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a/ tut an iti. JIJ4 441 40U2 CHKII I SI KV Ahl) kSSlLSiRiaX. itfon AMERICAN JOURNAL OF INDUSTRIAL MEDONE 35.281-286 (1999) Tissue Burden of Asbestos in Nonoccupationaliy Exposed Individuals From East Texas Ronald F. Dodson, PhD,'* Marion G. Williams, BSt` Ju Huang, ms.1 and James R. Bruce, mo2 Background The potentialfir asbestos exposure among members ofthe general population is appreciable, considering its widespread use in many products. This-study examined tissue burden ofasbestos in such a population. , ` Methods A group of 33 individuals who had no work history of occupational exposure to asbestos were included in the study. Tissue sectionsfrom areas adjacent to those sites sampled fir digestion were found to be without ferruginous bodies (FB) or histopathoiogy consistent wish asbestos-induced changes. All individuals had 20 or less FBs per gram ofdigested wet lung, a number considered to reflect general population levels. Tissue analysis of uncaased fiber burden was carried out by analytical electron microscopy. There was a trend ofa higher likelihood ofFB and asbestosfiber content correlated wixiuagt. Results The data ate not consistent with thefindings that chrysolite is readily found in lung tissuefrom the general population, in that none waskfound in 19 ofthe cures. It was almost as likely that one would find Omhophyllits (12 of 33 cases) in this study. The commercial amphiboles (amosite and croeidoUte) were occasionallyfound in the tissuefrom the general papulation and. when observed, were few in numbers. Twemywtix ofthe patients had no FBs and ten had no uncoated asbestosfibers within the Unfits ofdetectability in this study. Conclusions The total tissue burden of asbestos in this study is much less than earlier reported observations from other general papulations. Am. J. tnd- Med. 35:231--286. 1999. a mo Witey-Ua. Inc. ICEY WORDS: asbestos; general papulation; electron microscopy EXHIBIT ^lSQ INTRODUCTION The potential for asbestos exposure in our society includes both occupational and environmental contact. Esti mates of probable exposure to asbestos In a odds range of job titles can vary from possible to likely [Hammar and Dodson. 1994]. Some professions would more readily be expected to have contact with asbestos-comaining materials (ACM) while cartying out their jobs. Many, including Dcpamnera or css Sdegy and Efiwwraemal Sciences, Unhrarslly oi Tarn Heath Csntar atTylar. Tyler, Tea* Rufista Pahaloay Laban**. Ujfldn. Teas "Csmspandeftea its Roald F. flatten. PftD_ Fmtesw and ashman. Oepattnww of fled ffiesa and Endiwmental Sciences, Uiwersity of Teas Hearn Center stTyiar, 11937 US HigHway 271, Tylar, TX 75J08-31S4. S-otad: rdadSBflSuttictedu Accented 22 Hastier 199S. building occupants, are potentially exposed to asbestos as a background component in their daily work environment. Therefore, a work history may often not include exposures that were not remembered or recognized at the time they occurred. A retrospective assessment of past exposure can be achieved by tissue analysis- Tissue analysis reflects that part of the asbestos burden that has not been cleared by the time the sample is collected, and applying such techniques has offered insight as to past exposures often within occupation ally exposed cohoits [Hammar and Dodson. 