Document MMDY5rL3aGejZDXYJ6gXxrQLx

Radiographic and Physiologic Patterns Among Workers Engaged in Manufacture of Asbestos Cement Products A Preliminary Report Hans Weill, M.D.; Carmel Waggenspack, M.S.; William Bailey, M.D.; Mor ton Ziskind, M.D.; and Charles Rossiter, M.A. Although two-thirds of all asbestos fiber imported into this country is used in the manufacture of asbestos cement products, little information is available concerning health effects associated with asbestos exposure in this industry. Asbestos cement products which contain asbestos fiber, free silica and cement include shingle, pipe, roofing and siding. Although chrysotile is the primary type ot fiber utilized in this industry, several products contain small amounts of crocidolite because of its strength and resistance to acid corrosion. Methods An investigation of health effects associated with dust exposure in this in dustry was begun in November. 1969, with a study of currently emploved and retired workers of two plants in the New Orleans Area. Over 9S% of actively em ployed workers participated. Although shortly after the study began, a major work reduction occurred at one plant, 70% of the 184 employees laid off prior to their participation in this study were recruited. Of the retired workers residing in the New Orleans vicinity, 50% could be contacted and were able and willing to participate, A total of 908 workers From Tulane University School ol Medicine. New Orleans. La. (Dr Weill, Miss Waggenspack, Or Bailey and Dr Ziskind). MRC Pneumoconiosis Uni(, Penarth. South Wales. U K (Mr Rossiter) Presented at Second Skvtop Conference on Respiratory Diseases in Industry, Skylop Lodge, Skvtop, Pa.. Mas 17-19. 1973 Reprint requests to Professot ot Medicine. Dept of Medicine, Pulmonary Diseases Section, Tulane University School ot Medicine, New Orieans, La (Dr Weill), were studied. 871 men and 37 women. Their mean age was 36 years and they had been m the industry up to 40 years, the mean period ot exposure being 17 3 years Workers were given time off bv the companies and spent one-half dav in the laboratory where a respiratory and oc cupational questionnaire was ad ministered by a trained interviewer PA and both oblique chest <-rav films were obtained and a brief physical examination performed Studies of pulmonary function included spirometry to determine maximum expiratory flow rates, total lung volume and its com partments using helium equilibration, gas transfer utilizing the single breath carbon monoxide pulmonary diffusing capacity, and gas exchange during light and moderate levels of exercise, with determination of total ventilation and ventilatory equivalent for oxygen. Com plete plant records were made available and each worker's |ob history svas ab stracted. Exposure assessments were based on dust measurements provided by company industrial hygienists, the State Health Department, and the U S. Public Health Service. An estimate was made of dust level in million particles per cubic foot at each |ob site for each year. Improvements in dust suppression were reflected in decreased estimates. The constitution of the dust in terms of chrysotile, crocidolite and silica contents was also assessed. For each man, five ex posure indices were calculated from his detailed industrial history. These were total time employed, total dust exposure, the total of all exposure levels multiplied bv the corresponding periods posure: total chrysotile exp calculated as tor total dust but chrvsotile' proportion only crocidolite; and total silica expo* Chest x-rav films were read us nexv UICC Cincinnati Interna Classification tor the Pneumoco These films haxe been read by or expert member of the committee developed the classification Fil 69 nonindustriallv exposed indr matched as closely as possible ti and age were interspersed amo films of exposed workers Thes> were not identifiable as controls reader. Working Environment Because or the importance ot working environment to bi