Document 2JpD1K0k88Mo05wGZokrByvwp

i > <mnm> CC: Occupational & Environ Health Managers P&IRD Managers Plant Managers E. I. du Pont de Nemours & Company EQC Members WILMINGTON. DELAWARE 19898 EMPLOYEE RELATIONS DEPARTMENT July 13, 1980 COMPANY PHYSICIANS ASBESTOS-RELATED CHANGES The attached article by Sargent provides pertinent information regarding pleural plaques and the association with asbestos exposure and may be helpful to you. 3WK:ceb Attachment Bruce w. Karrh, M.D. Corporate Medical Director DUP 0 9 3 7 3 6 0 Thsrs's a world ol irungs wa r* doing something about DU 038331 Pleural Plaques: A Signpost of Asbestos Dust Inhalation & Nicholas Srgn& M.O.. Goorga Jacobson. M.D.. nC Jay 3. Gcrdonaon. M.Q. ile general contamination of the urban at have been implicated, but the highest rate of T mosphere by asbestos dust has become a association occurs with uthophyllite.' matter of public concern, Industrial exposure of In addition, other factors such as the site ud workers to this dust is also widespread. The nature of the geologic deposit of the asbestos radiologist and other physician! should be fa* may be important. For example, in the miliar with the occupations in which asbestos chrysotile mining areas of Quebec, the occur dust exposure occurs ud should be aware that rence of pleural plaques in miners is common in asbestos is used in more than 3000 arnmerciai some alines, rare in others, ud absent in one of items. The major cause for failure of public the largest mines not too distant from the health agencies to control asbeatosis is the iong others." Io nonoccupationaily exposed popula latent period (often 20 years or more) between tions. particularly in Finiud. the prevalence of the beginning of work exposure and the ap pieural plaques relates to the proximity of pearance of overt disease. The disease sow be residence to certain mining arena, and the air ing discovered was initiated by industrial ex is so polluted that even cattie are con posure during or before World War II. Before taminated.''1*'1* Sitmiariy, plaques have been the 1950s, few precautions were taken to observed in some agricultural populadons1* and protect workers from this noxious dust. Thus it in cattle1' in arena in whieh the soil is contain- follows that to prevent asbestos dust disease in mated with asbesdform materials. the year ZOOO we must recognize iu charac teristic radiographic appearance now and take PATHQGINfSIS AND PATHOLOGY .appropriate measures to rtduee exposure To date, no totally satisfactory explanation wherever evidence of cht disease ia found. has been developed to explain how the pleural r~Although asbestos dust inhaladoa is not the (sole cause of pieural plaques, it is certainly the, reaction that results in plaques develops in response to the inhalation of asbestos fibers ud most common. The association between pleural "plaque* and occupational or sonocsunational asbestos dust exposure has been amply con particles. Asbestos bodies have rarely been found in plaques." but asbestos fibers may be present. However, tbc lack of asbestos fibers ia firmed by population studies.'The prevaisiceof claques mentioned by previous investigators has pieural changes seen on radiographs has bean shows to increase ia relation to the estimated iargriy been due to inadequate techniques." 3y means of reeeacly developed techniques of dose of asbestos, the age of the patient, and the transmission electron microscopy, selective length of time after initial axposure to us- uea electron diffraction, ud microchemical bestos.'*"-0"' This is timber confirmed by a analysis of particles, muy small subralcro- fairly strong eorralation between pieural saopic asbestos fibers in pieural plaques have plaques found on postmortem studies1* ud a been identified unequivocally by morphologic, history of previous axposure to commercial structural, ud chemical studies.1*3* It is of types cf asbestos.1**' Ail varieties of asbestos intsrest that these art more ooneuuated in the calcified tones than in the fibrous tones.1* As bestos fibtrs are also commonly observed in the lung tissues of patients with plaques/ " l NtaMat Sargwu. MJ}u fnfamr af AatUetarr. LAC-VSC Vtdkti Codttr. lot A/tfdtx. Call/. Goon* ImSms. M.O.