1994], Ferrugi nous coatings form on a population of asbestos Abets that are greater than 8 pnt and. when seen In tissue sections in combination with fibrosis, are important in establishing die diagnosis of asbestosis (Craighead et a!.. 1982: dung, 1989]. ' --------- The use of tissue sections as a screen for ferruginous bodies (FBs) has Inherently limited sensitivity due to tho 1999 WRey-Uss, Inc. Riesivad Aug-16-89 1l:01aa Froa-303 431 4601 To- Pa* U HWBUI0010266 oa/ze/aa iz:ui tel 303 431 4602 CHEMISTRY AiND INDUSTRIAL 1^012 282 Oodsonetal. restricted areas scanned. Thus, digestion techniques permit a larger area to be sampled, yielding an inherent Increase in sensitivity from data-qbrained from tissue sections [WhitweU etaL 1977], Tissue digestion studies by Roggli et aL [1985] from North Carolina and Dodson a aL [1984] fas a eahart from East Texas and HoussaaJindicaxed a general population tissue burden of0-20 FBs ner gram wt weight. CompUcadag-tbe-iisterpretatioa of such.dam is the concern fh*r in some individuals, appreciable asbestos burden may oust with few orno asbestos Bodies being found in tissue sections [Womack and Wolery. 1917] or the fact that some individuals with appreciable fiber harden simply do aot readily coat the fibers (Dodsett ec aL 1985], An FB. when, detected. Indicates that some.level of past exposure has ocemred, and a person of that exposure included longer fibers {>3 pm). Wide the increase in the number ofasbestos bodies tadicates an increase in intensity -or duration a exposure,,the lack ofFBs as determined by light microscopy cannot be used to cxospoiatB the ruunber of uncoated fibers in the tissue. Light microscopy Is of limited value in countin' such uncoarsd fibers, since the majority arc coo small ro be visible [Cburg and Womack. 1980: Dodson et aL, 1990, 1991]. AS Srebra et aL [1993] noted, electros microscopy analysis may be 10 offer a-characterization of the quality and quantity of mineral fibers when asbestos body ctstints are within the range of background values. Much of the present data oa unseated fiber burden has been from cohorts with known past exposures to asbestos is occupa tional or para-occupational settings, and a limited number of these used counting methodologies, magnification, and analytical transmission electron microscopy as necessary to see thin, as well as short (<5 pm), uncoated fibers. In some of the more comprehensive studies on uocoated fiber burden in the general populations, Churg [1982] and Cfaurg and Warnock [1980] used analytical transmission electron microscopy and counted unearned fibers % l pm in length. Thor [Gmij and Waraock. 1980] conclusions were that the average luag in the urban environment contained mainly shorter fibers of chrysodle and noncommercial amphibole*. In a subsequent study [Churg, 1982] dm mean number of asbestos fibers was given mix 10*/gm dry lung, with more than 80% of the fibers bring chrysolite of less than 5 pm in length. la order to add to the hosts ofknowledge oa whet types anti levels of aabessos Abas use found m mother, mote ratal-based general population, tissue from 33 individuals with no known ocojpadoaal exposures were prepared for Light and electron microscopy analysis. Since histories are sometimes nor indicative of exposures, die criteria for analysis was rhnt none of ihe intfividsials would have more than 20 FBs per gram wet weight as determined by light microscopy and that no hissapathology consistent with TABLE L Age. Sex. Total Uncoated Asbesajs fibers and Famjgmatn Sadies per Case far Nonoecutrasoraly Exposed East Texans Total obotn CASE AgeSiei fa/gtndr} fanfmna Mms FB/gra etg FB/gmwri 1 12/F a0 2 15/M aQ a !3VM a0 4 18/M a0 s 13/M aQ s 21/M aa 1 2WF 34.000 io S . niA 393W0 3JQ0 9 %Mf, naooa Vi&ISQ ta 25# 32.600 18.000 ii ZS/M 0a 1Z 28tf 42.009 6,900 13 25/M IQ&GOO 17.800 i* 42JOTJ 0,108 IS 30/M 190.000 37,000 18 31/M 130,000 28.000 IT 34/M 3km 8.460 IB 35/M 140.000 33J00 19 37/F s0 20 37/M 00 21 38m 260,000 5*000 22 38/M 280.000 S7J3QQ 23 40/M 130,000 29.000 2* 1/M 00 25 41/M 36.000 8.100 26 44/M 87.000 ? 