Silicosis Appears Inevitable Among Former Denim Sandblasters A 4-Year Follow-up Study

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1 [ Originl Reserch Occuptionl nd Environmentl Lung Diseses ] Silicosis Appers Inevitble Among Former Denim Sndblsters A 4-Yer Follow-up Study Metin Akgun, MD, FCCP ; Omer Arz, MD ; Elif Yilmzel Ucr, MD ; Adem Krmn, MD ; Ftih Alper, MD, PhD ; Metin Gorguner, MD ; nd Kthleen Kreiss, MD BACKGROUND: The course of denim sndblsting silicosis is unknown. We imed to reevlute former sndblsters studied in 2007 for incident silicosis, rdiogrphic progression, pulmonry function loss, nd mortlity nd to exmine ny ssocitions between these outcomes nd previously demonstrted risk fctors for silicosis. METHODS: We defined silicosis on chest rdiogrph s ctegory 1/0 smll opcity profusion using the Interntionl Lbor Orgniztion clssifiction. We defined rdiogrphic progression s profusion increse of two or more subctegories, development of new lrge opcity, or n increse in lrge opcity ctegory. We defined pulmonry function loss s 12% decrese in FVC. RESULTS: Among the 145 former sndblsters studied in 2007, 83 were ressessed in In the 4-yer follow-up period, nine (6.2%) hd died t men ge of 24 yers. Of the 74 living sndblsters vilble for reexmintion, the prevlence of silicosis incresed from 55.4% to 95.9%. Rdiogrphic progression, observed in 82%, ws ssocited with younger ge, never smoking, foremn work, nd sleeping t the workplce. Pulmonry function loss, seen in 66%, ws positively ssocited with never smoking nd higher initil FVC % predicted. Deth ws ssocited with never smoking, foremn work, number of different denim-sndblsting plces of work, sleeping t the workplce, nd lower pulmonry function, of which only the number of different plces worked remined in multivrite nlyses. CONCLUSIONS: Th is 4-yer follow-up suggests tht lmost ll former denim sndblsters my develop silicosis, despite short exposures nd ltency. CHEST 2015; 148 ( 3 ): Mnuscript received November 14, 2014; revision ccepted Jnury 15, 2015; originlly published Online First Februry 5, ABBREVIATIONS: ILO 5 Interntionl Lbor Orgniztion AFFILIATIONS: Deprtment of Pulmonry Medicine (Drs Akgun, Arz, Ucr, nd Gorguner) nd Deprtment of Rdiology (Drs Krmn nd Alper), Attürk University, Fculty of Medicine, Erzurum, Turkey; nd Division of Respirtory Disese Studies (Dr Kreiss), Ntionl Institute for Occuptionl Sfety nd Helth, Morgntown, WV. This study ws presented in bstrct form (Akgun M, Arz O, Ucr EY, Krmn A, Alper F, Gorguner M. Am J Respir Crit Cre Med. 2014;189:A3171). FUNDING/SUPPORT : The uthors hve reported to CHEST tht no funding ws received for this study. CORRESPONDENCE TO: Metin Akgun, MD, FCCP, Deprtment of Pulmonry Medicine, Attürk University, Erzurum, Turkey; e-mil: kgunm@gmil.com 2015 AMERICAN COLLEGE OF CHEST PHYSICIANS. Reproduction of this rticle is prohibited without written permission from the Americn College of Chest Physicins. See online for more detils. DOI: /chest journl.publictions.chestnet.org 647

2 Denim-jen sndblsting is recognized cuse of silicosis, nd mny cses, some with ftl outcomes, hve been reported from different centers in Turkey. 1-7 Our previous work demonstrted tht mong former denim sndblsters who were exposed to silic for t lest 1 month nd who hd ltency period of t lest 10 months, 77 of 145 subjects (53%) hd silicosis in 2007, 6 bsed on the Interntionl Lbor Orgniztion (ILO) clssifiction of rdiogrphs of pneumoconioses. 