Document Eq74Lw3E47djnGXyQk44yaZ54

Pergamon ms SB0fl3-4878(00)qO41-T iM oosp. 1fySr> Vol 43, Na, ? pp. lj 2M| & }Ml BntkhOmifMtofltl H/jlm gaideoy PbbMed by SlMvIff Sefenee Lid. AB rigffia rtWuaroad nM fatOwdiriiUK. am 4S7t/0!2CM Amphibole Fibres In Chinese Chrysotlle Asbestos ANTJT TOSSAVAINENf*, MIA KOTILAINEN% KEN TAKAMASBIt, GCTOWEI PAN and ESA VANHALAf fDepanment ofIndustrial Hygiene and Toxicology, Finnish Institute ofOccupationalHealth, Helsinki, Finland, ^Department ofEnvironmental Epidemiology, University ofOccupational and Environmental Health, Kitakyushu City, Japan; ^Environmental Epidemiology Branch, Liaoning Public Health and Anti-epidemic Station, Shenyang City, PR China Ten ctsiyssfUe bulk samples originating Ibm sis Chinese cbxysatde mines were studied for amphibole fibres. Five or the mines operate an 'ahnmaflc radii whereas one exploits a dolotnltedtoated deposit. The asbestos fibre content in lung tissue was examined from seven deceased workers of (be Shenyang asbestos plant using these raw materials. The bulk samples were preheated with add/alkaU-dlgeatloit, and thereafter, seaming and transmission electron taksmeapy. X-ray mfcroanalyslx, selected area electron diffraction and X-ray powder diffractomefry were Used to Identify the minerals. Sample preparation or lung tissue involved drying and low-temperataure ashing. All ofthe bulk samples contained asnphihole fibres as an impurity. The amphibale asbestos contents were between 0.M2 and 0.31 w-%. Treraollte fibres were detected In every sample but antbophyllite fibres ware present only Ib the sample originating from the dolomite-hosted deposit. In fcampntson, antbophyllite (71%), tremoHte 0>%) and chrysotlle (10%) Were the main fibre types la the long tiisne samples Indicating foster pulmonary clearance of chrysotlle fibres. The total levels ranged from ZA to 148J million fibres Coyer 1 pm in length) per gram ef dry tissue, and they were consistent with heavy eccnpationsl exposure to asbestos. <S> 2001 BzitUi Occupational Ifygistie Society. Published by Elsevier Science Ltd. All rights reserved. Keywords: antbophyllite; treraelife; asbcatOB; lung tissue; Chins introduction TTemolite fibres ere common. natural impurities of chrysotDc ore and various mineral products- Despite low conccuttatiotut, inhaled amphibole fibres tend to accumulate in the lung tissue andmay contribute sig nificantly to the mesothelioma risk of chrysolite minds and millers (Case, 1991; McDonald et at., 1997). This hypothesis may not extend to taborhealth hazards Of chrysolite exposure (Stayner ef of., 1996). Chma h the world's third largest producer of asbestos following Russia and Canada (Kendall. 199$). China has recorded a total of 467 asbestos locations, She vast majority (95%) of which contain chrysolite asbestos (Lu, 1998). Eleven ofAc 14 major commercial deposits are hosted in setpontimsed ultramafic rocks, white three of than are dotaraite-bosted Received 8 Much 2000; in final form 25 May 2000. ^Authorto whom ctmeepondoncc should he aAlressetf. TeL? 4358-9-4747-233; fax; 4338-9-4747-208: e-mail: anttUos- aavastiCTi@occUp5tealth.fi and located in the north and northeast provinces of Liaoning and Hebei. The latter types occur as groups of tabular and lenticular ore bodies lying; along the bedding plane of host cock and are far smaller in size than the uitmmafic deposits. In eastern China the dolomite-hosted mines have been more accessible and thus exploited for thousands of years. The oldest artiEsct of asbestos cloth dates back to 1001-947 BC. The ulttwnafic chrysolite deposits axe locatedin west ern China and they contribute 96% of the country's total resources and the bulk of the total production. In 1995 the Chinese production chrysolite fwm 140 quarries exceeded 440 000 tens per year, of which about 300 000-350 060 toaa were consumed dom estically (Li, 1986; Huang, 1986; Lu, 1998). In many asbestos mines and manufacturing