,. L past 4 years that is, " every expert' s rates have been frozen, that is not the cas. m faefi nearly all o f your smaller shop or individual providers have enjoyed " PK increases if they asked for them. I recognize that our total invoices far exceed then, but for good reason. Bevond the obvious problems of a 7 year freeze, there are other vagaries of your filling system that simply appear to be illogical and have nothing to do wrth con tolling osta pin extmple a number of our full time B S. MS and PhD consultants are locked ,n at t e r a l i r i e filled them a, summer tntems. For example, we have a couple who b.11you at $75/hr (a rate from when they were still in school) and every ot tu at $13t)/hr. And fi:ere are other bureaucratic problems which is making it dlffif u1^ ! ^ Specifically, we are unable to get many new timekeepers approved This u g P ^ o U y be hat ing this problem, but it has been the case for more than 12 mo . At my request, our accounting department did a rough estimate comparing ourTurd ' ^r - m FiaU cnrl in-Tre urate rates We can document that m M OT we u " 2M 4 versus 2002 rates. In 20.0, the shot, tall was a *600,000 s t o r t a l i * , 0 rates). This was in la.ge i . J - * staff to - I of you. eases order to be financially viable. December 28, 2010 Page 3 Historically, as you know, beyond the " old rate" shortfalls, the time to payment has been the worst o f our more than 200 clients. Although the transition to the Collaborati cbilling system has significantly improved payments, prior to this transition, we payed the bank about S I 00,000 annually in interest to cover the difference between when %e had to pay our employees vs. when we received payment from Ford. Some case studies regarding most persons who are assigned to Ford projects To illu strate some o f the problems we are having with your account, I have selected a few consultants as examples. These persons are key members o f the team who know the science o f asbestos and brake wear debris, who therefore operate with considerab le efficiency, who can serve well your talented (and not inexpensive) outside counsel, and for these reasons, who like them to perform tire majority o f the Ford work. A s you will see, the salary increases alone (not to mention the increasing overhead and health care benefit costs) are creating billing structures that are no longer profitable for us. u> Name: Pam Chapman, M PH Current Friction bill rate: $180.00 per/hr Current Friction title: Managing Health Scientist Actual 2011 bill rate: $255.00 per/hr Actual 2011 title: Managing Health Scientist Difference in bill rates $75.00 per/hr or a 42% discount / loss Consultant's percentage increase in salary (only) since 2004 o f 49%. Consultant' s percent increase in total compensation since 2004 was 70%. Name: Brent Finley, PhD Current Friction bill rate: $375.00 per/hr Current Friction title: Managing Principal Actual 2011 bill rate; $475.00 per/hr Actual 2011 title; Principal Health Scientist and V P Difference in bill rates $100.00 per/hr or a 27% discount / loss Consultant' s percentage increase in salary (only) since 2004 o f 100%. Consultant' s percent increase in total compensation since 2004 was 200%. Note: This is currently what it takes to retain a super senior and well respected consultant within a firm like Exponent or ChcmRisk since they could easily work out o f their house and make more money if we were not able to compensate aggressively when they become relatively famous testifying witnesses. I am certain Brent is " far less" expensive to Ford working within our firm than if he December 28, 2010 Page 4 were to be an independent consultant like a Pat Hessel, Roy Balzer, Mort C David Garabrant. <u Dame: Meg M cKinley, M PH Current Friction bill rate: $145.00 per/hr Current Friction title: Associate Health Scientist Actual 2011 bill rate: $220.00 per/hr Actual 2011 title: Senior Health Scientist . Difference in bill rates $75.00 per/hr or a 52% discount / loss Consultant's percentage increase in salary (only) since 2005 of 35%. Consultant' s percent increase in total compensation since 2005 was 50%. o Name; Dennis Paustenbach, PhD, D A B 1 , CIH Current Friction bill rate: $425.00 per/hr Current Friction title: C hief Principal Actual 2011 bill rate: $575.00 per/hr Actual 2011 title: President and Founder Difference in bill rates $150.00 per/hr or a 35% discount / loss Name: Amanda Phelka, PhD Current Friction bill rate: $155.00 per/hr Current Friction title: Senior Health Scientist. Actual 2011 bill rate: $220.00 per/hr Actual 2011 title: Senior Health Scientist Difference in bill rates $65.00 per/hr or a 42% discount / loss 'Consultant' s percentage increase in salary (only) since 2004 o f 27%. Consultant's percent increase in total compensation since 2005 was 45%. Name: Sam Serrano, B S Current Friction bill rate $75.00 per/hr (Intern rate from 3 years ago) Current Friction title: Research Associate II Actual 2011 bill rate: $110.00 per/hr Actual 2011 title: Assistant Health Scientist i Difference in bill rates $35.00 per/hr or a 47% discount / loss Consultant's percentage increase in salary (only) since 2009 of 17%. December 28, 2010 Page 5 Another way for vou to understand our problem Another way to understand our predicament is to evaluate this issue on a " per case basis To estimate a per case " average loss" (what you might call a discount), we selected 10 cases from 2010. Billings would A ctual Billings have been if we for cases at F R IC current rates were on 2010 rates ChemRisk % loss change FRIG 929 40,784.56 53,059.00 .-12,274.44 -23% FRIG 923 12,229.50 15,746.50 -3,517.00 -22% FRIG 914 14,715.50 19,277.00 -4,561.50 -24% FRIG 911 16,906.50 21,847.00 -4,940.50 -23% FRIG 904 11,055.00 14,593.00 -3,538.00 -24% FRIC 888 11,154.75 - 14,626.75 -3,472.00 -24% FRIG 878 16,022.50 21,116.25 -5,093.75 -24% FR IC 873 35,485.50 46,592.00 -11,106.50 -24% FR IC 872 13,171.25 16,887.50 -3,716.25 -22% FR IC 871 27,534.25 36,475.50 -8,941.25 -25% Average -24% My proposal Dolores, currently, you arc among our largest clients. And, Ford has certainly be en a loyal supporter. The Big 3 were the foundation o f the firm during our formative years, and for this reason, I have tried to go the extra mile to try to satisfy your needs. Because o f the nature o f our industry, we have not had to discount our other work for other clients (other than, arguably, the government) for several years. Beyond that, it is never even requested because o f the pressure to retain scientists who know asbesios and toxic tort litigation. As you are aware, for many o f your toxicology or medical consmtants, they have more work than they can do, and I know that some of them have chosen not to always be available-to you in light o f the billing difficulties they be lieve that they have experienced. I woul d hope you agree that it is an appropriate time to set up a different compensation arrang ement with us for 2011. December 28, 2010 Page 6 Along those lines, and because your calendar has been too crowded for us to have a '`face to face discussion and resolution, for 2011, am proposing that we adopt one c 1' the two following approaches: 1) Implement 2011 rates at current titles and increase PO approval amounts. 1. Currently, 2a approval is case dependent but averages approximately $14,500. We recommend increasing .this to $18,125. 2. Similarly, 2b (deposition) is approximately $4,500. We recommend a comparable (25%) increase to $5,625. 3. Finally, Trial approval averages $5Ok' per case. We will need this increased to $62k. 2. G o to 2011 rates and back to a flat fee arrangement o f $24k per case to cover both phases 2a and 2b. Trial approvals will be for $62k. Brent and I, as well as the entire ChemRisk friction team, hope that we cam reach agreement in early January on our billing arrangements for 2011. I have asked that Pam Chapman be available to meet with you as soon as a date can be identified. I am led to believe that this can occur before Jan. 15th. She is the closest person to the financials for your projects. C losing Thoughts I believe you can assure your management that you have been " the good steward ' of ford resources over the past 8 years in your dealings with our firm. To be specific,, during this time period, when we were generally not " discounting" any o f our invoices, ford received approximately $4,000,000 in professional courtesies (which induces write offs, discounts on rates, and the interest on monies borrowed while waiting for payment), I tiiink you would agree that for a firm o f our size, this is a remarkable loss in inc ome. Let me close with another issue which the two of us have not discussed previousl y, and I am no: sure that outside counsel has brought this to your attention. Over the past 5 years, i have personally spent (in hard or soft dollars) a little more than $3M in profits (which ' would have been distributed to me or the staff) in asbestos related research which resulted in publications which have been enormously illuminating to the courts and juries, I did this because i believe that the courts deserve to have all the scientific information that can be brought to the table when reaching conclusions. In my view, these papers have dranged the scientific playing field in the courtroom. You know this better than anyone as you have seen the number of plaintiff verdicts decrease and the cost o f settlement go down ever time. As I am constantly reminded by the 1-14 person shops who work for Lord as experts (including Exponent, Veritox, and a host o f industrial hygienists), all o f them bast: the December 28, 2010 Page 7 background o f their testimony on our published papers. We know this because o f the dog fight we just went through on the Bankhead case. The Kazan firm successfully a rgued that even if Paustenbach and Ford were no longer in the case, everyone else was relying our published work so they were entitled to the basis for our conclusions. I will bring to your attention (attached) our recent paper on bystander exposure to asbestos. From what I can determine, it has been used in perhaps 30 " friction" cases over the past 90 days since it was published. This was a ChenrRisk funded paper which required no less than $300,000 in effort. I wish you the best this holiday season and look forward to seeing you in the month o f January. Sincerely, Dennis Paustenbach, PhD, D A B T President and C E O C C : C . Halseth J. Plensdorf J. Henderson M . Garavaglia D. Grams P,, Lankford P. Chapman P. Barnette Enclosures: Donovan et al, 2010 2004 ChemRisk Rate Sheet 2010 ChemRisk Rate Sheet 2011 ChemRisk Rate Sheet Critical Reviews m Toxicology Downloaded from informahcalLhcare.com by M s Carrie Kahn on 09,"23/10 Critical Reviews in Toxicology, 2010, 1-23, Early Online healthcare REVIEW ARTICLE Evaluation of bystander exposures to asbestos in occupational settings: A review of the literature and application of a simple eddy diffusion model Ellen P. Donovan1, Brooke L. Donovan1, Jennifer SahrneE, Paul K. Scott3, and Dennis J. Paustenbaai* 'ChemRisk, L .J.C ., San Francisco, California, USA, KihernMsk, L.L.C., Boulder, Colorado, USA, a n d ' ChtnMLsk, LUX'.,. Pittsburgh, PA USA - This article presents a review of the publicly available information as it relates to airborne asbestos conce nxrations at varying distances from a source in an occupational environment. Personal and area samples collected 5-/5 feet from the primary worker from workplace surveys conducted in the 1970s and area samples collet red 5-50 feet from the primary worker during more recent simulation studies were identified, compiled, and analyzed. As expected, airborne asbestos concentrations generally decreased with distance from the worker who perrormeo a ciiven task. Based on this review, however, the authors found that no systematic research to quantitatively relate fiber concentration with distance from the soured (including consideration of fiber length, dilution ventih don, ana initial momentum of the particle) has been conducted to date. A simple mathematical model was there ore used, ard the results were considered, along with available published data comparing exposure data for both worxeis ard persons/areas near workers. From this analysis, the authors offer guidance for estimating airborne asbestos concentrations at distance from a source. Based on the available data and our modeling results, the audio s propose the following approach as a rule of thumb: for persons 1-5 feet from the source, airborne asbestos con centrations can be roughly approximated at 50% of the source concentration; 35% at >5-10 feet, 10% rc r >f 0-c0 feet, and less than 1% at distances greater than 30 feet. This approach should be helpful for bracketing die ranee o f:ikely exposures to bystanders being evaluated in asbestos-related dose-reconstruction analyses. Keywords: Asbestos; bystander exposure; exposure assessment; indirect exposure; industrial hygiene, riea. held C o n te n ts Introduction................................................................................................................................................................................................................................ . M ethods......................................................................................................................................... ( Literature review.................................................................................................. , Mathematical modeling of airborne asbestos concentration with distance....................................................................................................... ; Generation of a "rule of thumb" to estimate bystander exposure at specific distances from a source............................................. Workplace surveys (1970s)........................................................................................................................................................................................................... , Simulation studies (2000s)........................................................................................................................................................................................................... ... Removal an d manipulation of gaskets....................................................................................................................................'.............................................~ Work with friction products (clutches and brakes)........................................................................................................................................................ Occupational use of coatings, mastics and adhesives, and phenolic molding com pound......................................-............................^ Summary c i available literature relevant to mathematical modeling of airborne asbestos concentration with distance.... 1 A d d m s fo r Correspondence: Eben P. D on ovan , Chem R isk, L .L .C ., 2S lessie Street, Suite 1800, San Francisco, C A 94105 1r-2A {'-rn.nil (Received 05 l-ebr.airy 20JO; revised 01 u ly2 0 1 0 ; accepted 0 4 ]n ly ;:0 i0 ) ISSN 1040-8444 pi int/ISSN 1547-6898 online 0 2010 Informa Healthcare USA, Inc. DOl: 10.3109/104' 8444.2010.506639 nttpiVwvov.mfonnahealrhcarr-.ccm Txc (HI 01 Ml T HEB L V 1% i" 2 if. P. Donovan etal. Results of mathematical modeling developed to estimate airborne asbestosconcentration with distance.................................id Proposed "ride of thumb" to estimate bystander exposure at specific distances from a source....................................................... 