8 In the current study, our primry im ws to reevlute these former sndblsters who hd terminted occuptionl exposure to silic dust prior to 2007, to determine whether the number of cses meeting dignostic criteri for silicosis hd incresed in the bsence of continued exposure. Second, we imed to investigte other helth outcomes (rdiogrphic progression, pulmonry function loss, nd mortlity) mong the subjects nd to exmine FOR EDITORIAL COMMENT SEE PAGE 574 ssocitions between these helth outcomes nd risk fctors tht hd been individully ssocited with silicosis in the erlier cross-sectionl study, 6 including exposure durtion, foremn sttus t work ( mrker of higher exposure thn pprentices), nd number of denim-sndblsting workplces in which they worked. Mterils nd Methods Study Popultion The source popultion of this study consisted of the 145 former denim sndblsters who hd interpretble chest rdiogrphs nd spirometry tests when studied in In 2011, temporry ntionl lw in Turkey gve right to compenstion to ll uninsured ptients with silicosis. Thus, we invited ll the denim sndblsters in our source popultion, regrdless of prior silicosis dignosis, to our tertiry-cre university hospitl to prticipte in our follow-up study. We offered ssistnce in prepring n officil ppliction for compenstion. For the nonrespondents to our follow-up, we scertined vitl sttus with our hospitl records nd the online Deth Declrtion System of the Turkish Helth Ministry. We included those who died between 2007 nd 2011 in this study. All living prticipnts gve their written informed consent, nd the locl ethics committee pproved the study protocol (registrtion number 2011/37). Study Procedures For bseline evlution, we used the findings of the 2007 study. 6 I n 2011 medicl interview, we confirmed tht ll prticipnts being reevluted hd no further exposure to silic dust. The sme technicin conducted pulmonry function tests in 2007 nd 2011 using the sme computerized spirometer (Vmx22; SensorMedics Corp), 6 recording the best FEV 1, FVC, nd FEV 1 /FVC rtio mong three cceptble efforts. We clculted FEV 1 % predicted nd FVC for ge, sex, nd height. 9 Stndrd posteronterior chest rdiogrphs of ll living prticipnts were tken t mximl inspirtion nd evluted ccording to the ILO clssifiction. 8 Three experts independently evluted 2011 chest rdiogrphs, blinded to the 2007 ILO reding nd clinicl dt of the prticipnts. Any disgreement ws resolved by consensus. Smll-opcity profusion ws clssified into four min ctegories (0 to 3) nd 12 subctegories, nd the ILO ctegories nd subctegories were used s indices of disese severity. We defined silicosis on chest rdiogrph s profusion of smll pneumoconiotic opcities of ILO ctegory 1/0 or higher. 8 We defined rdiogrphic progression s (1) n increse in smll-opcity profusion of two or more subctegories (ie, from 0/0 to 1/0 or from 1/2 to 2/2), or (2) the ppernce of one or more new lrge opcities (A, B, C), or (3) n increse in lrge-opcity ctegory (from A to B or from B to C). 8 Pulmonry function loss ws defined s 12% decrese in FVC, with guidnce from longitudinl interstitil lung disese reserch, 10,11 between 2007 nd All deths were ttributed to silicosis or relted complictions. Sttisticl Anlysis We used SPSS Sttistics softwre, version 20 for Mc (IBM Corportion), for sttisticl nlyses. The Person x 2 test nd the Mnn-Whitney U test were used to compre ctegoricl nd numeric vlues, respectively. We used binry logistic regression to test for ssocitions with predetermined risk fctors. A P vlue,.05 ws considered sttisticlly significnt. Results Of the 145 denim sndblsters studied in 2007, the follow-up study included 83 men (57.2%), of whom 74 hd both interpretble chest rdiogrphs nd vlid spirometry in 2011 nd nine (6.2%) hd died ( Fig 1 ). In comprison with the nonprticipnts in 2011, the study group hd less history