plains, air contamination exceeds the national standard of 2 mg/m* in terms of total dust, with trie worst levels in smaller enterprises (Cui, 1999). A national survey recorded 42S9 cases of asbestosis in China during 1946-1986 (Anon, 1992). In 16 large asbestos plants, 10.6% of the workers had some form of asbestosis EXHIBIT Q'\\ i HWBUI0010464 146 A. Tosssvaima er at (Report; on Compensating Asbestos Product Workers. For further analyses, the samples were treated with China NonnsetalUc Company, unpublished data, an acid/alkeU -digestion method (Addison and Dav 1990). Several studies have reported dose-response ies, 1990) in order to dissolve chrysolite. This was relationships between asbestos exposure and asbea- necessary tor the detection ofany amphibole asbestos taste (Huang, 1993; Wang and Lb, 1985). lung can in the products. The acid treatment dissolves magnes cer and meaattadkatM are known to occur excessively ium from, ebeysotile and strong alkali was then used among Chinese chrysolites workers (Zhu and Wang, to remove tbe remaining silica. AmpMbdtes are 1993; Zbu es of., 1990; Chen and Kong. 1992; Pang known to be more resistant chemically. The samples etal., 1997). were jree-bcated (600C) before the treatment with For this study duyaotito samples currently used at acid (2 N H,S04) and alkali (4 N NaOH). The the Shenyang Asbestos Material Plant wore examined remaining insoluble material was then prepared for In radar to determine the type* ofmbtetala present in the SEM viewing as described above. taw asbestos originating from sin Chinese urines. Tbe quantity of amphibole asbestos fibres in the Also lung tissue samples ofseveral weaken from this residual material was determined In toe following asbestos material plant were analyzed. The level and way. Approximately 0.5 mg' of the dissolution typo of asbestos fibres'were dotetmined by election residual waa weighed, mixed with distilled water and microscopy. Tbe mortality of the plant weaken: had filtered on a polycarbonate membrane filter. The fil been studied earlier. Significantly elevated risks were ters were crated with gold and viewed with the JEOL observed toe lung cancer (5MR=2.13) and pocumo- ISM 6400 at a magnification of 3000k. Each amphi- cosriosia (5MR**16.9) wrong 528 male workers fol bole fibre was Identified with the energy dispersive lowed for a period of25 ye. There was also a positive X-ray microanalyzcr sod fibre lengths and duuoetos gradient in the mortality rate for lung cancer accord were measured. Only perfect fibres with parallel sides ing to the cumulative levels of dust exposure that were at least 5 pm in length, less than 3 pm m * (Takahssbd el a!., 1997, 1998). diameter and with a tength/dlamctsr ratio more than 3:1 were counted. At least 200 fields or 100 fibers MATERIALS AMP METHODS were counted, on first to come basis. The weight per centage of the fibres was calculated as follows: Bulk Hamples Ten asbestos samples from the Shenyang Asbestos Wdgfcrtt = Materia! Plant were available for electron n&w staple and X-ray diffraction analyses. These raw materials originated from tbe following six mines: Kombcr ofItelUsxFteld me* (j*rostixAffliottnt ofsample to1)*to Shitnian mine of Sichuan province (Samples 1--3), Xirikang (nine of Sichuan province (Sample 4), Mon- The detection limit of the method is below 0.01 w- gyei mine of Qinghai province (Samples 5 and 6\ % (Hartflcaincrt. and Tossavainen, 1997). Qiiiaa mines of Qinghai province (Samples 7 and 8), The minerals preseal In toe remaining material Tuoliu mine of Xinjiang province (Sample 9) and (after add/aJkali-teeattliettt) were also identified by X- Jfttthou mine of Liaoning province (Sample 10). All ray powder difftactometry (Philips XTERT System) ofthese mines axe located in western China and they equipped with a Cu X-ray tube. Tbe powder samples exploit Hlframaftg socks except the last sampling alto were analyzed at a power of 50 