1:3 Discussion................................................................................................................................ 3................................................................................................................20 Declaration of interest............................................................................................................. '...........................................................................................................2.1 Critical Reviews in Toxicology Downloaded from informaheaUhcare.com by Ms. Carne Kahn on 09/23/10 For personal use only. Introduction Because of its unique physical and chemical properties, asbestos has historically been used as a hot surface expo sure preventive, as a filler for certain molded materials (and building materials), and as a flame retardant (Maines, 2005). In the Ur .ted States, asbestos began to be used around the end of the 19th century, and its overall consumption increased substantially during World War II due to its use in shipbuilding and repair (Balzer and Cooper, 1968; NIOSII, 1972). In later years, it was used mostly in the building and construction industry, which accounted for more than two- thirds of the total asbestos demand in the United States by the, 1980s (US 2PA, 1988). Thousands of commercial and industrial prod.rets and applications have contained asbes tos, including (1).insulation or filler, (2) blocks and pipe sec tions, (3) gaskets and packing, (4) cement sheets and paper, (5) textiles, (6) blankets or felts, (7) friction materials, and (8) other heat-resistant materials, such as phenolic resins, floor tiles, ceiling tiles, coatings, mastics, cloth, and gloves (Lindeli, 1973). Historically, hree types of asbestos have been used most frequently. Chrysotile (a member of the serpentine mineral family) was predominantly used through the 1930s, although dining World War II, amosite (an amphibole) was used exten sively in the US shipyard industry (Bowles and Stoddard, 1933; Bowles and Bar-dgian, 1951; Balzer and Cooper, 1968; Virta, 2005). Around die mid-1950s or early 19G0s, chrysotile fiber comprised the vast majority of asbestos used in the United States for a number of reasons, including the introduction of molded products in the marketplace and increased use in various building materials, including sealants (mastics, asphalt coatings, etc.). Starting in the 1970s, chrysotile was some times mixed with other forms of asbestos (such as cro- cidolite and amosite) for use in insulation and a very small fraction of gaskets (NIOSH, 1972; Mangold et al., 2006). Because of its widespread use, asbestos presented numer ous exposure opportunities for workers producing, handling, or using asbestos-containing materials in the manufactur ing, construction, maritime, and other industries (Maines, 2005). ' Knowledge regarding the health hazards posed by asbestos evolves, considerably throughout the 20th century (Paustenbach, 2304). In 1930, Merewether and Price con ducted the first epidemiology study in an asbestos textile plant, after which they concluded that a clear risk existed for developing a unique lung disease from inhaling asbestos dust (Le., asbestosis). They also noted drat exposure duration and amount of oust inhaled were key factors for predicting disease (Merewether and Price, 1930). With few exceptions, the workers evaluated in the studies conducted throughout the 1930s performed activities in manufacturing settings (i.c., among the dustiest environments). At the time, the scientific and industrial hygiene communities believed drat asbestos exposure could be significantly lessened by using engineering or administrative controls to reach acceptable airborne concentrations. By the mid- 1940s, focus expanded to include individuals who used, rather than produced, asbestos-containing materials. Some of t ie major studies of this era were conducted in the shipbuilding industry, cohere asbestos was heavily used in pipe covering and insulation (Fleischer et ah, 1946). Because of the ct. nfirted spaces and lack of ventilation inside the ships, as well as the large voi ume of asbestos-containing materials used, exposures iu this industry could be quite substantial Man? 1964). By, 1955, it was dear that sufficient exposure to asbestos could increase the risk of lung cancer (Doll, 19.45). In 196,0, Wagner et al. reported a causal link between mesothelioma and crOddolite exposure (Wagner et al., i960). Recognition of the hazards of insulation work in the shipyard in cu sin ' eventually broadened to include other trades in which insu lation use was also commonplace, such as construction, lr. the 1960s, for example, Dr. Irving Selikoff and his colleagues conducted a large scale study of over 10(. 0 union insu Lae;rs in the New York-New Jersey area (Selikoff et al., 5965a). They reported an increased risk of both lung ca ncer and mesothe lioma in this cohort, which included active workers as well as deceased or retired individuals, many of whom hac over 20 years of asbestos exposure (Selikoff et al., 1964, Selikoff et a l, 1965b). As more was learned about the hazard:: of asbestos, by flit late 1960s, concern about the hazards regarding the exposure of "bystanders" began to grow. Historically, this term has been used to describe persons who are in the in mediate vicinity of a worker handling asbestos-containing products. The dura tion and extent of bystander exposures can vary considerably (usually due to the magnitude of the exposure of the primary worker and the bystander's distance from that person).'Ihere have been some anecdotal reports of possible hazard to bystanders in the scientific literature; however, much of the historical concern and exposure estimates revolve around less ihari five studies (which were not intended uj quantity concentration al a distance from the source). Although i: was not until 1979 that the term ''bystander" was used in the peerreviewed literature (Lilis et al., 1979), similar terms have been used over the years, such as "indirect exposure" or "nearby m ii a mi t s l t ?!a lea Evaluation o f bystander exposures to asbestos Critical Reviews in Toxicology Downloaded from mfonT.ahealthcare.com by Ms. Carrie K.ahn on 09/23/10 For persona! use only. workers" In 1934, for example, Selikoff et al. first noted that "asbestos exposure in industry will not be limited to the particular craft that utilizes the material. The floating fibers do not respect job classification. Thus, for example, insula tion workers undoubtedly share their exposure with their workmates in other trades; intimate contact with asbestos is possible for electricians, plumbers, sheet-metal workers, and forem en..: (Selikoff et al., 1964, p. 146). Initially, the con cern for bystanders focused more frequently on persons who were near workers who handled relatively large quantities of raw fibers (e.g., asbestos mining or manufacturing). Later, concern was expressed regarding craftsmen who might be working in the vicinity of insulators (especially during initial construction or tear-down). Examples of typical work settings in which asbestos was used in the early years are provided in Figures 1and 2 indicating how some activities had the poten tial to general': very dusty environments in the immediate area, near the work task. In the late 1960s, several studies in British shipyards reported that significant airborne concentrations (up to 200 f/cc) could occur during the application of sprayed-on crocidolite asbestos insulation (Harries, 1968,1971a, 1971b). These findings were not surprising, given the method of application ami lack of engineering controls. These airborne concentrations were higher than what had been reported for non-shipyard settings or for shipyards in the United States, which also differed with respect to the asbestos fiber type present in the insulation and the method of application (Mangold et a l . 1970). The Harries studies alerted the indus trial hygiene community that although the primary worker, such as the spray insulator, might be protected because he used a supplied-air respirator, those within 100 feet of the sprayer usually did not wear respiratory protection and thus may not be as protected, indeed, tire shipyard industry was among die first in which increased awareness existed regard ing the potential for exposure to asbestos of workers in dose proximity to insulation work (specific precautions for "neigh bourhood workers," defined as workers not directly in contact with asbestos, but employed near or with asbestos workers, were actually described in Harries, 1971b). The potential for high exposure (i.e., airborne asbestos concentrations well over 100 f/cc d icing some activities) in this industry was pri marily due to Lie quantity of insulation used, confined work areas, inability io have high-quality local exhaust ventilation, and the use of amphibole asbestos during shipbuilding and repair. In the shipyard studies, bystander exposures were dis cussed genera y, rather than quantitatively, and they lacked a complete description regarding the concentrations with respect to distances from a source (i.e., an insulator). In, his 1971 testimony before Congress, Selikoff noted that "asbestos diseases were found not only in men directly working with the material, but [in] other people in the same industries as, for example, net only the insulation worker in a shipyard, but die electrician in the shipyard, the steamfitter, the shiphtter, the plumber, et cetera, because they were in the same atmosphere, on the same ship with the men actually using the material" (Selikoff, 1971, pp. 28-29). Figure 1. Application o f spray ir sulation. J r i a . ^ c o . -- ivTispip in fg a n A A v M r t o t - c u r d m jf V i s c h i n e b e lo r o a t r u n l c m t y ; 1v ` -t InaFauid Ventiliition wtw uppltM ocally (Hy iVai trry of I'irtlitti Kfitio# in/ /-rtkrnoi. iJiL) Figure 2. Asbestos carding plant. From Hi.inter. ldaS i/p. b/o). Ifeitze et al. (1966) conducted one of the first studies out side of the shipbuilding industry to evaluate die exposure of workers who sprayed asbestos insulation, raid they awe evaluated the exposure of bystanders I.Keit'xe et: al., 1972J, They were the first to provide quantitative information regsniing airborne concentrations measured at a distance iroui the spraying activity. They noted that they were interested in evaluating exposures among the workmen who acuve.y applied the insulation materials, as well as other workers wee were on the site during or shortly after the application [Items et ah, 1972). In the years that followed, additional studies oi craftspersons other than insulators were conducted Ferris et a l, 1971; TIM Factory inspectorate, 1973; N I0SH , iB'to: Rohl e t a l, 1975; Bell, 1976; Liukonene! al,, 1978; Fischbem et al., 1979; Vienna and Middleton, 1980; McMillan, 1988: Baker et al., 1985; Sprince et a l, 1985; Zoloth and Michaels. 1985; Drucker et al., .1987; Vertna et al., 2003). Ihe potential for bystander exposure to insulation work was recognizee, among these crafts, but it was also aden owfedged that uiesc workers often handled asbestos- containing materials in the ijq t a H ir m i i lu x Ci ilical Reviews in Toxicology1Downloaded from informahealthcare.com by Ms. Carrie Rahn on 09/23/10 For personal use only. 4 B. P. Donovan et al. course of their own duties. A comprehensive review published by Williams ct al. [2007) summarized the available asbestos air monitorin,.; data for these craftspersons. Although the majority' of the available air samples were collected during insulation work, the data were inadequate for estimating bystander exposures among the other craftspersons. It was noted by the authors that ''tire available data and our profes sional experience indicate that bystander exposures to most airborne particles were usually no greater than one-tenth the concentration measured in tire primary worker's breathing zone" (Willian ,s et ah, 2007, p. 372). Over die last 10 years, there have been an increased number of court cases involving bystanders or passers-by that have been termed "premises cases." The potential for exposure tu bystanders in proximity to work involving asbestos has not been well characterized to date. Much of the available eata were collected 30 or more years ago, and were not intended to quantitatively characterize bystander exposure, yet this information is often extrapolated to more recent exposures, which are, in general, considerably lower (Paustenbach, 2004). 'the purpose of this analysis, then, is to review die published literature to characterize the evolution of knowledge regarding bystander exposure to asbestos. Nearly 100 published studies describing persons working with or in the vicinity of asbestos were evaluated and ranked based on whether they contained sampling results and information regarding distance from the source. The scientific literature was also revie wed to determine whether any mathematical models specific to fibers could be used to estimate airborne concentrations ai various distances from a source. Relevant published data were assembled and coupled with results from a simple mathematical model to derive some general guidelines for estimating ranges of airborne concentrations for bystanders within 50 feet of a hypothetical source. Methods Literature review h comprehensive search of publicly available documents that directly or indirectly addressed bystander exposure to asbestos was c anducted. The search included studies cover ing industrial and shipyard settings, but excluded studies that presented data collected during asbestos abatement work. Several databc.se search engines (e.g., TOXNET, PubMed) were used to identify potentially relevant conference pro ceedings or publications in the peer-reviewed literature. Government documents, such as National Institute for Occupational Safely and Health (NTOSH) Human Health Evaluation (HITE) reports, and industrial hygiene text books were also considered. Although there are studies in the published literature relating to asbestos exposure to building occupants during routine maintenance activi ties (often considered a type of bystander exposure), these were also excl ided fro m iiiis rev iew , a s th e y rarely in c lu d e d precise measurements of distance from the source, and such work is often similar to abatement work. Nearly a dozen search terms were used in an attempt to capture the various ways that bystander exposure has historically been described, including: "bystander," "indirect," "secondary," "onlooker," "diffuse," "non-occupational," "viewer," "witness,'' "spectator," "eyewitness," as well as "tradesmen exposure'1 and "personal-versus-area sampling." "fire approximately 100 articles identified in fie initial search were ranked based on the follow ing criteria: ( I.) .spe cific reference to bystanders (or equivalent term), (2) avail ability of quantitative data, and (3) availability