7.080 27 47/M 42.000 8.400 20 49/M 68.000 17.000 29 SO/M 210.000 44.000 30 31/M 140.000 27,000 31 m- 290.000 S0.0SS 32 m- 180.000 42000 33 73/F 73.000 17,000 0 0 0 a 9 a 0 a a 0 0 0 0 a 0 0 0 35 Q 0 0 101 93 8 0 as a 0 98 0 120 0 87 a 9 Q 0 9 0 Q 0 9 a 0 0 0 0 0 0 0 20 0 0 a 20 21 0 0 20 0 a 20 0 20 0 20 asbestos-induced disease were present. The individuals were from rural areas or from communities in eastern Texas. METHODS Autopsy samples from 33 patients fTabie 1} who suet l&e criteria described below were selected for the Study. These individuals were from the eastern portion of Texas, as area which by definition Is rural In that there are no communities of 230,000 or greater populations. However, the cities in Che region do have considerable industry, including those produc ing forestry products, foundries, petrochcmically related industries, as well as various other types of manufacturing Rtceivid Aug-Z6-8S HiOZas FroB-303 431 4S0Z To- Fags 1Z HWBUI0010267 08/26/98 12:01 TEL 303 431 4802 ~ t. _ ** CHEMISTRY <LN'D INDUSTRIAL Asbestos Burden in the General Population 283 f facilities. Many of these industries have various asbestos 5 products in use in their facilities, wish some having considerc able potential for its disturbance. As with most at the * . country, choc is appreciable asbestos in place in schools, J. public buildings, and homes. Therefore, while the area may be defined as rural, the potential for contact with asbestoscontaining materials is common. The first criterion used to classify these individuals as pare of (he general population included an apparent lack of i job-related activities associated with occupational exposure jj to asbestos. Two blocks of tissue were sampled from the \ areas of the lung. The first was embedded in paraffin and sectioned for Ustopathologieal screening. IfFBs were found | in a ssedon or changes were observed which could be )= suggestive of asbestos-induced diseases, the patient was l; excluded from the study. The second series of blocks were used for digestion 'procedures (described below). To be ` included in the study, the individuals also were confirmed : via the analysis of die . digests, to have ferruginous body burdens of equal to or less than 20 FBs/gm wet weight. . The lung tissue was prepared for light and electron microscopy using Williams' modified bleach digestion pro: ceduns (Williams a al, 1982]. Briefly. 12 rites were sampled from normal upper and lower left lung parenchyma and r pooled prior to bleach digestion. The pools averaged 0.6391 012307 gm dry weight. Dry weighs were calcu lated using wet/dry ratios determined for each case. All reagents were prefiltered through 0.2 pin polycarbonate filters just prior to use. Pooled aliquots were collected on : - 0.22 pm mixed cellulose ester filters (25 mm diameter) for FB counts by light microscopy and on 012 pm polycarbonate filters (25 mm diameter) for FB and uncoaced fiber counts by i electron microscopy. The mixed cellulose ester filters averr aged 0.04-14- S 0.0046 gm dry weight of tissue. One-fourth 1 of each filter was made transparent with acetone vapor and analyzed by light microscopy at lOOx and 200x for establish ing'the levels of FBs in the tissue. The polycarbonate filters averaged 0.00827 = .000926 gm dry weight oftissue. The entire surface of each filter was t analyzed by light microscopy at lOOx and 2QQx for FBs. ; Carfaoa extraction replicas of each filter were mads by the 1 direct method An area of 1. Id mm1 was analyzed by ATEM at 16.000s for uncoaced Sbire and FBs. The mean detection limits were 8.800 %m wes and 44,000 %m dry, An ; additional area of 3.5 