of working s foremn, history of sleeping t the sndblsting work plces, nd smoking pck-yers ( Tble 1 ). Nonprticipnts nd prticipnts hd similr pulmonry function in 2007, but living prticipnts tended to hve more smll nd lrge pneumoconiotic opcities on their 2007 chest rdiogrph ( Tble 2 ). The men ge ( SD) of living prticipnts ws 27 6 yers in The men ge t deth of the nine who hd died during the follow-up period ws 24 yers (rnge, yers). The proportion of living prticipnts with silicosis incresed from 55.4% to 95.9%. Rdiogrphic progression nd 12% pulmonry function loss were observed in 82% (n 5 61) nd 66% (n 5 49) of prticipnts, respectively. Between 2007 nd 2011, both the smll-opcity profusion nd the presence of lrge opcities incresed significntly. Three exmples of rdiogrphic progression re shown in Figure 2. ILO clssifictions in 2007 nd 2011 re shown in Figure 3 for ech prticipnt. Tble 2 presents the 2007 clssifiction results for nonprticipnts, those who hd died, nd living prticipnts, long with 2011 clssifiction results for living prticipnts. Eight of nine 648 Originl Reserch [ 148 # 3 CHEST SEPTEMBER 2015 ]

3 Figure 1 Flowchrt. The 83 former sndblsters reported in the current study included 74 living prticipnts who hd new chest rdiogrphs nd pulmonry function tests in 2011 nd nine who were decesed. decedents (88.9%) hd severe ILO ctegory 3 disese in 2007, significntly higher thn both nonprticipnts ( P,.001) nd living prticipnts ( P,.001). Decedents were lso more likely to hve hd lrge opcities in 2007 compred with those who were restudied in 2011 (44.4% vs 10.8%, P,.01), s well s nonprticipnts (44.4% vs 3.2%, P,.001). Dt on FVC % predicted in 2007, long with the chnge mesured in 2011 for the living prticipnts, re shown TABLE 1 ] Chrcteristics in 2007 of Denim Sndblsters by Nonprticipnts nd Those Whose Vitl Sttus nd Medicl Tests Were Ressessed in 2011 Chrcteristics in 2007 Nonprticipnts (n 5 62) Ressessed in 2011 (n 5 83) Age t first dmission, y First exposure ge, y Ever smoker 46 (74) 58 (70) Smoking, pck-y Exposure durtion, mo Time since first exposure, mo Working s foremn 57 (92) 58 (70) Months s foremn Plces of work, No Sndblsting devices, No Sleeping t workplce 57 (92) 51 (61) FVC, L FVC, % predicted FEV 1, L FEV 1, % predicted FEV 1 /FVC % Dt presented s men SD or No. (%) unless otherwise stted. P,.05. by prticipnt in Figure 4. All but eight prticipnts hd decrese in FVC % predicted (89%), nd the men chnge in FVC % predicted for the 74 ws , with rnge of % to 21.0% predicted. For FEV 1, ll but six hd decrese in FEV 1 % predicted, nd the men chnge in FEV 1 % predicted ws , with rnge of % to 25.2%. For living prticipnts, the men FEV 1 % predicted ( SD) ws 100.3% 22.1 in 2007 nd 74.9% 24.4 in The comprble men vlues for FVC % predicted ( SD) were 98.7% 20.6 in 2007 nd 79.0% 20.7 in Comprison of 2007 chrcteristics of the prticipnts by rdiogrphic progression, 12% loss of pulmonry function, nd deth is shown in Tble 3. In multivrite nlyses, the only sttisticlly significnt reltion we found for ny of the helth outcomes nd for the predetermined risk fctors for silicosis found cross sectionlly in our 2007 study ws between mortlity nd number of sndblsting plces of work (OR, 3.16; 95% CI, ). The other predetermined risk fctors exposure durtion nd foremn work sttus did not enter multivrite models for ny of the helth outcomes. Discussion The most importnt findings of our study were the high incidence of silicosis nd progression of silicosis without further exposure to silic dust mong the former denim sndblsters. The silicosis prevlence rte for the 83 subjects with follow-up testing or vitl sttus