of mioimation regarding the distance from the primary exposure source or time elapsed after work involving asbestos was completed by the primary worker. Because many earl ier studies relied oi; area samples to characterize "nearby" exposures, no effort was made to restrict tire search based on sample type (he., personal or area sampling) or the analytic al method used (i.e. phase-contrast microscopy [PCM] or transmission electron microscopy [TEM]). Similarly, there wen no inclusion criteria for sample duration. Air monitoring data from studies that included saniyius considered representative of "bystanders," as well as chose: providing information regarding the distance from me pri mary source or time elapsed following the primary worker activity', were compiled and summarized. These studies ecu-cl be broadly categorized as either (1) workplace surveys & (2; simulation studies. The workplace surveys were conducted in several different industries during the 1970s, and included area samples collected anywhere from 1 to 75 feet hum the worker. Data collected during simulatioi i studies, wb ich typi cally contained more detailed quantitative asbestos exposure data for both the primary worker and bystanders, were also considered. In the context of this review and analysis, a "simulation study" is defined as a controlled exposure study in which a worker performs a series of tasks and air samples are collected simultaneously to measure airborne asbestos concentrations. Many of the simulation studies included area samples that were collected at a known distance ami loca tion relative to the primary worker in order to characterize exposures for a hypothetical bystander. In total, 12 simulation studies were identified as relevant, To facilitate data analysis, the available air sampling resides from the studies that presented individual sampling results were assembled into Excel spreadsheets (one per study). When possible, PCM measurements wei e adjusted for asbes tos fiber content according to the metho d outlined in NIOSI i Method 7402, in which the PCM fiber concentration is mi ltiplied by the ratio of asbestos fibers to total fibers observed in the TEM analysis. In cases where ihe PCM result was below the analytical sensitivity limit, but asbestos fibers ware detected in the corresponding TEM measurement, a value x one-half the PCM analytical sensitivity limit was multiplied by the ratio of asbestos fibers to total fibers observed byTEM. If the PCM measurement was above tire analytical sensitivity limit, but asbestos fibers were not detected by TEM, a valueor "0" was used for the POM-adjusled concentration in any calculations. Each study was evaluated in detail to identify possible bystander samples and link them tc the corresponding . H I B H T I U :i El tv; Critical Reviews in Toxicology Downloaded from infbrmaiiealtheare.com by Ms. Carrie Kahn on 09/23/10 For personal use only. worker sample(s). A variable for the distance from the primary worker was assigned to each bystander sample. In m ost cases, the distance from the worker was reported in the original study, and that value was included in our analysis. There were several cases, though, in which the authors of the original study reported that the work occurred in an adjacent area, but did not provide specific distance measurements. In these instances, the distances between the bystander and the worker we re estimated based on professional judgment. If the distance from tire worker was reported as a range by the authors, the midpoint of that range was used in tills analysis. After each bystander sample was linked with the appro priate primat'/ worker sample and a variable for distance from the source was added, the ratio between the airborne asbestos concentration for each bystander sample and the corresponding worker sample was calculated. This step also served to "normalize" the bystander samples to allow lor comparison across different studies (or activities within a sin gle study). The analysis was limited to worker-bystander pairs in which there were detectable concentrations of asbestos in the worker sample. It should also be noted that in several ot tire studies (Paustenbach et ai., 2006; Jiang et a l, 2008; Madl tal., 2008), samples were collected separately on the left and right lapels ol the worker and/or in time series (two succes sive 15-minute samples] and averaged to arrive at a single value for analysis, in instances hr which one or more of the individual samples were below analytical sensitivity limits, the samples reported as "non-detect" were included, in the calculation of an average value using a value of one-half of the limit of de tection (LOD). As part of a preliminary data analysis, the percent reduc tion in mean airborne asbestos concentrations at varying distances from the source was calculated for the various tasks that were evaluated in each study. If individual sam pling results were available, a Student's t test was used to determine whether there was a significant difference in the airborne asbestos concentrations of the bystander and worker samples. Variance between sample sets was assessed using Excel's "FrEST" function; based on these results, the Student's t-test was performed assuming unequal vctricLncG. The data from, the individual studies were also pooled into a single c.ata set for further analysis. An x-y scatter plot was generated in order to evaluate whether there was a rela tionship between the ratio of bystander to worker airborne asbestos concentrations and distance. Box plots were gener ated in order to determine whether there appeared to be a relationship with distance when all the available data were pooled. Secondary box plots and x-y scatter plots were also generated using a bystander worker ratio cutoff ol I (i.e., for anv bystan.de, worker ratios greater than 1, a value of 1was used) in an attempt to reduce some of (fie variability that was due to the high n u m b e r of ratio s based on bystander samples with <LOD results; this phenomenon occurred almost exclu; Lvelyin tire simulation studies. Samples were grouped by distance from the source/ worker into the Evaluation of bystander exposures to asbestos following categories; 1-5, ?5 -l0 , >10 -3C, and greater than 30 feet (Figure 3). It was assumed that the "source'' comp nsec. <. distance of 0-1 foot. Distances greater tl: an 50 feet away were considered too great to be significant y influenced by the single point source where the primary worker was engaged. Often, at distances greater than 50 few, backgmui Generations of asbestos, room ventilation, and other nearby activities would have more impact than the source itself. The mean bystanderrworker ratios were calculated tor each category of distance. Mathematical m odeling o f airborne, asbestos concentration with distance As will be discussed in greater detail, there was consider able variability in the available published data. Based or, the preliminary analyses, there was a general decrease in airborne asbestos concentrations at increasing distances from the source, but there were many inconsistencies in me data, and no clear trends for bystander exposures were seen. An additional literature review was therefore conducted to identify any mathematical models that could be used in predict concentrations of airborne fibres in the workplace. Initially, the focus of this additional review was on these studies that compared modeled estimates to measured fiber.concentratious. As noted previously, however, a fairly limited number of studies were found that reported fiber concentrations over time or at specific distances from a source. Because of the inherent variability ass ociatec with comp.rr ing bystander to worker air concentrations from simulation studies and workplace surveys, an indeor air eddy difusior: Prima.y worser concentration ar source 1-5 fe , from source SO0/, Source conceruration > S--1C fe e l from so u rce 35% Source concentration > 1 0 -1 0 reef from so urce 10% Source con cem raiijn . 3 0 fr et from s o u rc e 1% So urce concentration 0 5 10 20 30 40 50 60 70 30 SO ,0k D'sranc room source ms Figure 3. Proposed guidelines for estimating air rornc asDemos cjncuiura(ion at various distances from a point source. re ti ta hi r is l i re 6 E. P. Donovan et al. Critical Reviews in Toxicology Downloaded from mfonnahcalthcarc.com by Ms. Cam e Kahn on 09/23/10 For personal use only. analytical model for particulate emissions was applied for a simplified scenario to provide a point oi comparison to the bystander worker ratios derived from the published data. Although a mere complicated model, such as the Markov Chain Model (Kicas, 2001), could have been used, the Level of input data requdedfor such models is more suited to evaluate specific emission scenarios (i.e., a particular emission activity in a specific location), rather than the generic-assumptions used in this analysis. Because of the variability in activities, source characteristics, and types of indoor locations associ ated with die simulation study and workplace survey data to which the model results were to be compared, the eddy diffusion models (which require a lower level of source and location input data) were considered more suitable for dris application. Specifically, the indoor air eddy diffusion models devel oped by Drivas et al. (1996) and Kell (2000) for particulate emissions were used to estimate the airborne concentrations over time for a one time, point source release ot particles (in this case, fibers). These models are based on the same equations, except that the Drivas et al. (1996) model also accounts for surface deposition and reflection off of room wails. As such, [lie Drivas et al. (1996) model was considered to be more representative of a typical work environment, but bystanderworkcr ratios were also generated based on the Keii (2000j model, which does not consider removal from these transport and loss mechanisms, to provide upper bound concen nations. A scenario nfa "source" performing maintenance work near the m iddle.of a wall in a 100 x 100 x 20-foot room was evaluated. This scenario was meant to represent typical emissions that might be caused by a worker working with asbestos containing materials (e.g., insulation). Ihe emis sion source was assumed lo emit 9,290,000 Occupation Safety and Health Administration (OSHA) fibers (greater than 5 pm in l- ngth with an aspect ratio of at least 3:1) over a 15-minutc period of worker activity. This assumption essentially ignores the mass build-up during the activity, and treats it at an instantaneous release at the end of the 15 minutes, equivalent to a peak worker air concentration of 5 f/cc, at a height of 6 feet. Air concentrations were esti mated every 15 minutes after the emissions occurred for thc worker (0 -1 foot), and for bystanders who were 1-75 feet in a straight line distance from the source. All air con centration estimates were for a breathing zone height of 6 feet. Pot both the worker and bystanders, a 15-minute time-weighted average asbestos air concentration and the ratio of the worker and bystander air concentrations were calculated. Because the sampling duration for the simula tion study anti workplace survey data varied, a 15-minute time-weighted average fiber concentration was estimated in order to provide a value that would be representative of a short-term air sample that may have been collected imme diately after tne exposure activity in a m an n e r sim ilar to a simulation study: _ 'ihe proposed scenario is based on a single release of fibers into the air. As described in detail in Keil (2000), the equation that can be used when there is an instantaneous or pun release of a pollutant is: " 8( D i f where M is the number of fibers instant! / released; L is tilt' c o n c e n tra tio n (fibers/m3); D is eddy diffusion coeffickn. (mb's); i is time from start of generation (s); r is the radial distance from source (m). To account for additional transport and loss mechanisms such as surface deposition and reflection off roc-m walls, the following equations from Drivas et a l (1996) were used; Q C(x,y,z,t) = MAX_______ i R R -v R y ` 2) (4tTin)2 where c[x,y,z,i) is tile indoor concentration (libers/.art) at position x,y,z at time t in the room and Q,,, J s the total amount of fibers released at the source position (W ,;) - ^ | The ft , R , and ft. terms in Equation 2, which speedy tne wall reflection terms, are defined as follows for a recta agt.il; r room: (x + 2iL - x 0f ^ (x + 2/X ftx = 4D t 4X9 ( y + 2 iW --y 0)~ (y + 2 i W - y ri n,, __--------------------f a ----- 4D t ADt (z + 2iH - z ,, (z + 2 it: (5) 4D t 41U where X is the room length (m), IVis the room width tmX ant; H is the room height (in). To account for differences in the particle geometry between the standard spherical particle and tne cylindrical asbestos fiber, a fiber settling velocity was calculated using the method presented by Spengler et al. (2001). lo estimate a settling velocity that would be characteristic of the range of possible shapes associated with OSHA fibers, sealin g velocities were calculated for different com b in ation s oi particle density (2.4 or 2.6g/cm*), fiber diameter (0.2, On or 0.4 pm), and fiber length (5 or 10 ..cm), .the calculated settling velocities for the 12 different combinations of par ticle characteristics ranged from 0.001.1 to 0 005 m/s, arm the average settling velocity of 0.0028 m/s was used in me Drivas et al. (1996) model to be characteristic oi OSI fA nbers Because the effective eddy diffusion rate and ventilation rate are correlated with each other, the reported midpoin t oi the effective diffusion rate of 0.45 nrVmin and room ventilation rate of five air changes/houv for a I8f-x 120x20-tool mow tqi tl lid IHt T 'til L I N a Critical Reviews in Toxicology Downloaded from mfonnahealthcare.com by Ms. Carrie Kahn on 09/23/10 were used. These values were based on effective diffusion rates that were measured and reported from several other studies (summarized and presented in Keil, 2000). The fixed, input values used in the model are presented in Table l . Generation o f a "rule o f thum b" to estimate bystander exposure at specific distancesfrom a source In addition to presenting the results from the analysis of the published literature and modeling results, an exercise was also concocted to see how the results from each type o f available bystander data (simulation study results, work place survey results, and the modeling results for a simplistic work scenario 1aligned at specific distances irom the source. The purpose of this exercise was to develop a rough "rule of thumb" for several bystander distance categories. The specific distance categories were driven in large part by the distances for which data were available in the published studies. For example, many ol the simulation studies collected samples at a distance of 5 feet to characterize bystander exposures, so there are a large number of samples at 5 feet, but only a handful that were collected at shorter distances ranging from 1 to 4 feet. As such, it was difficult to provide meaningful com parisons at, say, 2 feet from the source, given that there may have been only one or two samples at this distance. The initial distance categories of 1-5, >5-10, >10-30, and greater than 30 