kV and 20 mA with (10), which situates ia north-eastern arina and s scanning speed of la/min for the diffraction angle belongs to tbe small dolomite-hosted type of asbes from S to 70 as well as in a step scanning mode for tos deposits. the mote accurate detection of amphibole phases and The samples were prepared tor scanning electron other minerals (Knhyanis el al-, 1996). To identify microscope (SEM) viewing by mixing about 2-3 g of too minor mineral phases, a computer was employed the material with distilled water and filtering a tow for matching toe X-ray diffraction (XW3) peaks with drops ofthe suspension through a Nudcpoie polycar the mineral powder diffraction file (JCPDS, 1989). X- bonate membrane filler (diameter 37 mm, pare size tay diffraction docs not differentiate fibrous and non- 0.2 pm). Eachpiece ofthe filter was coated with gold fifacous toons. in a Bat-Tec BCD 005 Sputter Crater tor 100 s. Rou In addition amphibole asbestos fibres were ident tine SEM viewing was earned out with a JEOL ISM ified by transmission electron microscopy (TEM) and 6400 electron microscope combined with an energy selected area electron diffraction (SAED) (JEOL JEM dispersive X-ray microanalyzcr (Tracer Northern TN 1220). Also tiie differentiation between antigorite and 5500). The panicles and fibres were identified by their chiysotilc was confirmed with. TEM observation end relative elemental peak intensities In comparison to SAED patients (Middleton, 1982). the respective mineral standards. Tbe collection time The presence of amphibole fibres was also verified of one spectrum was 20 s and ihe identification was with a dispersion staining method which, is based on based ott die silicon, magnesium, aluminum, lion and the differences between the refractive indices of a calcium peaks. particle and the immersion liquid (Anon, 1989). A HWBUI0010465 AropUifrOte fibres i& Otiinrare ehiyratHc asbestos ls? polarization microscope (Lotte Laboriux 12 POL 5} equipped with a phase contrast system was used for this purpose. Lmg iitxm samples From seven deceased workers of tire Shenyang Asbestos Materia! Plant, several gram* of fcxmaUnfced lung tissue was available Tor electron tniertascopie analysed and nunesal fibre counting. One worker of the seven was female. The workers were aged frora 51 to 72 yr (mean 60 yr) ofage at the time of autopsy. The workers had been employed at the plant within the years 1930-1983 with, a range of 6TM 31 working yean (mem 21 y*X Three were smokers. AH of them were diagnosed with asbestosis (Chinese grade 0- These workers worked only in Shenyang asbestos material plans; except for S66, who had also worked in mother asbestos plant in die same city for 6 yr. There was no evidence that anyone had an exposure history of artthophyllite asbestos. Interview data and company records were compiled to establish a lifetime job history for each subject. Environmental monitoring date were available for these workplace* in teems of gpaviroetric units. Cumulative exposure index (CET) is defined aa the product of exposure duration (yr), exposure level (mg/m*), the proportion ofworking hours with asbes tos exposure and asbestos percentage in the product, summed over each job (or job site) of the worker. The preparation of lung tissue samples involved drying, low-temperature ashing, dispersion in 0.5 N hydrochloric acid and filtration, cm a Nuciepore poly carbonate tHtor with a pore size of 0.2 pro (diameter 23 mm). A sector ofthe sample was coated with gold in a sputtering device (Bata Onion SCEX304). A blank w*S prepared and analyzed as a means ofcon tamination control. In addition, formalin fixative was examined to exclude contamination. (Tossavaincn et l., 2000). Mineral fibres were counted on lb screen with a JEOL 100 CX-ASID 40 electron microscope hi the SEM mode at an acceleration voltage of 40 kV. Alt Inorganic particles having a length to width ratio at least 3:1 and parallel skies were defined as perfect fibres and counted (Hactikamen and Tossavstnen. 