determintion in 2011 incresed from 60.2% (n 5 50) to 96.4% (n 5 80) in 4-yer period, fter men occuptionl exposure of, 3.5 yers nd men ltency since first exposure within 11 yers. Of those who did not die of silicosis, most hd two-subctegory rdiogrphic progression (82%) or pulmonry function loss 12% in the FVC (66%). In fct, of the 74 surviving prticipnts, only one hd neither ny progression of rdiologic bnormlity nor ny pulmonry function loss. Our study is unique in describing the rdiogrphic course of silicosis in denim sndblsters nd hving 4-yer follow-up period. The only other follow-up study of denim sndblsters, t 29 (SD, 20 months), showed ll pulmonry function test nd % predicted vlues declined in cute nd ccelerted silicosis nd only diffusing cpcity of the lung to crbon monoxide declined in chronic silicosis cses. 12 Our findings extend wht is known bout pneumoconiosis rdiogrphic progression nd pulmonry functions over time without further exposure nd bout impirment of lung function with rdiogrphic progression Although we hd dignosed journl.publictions.chestnet.org 649

4 TABLE 2 ] Chest Rdiogrph ILO Ctegoriztion by Nonprticipnts, Decedents, nd Prticipnts by Yer of Exmintion ILO Ctegory Nonprticipnts b (n 5 62) Decedents c (n 5 9) Prticipnts (n 5 74) Yer of dt Ctegory 0 35 (56.5) 33 (44.6) 3 (4.1) 0/ / / Ctegory 1 14 (22.6) 1 (11.1) 20 (27.0) 24 (32.4) 1/ / / Ctegory 2 8 (12.9) 8 (10.8) 22 (29.7) 2/ / / Ctegory 3 5 (8.1) 8 (88.9) 13 (17.6) 25 (33.8) 3/ / / Lrge opcities 2 (3.2) 4 (44.4) 8 (10.8) 18 (24.3) Type A Type B Type C Overll ctegory dt given s No. (%); subctegory dt given s No. ILO 5 Interntionl Lbor Orgniztion. The smll-opcity profusion ctegory nd the presence of lrge opcities were both sttisticlly significntly different between decedents nd both prticipnts ( P,.01) nd nonprticipnts ( P,.001) nd within prticipnts studied in 2007 ( P,.001) nd reevluted in 2011 ( P,.001). b Prticipnts from the 2007 study who were not included in the 2011 follow-up. Dt listed from these prticipnts re from the 2007 study. These prticipnts were not included in the follow-up becuse they hd no new chest rdiogrph or pulmonry function test to evlute. c Prticipnts from the 2007 study who were decesed t the time of the 2011 follow-up. some ptients with cute silicosis mong the former denim sndblsters in the pst, they died before the 2007 study 3,6 ; thus, this study only includes cses with ccelerted silicosis. In univrite nlyses, we determined tht younger ge nd younger ge t first silic exposure were significntly ssocited with rdiogrphic progression. Becuse smoking history nd smoking pck-yers were ssocited with older ge (dt not shown), those with progression in rdiogrphic nd pulmonry function indexes nd those who died were less likely to hve ever smoked; those who died hd significntly fewer men pck-yers of smoking. Rdiogrphic nd 12% pulmonry function deteriortion, nd mortlity were ssocited with working s foremn nd with sleeping t the workplce, during which workers hd pssive silic exposure, resulting in round-the-clock exposure. Mortlity lso incresed with number of plces in which they hd worked, which my reflect turnover from workplces with poorer conditions. In ddition to silicosis, this sndblster popultion hs contributed to studies of other helth conditions ssocited with silic exposure nd ffecting their qulity of life. These include eye nd upper irwy problems 17 ; pneumothorx, even bilterl 18,19 ; nd TB. 20 Also, psychologic problems re common, 21,22 in tht mny ptients hve reltives or friends who hve died of silicosis, nd they know tht there is no long-term curtive tretment of the disese except for lung trnsplnttion. 23 Producing fshionble worn-out jens by sndblsting of denim begn in Turkey fter 1992 nd reched its pek round Following the deth of the first two cses nd emergence of other silicosis cses, 1-6 the public strted to relize the mgnitude of the problem nd most of the workers quit their jobs. In response to public indigntion, the government provided ptients 650 Originl Reserch [ 148 # 3 CHEST SEPTEMBER 2015 ]