feet were developed based on the frequency distribution of bystanderiworker ratios that were generated for the pooled data set where all the samples that could not be analyzed ( i.w o r k e r samples with airborne asbestos con centrations reported as below the I.OD) had been excluded. For each of these categories, the bystander: worker ratios were averaged for any distances that were within the range (i.e., ratios reported at 6, 9, and 10 feet would have been averaged together to generate a single ratio for >5-10 feet category). Initially, this averaging was done separately for each type of 'Evaluation of bystander exposures to asbestos bystander data. Tire modeling results based on Drives et al. (1996) .were used as the starting point because (bis model was considered to be more r e p r e s e n ta tiv or a n occupational setting; the average values from the other types of data ware then evaluated, and, if necessary, used iu adjust the pruposed rule of thumb for each distance group, 'the factors by which the concentration reductions predicted by this model were adjusted differed within each distance category basec on the similarity of results across the other types of data, in all cases, the adjustments of the initial esriri lates were based on professional judgment. The limitations of this approach and. the uncertainties in the underlying data are discussed laiei in more detail. R e su lts Based on the literature review, neatly 1CM.Ipotentially relevant studies were identified. Only, 19 studies were identified in ti ltpublished literature, however, that met t ur inclusion criteria (see Table 3). All air samples reported ui the various studies measured OSHA fibers, defined as being greater than 5 |i.ii in length with an aspect ratio of at leas. 3:1. lire stud ies are described more specifically by activity below. Workplace surveys (1970s) Seven of the 19 studies included in this analysis were work place surveys conducted in the 1970s (Keitze et al., 119V2; Rohl-et al., 1975, 1976; Barnes, 1976; Lorimer et al., 1976; Fischbein et al., 1979; Verma and Middleton, 1980). The available sampling data from these surveys are p a w ' i in Table 2. The first study to specifically measure anlx ill asbestos concentrations at fixed distan ces to m the otuue was published by Keitze et at. in 1972, and examined workers who applied spray-on asbestos insulation. During this pros ess, a worker holds a hose from which asbestos insula! ion fab le U Parameters used in the Drivas et al., (1996) and Keil (2000) air dispersion models to predict airborne fiber concentrations at various as la n t Parameter N u m b er o f fibers em itted from source, Q x^ Length of emission, Temit Fresh air ventilt.on, a Fiber length, FI Fiber diameter, Fd Particle density, i.i D eposition rate, v/d Length of die room, L Width of the m ort, W H eight of die 100 m, FI Surface area for deposition, A Room volume, V Effective indoor diffusion coefficient, D Kao of surface area and volume, A W X coordinate for source, Y coordinate for source, Y 5 Z coordinate for c.ource, Zn Value O OQF i.DF 900 0.0014 5, 10 0.2, 0.3, 0.4 2.4, 2.6 2.77E-03 30.5 30.5 6.10 929 5663 0.0075 0.164 0 0 1.8 Units fibers s 1/s pm prn g/cnP m/s in m ni irF in3 mVs in m m Notes - ........ . Source located at (0 ft, 0 ft, 6 ft); 5 f/cc in breathing zone 5 air changes pet hour Range of fiber lengths assum ed for asuesios fibers Range o f fiber diameters assumed fur asbestos libers Range of particle densities tor syntlier c vitreous nbers item Spongier et al. (2001) Deposition rate for particle density of .-1-2.6 g/cc; die meter o: 0.2-0.4pm ; length of 5-10 pm 100 ft x 100 ft x 20 ft room 100 ft x 100 ft x 20 ft room 100 ft x 100 ft x 20 ft room Area of room floor (100 it x 100 ft) . Volume of 100 ft X 100 fr x 20 ft mom 0.45 m V m in far 180 x 120 x 20 ft room Source located at breathing height of sit ________ 1; 11S Ml T Bl L I !hl iKf 8 R Donovan et al. Critical Reviews in Toxicology Downloaded from informa.healthcare.cotn by Vis. Carrie Kahn on 09/23/10 For persona) use only. Table Z- Airborne Concentrations of Asbestos Fibers (Greater than in Length) Measured at Various D istances iiotn a Worker Performing a Take (1972-1980). Activity Number of Sample samples type Sam ple time Point source sample Bystander sample Distance from poi it (minutes) concentration (f/cc)* concentration (f/cc)" source (feef)"" Reference Spray insulation studies Application of sprayed NR Area NR 80 5 insulation Application ofspraved 1 Area NR 52(23-85) 71 insulation" 1 Area NR 61(32 100) 70 1 Area NR 06.75 (34.5-39) 17 i Area NR 35.2 (20-49) 66 1 Area NR 37.6 1 Area m 10 1 Area NR 46 1 Axe a NR 1.12 I Area NR 1.55 1 Area NR 1.01 i A le a NR 4.22 1 Area NR 0.55 l Area NR 0.51 1 A le a NR 0,28 i Area NR 0.76 i Area NR 0.26 20 10 10 15 20 20 35 75 30 m in lapse 30 m in lapse 30 min lapse 30 min. lapse 60 ruin lapse 60 min lapse GO min lapse 60 min lapse 60 min lapse Barnes, i0'76 Reitze et ab, 14 72 Studies of consumer spudding, patching, asul taping compounds Pole sanding ? Personal 1 h 10(1.2-19.3) 8.6 (3.5-19.8) 0 ftobl er id., 1975; Tischbein at ni., 1979; Verm a Utah, 1080 Hand sanding Dry mixing 2 Personal 1 h 2 Personal 1 h 2 Personal l h 3 Personal lh 2 Personal lh 5.3(1.3-16.9) 47.2 (35.4-59) 4.0 (0.7-8.8)" 2.3 (2.1-2.5) 4.3 (1.5-7.1)" 5.8(0.5-13.1) 2.6 (2.1-3.1)" 25 8 15 10 tu 20 lb to 3o Automotive and heavy truck studies Blowing dust from brake 3 drums (using compressed air) 2 1 1 1 1 I 1 Grinding used linings 1 (heavy truck brake service) 1 1 1 1 Reveling new brake linings 1 (heavy truck brake service) 1 1 1 Personal Personal Area Area Area Area Area Area Area Area Area Area Area Area Area Area Area 3 to 8 3 to 8 NR NR NR NR NR NR NR NR NK NR NR NR NR NR NR 16(6.6-29.8) 3.75(1.7-7.0) 37.3(23.7-72.0) __ __ 3.3 (2.0-4.2) 2.6 (0.4-4.8) 0.3 0.8 0.2 0.1 0.1 0.1 1.2 1.7 1 0.6 0.2 0.6 0.5 0.3 0.3 5 tn 10 LO to 20 10 20 12 (5 m in lapse i 50 (5 rnin lapse l 65 (7 m in lapse 1 75 (14 mill lapse) 10 10 25 25 60 8 12 12 30 R o h le ta l., i9/o; Lo rimer cl al. .....-- .... --.......-.......- NR= Not reported. NVtean concentration presented, if m ultiple sam ple results available. Reported ranges are in paiem hescs. '"`Time lapse from activity o f primary-worker (source) also considered a type of bystander sam ple. The authors did not indicate how sam ples collected at varying distances from spray operations correlated with me -or p o n e o worn also noted that ventilation conditions varied throughout the study. ''Samples collected in adjacent room. IM Ml IT i l L S M Ke Critical Reviews in Toxicology' Downloaded from inrormahealthcare.com hy Ms Cam e Kahn on 09/2 J/ 10 10 E P. Donovan el a.l. Tabic 3. Continued. Study D istance [torn the source . Faustenbacb e ta l., 2006 Sam ples collected 2-4 it from removal of autom obile exhaust systems containing asbestos gaskets ' Jiang et al., 2008 Sam ples collected on either side of worker, 6ft from handling, unpacking and repacking of clutch discs, cleanup and clothes handling , Sam ples collected 50 ft from handling, unpacking and repacking o f clutch discs, cleanup and clothes handling Mddl et al., 2008 Sam ples collected on four sides of worker, 5 ft from packing and unpacking brake shoe and pad boxes Sam ples collected 25-30 ft from packing and unpacking brake shoe and pad boxes Pausienbach et c !,, 2004 Sam ples collected 6 ft from application of mastics, coatings and adhesives Sam ples collected 6 ft from spill clean up of mastics, coalings and adhesives Sam ples collected 6 ft horn removal of mastics, coatings and adhesives Sam ples collected b ft from sweep clean up of mastics, coatings and adhesives M ovvatetal., 200 , Sam ples collected on four sides, 6ft from band sawing of phenolic molding material Sam ples collected on four sides, 6ft from belt sanding o f phenolic m olding material Sam ples collected on four sides, 6ft from press drilling phenolic m olding material Samples collected on four sides, 6ft from sweep cleanup during saw ing, sanding and drilling Cohen and Van Orden, 2008 Samples coLLected on four sides, 5-10 ft from the removal of auto motive clutches , Fowler, 2000 Sam ples collected 2-3 ft from bandsawing sheet gasket material Congo et al., 2001 Sam ples collected on four sides, approximately 7 ft from scraping and hand wire brushing large flange assemblies Sam ples collected on four sides, approximately 7 ft from power wire brusing of large flange assembly Uulconert and Whir, 2005 Samples collected 10 ft from disassembly of a diesel engine Sam ples collected 3 ft" Horn disassembly o f a diesel engine "Distance from peint source is estimated. Sample type Area Area Area Area Area Area Area Area Area Area Area Area Area Area Area Area Area Area Personal Sample tide Bys wilder Bys'.andci: Rem cue are; Byv.ander Remote are; Are.; Are. Are: Are; Are; Are. Are.. Are;.Are;Are: Bystander Bysi iinner Are;: O 'os Aver is shot out of the nozzle and projected over distances of 30 feet or greater. Erea samples were collected at 10-75 leet from the spray nozzle during application, as well as at 30 and 60 minutes alter spray operations had ceased. As expected, airborne fiber concentrations decreased with time at 30 and 60 minutes alter spraying stopped. The samples collected at increasing distances during spray applications, however, did not follow an obvious pattern with regards to distance, which was noted by die authors to be "because of changes in on-site ventilation," In addition to the Reitze et al. (1972) study, a 1976 survey of asbestos spray operations in Sydney, Australia, also reported an airborne fiber concentration of 5 f/cc at floor W ei, 20 feet below the spray point during the application pi oc:ess, which was approximately 6% that of the spray operator (Barnes, 1976). Because spray insulation is such an unusual circumstance and the samples were col lected ''below" the operator (literally on the floor below scaf folding where a worker was applying the spray insulation), these data are not very informative. Indirect exposure to asbestos was also studied among workers using several types of construction materials, including spackling, patching, and taping compounds. ;\ total of 14 personal samples were collected at varying dis tances during mixing of the materials (prior to application) and during sanding (either by hand os using a pole) after application. O f these samples, eight were collected between 8 and 20 feet from the primary activity', and the remainin g so: were collected in an adjacent room at distances ranging iroai 15 to 35 feet from the worker. These data are presented in three different publications (Rohl et al., 1975; Fischbem etaf, 1979; Verma and Middleton, 1980). Measured airborne con centrations were slightly lower as distance from the worker increased, although the magnitude of this difference varied across the tasks that were studied. Fo:; the pole and hai o sanding bysta nder samples, which were collected 8 lent away from the'sander, this difference ranged from 50% to 80% x: the concentrations at the worker. For tire dry mixing samples, the airborne concentrations ranged front approximately 5% to io% (at 10-20 feet and 16-35 feet in an adjacent room, respectively) of that of the worker. Brake repair maintenance workers in New York City were also monitored during a variety of tasks, including blowing 1:valuation of bystander exposures to asbestos Critical Reviews in Toxicology Downloaded from nfomiaiicalthcarc.com by Ms. Carrie Kahn on 09/23/10 For personal use only. out dust front drum brakes, renewing used brake linings by grinding, and beveling new linings (Lorimer et al., 197(3; Rohl et al., 1976). Personal samples collected 5 10 feet away from the primary a stivity (3-8 minutes) were 20% the value for the worker performing brake blowouts (16 f/cc). The aver age concentraLion for samples collected 10-20 feet from the primary worker was approximately 15% die value reported for the worker. Area samples collected between 10 and 75 feet from the v'orker were significantly lower (0.1 0.8 f/cc); however, sample duration was not reported, and four of the six samples were collected between 5 and 14 minutes after tire worker cm apleted tire blowouts, making direct compari son difficult, k uring grinding of used brake linings, airborne concentrations in area samples were approximately 33% to 20% to 5% that of the worker during grinding of used brake linings at distances of 10, 25, and 60 feet, respectively. During beveling of new linings, samples collected at distances of 8, 12, and 30 feet had airborne asbestos concentrations that were approximately 2%, 1.3%, and 0.8% that of the worker, respectively. Sim ulation studies (2000s) Twelve of the .9 studies that met the criteria of this review were simulation studies conducted in the 2000s. The majority of the available data were collected to characterize exposures associated w in using products in which the asbestos fibers were encapsu. ited (that is, the asbestos was often embed ded in a polyrr; er or tar-like substance). As such, the airborne concentrations of OSHA fibers were orders of magnitude lower Oran what was reported in the workplace surveys of the, 1970s. A summary of tire concentrations measured for workers and by slanders in the simulation studies is presented in Table 4. Raw data vrere available for approximately half of the simulation studies, whereas average values were presented in the others. In many cases, tire reported results had been converted to 8 hour time-weighted average (TWA) values for purposes of comparison to occupational exposure limits. In some of these hudies, "bystander" or remote samples (usu ally area samp.es) were collected at more (Iran one distance from the worke r, and the authors conducted statistical analy ses to determine whether concentrations were significantly different at greater distances. Wherever possible, these results are presented. Removal and manipulation o fgaskets A number of simulation studies have evaluated the removal, manipulation, and installation of asbestos-containing gaskets. Three of these studies assessed airborne asbestos concentrations associated with changing gaskets on flanges or valves. The work was performed in enclosed, ventilated chambers in two o f the studies (Fowler, 2000; Longo et al., 2002), but not in the third (Mangold et al., 2006). The results r e p o r te d b y M a n g o ld e t a l. (2006) w ere c o lle c t e d o v e r nearly a 10-year period, and were intended to characterize a maximally exposed worker (i.e., one who handles gaskets and packing ail day). Personal and area samples were taken over an 8-hour workday as workers performed various tasks with packing and gasket materials. Because all PCM results (worker and bystander alike) were lest than 0.01 i/ee and did not differ significantly from backgrc: und, this study was of limited use. The lw o studies that collected short-term samples (=:30 minutes) in ventilated enclosures reported higher airborne asbestos concentrations than what was found by M angold etal. (2006). Specifically, Longo etal. (2002) collected p e r sonal and area samples (15-30 minutes) during scraping and hand-wire brushing of four large flange gaskeis and during power-wire brushing of a large flange assembly. Area samples were located in four equidistant quadrants at