- frdfaaaar af 1ladi^+fy, LaC-tlSC Vadfcaf Cantor. La* Aityaltt. Call/ lay S. CorOeasee. M.D.: Atilttnt frofitter af Kadiatagy, LAC-CSC Midled Cast. Cat Astftiu. Call/ Aattrau 'anna timid ia addrauad is ftktaim Sartata. HJ-. lot ifT. Dtpamaau af AadSolofy. LaCCSC Xidled Conor. 1109 M. Stdta Strata. Car Aiofiia. Calif. 900S3. S1977 if Grama A Strata*, hat. ISSX OOST-mX. Inhaled fibers longer than those that can be phagocytosed by histiocytes or glut cdls move downwtrd and outward in the lungs. Thu type of gravitational movement (so unusual in other pneumoconioses) is influenced by the comet* denes of three variables: the presence of tain, sharp asbestos fibers; the soft, easily punctured pulmonary structure; ud the constant mouoa of the lung." Smwi at daatttfamar. Vat. XB. Ha. a iOc-owi. 1 ST? 1ST DUP 0937361 DU 038332 najHAL HAcuts :js DUP 0937362 rtj. x >wii< twft At w*a-4*vlee*e Meant *W iMh Mweat WW| tonneel imw. Hm mr* rnn^ht lewewet tlteen toe itka, tore era eteone era teen to W*i. mm HOI# (in mmtrmt neeele, Tteenra it fra hwim mrnm mt mftrltttr It rnitmu itrttmtitr m era riftra teeefeef mat immtta* Mtmm Mitt mt mrmut *i era t*t h>-- K *> * -- WMI Sonedcifitd Pteurot Plaqua Nbncalrified hyalmixed pleural plaques arc not visualized radiographically until the Obroua tissues suiBrieatiy thick: thus they often jo un detected. and thdr prevalence during life is uadcrataaaied. Only s small percentage of early plaquee identified at postmortem ccaminatioq have been detected on routine PA ra diographs/ In this projectioti a weil-deveioped pleural plaque results ia either a projUt presentation or an ct fact presentation. The piaque in profile appears as a sharply marginated white band of water density, roughly paralleling the inner margin of the lateral thoracic wall. It ia usually not obscured by the overtying scapular shadow (Fig. 2). The very early plaque will show only a thin white line of increased density adjacent to the rib that has been likened to a flange.1 Thus me profile line of early plaque formation is easily overlooked and often detected only in retro spect (Pig. 3% particularly when it resembles the normal inner rib surface. As it enlarges, it becomes somewhat oval and moderately protuberant, with tapering superior and inferior margins typical of an extrapleural lesion (Pig. 4). A plaque rarely extends vertically more than DU 038333 njujui *>aua ;*i 9 t^ f6 0 dOQ *%. S. *um suuv <bt<* nMi f iuf*i As t*r # It) fttyit iau *iw. T> v tO t4#t **# v*m nmm is Knmhfmu*cknlTr>a*rnsMwtirwci-wri w_k*ttmWfMallN^<*m/s.m.#9As1.tftAtM)WnPaMrV*tvMdtm*a<lM.|*TUl!HmaartiiW^inatKtMMvw4i1iiimMflmNmwA--*9tv<*4*I(MM(aM*t<tf*ttf {IsfTr(rsVtwuMnvIjt.. DU 038334 muRAk wjuaua greater or lesser extent, deposition of fat. The sharp medial margin of the shadow is best seen when the x-ray beta in tangential to the surface of the tissues causing this shadow. This normal pleural shadow increases in width as ic is traced superiorly toward the first rib: it usually tapers rapidly inferiorly, becoming imperceptible below the level of the 4th intercostal space. In the PA projection the thickness of the shadow is never greater than 3 mm; however, in the oblique projection this normal pleural shadow is wider. varying from 0 to 10 mm in the men and somewhat less in women.* Occasionally, a very thin, barely perceptible line may be seen medial to the lower half of tha lateral thoracic wall: l mm has arbitrarily been designated as the maximum acceptable thickness of this normal pleural shadow below the level of the 4th inter costal interspace. The costal slips of origin of the sermus an terior and external abdominal oblique muscles have a characteristic radiographic pattern: a rhythmic sequence of shadows between suc cessive intercostal spaces (Fig. i\ They are most commonly visible over the 3th rib, but the 7 th rib is siso affected, and occasionally all of the ribs from the 3th to the 9th are involved. They appear as one or two distinct triangular shadows or a combination of two opatitiea su perimposed. They should not be mistaken for multifocal plaques, which may also show a series of shadows. Multiple plaques are more likely to differ from each ocher in sixe