5 with silicosis free ccess to helth cre nd bnned the process of sndblsting with silic brsives in Since mny ptients with silicosis hd no helth insurnce nd were too impired to work, the government provided compenstion vi temporry lw vlid for 3-month period for workers who hd previously worked in compnies in which ⱖ 15% of the workforce hd developed silicosis. This lw did not cover the fmilies of workers who hd previously died or workers who hd not progressed to silicotic impirment t the time of the lw s pssge. Of the pplicnts with vlid ppliction for compenstion nd dignosed with silicosis in 2011, only 48% received disbility compenstion.24 Our study shows tht silicosis progresses with time in the bsence of exposure nd tht such temporry lws will not cover ll the workers t risk who hve not yet developed impirment from the disese. Although Turkey bnned sndblsting of denim jens, the occuptionl helth consequences re globl s long s sndblsted jens re sold, becuse production hs shifted to other countries, including Bngldesh.25 Another preventive pproch would be for clothing mnufcturers to clrify their policies on purchsing sndblsted denim in light of the mortlity nd morbidity from silicosis ssocited with this process in the globl supply chin.25 Figure 2 A-C, Chest rdiogrphs showing progression in three different cses. A, Incident smll opcities to Interntionl Lbor Orgniztion subctegory 3/2. B, Incident smll opcities to ctegory C lrge opcity. C, Progression of lrge opcities from ctegory A to ctegory B. Our study ws limited in tht we were not ble to recruit 62 of the 145 workers evluted in Some of the nonprticipnts my hve sought evlution t other cdemic medicl centers; one is equidistnt from their villge. The nonprticipnts differed from study subjects Figure 3 Rdiogrphic progression during the follow-up period by individul prticipnts showing Interntionl Lbor Orgniztion smll-opcity profusion nd lrge-opcity ctegory on the verticl xis. Lrge-opcity ctegories A, B, nd C re indicted by brs of lengths 1, 2, nd 3 units, respectively. Decedents re indicted in the top row on top of the pproprite histogrm br. journl.publictions.chestnet.org 651

6 TABLE 3 ] Demogrphics, Pulmonry Function Indexes, nd Exposure Chrcteristics in 2007 of 83 Former Sndblsters Assessed in 2011 by Rdiogrphic Progression, 12% Pulmonry Function Loss, nd Deth Rdiogrphic Progression Pulmonry Function Loss Deth Chrcteristic No Progression (n 5 13) Progression (n 5 61) No Loss (n 5 25) Loss (n 5 49) Alive (n 5 74) Ded (n 5 9) Age in 2007, y Age t first exposure, y Ever smoker, No. (%) 10 (76.9) 44 (72.1) 22 (88.0) 32 (65.3) 54 (73.0) 4 (44.4) Smoking pck-y Exposure durtion, mo Time since first exposure, mo Work s foremn, No. (%) 6 (46.2) 45 (73.8) 20 (80.0) 31 (63.3) 51 (68.9) 7 (77.8) Months s foremn Plces of work, No Sndblsting devices, No Sleeping t workplce, No. (%) 7 (53.8) 36 (59.0) 18 (72.0) 25 (51.0) 43 (58.1) 8 (88.9) Height, cm FVC, L FVC, % predicted FEV1, L FEV1, % predicted FEV1/FVC % Dt re presented s men SD unless otherwise indicted. Sttisticlly significnt. 652 Originl Reserch [ 148 # 3 CHEST SEPTEMBER 2015 ]