a distance of 2.1 in (approximately 7 feet) from the work bench during the activities. Because a.i average value wus not reported for the area samples, it was not possible to directly compare worker and "bystander" values for this activity; however, the minimum and maximum values reported for the area samples were approximately 25% to 33% of those reported for the worsen Bystander area samples collected during power-w.re brushing were approximately 50% of what was reported among the cor responding worker samples. Similar ratios were observed among personal and area samples collected during a simu laiion study involving band sawing of asbestos sheet gasket materials (Fowler, 2000). It should be mentioned that there were several analytical and study design issues with he Fowler (2000) and Longo et al. (2002) studies, which are discussed in more detail in Madl et at. (2008). The ratios of concentrations between the bystander and worker sam ples, however, were fairly consistent with values reported in other simulation studies. Other gasket studies included in this analysis involved installing and/or removing gaskets in automobiles, in 2006, Pausienbach et al. published their findings regard ing personal and bystander exposures to asbestos during the removal of automobile exhaust systems containing asbestos gaskets. In this study, a considerable portion oi the available samples were below' analytical sensitivity lim its. In total, for workers, 17/23 (74%) of PCM results and 18/29 (62%) of TF.Ivl results were belc.w analytical limits and were reported as undetectable, whereas29/33 (76%) ul bystander PCM results and 35/41 (85%) of bystander TEM results were below analytical limits, 'the lack of detectab .e asbestos concentrations in the bystand er samples was also noted in the Blake et al. study, in which area samples were collected from nine locations at distances ranging from less than 1 foot to 50 feel from the teat area (Blake et an, 2006). O f the 43 area samples, asbestos fibers were orry detected in 8. Further, the average concentrations repre sent a combination of activities, and it was not possible to quantitatively characterize the degree to which airborne concentrations decreased with increasing distance, from the w o rker. The authors noted, however, that the highest reported sample result occurred in one of the comers of the shop, and not in the immediate work area (Blake et al., 2006). All but two of the samples collected in a gasket IR 41 tat HI I f VSi L I W; %' Critical Reviews in Toxicology Downloaded from informahealih: For censorial use only. Table 4, Samples collected to characterize bystander exposures to asbestos fibers (greater th an Sum. In length) dur Activity Mtimber o f Sam ple samples type Sample time (minutes) Point source sam ple concentration (f/cc)* Autom obile studies (gaskets) Removal of automobile exhaust systems containing asbestos, gaskets in tour single and two double exhaust engines 6 Area 30-50 0.018 (0.002-0.04) Autom obile studies (clutches) Handling, unpacking, and 40 repacking boxes of automobile clutch discs Stacking clutch boxes 2 Cleanup 6 Clothes handling 2 Handling; unpacking, and 20 repacking boxes of automobile clutch discs Stackin g d u tch 15oxes 1 Cleanup 3 Clothes handling 1 Removal of automotive clutches 58 Area Area Area Area Area Area Area Area Area 30 30 30 30 30 30 30 30 26-161 0.044 (0.000-0.366) 0,2125 (0.180-0.24-5) 0.002 (0.000-0.006) 0.0015 (0.000-0.005) 0.044 (0.000-0.366) 0.2125(0.180-0.245) 0.002(0.000-0.006) 0.0015 (0.000-0.005) 0.047 (0.015-0.13) Automobile studies (brakes) Filing o f brake shoes Hand sanding brake shoes Arc grinding I Arc grinding 11 Cleaning Ik H iu g and u np '--':-'g h-?.ke pads Packing ana unpacking brake shoes Cleanup after packing and u n j>ac1h ng a or!vi ria s Clothes bondikie after packing end ur.varidng acn'vit:as 4 Axe a 2 Area 4 Area \ Area ?. Area 4 Area 1 Area 2 Area 4 Area 1 Area 2 Axe a 4 Area 1 A re. a 2 Axe a Area 16 Area 2 Area ) Arvo Associated worker samples ranged from 30 to 107 m in; sam ple duration not reported ` for individual area samples 0.0356 0:0684 0,4358 0.1734 0.0000 30 0.2974(0.003-1.190) 30 0.0695 (0.021-0093) 30 3.004 (0.002-0.033) 30 Q .U ii i'u.DO r- 0.01 5j rare.com by Ms. Carne Kudin on 09/23/10 ig sim ulation studies (2000 2008). Bystander sample concentration (f/ccb' Distance from source (ft.) 0.008 (0.0008-0.015) 2-4 0.0025 (0.000-0.019) 0.010 (0.003-0.016) 0.000 (0.000-0.000) 0.000 (0.000-0.000) 0.000 (0.000 0.003) 0.000(0.000-0.000) 0.000 (0.000-0.000) 0.000(0.000-0.000) 0.013 (<0.002-0,03) 0.0128 0.0037 0.0097 0.0091 0.0092 0.0266 0.0828 0.0389 0.0186 0.0372 0.0154 0.0000 0.0000 0.0000 0.0166(0.001-0.076) 0.065 (0.002-0.038) 0.002 (0.001-0.000) 0.010 5 5 5 5 50 50 50 50 5-10 <10 >10 <10 10 >10 <10 O >10 <10 10 >10 <10 10 >10 5 5 5 5 co Reference Its Paustenbach et al., 2006e h-- o 6n; Ci Hang et al., 2003 Cohen and Van Orden, 2008 Blake et a l, 2003 Mach et a l . 20Q8 Critical Reviews in Toxicology Downloaded from infon-nahealthcare.com by Ms. Carrie Kahn on 09/23/10 For personal use. only. laD-ie't. OUilllliUCU. Activity Packing and unpacking brake pads Number of samples 13 Parkinp- and unnacking brake 5 shoes Cleanup after packin g and 3 unpacking activities Clothes handling after packing and unpacking activities Gasket Studies Disassembly and assembly of 12 flanges Cutting gaskets using circular 8 cutter Cutting gaskets using hand 8 shears Cutting gaskets using ball peen 8 hammer Shaping gaskets using scribe 8 Gasket removal 8 Flange face cleaning using putty 0 knife Flange face cleaning using hand 8 wire brush Flange face cleaning using power 8 ware brush Packing removal and installation I Packing removal and installation 8 Band sawing sheet gasket 1 material 1 Scraping and hand wire brush 24 ing large flange assemblies Power wire brusing o f large 16 flange assembly Gasket removal 1 i 1 1 vs i .eFb* . i Dnv 1: Ths assembly of a m edium 2 * engine --- Removal !~ .... Sample type Area A.re a Area Area Area Area Area Area , Area Area .Area Area Area Personal Area Area Area Area Area Area .Are e Area /Arc a Area Area .Are a Anm Sanrole time (minutes) NR NR NR NR 4 hf 8h 8 h 8 h 8 h 8 h 8 h 8 h 8 h 4.5 4.5 25 6 15-30 15-30 148* 151 148c 15k 148' 15D 120'' 29-GO Point source sample concentration (f/cc)* 0.2374 (0.008-1.ISO) 0.0646 (0.021-0.193) 0.004 (0.002.0.006) 0.011 (0.007-0.015) 0.004-0.005 <0.005 <0.005 0.005 <0.005 <0.005 <0.005 0.007 0.003 <0.011 <0.011 2.2-3.1 3.1-4.9 2.3-24.0 14.9-3 1 0.0035 O.0O3h 0.0035 0.0035 0.0035 0.0Q.35 0.0004 <0.028-<0.04 G Bystander sample concentration (f/cc)* 0.0082(0.003-11.017) 0.001 (0.001-0.002) 0.003 (0.001-0.006) 0.002 Distance from source (ft.) 25-30 25-30 25-30 25-30 Reference 0.003 (0.002-0.004) 0.008 (0.002-0.006) 0.004 (<0.003 -0.006) 0.006 (0.004-0.007) . 0.003 (0.002-0.004) 0.002 (<0.001-0.002) 0.001 (<0.001-0.002) 0.003(0.002 0.005) <0.009 0.004 (0.002-0.006 0.75-0.85 1.8-2.3 2.1-8.4 V .b -ib ./ 0.0017 0-00] 3 0.0011 0.0026 0.00.17 n.nno" 0.0009 <Q.021-<0.022 (opposite end of 3x.3x3m enclosure) 5.0-10,0 M angold e ta l, 20Dob 5.0-10.0 5.0-10.0 5.0-10.0 5.0-10.0 5.0-10.0 5.0-10.0 5,0 -10.0 N ik 5.0-10.0 -2 -3 (60-30cm) Fowler, 2000" -2 -3 (60-90cm) -7 (2.1 m) Longo eta l., 2002t -/ (2.1 m) S 15 18 19 30 2C 13 10 Blake et ai., 200 A i.iukc-ncn a.nd Weir, Z( JU5" Tabice. cendnued un m va ..ny Evaluation of bystander exposures lo asbestos oo oV . oo d Criucal Reviews in Toxicology Downloaded from informahcolthcarc.com by Ms. Cam e Kahn on 09/23/10 For persona! use. only jv )9 u naouoQ y ' ] Table 4. Continued Activity Day 2; Disassembly of a m edium duty diesel engine -- Removal of gaskets and cleaning o f gasket Number of samples 6 Sam ple Point source sam ple Bystander sample Distance from source Type__________Sam ple tim e (minutes)________con centration (Ly'cc)*________ concentration (f/c.c)^_____________________ (ft.)_____________________ R eference Area 11-64 c0-021-c0.12 <0.02-<0.118 10 1 Personal ID c G .0 2 l-< Q .1 2 <0.113 2-5 ' Day 3: Disassembly of a m edium 2 Area 38-192 0.012- <0.023 <Q_QG7-<Q.034 10 duty diesel engine -- C le an in g of gasket and other surfaces 2 Personal . 38-1S2 0,G12-<0.023 <0,OG8-<(R035 2-5 Mastic studies Application of Lagtone 31-95 12 coating Application of Sealfas 41-36 8 Application of C .I M astic 60-25 12 Application of fibrous adhesive 4 81-27 Spill lean up o fL a g to n e 31-95 36 Spill clean up o f Sealfas 41-96 36 Spill clean up o f C .I- M astic 60-25 36 Spill clean up of Fibrous 36 adhesive 81-27 Sanding ofLagtone 31-35 12 Sanding c f Sealfas 41-36 12 C .I. M astic GO-25 4 Removal ofLagtone 31-95 12 Removal of Sealfas 41-36 ' 12 Sweep cleaning o fL a g to n e 31-05 12 Sweep cleaning o f Sealfas 41-96 12 Area Area Area Area Area Area Area Area /Area Area Area Area Area Area Area NR ND NR ND NS ND NR ND NR t 0.068 NR ND NR ND NR ND NR NR NR NR NR NR ' NR ND ND ND ND ND O.OSO ND 0.0092 (N D -0 .15) 0.0092 (ND-0.012) 0.0055 (ND-0.0063) 0.01 (ND-0.011) 0.014 (ND-0.031) 0.01 (ND-0.012) 0.01 (ND-0.018) C.012 (ND-0.018) 0.015 (ND 0.021) 0.011 (ND-0.014) 0.011 (ND-0.011) 0.013 (ND-0.018) 0.012 (ND-0.018) 0,0-11 (max of 0.062) 0.011 (ND-0.014) 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Paustenbach et ah, 2004b ' Phenolic Molding Stuides Band sawing o f ph en o lic m old- 12 Area 30 0.11 (<0.04-0.21) 0.07 (<0.03-0.32) 6 Mcvvat el al., 2005 ing material Belt sanding of p h en olic m eld- 16 Area 30 0.03 (<0.03-0.05) 0.04 (<0.02-0.08) 6 ing materia] Press drilling ph en o lic m old ing 16 Area 30 <0.01 (<0.C1) 0.01 (<0.003-0.02) 6 material Sweep cleanup during sawing, 36 Area 30 0.02 (<0.01-0.08) 0.01 (<0,003-0.03) 6 sanding and drilling; *M ean concentration presented if multiple sam ple results aval table. Reported ranges are in parentheses. Results presented as PCM-adjus:red for asbestos content, unless otherw ise noted. *S- r~in !c r,"':: -'c r; m.-'tr'-'C'r1: r-- 9 h VTOtiA s. ^Sample results repur ted as P C M results, not P C M adjuster;. g tiJistancc from point source is estimated. ffl 'Camples mere reported, o n ly wit on asbestos fibers were detected. eA personal sa m p le vm s taken on ly d u rin g one portio n of the d ay. It w as then co m p s roc tc 3 p rim a ry s o u rc e s a m p le fro m that ism e period only. ND-- N et detected. g N R - Nut repoituu. N'i.-R' IR c tampir v.-;:s reported so a bvoianm.:; sw nrie u): so vet; ic r t w nnonr close :>y, h-m n o: a :. v. a00001100 ..H'-uuiec. J'ui K Critical Reviews in Toxicology Downloaded from informahcalthcare.com by Ms. Carrie Kahn on 09/23/10 For personal use only. study conducted by Liukonen and Weir in 2005 were less than the analytical limit of detection (Liukonen and Weir, 2005). This study did not provide any useful data for this analysis. Work with friction products (clutches and brakes) In 2008, two studies were published that characterized airborne asbestos concentrations associated with handling clutches. The first of these, by Cohen and Van Orden (Cohen and Van Orden, 2008), assessed bystander exposures using area samples taken in four different directions 5-10 feet from where :he mechanic disassembled and removed manual clutches from a variety of vehicle types. Although dris study did not present area sample results separately by distance (5 versus 10 feet from the mechanic), the authors noted that the area samples "were significantly lower than those obtained from the m echanic'' (p value not provided). The average concentration reported for the bystander (area) samples was approximately 30% the average concentration reported for the worker. lire second clutch study (Jiang et a!., 2008) evaluated air borne asbestos concentrations associated with handling of dutch parts (stacking, unpacking/repacking of boxes con taining clutches), as well as cleanup and clothing handling. Worker samples were collected as two sets: two 15-minute consecutive samples [n~ 4, left and right lapels) and one 60-minute sample (n = 2, left and right lapels). During each sampling event, 30-minute bystander samples were collected at two locations 5 feet from the main activity, as well as at a remote location (50 feet). For purposes of this analysis, tire two 15-minute consecutive samples were aver aged and con: pared to the 30-minute bystander area sam ples. Ih e aut.iors noted that airborne concentrations for the workers were considerably higher in the first of the two consecutive samples; however, because the corresponding bystander samples were 30 minutes, it was not possible to directly compare the worker and bystander concentrations for the shorter sample duration. Bystander samples were 4-10% that of the primary worker during these activities. Just over half (27/50) of the bystander (5 feet) samples were non-detects, whereas nearly all (24/25) of the remote back ground (50 feet) samples were reported as such. This study also reported ihat airborne asbestos concentrations differed significantly between (1) workers and bystanders 5 feet away (p<.005), (2) workers and bystanders 5.0 feet away (p < .005), anu (3) bystanders 5 feet away and bystanders 50 feet away (p < .05). In a simile.r study involving brakes, Madl et al. (2008) measured airborne asbestos concentrations during the unpacking ar.d repacking of brake pads and shoes. Again, two consecutive 15-minuie worker samples, as well as one 30-minute worker sample (collected concurrently with the two 15-minu:e samples), were obtained. Four area sam ples were collected at breathing zone height at distances of 1,5 m (5 feet) and between 7.6 and 9.1 m (25-30 feet) from the worker; these were 30-minute samples that cor responded to the two consecutive 15-minute samples. Like Evaluation of bystander exposures to asbestos 15 the Jiang et al. (2000) study, bystander asbestos concealra tions were approximately 4-10% that of the primary worker; this difference was statistically significant (p< .05), as was a comparison between the worker anc. remote (25-30 lent) samples. Ure second brake study (Blake ei al., 2003) presented data collected during six complete (four-wheel) brake changes involving sanding, arc grinding, and cleaning operations; one cleaning test was also performed. Although individual sampling results were not available for die area sampl es that were representative of bystanders, the authors report eel dud there was not a statistically significant difference between the samples in close proximity to the work and those collected at the opposite ends of die shop. Individual results were available for area samples collected approximately Ism (10 feet) from the primary worker (three samples were referred to as "bench" by the authors, and presumably represented an adjacent workbench). Area samples during the canons activities were approximately, 20-25% the values reported for the primary worker. Occupational use o f coatings, mastics and adhesives, med phenolic molding compound Two simulation studies involving the application, remov'd, manipulation, and cleanup of several materials drat con tained-encapsulated asbestos were considered in this review- The first of these, published in 3004 by Pausten bash et al., evaluated airborne asbestos concentrations during a variety of tasks involving asbestos-containing coatings, mastics, and adhesives. This study was of limited use in tills analysis, primarily because only (1of 452 samples had detectable levels of asbestos fibers Paustenbach et a l, 2004). In 2005, Mowat et al. measured airborne asbestos expo sures during band sawing, belt sanding, drill press operat ing, and phenolic molding material (B ikelite) cleanup, fo r each activity (performed in four 30-minute replicates), (out area samples were collected simultaneously at breaching zone height at a distance of approximately 1.8 rn (6 feet) from the center of the work surface. Of the bystander (.area) samples, just over half (57%) were belt: w the analytical se n sitivity limit. A similar proportion of nc:n-detects (00% I 1va noted among the corresponding worxer samples ! y mat et al., 2005). Average asbestos concentrations dm it g i i various activities were similar' for die bystander (ait.