response, the manufacture of a cement products Mill be debnefly. Bags of asbestos fiber pacompressed form are delivered t car and stored in the plant. Althoi provements in packaging hast made, bags occasionally tear yv, sequent dust emission The t asbestos are opened, the block broken up and, finally, the com charged with the material 1 fibers are "opened" by mean blower and cyclone and. m t process, fibers are then discharge beater and mixed into the cemer Silica enters a dry mix bv y\. shaker and reground scrap is srot it also enters the new mix artebeen dumped by wheelbarroyy hopper after which it enters th 248 j BB 0015790 | -U ftV ? and is h endec to the slurry 7ne slurry h molded and ?ohd parhcles collected on 3 sc-een. w-vcn >s 'hen transferred to j felt where the stock accumulates on a 'oiler Atter a -eoes ot manefers. a wet I sheet i' ;rmed Cutting c the wet sheet 7 lr <*1 d' "Vi "~4'r- 7* - -Ot a^'O' f# ,-- ' ^ -* ; ' 'VtjC'.O' ,,j- . -ized sheets are 'hen cured tor a vee\ and. after the sheet is considerable PROFUSION Total Dust Exposure (MILLION PARTICLES PER CUBIC FOOT - MONTHS) dner, it enters the punch press tor more tvec'se sizing and introduction or nail 250 251-500 501-1X0 1001-2000 2001*4000 4001 4- -oies >nto the -htnele Energy applied to this relatively drv product during the % and % 98 94 97 93 88 77 operation is associated with dust Cut ting ot iVfuaated -hivting aUo results m tne dust oroduction Final curing is per- /i 25 1 44 9 tormed in large autoclaves Important dust exposures occur either early in the process where the nber is unpacked, the y0 Z\ and h 0 1 21 4 '8 conveyor 'oaded and nber discharged into the bea'er, and late- w hen the dry product is sawed or punched for sizing */.+ 00 02 4 6 to commercial specifications. Results With this mixed dust exposure to (161) (67) (105) (122) (209) (231) fif l. -- Kitts {%) of tmill round* opieibts for total dust citeform. asbestos and s iica rad'ographic patterns have included small rounded as well as irregular or linear opacit'es The new radiograDhic classification separates the type or small ooacity into rounded or irregular and is. therefore, suitable to characterize patterns encountered in this small opacities are combined, the prevalence ot anv diffuse parenchymal change can be related to total exposure fFig 3) Since these changes result from both asbestos and silica exposure, an attempt was made to determine it predominant type ot exposure influences radiographic pattern A clear association between ex pected silica exposure and rounded opacities ot irregular opacities and a-t>estos exposure was not seen (Fig 4). industry _ Prolusion or these small opacities is graded bv 12 categories tanging from 0 - to 3 4. Preliminary analysis ot the type and Total Dust Exposure prolusion ot d'ttuse opacities in relation to dust exposure reveals that higher cumulative exposures are associated with higher rates of bofh tvpes of o- PROFUSION (MILLION 03mCLS PER CUBIC FOOT -- MONTHS) - -Si 5 250 251-500 501-1000 1001-2000 2001-4000 4001+ pacittes ;n this industry' For small round ed opacities, definite radiographic % and % 97 97 96 89 82 82 changes, ot 2,1 category or above, begin to appear arter cumulative exposure or 1,000 million particles per cubic toot- /i 2 2 3 7 II 9 months iFtg 1| There is an increase in rales ot abnormal radiographic patterns as this evposure rises. Except for rw o in- %, >5and)fc 0 O 1 2 25 dividuals m low dust exposure categories read as having category 2 ,regular opaeties. a similar pattern is 2/ + 1 1 0 2 5 4 "sn for this tvoe of radiographic change (fig 2) One ot these workers had bilateral basilar pneumonia with ap (161) (67) (105) (122) (209) (231) ------------------------------------------------------ --- propriate wmntoms and there might be differences ot opinion regarding the 7~ 8B~001579*? profusion cla-Mtication in the other, however, ihev were lert in the nrorusion category designated on the nrst reading, finallv, when -ounded and irregular