1997). Qeavage fragments were not included. At a magnification, of SOOOx, 13-23 fibres were counted or a minimum of 400 viewing fields were analyzed in order to reach as analytical sensitivity of 0.1 million fibres!. AH inorganic fibres longer than 1 pm were recorded. An energy dispersive X-ray micmattalyzcr (Noras Instruments 5502N) was used to determine the fibre type by comparing peak ratios (Mg, Si, Cat, Fe) to standard spectra. The presence ofanfoophyliite asbestos was confessed withX-rayspectra and SAED pattern with analytical TEM. The spectrum of the anfoophyliite fibres was similar to the UICC standard. These measures were necessary in order to dis tinguish. fibrous talc from anihophyllite. The concea tzations of anfoophyliite, tremolitc and chrysolite fibres per gram dry tissue are reported in the results. The category of chrysolite includes some fibres, which were too fine to be identified for certain. Some of them, might be other margrofe fibres end so the subclass 'chrysotile fibres* should be interpreted as the maximum concentration of chrysolite m the samples. `Total silicate fibres' sums up all the counted fibres (also including some AlSi fibres). results Bulk samples All of foo chrysolite samples contained amphihole fibres as an impurity. Tremolitc was -identified from every deposit, but anfoophyliite was found only in dolomite-hosted chrysotile (Sample 10, Jlnzhou, Liaoning). In. addition to chryaotilc, the samples con tained smalt amounts of other minerals. These min erals included talc, antigente, quartz, nlbite and iron oxide (magnetite, haematite), Chrysotile, tremolite, iron oxide and talc woe identified with the routine SEM viewing without chemical treatment offoe sam ple. The qualitative results of the bulk samples ore summarized in Table 1. The tremolite contents of the samples were 0.0020.310 w-% whereas the antbophyltitc content (except Sample 10) was below 0.01 w-% (Table 2). Ou an average 84% of the bulk chrysotile samples (range 78-95%) was leached in the acid/alkati digestion (Fig- J)Anihophyllite was foe predominant fibrous smphi- bole in Sample 10 (0.040 w-% anihophyllite, 0.006 w-% tremolitc). Between the samples, there was over 100-fold difference in the ampbibole content in weight and about 60-fold difference in. fibre number, bi total 400 acmolite fibres (over $ pm in length) were counted and measured. The mean length was 8.8 pm and foe mean diameter 0.76 pro. The number of counted, and measured aathophyllite fibres (over S pm) was 38 and thdr mean length was 14.9 pm and diameter 0.98 pm (Fig. 2\ Lung Ibsue samples Anihophyllite and tremolitc fibres were foe main fibre types in the lung tissue samples. Anfoophyliite fibres were detected In every sample amt foe levels were from 0.2 to 105 million fibres per gram of dry tissue (Tables 3 and 4). The fibre concentrations (over 1 pm in length) were ftom 0-5 to 11.7 million fig for tremolitc and 1.6 to 15.6 million fig for chrysotile. Although the fibre levels are very high, there was no obvious correlation between mineral Shat concen trations and exposure doses, age or smoking habits in this series of exposed weakens. On average, 71% of all mineral fibres were enthophyilite, 9% were tramlife and 10% chrysotile. The most significant result of the lung tissue analyses was tbe presence ofanfoo- HWBUI0010466 148 Semple no. Table 1. Qualitative results from bulk samples Mine (WO)", province (type of deposition) Finding* (and analyses)" I. SJtimlan (U), Sichuan (ultramsfk; socks) ChqrMile {1% tomditafl). antfgorito(23.4,5X !a!c(l,2X Z. Shim!an (U> Sichuan (oltmtnafte rocks) Chryiatile (1), tremolite 2X antigorite(2,3,4,5X iron aside (2), quartz (3), tala (2) 3. Shuman ftJX Sichuan (ldinmsfie rocks) Chtywtilo (1), trcmolittv antigarfto (2,3,4,3). quartz (3) 4. Xiflbng (OX Sichuan (ulteamafic rocks) CfujwrfDe ()> tremolite (1,2) 5. Mongyel (O), Qinghai (ufeenufie rocks) Chtyaatile (U), andganiB {2,4,3X iron, aride (2). tale m 6. Mongyei (O), QJnghai (tdtramsfic rocks) CniysatHc (IX tremolite (L2.3X saligorite (2,3.4,5X quart* (3) 7. Qiliut (O), Qinghai (sstamafic rocks) CJuysotOo (1), tremolite (2), iron oxide (I), antigorite (2A44X Quart* (3). magnetite (3). 