} and worker (personal) samples, regardless oi whether the samples re p o r te d as less th an tile limit of detection .st:re analyzed using a value of one-half the limit of detection os the fullTimit of detection. Ratio of bystander:worker asbestos concentrations In addition to comparisons of bystander to worker aitborne asbestos concentrations within the individual studies, the results were compiled into a single data set. As noted previously, worker-bystander pairs in which the worker sample had a result below the LOD were excluded from further analysis. No discemable trends tit lies W T lit t. - 14 ure Critical Reviews in Toxicology Downloaded from jrifonitahealthcare.com by Ms Cam e Kahn on 09/1 16 E. P. Donovan et al. wore evident when bystander:worker ratios were plotted in d ep en d en t!again st distance from the primary worker (Figures 4 and 5). Similarly, the box plots by distance groups (1-5, >5-10, >10-30, and >30 feet) did not follow a linear pattern (Figure 6). Within each distance group, the average bystandenworker ratios were as follows: 1-5 feet, 0,08 (range = 0-1, 0 = 0.17); >5-10 feet, 0.61 (range = 0.01-l, a >0.33); >10-30 feet, 0.11 (range>0-1, o = 0.05); and >30 feet, 0.10 (range = 0- 1, cj> 0.09). It should be noted that the bystander: worker ratios at the >5-10 feet distance group were much higher than the other three groups. Nearly all of these samples were from the Mowat et al. (2005) study, which had a significant number of samples less than the LOD. 60 i i COoJ 50 i i i Q) ^0 ^ i 0 . o 40 i O hV : tn Cd b 30 1 o_ "* ^ 1 bO 20 ae>i :o 10' U f..................... 11 \ '1 ' 9 ' ! * f ; -O v -0 0 i ] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Bystandenworker exposure ratio Figure 4!. X-Y .scalier plot for published data, bystandenworker ratios of airbone asbestos concentrations at distance Torn a source. ! s 60 . v. | -: 50 ~luiniv*i-4,4.t|1; ;!; -... ...4 40 ; j 1i 30 > 20 `_V__v'1t!|!_wY*w-t_0A<>4j.:';_*+_V*_^..**.<..V'*.'V.V'' y4- m 10 00.00 0.20 0.40 0.60 0.30 1.00 Bystandenworker exposure ratio 'figure 5. X-Y scalier plot for bystandenworker ratios o f airborne asbestos concentrations with all ratios >1 replaced by 1. Figure <5 6-10 11-30 >30 Distance from primary worker (feet) Bux plot by distance groupings for bystandenworker ratios of airborne asbestos concentrations with all ratios >1 replaced by 1. U u S t HI T B L i iC K-l Critical Reviews in Toxicology Downloaded from infomiahealthcare.com by Ms Carrie Kahn on 09/23/1U For personal use only. Sum m ary o f available literature relevant to mathematical modeling o fairborne asbestos concentration with distance Because the available published data could not provide resolution or the relationship between airborne asbestos concentrations with distance from a source, an additional literature rev tew was conducted to determine whether mathematica. models could be used. Although there are rto commonly applied models that directly address asbestos fiber concentrations in air, there are several that have been developed in an attempt to understand the characteristics of airborne particles, including their movement in ah' and the rate and distance at which they are likely to settle out of air (Timbrell, 19(15). Some of the basic assumptions set forth in general particle movement models include the idea that fluid or air is incompressible, that there are no walls or other parti cles nearby, that motion is constant, that the particle is a rigid sphere (or spherical equivalent), and that the fluid velocity of air at the particle's surface is zero (Hinds, 1999). O tiler authors have also explored the effects of forces out side of settling velocity' on tire removal of particulates from air. Reist indicated that in more turbulent airflows, such as what would he expected in a typical workplace, particles may be remov ed from the air by mechanisms other than set tling, including impaction on other bodies, centrifugation, agglomeration, Brownian motion, and diffusion (Reist, 1975). According to Drinker and Hatch (1954), diffusion is the pri mary method by which micron-sized particles are removed from the air. It is also important to note that dynamic projec tion of small particles (i.e., adding kinetic energy ofvelocity) does not appe ar to significantly change the distance that they travel. For example, a 10-pm round unit density particle with an initial velocity o f 5000 cm/s will be significantly affected by tire viscous forces of air, and, despite its initial velocity, will travel only approximately 4cm before stopping. Likewise, a Lp m round unit density particle will travel only approxi mately 0.4 rntm after being projected at the same initial veloc ity. As Drinker and Hatch note, this finding is important to the study of dust dispersion in industry because it indicates that the extension or reach of microscopic particles in the work environment is not dependent on the kinetic energy of the particles or the- energy with which they are released into the environment, lather, the small size of diese particles causes them to be affected by the viscous forces of air, and signifi cantly reduces the distance that they are able to travel. In situations where a clear generation source of a con taminant exisis in an enclosed space, a multi-zone model approach has been used to characterize the differences in contaminant concentration in different areas of the space with increasing distance from the source. In the transient two-zone model, a localized box or space that contains and surrounds the generation source o f a contaminant is typically defined as the "near field," whereas the rest of the room or w o rk s p a c e is c: e fin e d as th e "lax Held." 'The n e a r fie ld is m o st commonly defined as a sphere or hemisphere with a radius of approximately arm's length, or 0.78 m (2.5 feet). This defini tion is consistent with the conventional industrial hygiene Evaluation of bystander exposures io asbestos 17 definition of the breathing zone, as well as other publish, studies that have used the transient two zone model (Kofi 2000; Nicas et ai., 2006; Keil et al., 2009). The two zone mode. has been used to predict chemical or paniculate exposure for a diverse range ofpublished exposure scenarios (Ktril ami Murphy, 2006; Vernez et al., 2006; Armstrong a id Haas, 2007 Gaffney et al., 2008). A model wide three or more zones car: also be used to further differentiate the space if needed (UR. EPA, 1997), but the improvement in precision is often not worth the effort, since differences between the second anc third zones may be small (Sahmel et al., 2009). Particle models can be adapted to characterize airborne fibers. Because asbestos fibers are not spheres, a correction factor such as the dynamic shape facto : (defined as die mao of the actual resistance force of the nonsphencal particle to the resistance force of a sphere having the same volume and velocity, referred to as the aerodynamic diameter) can un applied (Reist, 1975; Hinds, 1999). The asbestos fiber char acteristic of a very consistent diameter along the length of a fiber has led some researchers to attempt to estimate ah con centrations and movement of fibers using a cylinder shape for aerodynamic purposes (Bragg et al., 1974; Assuncac and Corn, 1975). Beginning in the 1970s, the scientific communin' l a i to look at modeling asbestos exposures (Bragg et a l , , 4, Sawyer and Spooner, 1978; Committee on Indoor Pollutants Board on Toxicology' and Environmental Health Hazards, 1981). For example, the National Research Council's Committee on Indoor Pollutants reported that fiber set tling velocity depends far more heavily on fiber diameter than on fiber length, and estimated that in still air in a room with a height of 3 m, a liber with dimensions 5 pm long by l pm in diameter would remain airborne for approximately 4 hours. The committee further estimated that a liber of the same length with a 0.1 pm diameter would remain air borne for closer to 20 hours. In 1978, the US Environmental Protection Agency (EPA) also evaluated the speed with which asbestos fibers may settle out of air (US EPA, 197b), They estimated that settling velocity was more strongly dependent on fiber diameter than on length, and deter mined that settling velocities for fibers that were 5. 2, aim 1pm in length with a 5:1 aspect ratio would require 4, 29. and 80 hours, respectively, to settle out of still air from a height of 9 feet. They further estimatec that air turb uierieo would prolong the settling and cause reentrainmeru of fallen fibers, According to these report s, OSTIA fibers fee., those equal to or longer than 5 pm) tend to have siiccuu settling times than shorter fibers, and the fiber aspect ratio has an important influence on the concentration vs. settling time relationship. There was no discussion in these repor.s of the relationship of concentration decrease with distance versus-particle or fiber length. Despite these calculated estimates of the Fine required fox a sb e sto s fib ers to settle ou t o f air, T o th la b o ra to ry and field .studies have shown that asbestos fibers appear to remain airborne for shorter time periods than would fee expected based on such modeling. In a study conducted LB B. P Donovan et al, by Ivfoorcraft and Duggan in which airborne asbestos con centrations were measured in a room with no mechanical ventilation after vigorous dust disturbance, for example, the if reflection and deposition did not occur. Our re hew of die available particle and fiber literature appears to support this approach. authors found that the asbestos libers settled out of air more quickly than was expected based on their settling velocity Results o f mathematical modeling developed to estimate calculations (Moorcroft and Duggan, 1964). Specifically, airborne asbestos concentration with distance the duration for which the disturbed Fibers remained air The bystandenworker ratios generated by lire eddy tiifmsiiiu borne was less than 1 hour. It was postulated that additional models with and without deposition and reflection are pro fiber removal mechanisms other than gravitational settling seated in Table 5. Under the Drivas et al. (1996) mode! that were at work in die study space, including interception includes reflection and deposition, the predicted bystander and impaction on surfaces, or possible electrification of concentrations relative to the airborne concentration at the fibers and subsequent removal from the air by electri the source, were 37% at 3 feet, 2% at 10 feet, and 0.3% at 15 cal forces. The uthors indicated that less than 25% of the feet. The ratio increased significantly at a distance ot 20 fe e t fillers counted had a diameter of greater Iran I pm, and (0.03%), and all calculated ratios at 25 feet or greater were almost all fibers had aspect ratios of greater than 10 to 1. less than 0.0001%. , ss Similarly, limited measurements by Cornet al. (1966) found Using the Keil (2000) model without reflection anu depo that few p anicles above 5 pm in size remained suspended sition, the decrease in predicted airborne asbestos conceit m air, despite calculations that showed that room air cur nations with distance from the source was less Giainauc. a s rents could theoretically keep particles up to 90 pm in size noted previously, the purpose of this mo del is to provide an airborne. The authors hypothesized that this finding could "upper bound" on the expected concentration relationships 0 be due to one or more of three factors: (1) effects of the between a bystander and worker. Under this second set or 1 slow-moving air boundary layer that adjoins the surfaces conditions, this model assumes that the only mechanism by of objects and s:.ows the speed of particles traveling close to which par ticles are removed from tire air is dilution by room these surfaces [therefore reducing the ability of particles to ventilation, an assumption that would tend to over predict me be pulled back iato room air currents once they enter this air actual field concentration of the fibers. Under these condi boundary layer); (2) the likelihood of air currents to deposit tions, the predicted bystander concentrations, relative io me I particles as frequently as they remove them from suifaces, airborne concentration at the source were 83% at 3 feet, 33% 1 or (3) the inertia of particles in motion resulting in rapid at 10 feet, 14% at 15 feet, 7% at 20 feet, mid 0.8% at 30 icct. deposition by impaction on surfaces. For distances greater than 50 feet, tire ratios were less than 0.0001%; in other words, there is virtually no impact of Ore To evaluate the potential for reentrainment of dust once it has settled out of air, Corn and Stein (1966) also evaluated asbestos emitted from a point source, for OSfiA fibers, m ins g the forces by which particles adhere to surfaces, including tances'greater than 50 feet. This finding is entirely consistent c mechanical, electrical, and air drag forces. Based on calcula with what has been predicted by both the dreoiies desciiueti a tions using experimental data for the adherence of particles above and most field studies. o less than 80 pm in size, they estimated that particles in this Proposed "rule o f thum b" to estimate bystander exposure a size range were unlikely to encounter mechanical, electrical, g or velocity forces alone in the typical occupational environ at specific distancesfro m a source ment that were sufficient to break die adhesive forces of In this analysis, the calculated or modeled bystandei monvei particles on suifaces. They concluded that active disruption ratios differed at specific distances from t ae source. Howeve of particles from human activity would be required to cause based on our understanding of the individual studies, we felt that it would still be a worthwhile exercise to consider reentrainment. the data together for purposes of developing a rougn rule UC In summary, based on our literature review, there of thumb" for evaluating bystander exposure with distance were no widely used mathematical models that could be from a source. As described previously, the lesults hasco applied to estimate airborne fiber concentrations at varying on the Drivas et al. (1996) model were c onsidered a starting distances from a source. M uch of the work that has been point, and any adjustments to the modeled values were based conducted thus far has involved applying a correction fac on professional judgment. A summary of the values used to tor to particle m