mm: was examined at l.SOQx for FBs. ; A JEOL 1D0CX ATEM murfaeed to an EDAX NX-2 X-ray - analyzer was used for the analyses. Seleetad son eisc&aa ; diffraction (SAED) was used for foxthar analysis of asbestos ; fiber*. Uncoated fibers were defined as those sQJ pm long , with aspect ratios S3: t. Reagent and filter blanks were analyzed as pan of the quality eontzol procedure. r RESULTS Seven of the individuals were found to have 20 FBs/gm - wet weight. Ho FBs were observed in the remaining 26 individuals (Table I). There was a higher likelihood of finding an FB in the older half of the study population, beginning at age 35. Four females were in this group, two of wham (Casts 31 and 33) were found ts have 20 PBsfgm wet. five males in this group were also positive for FBs with 20/fm. wet. There was a ugax&OK positive correlation between the FB and total uncOMed asbactss etmcetuxasiODa (P < 0.01). Aka. there was a positive coirelation between age and total unseated asbestos concentrations (P < 0.00. The highest concentrations of uncoetcd asbestos fibers. 290,000 fibers/gm dry, occurred in a 68-year-old white female (Case 31) and e 38-yeax-aid'male (Case 22) ETStble t). However, the composition of the asbestos burden in these two cases differed greatly. The individual who had been a housewife was found to have predominantly aathcphylUis llhets, with a lesser component of the burden being aremo- lire. Mo other asbestos types were found, la the TMdr (Case 221), the prevalent type of asbestos was chrysotile. with a smaller component consisting ofan equal amount ofamosite and actinolite. The most commonly encountered type of asbestos among the group was chrysotile, found in L4 of 33 cases. (Table IL Fig. 1). Chrysotile was found as the highest concentration of the asbestos types in six cases. No chryso tile was found in 19 of die cases, Atnmite was found in only three of die cases and was dm predomman type of fiber in only one (Case 9). The other amphibole commonly thought ofas a commer cial component, crocidolice. was found in thro* of the case* and was act the prevalent type of asbestos in any of these. The second most commonly encountered osbesto* type was anthophyllite (12 of 33 cases). Anthophyiltte was the predominant asbagtos type in seven of the cases and the only asbestos found in three of them. Tremolitc. was found in eight of the eases, making it a more commonly encountered asbestos than cither of the commercial amphiboles. Four of the eases were found so have acdnoUte fibers; 10 of the 33 patients had oo asbescos fibers detected. The average concentration of uncoaced asbestos fibers for the 33 samples was 84,000/gm dry, while dm for the 23 patients that were positive for fibers was 120,000/2 dry. Hie asbestos concentrations were skewed us seen ia Figure 2. which is typical of these data Most of the asbestos and nonasbestos fibers were classified as short fibers (<S pm) (Tables ED, IVAJS). The only asbestos fibers that met the Stanton hypothesis criteria (length a8 pm and diameter <0.25 pm) were 5% of the aathophyllits libers. Nano of the nonasbestos fibers met the criteria (Thbte 1VA). The percentage of fibers that met the NIQSH counting criteria for PCM are found in Table IVB. When the asbestos fibers were considered as a group, 79% were less than 5 pm in length compared to 95.1% of the nonasbesms fibers. Only 9.7% ofthe asbestos and 4.5% of the nonasbestos could have been counted by NtOSH/PCM criteria (>5pm length). Racaivad Aug-26-Si 11:Q2ao Fros-303 431 4602 Ttr Paga 13 04/Kb'/98 12:01 TEL 303 431 4602 Cf* CHEMISTRY AND INDUSTRIAL ion. 284 Dadsanetal. TABLE fl. Uncoated fiber Data per Case (fibers/g Dry) (or Mormccupationally Exposed last Texans CASS Total assesas Chrysatfla Amositt Craddalitg TremalltB Acrlnafit* 1 2 3 l s s 7 a 9 10 u 12 13 u IS IS IT IS 19 20 tl 23 23 2A 25 26 27 Z8 29 30 31 32 33 Av. all <3. Av* S3, 0 0 0 a 0 h 34.000 33.0(30 1101330 92.000 0 42,000 '* loojQoa 42.000 . . 