8. QHJan (OX Qingbai (uhremafic rodka) Ctuytntilo (IX tremolite (2), anrigonte (23.4,3), iron axid*C2X haematite (3), Quartz (3) 9. Tnolra (UX JUnjiang (uJtranmflo recks) Chrysolite (IX anKgonte (23,43). tremolita (23), iron osido <2X t*ic (2),nickoI PXquaaz (3) 10. Jhubou (UX Liaoning (dolomite-hosted) Chrysolite (IX anthophylilfc (2), ttemolilaQj!). iron oxide (2X talc (23), dolwnite (2), quartz (3). antigeriw (23AS) UaUndugroutd mice; Cfespen easting mtec. `"Aualysea: J. SEMetKatmlng electron mkroscepc; Z A/A=*ddAilioali (restroom; 3. XRD=X-xay dtUssetometry f the (osidttal after A/A treatment; 4. TEM=tronaniasion electron mkromiope; 3. SAKOsdected area electron diffraction, Sample no. 12. 3. 4. S, 7. 8. 9. 10. 10. Table 2. Ttanolits rod aatbaphyllitB fibre P'S pm) content of the hulk samples IVeiRoUtfi content v*-% Tremolite fibn/pg Tremolite fibre length (Jim) Bangs Mean Tremolite fibre diameter (pm) Range Mean 0.270 0.110 0310 0.060 0.034 0320 0.007 0.002 8.090 0.006 Amhophyllife cordon* w-?4 0.040 180 28 185 38 13 39 4 3 44 $ Anthophyllite ffines/pg 1 3-21 3-183 73 9.8 3-29 7.9 3-41 9.4 s~m 11.0 5-49 99 7-7 7.0 5-43 53 5-73 10.1 3-22 9A Amlhsptenite fibre length (pm) Mean. 14.9 03-2 0.73 03-2 0.83 03-2 0.73 03-1.5 03--Z5 0.73 0.73 0.5-ZS 0.90 03-1.3 i.03 03-0.8 0.60 03 -2 03-1.3 0.83 0-67 Anthophyllite fibre diameter (pm) Mean 832 ojw phyllite him) tremolite fibres, since the persons bad been exposed only to Chinese chrysolite. No amosite or ctoddolite fibres were detected The mean values for fibre Icsgtft/diaineter woo 9.97/0.14 jirrt (M=6) for chrysolite fibres, 9.01/0.67 |&a (Afcl21). for aathopbyllite and 8.13/0.44 pm (M=I7) fee tremolite. DISCUSSION Most of the fibres found m the lung tissue samples were smjihtbote asbestos fibres, white the bulk samples mainly consisted of chrysolite. Id tfaeao Chi nese chrysolite products the levels of antphtbote impurities were substantial, sithough die differences between the mines were large. Trawoliw; was detected in every bulk sample, while anthophyllite asbestos occurred only in one of the mines (Jinzhou, Liaoning). Tlic geological setting of tins mine differs hum the others and evidently the doiomiUi-hosted mutes in north and northeast of China are more likely to contain anthophyllite asbestos than the uiiratrmfic chrysolite deposits. Jinzhou mine is located dose to the material plant, and therefore its raw material has undoubtedly been extensively used in the past years, the proportions of she used asbestos from each mine are not known. Few studies have examined impurities of Chinese ebrysotife, except for qualitative analyses showing `little amount' of amphibole in die duysotOe product of Qilian mine (Rang and Peng, 1997). A small amount of tremolite was detected in the chiysotSe mine of Cfctaoyang mine. Liaoning province (Li. HWBUI0010467 Amphiboie fibres la Chinese ehjyswtile mbestos 149 Kg. 1, Typical eppnaimcc of a tmtk sarojpia observed by SBM: (t) -undignted. (b> atcjdfclkali-dJgCBted. s-m awe ts.u> cim.4 pm ?.* Fig. 2 3*z*s diatributlcms of Ueznelits and sistibepfeyltfis ilferes In CUnese chiysolilc samples. 1916). Wang et al- (1988) analyzed asbestos fibre types in die lung specimens of IS Chinese asbestos workers exposed to cfaysofcsto and reported 34 of 35 uncoated fibres to be of the amphiboie type and one chrysolite fibre. Chrysolite fibre* tend to leach out from the tupg tissue, while the umpfaibote asbestos fibres ate more resistant and remain in. the tissue (Finkelatein and Dufreatte. 