odels to account for differences in fiber derive the rule of thumb is provided in Table 6. characteristic!:. The available information about particle ot For persons between 1 and 5 feet from the wotkei, it s fiber behavior in air indicates that multiple forces, such as expected that die airborne asbestos concentrations would settling velocity, interception and impaction on surfaces, be approximately 50% of that measured at the source. This and possible e lectrification of the fibers may all play a role estimate is based primarily on the Drivas et al. fi996 ] moo- in removing niters from the air, which is consistent with the eling results, and is conservative in comparison to trie average assumptions set forth by Drivas et al. (1996). As noted pre b y sta n d e n w o rk e r ratio reported for the! VatiOUS SimuldliU: viously, we considered the bystander estimates generated studies for which data were available (8.2%), However, using this model to be based on a more accurate represen because there were no workplace surrey data (whicn m u tation of workplace conditions, whereas Lire the Keil (2000) higher initial airborne asbestos concentrations) m this model was used to provide an upper bound concentration B I S H T t L. t tv A Crilical Reviews in Toxicology Downloaded from mformahealthcare.coin by Ms. Carrie Kahn on 09/23/10 For personal use only. Evaluation of bystander exposures to asbestos IS Table 5. M odel precicteil relationship between the airborne concentration of asbestos fibers (greater than 5pm in length) and the concent! anon alvari o u s distances (cone entrations are based on L5 m inutes of possible em issions at tire s o u r c e ) . ______ ^______ ________ ______________________________________________ ___ Mode! with Reflection and Deposition (Based on Drivas et al, 1396) M odel without Reflection and Deposition (Based ori veil, 2000) D istan ce from source (ft) 0 1 2 3 4 5 6 7 >7 y 10 n 12 13 14 15 15 17 IS 19 20 25 30 3b '10 45 50 55 60 65 70 75 i 5 min time averaged concentration (f/cc) 0,43 0.38 0.27 0.16 0.094 0.060 0.041 0.029 0.021 0.014 0.0097 0.0065 0.0043 0.0029 0.0019 0.0013 0.00082 0.00054 0.00034 0.00022 ' 0.00014 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 Ratio of bystander:wovker airborne asbestos concentration 1.0000 0.8840 0,6229 0.3748 , 0.2102 0.1303 0.0959 0.0684 0.0481 0.0332 0.0224 0.0150 0,0100 0.0067 0.0044 0.0029 0.0019 0.0012 0.0008 0.0005 0.0003 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 , 15 m in time averaged concentration (F/cc) 0.028 0.028 - 0.026 0.024 0.022 0.019 0.017 0.015 0.013 0.012 0.010 0.0088 0.0076 0.0065 0.0055 0.0046 0.0039 0.0032 0.0027 0.0022 0.0018 0.000G7 0.00022 <0.0001 - <0.0001 <0.0001 <0.0001 <0,0001 <0.0001 <0,0001 <0.0001 <0.0001 Ratio oi bystandei:(worker airborne asbestos concentrate; 1.0000 0.9814 0.9298 0.8555 0,7710 0.6864 0.6077 0,5367 0.4730 0.4152 0,3623 0.3139 0 2699 0.2304 0,1953 0,1645 0.1379 0.1150 0.0956 0.0791 0.0653 0.0237 0,0077 0.0022 0.0006 0.0001 0.0000 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 T able 6. Su m m ary , >f data used to derive ''rule of thumb" for bounding bystander exposure estimates. Model with reflection and deposition M odel without reflection and depo sition (based on Keil 2000) Distance from souri:ee N M ean bystander; worker ratio N M ean bystander: worker ratio i - 5 ft >5- i() ft 6 0.54 5 0,07 6 0,87 5 0,48 >10-30 ft 12 0.004 12 0.14 >30 ft 8 <0.00001 8 0.00 * For m odeling rcsu.ts, N is the num ber o f distances for which bystander concentrations were estim ated. Combined data sd based on published simulation studies a id workplace surveys N Mean bysie ndei ; worker ivnio 5.0 131 0.08 0.20 51 C.1.U U ht) 30 0.11 0.23 34 6.10 . 0.4? See Table 5 for data chat were useed in calculation. distance category, we did not feel that we could justify low ering the proposed reduction, 'llius, because the Drivas etal. (1996) estimate of 50%was dose to die midpoint of the upper bound average cf 87% based on Keil (2000) and-the average reported for the published data (8.2%), we chose to keep this number as the p roposed value for this distance category. At distances cf>5-10 feet, the results based on Drivas et al. (1996) decrease from 9.6% at 6 feet to 2.2% at 10 feet (average value is 6%), whereas the corresponding values based on the Keil (2000) model range from 60.8% at 6 feet to 36.2% at 10 feet (average value is 47.9%). The average bystandenworlfor ratio based on the published data is 61%. !t should be noted, however, that of the 51 samples from the published data set that comprise this group, 44 are from the Mowat et a l (20(lb) study, which had a very high proportion of samples below die LO D .`Because the samples in this particular study were collected in groups of two or lour an d av erag ed together, it was often die case that one to three cf those individual sample results were less than the LOD, hut included in cur analysis because at least one of the other samples used to Ciitical Reviews in Toxicology Downloaded from nformaheaJlhcare.com by My Came Kahn on 09,23/10 20 E. l\ Donovan etal. calculate the average value had a detectibie result. The air borne asbestos concentrations measured in this study were extremely low in both the worker and bystander samples, so the higher byj tandertworker ratio calculated in this analysis for the Mowat et al. (2005) study should be interpreted with caution, lne re naming seven samples were also from simula tion studies with lower asbestos concentrations; the average bystandenwor cer ratio among these samples was 37.9%. For tnis distance group, a value of 35% was selected for the rule of thumb. Between >1 i) and 30 feet, the Drivas et al. (1996) model predicted reductions from 1.5% at 11 feet to 0.001% at 30 feet (average eduction was 0.4%), whereas tlie corresponding Keil (2000) values were 31.39% at 11 feet and 0.77% at 30 feet (average reduction was 14%). There are relatively few simu lation study results for this distance range; notably, nearly all available data correspond to very low airborne asbestos concentrations (<0.01 f/cc) at the source. For the workplace surveys, the wc rker to bystander ratios vary considerably by source/activity Irom 01% during hand sanding of patching compounds at i 5 ieet to 5% dining a brake blowout at 20 feet, it should be noted that the data generated during sanding of patching ar..d spackling compounds (described previ ously) reflect tauly similar airborne asbestos concentrations between the source and nearly all distances for which ah samples were collected. Tire average reduction based on the published studies at >10-30 feet was 12%. For this distance group, a value o: 10% was selected for the rule of thumb. Lastly, a factor of 1% was selected for distances of 30 feet or greaier. At 30 feet, estimates from both models are below 0.1%. The average value for die published data was higher at 9.1 ai, but, again, the data were dominated by simulation study results wit nvery low airborne asbestos concentrations. ihe simulation studies considered in this review included remote area samples at 50 feet, and the reported concen trations among these samples were less than 1% of those measured for the worker. Although it is possible that smaller fibers (those les, than 5 pm) could "drift" longer distances, there are numerous factors that indicate that such drifting is unusual, and even when it does occur, the actual concentra tion (by mass) is very small. ' the simulation studies involving asbestos-containing, encan sulated products. Despite the obvious differences m the dim, sets, airborne asbestos concentrations i:i bystander samples were, as expected, nearly always lower than the correspond ing worker samples. The magnitude of this difference varied considerably among the held sludies, v/hich hampered our ability to make meaningful comparisons. Nonetheless, the topic of particle physics and particle dynamics has enjoyed a considerable amount of study over the past 40 years, and it would be erroneous to suggest ihat, at least for general estimation purpose:,, the airborne con centration in the typical workplace cannot be predicted if there is some knowledge of the panicle size disiribudo.i (aerodynamic mean diameter) and the magnitude of the point source. To that end, a simple mathematical model was incorporated into this analysis to characterize the rela tionship between breathing zone concentration at a source and distance; as expected, the predicted airborne asbestos concentrations decreased with distance from the source. It should be noted, however, that this model is relatively simplistic, in that it is based on a single worker in a single room with typical room ventilation (dilution ventilation). We did perform one exercise where net advective airflow was included in the models (data not shown), but die impact varied widely depending on where the ventilation source was placed relative to the bystander (i.e., directly upwind or along an axis perpendicular to the bystander, creating a crosswind) (Keil et ah, 2009). It was determined that lor purposes of this assessment, a simpler m odel as preferable. As such, the models used in this analysis are not be able to account fot situations in which th ere m a y be lo c a l exhaii-it ventilation, open window's, large body cooling fan s, or high dilution ventilation (such as in some hot workplaces, lot example ship boiler rooms or steel mills). Based on the available published l ierature and the modeling results, we have proposed general guidelines for estimating bystander exposures to airborne asbestos if the airborne concentration for the worker is known, and if tire distance from the source is less than 50 feet. We also pro pose that, going forward (for future published papers), there be agreement that die term "bystander" shall describe persons working 3 to 10 feet from die primary worker, as it is more Discussion likely that these individuals may be working on their awn Based on this renew, two primary sets of data for character izing bystander exposure to asbestos were identified, 'ihe first included short-term peak (task-based) samples col lected during workplace surveys conducted in the 1970s involving activities in which airborne concentrations could be appreciable (particularly during spray-on asbestos opera tions). 'Ihe second set was comprised of simulation study results. Unlike the field studies, the simulation studies were designed to obtain a general understanding of bystander exp osu re, an d , ;i: I ax im p o rta n tly, b e n e fited from very low limits of detection, and data with very good quality control. Airborne asbestos concentrations in the workplace surveys were orders of magnitude higher than what was observed in tasks, handing the primary worker tools, or simply stand ing guard (as seen with welding or dem i-up duty), and not directly assisting the primary worker. This distance is genet ally consistent with what has been considered in the simula tion studies to be representative of bystander exposure (5-10 feet), and, in fact, the term "bystander" has iTien been used to characterize samples at these distances in i large fraction of published studies. For distances less than i: feet, we propose that the term "coworker" or "assistant" be used. Because a coworker may be in very close proximit to the primary w orker, it is possible that this person may actually be assist ing the worker in performing the task at hand. For persons working at distances 11-30 feet from the pr: maty worker, we suggest die term "remote bystander." id u a b t l i. a k < Critical Reviews in Toxicology Downloaded from informahealthcare.com by Ms Carrie Kahn on 09/23/10 For personal use only. There are several sources of uncertainty in this analysis, most of which stem from the variability of exposure scenarios and asbestos products that were evaluated in the individual studies and issues in the various data sets used to arrive at a single factor for each distance group. First, there were few workplace studies in the published Literature that provide air sampling data at known distances from a source. The 1970s studies included in this analysis span a wide variety of workplace cc aditions, and are not direedy comparable. All of these studies were conducted more than 30 years ago, and none were intended to answer the questions raised in this paper. Shortcomings of these early studies were that insufficient samples were collected, and that fiber length or diameter analyses were not rigorously evaluated. Had these shortcomings b ten addressed, the differences in the ability of very small fibers (shorter titan 5 pm), OSHA fibers (longer than 5pm and often less than 40pm), and very long fibers (those greater than 40 pm) to travel specific distances could have been bene: characterized. Analytical procedures and quality control were less rigorous at that time, although this is probably not a large source of uncertainty, given the mag nitude of the airborne concentrations. Later studies included craftspersons wl o were likely bystanders to insulation work, but often also personally handled asbestos in the course of their own work, making it nearly impossible to make infer ences about the aoint source to distance relationship. Second, the more recent simulation studies included in tins analysis wer a conducted during activities resulting in air borne asbestos concentrations that were orders of magnitude lower than die 1570s workplace studies, in some cases, half or more of the samoles (worker and bystander alike) were below analytical detection limits, limiting their utility to aid in this assessment. In our analysis, we excluded worker-bystander pairs in which t.ie worker sample (or pair of samples, such as left and right1apels) was below the LOD. We did, however, include bystanc sr samples that were less than the LOD by using a value of one-half the LOD in the calculation of the bystander worker ratio. This inclusion could have served to underestimate tire reduction in airborne asbestos concentra tion with distant 2 because a value was used when, in fact, the asbestos fibers nay have already settled out of the air. The basic comparisons (i.e., percent reduction) of mean airborne asbestos concentrations among workers and bystanders may have also been impacted by the preponderance of samples below the LOD, as most of die mean values reported in the simulation studies included some results that were less than the LOD, Had th ere been higher concentrations at the point source, or had it been possible to have a lower limit of detec tion for samples taken at specific distances from die source, more could have been learned from tirese studies. Madl et al. (2000) reported a statistically significant difference between worker and bystander (5 feet) airborne asbestos concentra tions, as well as between the samples for the bystander at 5 feet and the bystander at 50 feet. It is possible they this differ ence was observed most clearly in this study because a larger number of samp .es were collected, tirus allowing for genuine differences in concentration to be measured. Evaluation of bystander exposures to asbestos 21 Lastly, as we have indicated, there is me lerate uncertainty regarding the precision of our estimated n ie of thumb, bus it should be acknowledged that the universe