190,000 . 130,000 32000 luttsoa Q 0 350,080 280,000 138000 0 38,000 67.000 42000 0.000 210,000 140.000 2301103 '1604)00 rsxao 88.000 us,sso 0 a 0 s 0 -0 34,000 0 33,000 - 464100 3 41.000 $1,000 0 0 0 32.000 71.000 0 0 1304180 710.000 48,000 0 0 43.000 Q 34.Q0Q 61000 93.000 0 0 a 23,000 664100 0 a a 0 0 0 0 0 70.000 0 0 a 0 a 0 43.000 0 a s 0 3 424)00 0 0 0 0 0 8 0 0 a s a 4.700 524100 9 a 0 Q Q 0 9 9 a -384100 0 0 a Q 0 0 0 9 0 a 0 0 0 a 0 0 0 0 a 46.000 0 36X00 0 3,900 43.000 0 0 a 's 3 0 s `0 0 .0 0 0 51.039 42,000 48.000 `0 .0 00 Q 44.300 a 0 0 -0 43X83 a 9 3 a sr.oaa 36.000 73,000 13,000 34,000 0 a 0 0 3 3 0 0 0" s 0 3 9 3 3 43,000 0 3 fl 0 44,003 *2.000 43,090 S 0 0 0 0 0 a 3 0 Q 5.300 43.000 Amnspnyuin a 3 `a 0 3 0 3 3930 3 .0 3 \o 3 -3 140.000 *3xco a 71.coo 0 0 44X80 0 *133 3 35l33B 3 *2.30 2*908 1304X0 a (91380 11Q.3Q0 0 28.300 77.300 NQQstKSSs 37,TO 400X00 340X03 230.009 $10,000 1304103 1,160X00 160AKS 113,600 32&M 7404110 xmm fwjyw 470,038 333.069 470.030 730,000 210X00 '4904)80 4504100 1.633.030 1TOU990 ixsoxso - 7SELSS9 750X00 1,1704100 118.000 U00.800 zmm 3.670.000 T,678.900 1.S30XQ0 346900 630.080 650X88 The highest total of uacoated asbestos fibers found in the gnup was 390.000 fibars/gm dry weight (Cases 23 and 31). Three of die four heaviest burdens of uncoated fibers were in individuals tit wham at least one FB had been found (Cases 22. 29. and 11). Howevet the third highest level of uncoated asbestos fibers was found in an individual in whom no FBs were detected (Case 21). The neaaabestos fibers consisted of 39.3% aluminum silicates. 31.5% mind silicates. 6.9% magnesium silicates. 5.6% silica. 10% titanium, and 6.7% Iran. DISCUSSION The work of Churg and Wansock (1980J suggested substantial amounts of asbestos, mainly chrysodle and noncommercial amphiboles, in the average lung in an urban environment. In the same study, the asbestos body content for 21 subjects was reported to be from 2roS4 per gm ofwet lung. The FB data, in the present surly are more consistent with the previous levels encountered in our laboratory for general populations and the levels repotted by Roggli et ai. (1986). Churg and Wamock (1980J also reported that 80% of the unseated asbestos fibers in this general population group were chrysorile and 90% of the chrysodle were -eS pro in length. In the present cohort. 33% of the unctsuod asbestos fibers were chrysolite and 86% were <5 pm. Seventy-nine percent of alt asbestos fibers were <5 pm. The study fonher concluded that 95% of the amphiboles were noncommercial Ratalvad Aug-26-88 H :02aa Frsa-303 431 4302 Tot- Pm 14 HWBUI0010269 /U M/ i.tIJ4U-m41-1M.AL> (4J0X5 Asbestos Burden in the Central Papulation 28S TABLE UL Fiber Characteristics: Geometric Means for Nonoccupaticriaity Exposed East Tear.* Fiber type U"fW (tunl Wt&ft fount Amsait* OnddoUta Trarasltw MnuptiirSito sansnastjotas 1.01 1.60 2.11 z*a 1 JO Z37 147 - 04fl ai< o.t r 0.19 02* 023 aiG * A^nt ratfo 29.23 11.70 12.TS SL11 8.11 1E.03 843 ASTypa* f*Mm 9f CMS Ast&epay&SIg As!ias0ia JUnoailft TABLE W(AJ. Fibers Fitting th# SlaiSBan Hypothesis* for Hotioca^afenaity Exposed EastTeam FIGURE 1. Percent danmoan or asQesns type in lung samples rrom 33 East Tesro net saasajams} gxessed sb asaessas, 1S96, Shl asysatiK Affisdte CwcWoWc Trcrafitc Mnsfds Arahsiutjitits A9nanes(i3t(B "Unsffl >80 |US ass tmmetsr *023 itm. PtttUBQI 0.0 04 OS ao 04 5.0 0.0 table nr(B). fibers Meeting ana cmmmme sy MQSH Ctiteria lot Nanamipadonaiiy exposed East Texans 040 51-108 3SI-ISS 1S14JS 20(410 Rings: fites/g dry X 1,000 tajmoar t fawi 451400 Fiber type Percentage >5 ion Percentage mecaeta try right iQicntsaijitf* FIGURE 2. Oismttaxm By mttiasbesta concentration itt 33 East Texara. 