7 Figure 4 Pulmonry functions (FVC % predicted vlues) by individul prticipnts in the study group, with the sme numbering system s used in Figure 3. Light gry brs indicte the 2007 vlue for decedents, indicted in the top row bove the pproprite histogrm br. Htched brs indicte 2011 increse in the 2007 vlue. Drk gry brs indicte the mgnitude of decrese of pulmonry function in 2011 compred with the 2007 vlue, the ltter being the sum of light gry nd drk gry brs. in hving higher proportions of foremen (92%) nd those who slept in the sndblsting workplces (92%), both chrcteristics ssocited with worse helth outcomes mong those who were ressessed in We conclude tht our prticipnt smple my hve underestimted the burden of silicosis nd its progression in the entire cohort evluted in With the smll numbers of decedents nd prticipnts, we hd limited sttisticl power to demonstrte differences in determinnts of helth outcome, if they existed, in severl indices of exposure risk, such s exposure durtion nd time since first exposure. Another limittion of our study ws the lck of clinicl lbortory evidence of the prevlence of mycobcteril infection in this popultion. Without sputum smer nd culture results, we could not be confident of rdiologic differentition between silicosis nd pulmonry TB. Some prticipnts hd pst physicin misdignoses of TB before physicins becme wre of possible silic exposure in these ptients. For this reson, we did not seek prticipnt report of prior TB dignosis nd cnnot evlute ny influence of mycobcteril infection on disese progression. The strengths of the study lie in the comprbility of mesurements t the 4-yer intervl. The sme technicin used the sme pulmonry function equipment to ssess progression of respirtory impirment. Two of the three physicins providing ILO clssifictions of rdiogrphs hd previously red the 2007 chest rdiogrphs nd performed the 2011 redings independent of ech other nd without reference to the erlier reding or physiology. Vitl sttus determintion ws robust, using ntionl resources. Finlly, the community-bsed recruitment of former sndblsters in llowed composite picture of morbidity from silic exposure in mny workshops, substntiting n industry-wide risk. Indeed, mortlity ws ssocited with the number of workplces in which sndblsting hd been performed, likely reflecting vrible work conditions cross the industry tht my hve motivted former sndblsters to move from poorer estblishments to somewht better ones. Conclusions Our results suggest tht lmost ll former denim sndblsters will develop silicosis, nd tht progression of impirment to disbility is expected over time. Thus, temporry compenstion is insufficient in Turkey, nd globl mesures to prevent silicosis of workers in this industry re needed. journl.publictions.chestnet.org 653

8 Acknowledgments Author contributions: M. A. hd full ccess to ll of the dt in the study nd tkes responsibility for the integrity of the dt nd the ccurcy of the dt nlysis. M. A., O. A., E. Y. U., A. K., nd F. A. contributed to study design; M. A., O. A., E. Y. U., A. K., F. A., M. G., nd K. K. contributed to dt nlysis nd writing the mnuscript; M. A., F. A., M. G., nd K. K. contributed to revising the mnuscript. Finncil/nonfinncil disclosures : The uthors hve reported to CHEST tht no potentil conflicts of interest exist with ny compnies/orgniztions whose products or services my be discussed in this rticle. Other contributions: The uthors thnk the Americn Thorcic Society s Methods in Epidemiologic, Clinicl nd Opertions Reserch Progrm. The findings nd conclusions in this report re those of the uthors nd do not necessrily represent the views of the US Ntionl Institute for Occuptionl Sfety nd Helth. References 1. Akgun M, Gorguner M, Merl M, et l. Silicosis