Journal of Occupational Medicine-Vol. 15. No. 3/March 1973 249 perhaps because the range or exposures to these hvo materials ssas limited in these plants. Increasing profusion ot rounded opacitie1 svas associated with increasing total dust, silica and asbestos exposure, this pattern being better related to dust exposure than were irregular opacities. Although it is difficult in an\ stud* of this type to separate clearly \ears ot exposure from total dust exposure, it can be seen that the presence ot diffuse changes on the chest x-ray correlated better with toal exposure than simplv with sears m the industry . Analyses to date have not considered size of either 'vpe ot opacity. Readings ot the 69 control x-ravs included 66 with a 00 category and three svith a 0'1 category. Anticipating that those individuals svith small rounded opacities might hase dinerent pulmonary function patterns than those svith irregular opacities, mean values for lung volumes, gas transfer and expiratory flow rates are expressed in percent of predicted where indicated and compared in groups with irregular opacities, rounded opacities, and negative chest films. Although emphasis will be placed on groups exhibiting ' definite- or category 2 changes mean salues in category 1 prolusion are also plotted. In the category 2 groups, total lung capacity and vital capacity differ significantly from the 0 group; mean salues for both these volumes are con* siderably lower in the group svith irregular opacities than in the group with rounded change (Fig 5). Residual solume was significantly higher in the rounded group than in the irregular group with residual volume to total lung capacity ratio differing m the same direc tion but not reaching statistical significance. The category 2 rounded opacity group had a mean RVITIC which differed significantly from the 0 group. Pulmonary diffusing capacity m both groups with category 2 opacities was significantly Iosver than in the group svith no radiographic changes (Fig 6) and mean D: was considerably lower in the irregular group than in the rounded. This difference was not statistically significant. Alveolar volume was lower m those with irregular opacities while diffusion constant (K) was lower in the rounded group. In neither case was this difference between groups statistically significant. K m the rounded group, and alveolar volume in the irregular group, 250 MAXIMUM PROFUSION Total Dust Exposure (MILLION PAfmcUES PER CUBIC FOOT - MONTHS) < Z30 251 -500 501-1000 KW-20C3 2301-4000 CGI %ond % 95 93 94 81 70 6( 7, 4 6 4 II 16 17 Vo 'A ond Vz O 0 2 3 6 13 *A + 1 1 0 5 8 1C (161) (67) (105) (122) (209) (231 H| 3. -- Bite* (%) q1 round** or irrtfular small opacities ter. tetit dust cateform. (22) ((6)000) (27) (23) Fi| 4. -- Ritfiainphic chanjei and upaiuri. I BB 0015792 1 Radiographic and Physiologic Patterns and Asbestos Cement Products Weill z-% ftSKTED TU N (BOD) BO- (15) Cl) (28) (23) VC ir * RV IR -2- no+ * -1- too- -O- 90- -2* -0- -f* -K -2- + 80- -2- 70-1 ** -2-2- + i * '2" Sj AM tax* *0* iM ! t *2` SiQdrft frt "t at sx, noFUSION 0*0/-,0/0,0/1 I* I/O, 1/1, t/2 2 2/1 or mor* Fit 5. -- Lm| mInhim. % PREDICTED (800) 0-15! (21) (27) (23) wo- -O- -F- -I- I ft i --i I# *0-- *, 130 120 90- -2- -2110 RV/71X % IR 40- -235- -1- -2*1- 30- -0- TYPE ot SMALL OPACITIES I IrrA^iAa- only N * PounOArf Ml/ * LITE'S 5.0- va i ft O-I-2- 4.5- -f* -2- 4.0- pleural ettect on lung volumes is sltghtlv greater in those with category 2 irregular changes than in the same profusion group with rounded opacities Pulmonary diffusing capacity' is reduced bv the presence or pleural changes in the rounded opacitv group, unchanged m those with category 2 irregular cnanges and oaradox/cailv increased m me tew subtects with irregular category 1 changes In summarizing this pan or the analysis it aopears that indiv-duals \%.n moderately advanced profusion o* irregular opacities tend to have 'ewe' lung volumes and pulmonary dihus-ne capacity than those with