1990. types and due two-dskds of ail amphibotes were <5 pun in length. Eighty-three percent of the amphiboTes in the present study were noncommercial types and 73% of these ware <5 pm in length. The source of andiophyllite in the general population from East Texas is presumed to be from exposure to products which contain the fibux as an associated component. For example, anthopbyiliie has been reported as coexisting with dwysotile [Kohysnu et ai, 1996] talc, cordierisa, and pfaiagapite. There are no naturally oceumns outcrops containing aochophyilite in eastern Texas. Amhophyllite has been used in very limited commercial applica tions worldwide (Sdikoff and Lee. 19781, with one plant in the Northeast using the material as a component in the manufacture of plastic tanks. There was no indication of contact by members of this study group with such commer- Otrjstfflia MBBsftB Tremooe MHc Anthqitiyine Attsoaasfissss 134 23.0 0.0 11.0 a.s 304 5.0 ">S wa Mngn arm >8.33 pm ttameor. 0.0 254 04 T14 04 184 45 dal produsts. While this .-study consisted of individuals from larger sides, the potential for exposure to osbestoseemtaiaing products existed for these individuals, as with chose in the present study from sources at work, schools, and homes. Furthermore, the method of analysis and counting criteria allow a comparison between these "general popula tion'* groups. In contrast to a common presence ofchrysodle Received Auc-ZE-99 tl:0Z*a Froa-303 411 460Z Ttr Pagt 15 HWBUI0010270 08/28/99 12:02 TEL 303 431 4802 " ? TTs CHEMISTRY AND INDUSTRIAL 141016 -286 Godson et al. ia members of the general population, less cfasa 50% of the asbestos bodies or asbestos fibers. The overall tissue burdens individuals in this study (14 individuals) had denccrnhlc Tended to be highest in the older individuals in the study. levels of chrysodle. While there may eermmly he hij&ec "background1* levels in other general populations than those present in East REFERENCES Texas, the area has no shortage of asbestos in indostry, private homes, schools, and public taildines, (l should also be remembered that chrysodle clears more readily than omphifaolc and thus, over time, the hxKjf-btadca represents a Quxg A. 1992. Fiber counting sail analysis ia ilw diarnosir of aibesas- rclacM alien*. Hum Pathol 13381-392. Chut;A. 1989. Ths diasonsis of axbescoas. Hum Padiot 2H;97-99. small fraction. of ralrainl chrysodle. Within the detectable ChunA.'MwoosStMS-. 1990- Asbcuos Ktraa la tJw limits of the present study it was, inTfset, more likely that as Rev Rrapir Dix 12S&SMW. pepidutao. Am individual would bs found to have a "aoacommcseinl'' naphthoic (17 out of33) than chrysodle (14 aat of33). Staaolite has been linked to chrysodle exposure in' v same settings, as discussed In a recent review (McDonald andsMcDanald, 1997]; however; there was ad similar , correlation found In die present study. EJglK(23*&) of chc:33 patients were positive for tremotaaml only three of these Cralgaraa iE. Aaranass ft. Qitsrf A, Craw RfY, faraotrasa /. Frm PC Secsaavar TA VgUyathoa V. Wall H 19SX. The pathology of sshesau, aandared diseases of the kagi aad pkmal esvidra: Diagssscie attetia sad propmdsradiatsditasL Arch PatboiLab Med tO&S4*-J96. Oodssa'&E GeenaSapeg SO. WlUlaras MG. Cum CJ, O'Svliivaa ME Hume GA 198*. Asbesas commit in tunas of ocaiputeasUy andWniMaipariOR. ally exposed badfridmls. JAMA 352:a8~71. had chrysotUe