cused by sndblsting of jens in Turkey: report of two concomitnt cses. J Occup Helth ;47(4): Gur A, Kiyik M, Kilic L, et l. Silicosis in denim sndblsting textile workers (two cse reports). Eur Respir J ; 26 (suppl 49 ):147s. 3. Akgun M, Mirici A, Ucr EY, Kntrci M, Arz O, Gorguner M. Silicosis in Turkish denim sndblsters. Occup Med (Lond) ;56(8): Cimrin A. Silicosis over gin; cuses nd responsibilities. Tuberk Torks ;55(1): Shbz S, Inönü H, Ocl S, et l. Denim sndblsting nd silicosis two new subsequent cses in Turkey. Tuberk Torks ;55(1): Akgun M, Arz O, Akkurt I, et l. An epidemic of silicosis mong former denim sndblsters. Eur Respir J ;32(5): Yilmz S, Bogtekin G, Senyigit A, Buyukbyrm H, Senyigit A. Silicosis due to denim sndblsting: four cses. Turkiye Klinikleri J Med Sci ;29(3): Interntionl Lbour Office (ILO). Guidelines for the Use of the ILO Interntionl Clssifiction of Rdiogrphs of Pneumoconioses. Revised edition, ILO Occuptionl Sfety nd Helth Series No. 22. Genev, Switzerlnd; Interntionl Lbour Office; Qunjer PH, Tmmeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernult JC ; Officil Sttement of the Europen Respirtory Society. Lung volumes nd forced ventiltory flows. Report working prty stndrdiztion of lung function tests, Europen Community for Steel nd Col. Officil sttement of the Europen Respirtory Society. Eur Respir J Suppl ;16: Cottin V. Chnging the idiopthic pulmonry fibrosis tretment pproch nd improving ptient outcomes. Eur Respir Rev ;21(124): Tniguchi H, Ebin M, Kondoh Y, et l ; Pirfenidone Clinicl Study Group in Jpn. Pirfenidone in idiopthic pulmonry fibrosis. Eur Respir J ;35(4): Bkn ND, Özkn G, Çmsri G, et l. Silicosis in denim sndblsters. Chest ;140(5): Petsonk EL, Rose C, Cohen R. Col mine dust lung disese. New lessons from old exposure. Am J Respir Crit Cre Med ;187(11): Lney AS, Petsonk EL, Attfield MD. Pneumoconiosis mong underground bituminous col miners in the United Sttes: is silicosis becoming more frequent? Occup Environ Med ;67(10): Crneiro AP, Brreto SM, Siqueir AL, Cvrini F, Forstiere F. Continued exposure to silic fter dignosis of silicosis in Brzilin gold miners. Am J Ind Med ;49(10): Kreiss K, Zhen B. Risk of silicosis in Colordo mining community. Am J Ind Med ;30(5): Yoruk O, Ates O, Arz O, et l. The effects of silic exposure on upper irwys nd eyes in denim sndblsters. Rhinology ;46(4): Aydin Y, Turkyilmz A, İntepe YS, Eroglu A. Simultneous bilterl spontneous pneumothorx: rre emergency clinicl condition. Eursin J Med ;42: Kynr H, Aydın Y, Akgün M, Türkyılmz A, Eroğlu A. Pneumothorx in the cses with silicosis due to denim sndblsting. Türk Göğüs Klp Dmr Cerrhisi Dergisi ;20(2): Ozden K, Arz O, Yilmzel Ucr E, Alper F, Akgun M. Co-existence of tuberculous meningitis nd pulmonry tuberculosis in denim sndblster. Eursin J Med ;44: Yildiz T, Eşsizoğlu A, Onl S, et l. Qulity of life, depression nd nxiety in young mle ptients with silicosis due to denim sndblsting. Tuberk Torks ;59(2): Sunl A, Sunl O, Ysin F. A comprison of workers employed in hzrdous job in terms of job stisfction, perceived job risk nd stress: Turkish jen sndblsting workers, dock workers, fctory workers nd miners. Soc Indic Res ;102(2): Helvci A, Meydn B, Akin O, et l. A single lung trnsplnttion for silicosis: the first successful lung trnsplnttion cse in Turkey. Türk Göğüs Klp Dmr Cerrhisi Dergisi ;19(3): Uzunoğlu B, zkr Ş, kmen M, Aritürk O, Tüzün D, Arntş K. Determining silicosis ptients without insurnce with temporry lw. Turkish Thorcic J ;14(2 suppl 1 ): Hobson J. To die for? The helth nd sfety of fst fshion. Occup Med (Lond) ;63(5): Originl Reserch [ 148 # 3 CHEST SEPTEMBER 2015 ]