and shape, unlike muscle shadows, which are usually more uniform in siza. Tha muscle shadow usually has one sharply defined border and elsewhere fades into the surrounding soft tissues. A slightly oblique projection will often resolve this difficult problem. A plaque that is well defined in profile becomes 31 defined when rotated to an m fact position. Additional plaques art oft seen on the routed film. Plaques may become more distinct as rotation moves the overlying muscle shadows, whereas muscle shadows will alter their shape or disap pear. Pleural thickening should not be confused with extrapleural deposits of fat. The ooiiqus view is again helpful, the fat producing x wavy margin most prominent on the posterolateral surface of rise ribs, usually sparing the anterior and paravertebral areas." Tomography may be : ! Mfi MHwi iNSi Mm 94 Miffifiii mwifig mifiyi mmmtm <**. Thwm feflrani nwiwfifi >lww< Th mm4Uk marfana hdpful in revealing fst density in contrast to the water density of pleural thickening. Cdeified Pleurd Plaques Pleural calcification usually occurs ZO years or more following exposure to asbestos, t he in cidence increases with the umc interval." The exposure to asbestos does not have to be prolonged: it can be on the order of only a few weeks or months, depending on die concentra tion of the dust. However, calcification in pleural plaques is a relatively uncommon ra diographic finding. It is much more common histologically, occurring in approximately 37% of plaques.11 Radiographically demonstraoie evidence of intcrsuual pulmonary disease nas been reported in only one-third of patients with pleural olaoue calcification, but conversely more thin 30% of patients with extensive DUP 0937364 DU 038335 fliL ib O DU 038336 UJJftAi. n>OJB S|H ( Ml lecupennaaf mdamie tathophylliifubtstoiis. A.cts RadU ISopptf (Siocihl l9*:l-7. 1940 10. igriwi lb Heard planum tad uOoaiat; Further otemvntiodd M mdauie ud other ooooccupauoaai as* baauaep. Aaa NY AeadSd l32d235-239.1963 11. Kreai L Compotarind taasofnpfcy uirnf thd E.M.I. ttard purpose scaaacr. Sr J Radioi SO*- 1977 IX Uaptaad* JH. WaUaaa WPM. Siapeoo MJ: Undodaa wnrkei ia Belfast. Mobidity of stdl u sort Sr J tnd Mad 3:217-125. in 13. La Sceffsai L, Mania JC. Ontif S. at tis Stmetara tad asmpoaiooe of piauni picquat, ia Bote-iio ?. GJioa JC Tinbrail V at ai (adsk Stoleped Effaeu at Aakenae. Proeeedinp at i Workiaf Caaftraaaa. [ataraatioaai A|aoey for Raaedreh oa Caaaar (19723. Lyon. Franc*. CARC Sctouuiu PubtScsuci I. 1977, pp 2*0-237 Id. Mattaoa SX Wntst T: Mourd pUpum tad * potut to ubaatoa. A riiiria-ni material front a Swetiak luap diaicScaodJ Rdpir Ota (Sappil 73:1--at. 1970 13. Maarmaa U Ashauea bodias aad ptaarai piaquae at a Finnish sartaa of tutopay cam. Acta Pathol Mkrooioi Scsad(SupptlSHt9M Id. Ochs CW. Smith !t`. CSrotk pionrd thtokmap: Soma obtaratdaat oa causa add pithoponests. MJit Mad |dt:77-ll. t7* 17. Raooy X Moakowia M: Sdorodorma. piaarai citaSaawa aad raaseatom call sarooota of the loop. Qmt 40J7I-J73. 1971 dir It. Rattiter CE. Bristol U. Ctruer ?H. et si: R> dioprtpkic ctaapa a ehryaocie tshmtos aaa ud atil orders of Qurtoe. Ards Eariroa Halid 24:>|-iC0. 1971 19. Rout V, Snidery J: Aauotopjr of piaurai piaqaae. Thors* 23*79-04.1970 20. Sariaot SN. Jteobaoe G, Gcrdoasoa J: The tipsuflcaeca at baUiarai piaarai ttoderstop la Use diapsotts of tsbeatstit. (ia praat) 21. Soiacsu FD. Siatty S. Narad S: Muitipit piaarai aoduiac. Qatt39:d73-47d, 197 ( 2X Sdikoff U: Tho oesarraast of piaarai calafieatiefl uioap uiattai atuiauoa workers. Aaa NY Acad Scs 13X331-147, 1943 2X Sdiaf U: Psraoed aomasunieaiiots. 24. Shears X Templeton AX Sleets of assesus its dock* yard worears. X Modi 3:574.579, 19dl 25. Thompson JC: The pnibopeneda of pleural pi aquae, ia Shapiro, Ha (edk Proetodtop of tlso lateaationsi Corfarmca of Hseuatoasaiotia. Jokaumbtrp, Sooth Atrip (1909V Capo Town. Oxford Uttrrarjicy Proas. 1970. pp 7M74 it. VlOtari M: Ultrasound examination of pleural plaques. Acta Rsdili (Suppi 3QI| 1970. pp 1-42 27. Via Va: Sktrapicnrai coital fat. Rsdiolofy If 2^43-545.1974 3. Zoic* C. Snriko* T. labadiav L: Plmrd ubectsais a aprseslturd workart. farina Raa 1:2X7-292.1947 DUP 0937366 DU 038337