fibers. The small percentage with trnnaUte in drfs more rural popniadon amnaso with tea from the study ofSrebro ana Roggtt (1994] in which mis asbestos type was considered "tuco^jubtqtuiotis and.represents the most common amphibole fiber in the lungs ofurtoaoltel/' It is not posstble ln either study to define me source of the tremolice. but (r should be appreciated that chrysatOe is not the only (mineral la which tremolite may be present. The commercial ampMbotes were the ieast likely form of asbestos to be encountered. Three of the patients had amosite fibers, which in the heaviest cencencradoa was Dodams 8K WUUaasa MG. OSiiilinn MP. Com Cl. OmaUm; SO. Hum GA. ISSS.AeoeifemuaooftbttfemiKmouabadyaaduaeosuedS&Kreottnae ia the lungs of former asbestos woriuts.AaRev Rapir DU 133:143-147. Dediaa RE WUUaaa MG. Cara O. Sralla A Bianchi C. 1990. Asbestos OStttaaX of lung tssaott. lymph nodes and plmuzti planum ftvtm foimor. shipyard workers. Am Rev Roapir Die 143:843-847. Dedsoo RE WtlUagae MO. Com O. 9raUo> A SUuachi C. 1991. A cosnpariajs of asbestos burden in fang parenchyma. lymph nadm and plaques-Ana NYAa4 Sd 643:53-40. HommwSR OodsonSF. 1994. Aatxsmsa. In: Ball OH, tfammar ST. edimra. Fdlraonary pattwslosy. J*mr Torte Spnessn.vtag. pp >MH_dS3. 70,000 fibets/gm dry weight. None ofthese individuals were from me Tyler area, winch had been the site of an amosite manufacturing facility between 1954 and 1972. Twenty-five percent of the amosite fibers were >5pm in length (Table IVB). Three of the patients had crocidolite fibers, with Kohyama M. Shmotara. V. Sumtu Y. 19%. lAwetal phases and some reswauiwd otovacKmdm of dm- taacnrasacal Um Azamat Caaeer of standard asbeosea samples.Am J fed Med 3tfe5tS-i2S. McDonald SC. McDonaldAO. 1997. Chraotile. ifemufitc and carehtupmic* ity (Abdnctl.Ana Geeup Hyg 41:899-701. similar concentrations in the range of 36.000 to 46,000/gm Roggli VL. Fisa PC Brody Alt 1988. Asbestos ennui ui'lung tixois in dry. When croddolite fibers were found, they were <5 pm asbestos associated diseases: A study of ISO cues. Sri Ind Mad 43:18-38, - long. Sdfkoif U. Use DHK. 1978. Asbestos and disease. .Yew York: Academic Press, pp 51-69. CONCLUSIONS Seehra SH. Roggii Vt,, 1994. Aobsh3K.<ahua<i disa* assessed wiih The conclusions from this study are that there were few FBs found in nonoccupationaliy exposed members of the general population from East Texas, in that none were observed in 26 of 33 samples. The untreated tissue burden of e-xptmiK to ssbestifara tremalifc Am J lndMed26:S09-3ll Srebra SH. Rsspi VC, Sanaa Of- 1995. Mallgnaat EKmclioma asrasiaid wida low ylnwavy duw abiitM kuidvosa A light and aeanniag .electron imasscopic analysis of (8 cases (Abstract!. Mod ftifcoi S:6i4-` 621 asbestos in this group was found to total from 0 to 290,000 fihers/gm dry weight. Quysoale and rraneommereul ampluboles make up the predominant oncoated fiber types encountered, with commercial amphibolies bring found in few patients and, when pressor, in cumbers of less than Wsraocfc ML. Woley CL 1937. ASboms bodies or fibers and (he dragnai* of asbedmta Eavtan Res dA29^14. WhirareU F. SeasJ. OUrailciw M. 1977. KctoOOMftip eawcca oetupatiisa and osbmm>4ttM esnunt of dm longs ia paaous wid> piul nrnxha. tarns, iuai cinm; and oilier diseases, tboras 32G77-38& 70,000 fibers/gm dry weight. In the present study, ten individuals within the limits of applicable detectability were not found to have either WUlkuaa MG. Oadsaa RE Cora C. Huai GA. 1982. A ptcwodina tes the uolstioa of amotiu aslnstm ood feovssntMs bodies fora [uns nuiw rad spamm. 1 Toxical Environ Health 10:627-638. Ricilvsd Auf26"S8 iliBlaa Ffoe-303 431 4EB2 To- PU< 16 HWBUI0010271