of potential values for estimating the airborne concentration of OSHA fibers, a : a distance, is limited because of particle physics, as well as trie matter of mass balance. For example, it is known that the vast majority, of the larger panicles or fibers deposit fairly dose to die source, only a lesser amount is lef. and available for transport to much longer distances. With respect to uncer tainty regarding the relationship between airborne asbestos concentrations and distance from a source, we considered offering up a range for each distance, but, given the vagaries of air movement arid deposition (and agglomration) that can occur in die workplace environment, add! tional precision is probably not necessary. For example, even when the let: and right lapels of a worker doing a particular t isk are sampled, It is not uncommon for the values to be different by a factor of 2 at low concentrations (e.g., 1versus 2pp rn). The purpose of the rule of thumb is to help the exposure or risk assessor develop an understanding of die l ikely red u c tions that will occur in asbestos concentrations based on increasing distances from the source, as well as fiber-specific properties including diameter and length. Thus, given that there is currently no guidance offered for et tirnating historical exp o su res of workers in the typical "open industrial environ ment," we believe that providing this analysis of both field data and current dispersion models will be helpful to those involved in estimating asbestos concentrt ions in workplaces for which no quantitative exposure data exist, such as in his torical exposure reconstruction efforts, IF for example, one were interested in determining whether respiratory protec tion would be needed for potential bystanders in an active workplace, use of the proposed rule of thumb would be too uncertain given that there is the option of collecting quantita tive exposure data such as air samples that are specific to u ie workplace of interest. This review of the literature indicates that much more research is needed to quantitatively understand the relation ship between the airborne concentrations at the source versus the concentrations at a distance, especially lor libers between 5 and 20 pm and those greater than 20 pm (i.e., those o: bio logical significance). We suggest that future studies incorpo rate air sample collection at numerous feed distances hem a source (north, south, east, west), along with consideration of fiber length and aspect ratio. Ultimately, such studies will help fine tune existing,mathematical models for particuiatus. Such studies would also greatly advance the development ot new models that more accurately characte size the movement of asbestos fibers in the air. Given the increased interest in conducting dose-reconstruction studies in an attempt to pro vide dose components in epidemiology studies, finis work, then, appears to be worthwhile. Declaration of interest A small portion of the research associated with tins work was originally done in preparation for litigation and was m t a J4 T lli L : fij K'l. "" For personal use only Critical Reviews in toxicology Downloaded from infomiahc.althcare.com by Ms. Cam e Kahn on 09CVI0 O') B. P. Donovan at at. supported by a number of companies that have been, and are, involved in asbestos-related litigation. The authors were not compensated for most of the work of compiling the information for this article, or for preparing it. One of the authors (D.).P, i has served as an expert in asbestos-related litigation. References Armstrong TW, Hat sCIS. (2007). Quantitative microbial risk assessment model for Legionnaires' disease: Assessment of human exposures for selected spa outbreaks J Occup Environ Hyg 4:634-646. Assimcao J, Com M . (1975). The effects o f milling on diameters and lengths of fibrous glass arid chrysotile: asbestos fibers. Am Ind Hyg Assoc 1 36:011-819. fiukci EL, Dagg 1, : al. (1985). Respiratory illness in the construction trades. I. lire significance of asbestos-associated pleural disease amung sheet metal workers. I Occup Med 27:483-489. Baker IL, Cooper v\ C, ( 1968). The work environment olinsnlating workers. Am lnd Hyg Assoc J 29:222-227 Bat-nos It. (1976). Asbestos spraying, an occupational and environmental haz ard. Med J An; t 2:599-602. Bell A, (1976). Indus trial hygiene and occupational health studies in Australian (New South Wales) shipyards. Environ Res 11:198-212. Blake CL, Van Circle:: DR, et al. (2003). Airborne asbestos concentration from brake changing, does not exceed permissible exposure Unlit. RegulToxicol Pharmacol 38: -.8-70. Blake CL, Dotson G , et al. (2006). Assessment of airborne asbestos exposure duiiog the servicing and handling of automobile asbestos-containing gaskets. Regul Toxicol Pharmacol 45:214-222. Bowles O, Barsigian PM. (1951). in: M cCann PW, qd. Minerals Yearbook: 1951, Washington D O US Department of the Interior, Bureau of Mines. Bowles O, Stoddard BH. (1933). In: Kiessling OE, ed. Minerals Yearbook: 1932-1933. W.i, hington D C: US Department of Commerce, Bureau of Mines. Bragg GM , van Zuidt-n L, et al. (1974). The free fall of cylinders at intermediate Reynold's uumt ers. Atmos Environ 8:755-764. Cohen HJ, Van Ordcn DR. (2008). Asbestos exposures of mechanics performing clutch service 0.1 motor vehicles. J Occup Environ Hyg 5:140-156. Committee on Indoor Pollutants Board on Toxicology and Environmental Health Hazards A. o. L. S. N. R. C. (1981). Indoor Pollutants. Washington, DC: National Academy Press. Corn At., Stein F. (19:6). M echanism s o f dust redispersion. In "B .R . Fish (ed.) Surface Contamination. London, Pergamort Press, pp. 45-54. Doll R. (1955). MorU-.ity from lung cancer in asbestos workers. Br J Ind Med 12:81-86. Drinker P, Hatch 1. (li,54). Industrial Dust: Hygienic Significance, Measurement, and Control. 2m. ed. New York: McGraw- Hill. Drnckcr b, Nagin D, .a al. (1987). Exposure of sheet-metal workers to asbes tos dining the construction and renovation of commercial buildings irt New York City. A case study in social medicine. Ann N Y Acad Sd 502:230-244. Ferns BG Jr, Panadit e MV, et al. (1971). Prevalence of chronic respiratory disease. Asbcstosis in ship repair workers. Arch Environ Health 23: 220-225. .. ischbem A, Kohl AN, et al. (1979). Drywali construction and asbestos expo sure, Ain Ind Hy; Assoc J 40:402M07. Fleischer WE, ViiesFI. etal. (1946). A health survey o f pipe covering operations in constructing naval vessels. J ind Hyg Toxicol 28:9-16. fowler OP. (2000). Exposures to asbestos arising from bandsawing gasket mate rial. Appl Occup Environ Hyg 15:404-408. Catlriey S, Moody E, e: al. (2008). Worker exposure to methanol vapors during cleaning of sem conductor wafers in a manufacturing setting. J Occup Environ Hyg 5:313-324. Harries PC. (1968). Asbestos hazards in naval doc.cyards. Ann Occup Hyg 11:135-145. '* H an ies PC. (1971a). A:- aestos dust concentrations in ship repairing: A practical approach to imp roving asbestos hygiene in naval dockyards. Ann O ca ip Hyg 14:241-254. Harries P C. (I9 ?lb ). A comparison of mass and fibre concentrations of asbestos dust in shipyard insolation processes. Ann Occup Hyg 14:235-240, Hinds WC. (1399). Aero mlTechnology: Properties, Bcdiavior, andMeasui'ament of Airborne Parades. New York: John Wiley & Sons. HM Factory Inspectorate. (1973). Probable Asbestos D u n Concuntraions at Construction Processes. London: Department of Employment Her Majesty's Factory Inspectorate. Jiang GC, Madl AK., et al. (2008). A study of airborne cluysotiie concemranous associated with handling, unpacking, and repacking boxes uf automobile dutch discs. Regul Toxicol Pharmacol 51:87-97. keil C. (2000). Mathematical Models for Esrimaiin st Occupational Exposure to Chemicals. Fairfax, VA; American Industrial Hygiene Association, Exposure Assessment Strategics Committee. Red C, Murphy R. (2006). An application of expose rc modeling in exposure assessments for a university chemistry teati ing laboratory, j Occup Environ Hyg 3:99-106. Kcil CB, Simmons CE, et al. (2003). Mathematic; I Models for Estimating Occupational Exposure to Chemicals. 2nd e.l. Fairfax VA: American Industrial Hygiene Association (AHIA). l.riis 11, Damn S, et al. (1979). Asbestos disease in mairiteru-.pce workers of Onchemical industry. Atm N Y Acad Sci 330:127-135, Lindell K. (1973). Industrial Uses of Asbestos. In: Bogovsk; i> Trimbreii Gilson jc , Wagner JC, eds. Biological Effects of Asbestos, Proceedings of a Working Conference Held at die Intermit!.mal Agency fur Resemc.i on Cancer. Lyon, France: International Agency for Research on Cancer (iARC). Scientific Publication No. 8, 323-328. I.iukonen L, Sri II KR, et at (1978). Asbestos Expose rt from Gasket Ope run me. Bremen (on, WA: Industruial Hygiene Branch, Occupation;:! ; rut Environmental Health Service, Naval Regional .Medical Center. LiukoncuLR, Weir FW. (2005). Asbestos exposure iron, gaskets during disassem bly of a medium duty diesel engine. Regul Toxicol Pharmacol 41:113-121. bongo WE; EgeUnd WB, el al. (2002). Fiber release during the removal of asbestos-containing gaskets: A work practice simulation. Appl O ccu p Environ Hyg 17:55-62. borfmer WV, Kohl AN, et ai. (1976). Asbestos exposure or brake repair v/orken, in the United States. Mt Sinai J Med 43:207-218. * Madl AK, Scott I.L, et al. (2008). Exposure to chrysotile asbestos associated vritl. unpacking and repacking boxes ot automobile b ake pads and shoes. A m . Occup Hyg 52:463-479. Maines R, (2005). Asbestos and Fire: Technological Tradeoffs and die budv :u Risk. Piscataway, NJ: Rutgers University Press. Mangold C, Kecxett RK, et al. (1970). Asbestos Expos .ire and Control ui pager Sound Naval Shipayard. Bremerton, WA: Industrial Hygiene Dick,ion, Medical Department, Puget Sound Naval Shipyard. Mangold C, Clark K, et al. (2006). An exposure study of bystanders arm work ers during the installation and removal of asbestos gaskets and packing, j Occup Environ Hyg 3:07-90. Marr WT. (1964). Asbestos exposure during naval vessel overhaul. Am Ind Fiye Assoc I 25:264-268. ' McMillan GH. (1983). Ih e health of welders in navy dockyards. The risk oi asbestos-related diseases occurring m welders, j Occup Med 25;72v-7:n; Mcrewether ERA, Price CW. (1930). Report on Eiieds of Asbestos Duse on the Lungs and Dust Suppression in die Asbesco;- Industry. Pan [ and ii. London: His Majesty's Stationery office, 1-34, Moorcroft JS, Duggan MJ, (1364). Rate of decline of asbestos fibre concentration in room air. Ann Occup Hyg 28:453-457. Mowat F, Bono M, et al. (2005). Occupational expose.re to airborne atbesj.n from phenolic molding material (Bakelite) during sanding, drilling, and related activities. J Occup Environ H yg2:497-507 Micas M. (2001). Modeling turbulent diffusion and adv>: ction olindoor air con taminants by Markov chains. AIHAJ G2:H9-158. Nicas M, Plisko Ml, et al. (2006). Estimating benzene ex tosure ar a so lvcut pans washer. ) Occup Environ Hyg 3:284-291. NIOSH. (1972;. Criteria lor a Recommended Stand ai d: Occupational Exposure to Asbestos. Cincinnati, OH: US Department of Health, Education, and Welfare, Public Health Service, Health Services and Menial K eiuh Administration, National institute for Occupational Safeiy and Hearih (NIOSH). NIOSH. (1975). Study of Sheet Metal Workers. Cincinnati, OH: National Imocuce for Occupational Safety and Health. HSM 099-71 55. Paustenbacli D}, Finley BE, et al. (2(X)4). Environmcatal and occupational health hazards associated with the presence of asbestos in brake linings and pads (1900 to present): A state-oFthc-an xe. ievv. j Toxicol Environ Health B Grit Rev 7:33-110. Paustenbaoh I)J, Madl AFC, et al. (2006). Chrysotile asbes:os exposure associated wim removal of automobile exhaust systems (ca. 1945-1975j.by rnechr tries: Results of a simulation study, j Expo Sci Environ Epidemiol 16:158-171. PaustenbachDJ, Sage A, ctol. (2004). Occupational exposure to airborne asbes tos from coatings, mastics, and adhesives. j Expo Anal Environ Epidemiol 14:234-244. m u i3l H T S L i iri H Reisl PC, (1975). Counting asbestos fibers by the most probable number method. Am In i Hyg Assoc I 36(5):379~384. R eiue WB, Nicholso n WI, et al. (1972). Application of sprayed inorganic fiber containing asbestos: Occupational health hazards. Am ind Hyg /Assoc f 33:178-191. Kohl AN, Utnger AM et al. (1975). Exposure to asbestos in the use of consumer speckling, patenting, andtaping compounds. Science 189:551 -553. Rohl AN, Langer AM, fet ah (1976). Asbestos exposure during brake lining main tenance and re 'air. Environ Res 12:110-129. Sahinel I, Ulrica K, et al- (2009). The use of muliteone models to estimate an air borne chemica. contaminant generation and decay profile: Occupational exposures of hairdressers to vinyl chloride in hairspray during the I960 and 1970s. Risl. Anal 23:1699-1725. Sawyer RN, Spooner CM . (1978). Sprayed Asbestos-Containing Material in Buildings. A Guidance Document. Part 2. Research I riangle l'ark, NC: United States Environmental Protection Agency. Selikoif IJ. (1971). Dr. Sclikoff Testimony before the Chicago City Council, Chicago, IL. Selikoif II, Churg I, et al. (1964). Asbestos exposure and neoplasia. JAMA 188:22-26. Selikoif 11, Churg 1, e al. (1965a). Hie occurrence ofasbestnsls among insulation workers in the United States. Ann N Y Acad Scl 132:139 -159. Seiilcoff II, Churg I, ot al. (1965b). Relation between exposure to asbestos and mesothelioma N EnglJ M ed272:560-565. Spongier I, Samct J, et al. (2001). Indoor Air Quality Handbook. New York: McGraw-Hill Professional. Spiincc NX,, Oliver 1.2, et al. (1985). Asbestos-related disease in plumbeisund pipefitters employed in building construction. I Occup Med 27:771-775. Evaluation of bystander exposures to asbestos 23 Timbrcll V. (1965). The inhalation of fibrous dusts. Ann Ny Acad Set: 532: 255-273, US EPA. (1978). Splayed ACM ill Buildings: A Guidance Document. Research Triangle Park, NC: US Environmental Protection Agency (ERA), Oincc of .Air arid Waste Management, Office of Air Quality Planning and Standards. US EPA. (1988). Asbestos Exposure Assessment. Washington, DC: Unites. 3 Environmental Protection Agency, Chemical Engineering Hrancn OiEcu of Pesticides and Toxic Substances. 1)5 EPA. (1997), Exposure Factors Handbook (final Report). Wasnkigren, 1./C United States Environmental Protection Agency Venna DK, Middleton CG. (1980). Occupational exposure to asbestos in he drywall taping process. Am ind Hyg Assoc I 41:2.:,4-269. Vterma D K .'K um I.A, et a l (2003). Current chemical exposures among i ininrio construction workers. Appl Occup Environ Hyg 181031-1047. VernezD, Bruaai R, etal. (2006). Acute respiratory syndrome alter inhalation or waterproofing sprays: A posteriori exposure- response assessment in ! 02 cases. J Occup Environ Hyg 3:250-261. Villa RJ.. (2005). Mineral Commodity Profiles--As restos. Boulder, c.O. ' Geological Survey. Circular 1255-KK. Wagner )C, Sleggs CA, et al. (I960). Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province. Hr ) Ind Men 17:260-271. Williams PR, PhclkaAD, et al. (2007). A review of histo rical exposures tc asbus tos among skilled craftsmen (1940-2006). J Toxicol Environ Health B Crii Rev 10:319-377. Xoloih 5, Michaels D. (1985). 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