rounded opacities Hvperintlation is associated with rounded nodular changes but sptromemc flow rate measurements which are generally artected bv lung volume changes, do not separate rhe groups These associations fo- i uns volume reduction changes m pulmr narv dirtusing capacity and hype inflation are consistent witn'the hyp hesis tfat the small rounded opa > s are j manly je to silica ex pose, vvhile ir -gular o iacities md'cate predominant , 'lestos ect A- > an ticipated additional ventilatory distur bance associated with silica exposure was not detected in tnese individuals, perhaps because ot the high prevalence of always disease in a smoking popu.ation and the recently demon strated changes in small airways or in dividuals exposed to asbestos dust 80- 2- - ? 70- ** ** Hoo * 90 153.0- * * a2"Si9.diff' *0* ot.05 ** *2* Si* diff '0* at 0 PROFUSION 0 0/-. 0/0, (VI 1 - I/O, I/I, 1/2 2 2/1 + Fit L -- Cat toiMtw. TYPE erf SMALL OPACITIES I > Irroqulor only H > Roundd only did direr vignmcantlv irom this mean function is displayed tor the same groups i value in the normal x-rav group FE\ . with and without parenchymal changes FEF^.v and FE\ \C were significantly (Fig 8). In the irregular and rounded lower in the two groups with definite opacity groups, turther reduction of vital -tf- 1/ radiographic changes than in the normal capacity, torced expiratory volume and ^rav grouo (Fig ~) None of the ex- residual volume is observed in the Prraton. flow rates, however. separated presence or radiographically apparent the irregular trom the rounded opacity- pleural change This ettect tor vital group The additional errect of pleural capacity and FEV is also present in f changes on selected parameters or lung those without parenchvmal changes The $ Journal of Occupational Medicine/Vol. 15, No. 3/March 1973 | BB 0015793 Comments "" r the first phase of this investigation we were concerned with radiographic and physiologic evidence of dittuse pulmonary change due to dust exposure in the manufacture of asbestos cement products These changes were related to indices ot exposure but our data allow conclusions only concerning morbidity In the next phase, information on mor tality. particularly in relation to car- cinogenesiv will be obtained. We have been describing biologic changes related to exposures beginning 20 or 30 years ago tor most workers who demonstrate disease at this time These exposures were much higher prior to the in troduction or modern dust control methods One can conclude tentatively that there is a cumulative level ot ex- J 251 posure in this mdusrrv at nbrogenic ertects associated with dusts are unlikelv to occur Perha level will have been reached whm i< universal conrarmance to the > establish'd T1A oi i tih-rs r*'r " ficient Mmultdneou' imivii'i .n count air sampling data a'e n* e av, to allow tor reliable comer' or total dust expressed in 01111100 no per cubic toot to ebe's per ml 8athe limited available information . servative conversion ratio might tibers per ml 'or one MPPCF The limit ot our third dust categ equivalent to somewhat more MPPCF tor a working iee;:me vears. This would comomr wt recent emergencv TLC ot 5 nbAgam. this ri'lafes to the r developing pm-umui omnsi > provides no information concern:r excess risk of neoplasm. FmalK appear to be dirferences m pain function patterns between groups small irregular and small ro opacities. Although we have not able to distinguish between cons xposures of asbestos and silica jroups. the phvsiologic patterns that rounded nodules seen on c` rays mav represent a predominan effect while irregular or linear c1 are associated with an asbestos en this time, reasons whv individuals industry with seemingly simil. posures develop such dn radiographic and phvsiologic p are not clear I'QfTl ffW irMlfjf- cuoat.or'** EovironT,e"43. Hea rn or t-- Asbestos Mining Assocaron and Grant 0583^*05 MH, Setnesoa. Md J_BB 0015794 | 252 Radiographic and Physiologic Patterns and Asbestos Cement Products.TA