1999). Therefore. the exposure to Chinese chrysolite might have resulted in the high. level of amphiboie fibres in the lung tissue. These amphiboie concentrations may have accumulated over a long period of time through the primary exposure to ebrysotite having a low percentage of amphiboie asbestos as an. impurity. Five of the seven samples exceeded the limit of 5 million amphiboie fibres (>1 pro) pec gram dry tissue which can be associated with a twofold ask of lung cancer (Consensus Report, 1997). In both bulk and lung tissue samples, tmlhophyitite fibres were somewhat longer and thickerthan beroolite and clearly coarser than chtysotiis fibres. Earlier studies from Russia and Canada have sug gested high pulmonary levels of chrysolite and tremolilc fibres among duysotile miners and millers. la the study of Aabcst, Russia, both chrysotile and atttphibole were detected in the lung tissue samples, la 24 Russian chrysolite miners, millers and produce manu facturers, die pulmonary concentrations of retained fibres (over 1 pm In length) were 0-8-50.6 million ftg for chrysolite and <0.1--1.9 million fig for atnphihotes (treroolite and anlhophyilite). The concentzaticina were lower in 23 persona without any known occupational contact with asbestos; 0.1-14.6 million fig for chrysotile and <0.1-0.7 ttiHKan % for amptn- balcs. On average, 90% of all iraorgank fibres wens chrysolite and 5% tremolitc/anlhophyltite (Tossavainm et 2000). In the .Thetford area of Quebec, the mean concen tration of tremolito in 22 male mesothelioma patients exceeded the chrysotile concentration (105 vs 12.9 million fibres of all lengths per gram dry tissue) whereas in Asbestos, Canada, the corresponding lev els wens almost equal (3.40 V8 3.54 million ffg) (Greenef of., 1997). The tremolitc content, ofthe Can adian chrysotile ore is less than !%- It seems likely that even a smalt quantity of amphiboie fibres in chrysotile asbestos ore constitutes an important source ofexposure (Dufieane et aI., 1995,1996; Case et al, 1997). The use of commercial amphiboles (amosite, croddolite) has also been related to tissue levels in Canada (Takahashi et at, 1994). No amosite or cro- HWBUI0010468 V \ HWBUI0010469 Am^ilbote fibres m Chinese duysotile asbestos 151 Table 4. Mineral fibre concentrations la foe lung tissue of ajbostoa weaker in Shenyang asbestos material plant, China Sample no. Gcmcentmtkm, million fibre* (aver 1 pm in length)/; dry tissue Anthaphyllito Tianolite Ctayzotife Total sdirste S21 2X1 3.9 7.4 36.9 S22 1MA 5.6 5.6 122.8 S26 103.4 11.7 15.6 148,3 SS4 7A to <0.5 123 S66 13 2.S 1.6 7.3 sm S.l 0,3 3.7 113 S73 03 13 <0-2 2.4 ekloHte fibres were detected in any of die samples neither fern die Russian chrysolite mining area (ToasAvaurten ef oi., 2000) nor in this atody from China. This could be expected since the geological processes involved in die sopentitiizathBt. ate such that drey ora unlikely to coexist, geologically with chrysolite (Addison. 1999). hi SI ebrysoote samples from various sources, the mean tremalite content was 0,09% with a range from 0.1 fas 0.6% in 28 samples where tretooiiae was detected (Addison and Davies, 1990). Ambophyilite Dims have been detected by XRO and XEM also in Zimbabwean chrysotiie (Kbhyama et et^ 1996). The EU Begukdons will prohibit the importation, use and sale of new and second-hand products coa- tainiag chrysotiie asbestos by the year 2005 (Commission Directive 1999/77/EC). There has been concern about the health risks associated with ampfiibole contamination In chrysotiie products and materials (Howie, 1999; Addison, 1999). Considering die proposed limit of 0.05% tmnolito asbestos in chrysotiie (Bowie, 1999), dm data obtained here (up to 031%) suggest that amphthate fibre aw signifi cant impurities in some grades of Chinese chrysotiie, a foot that has been poorly documented until now. mwmmcEs Anon. Manual of nutiytiml methods. Asbestos puMIcatfaas, 3td <xL Msdotwl InaKtUW for Otxugasiow! Sadcty end Wealth. Method 9002. 191#. Anno. Atlas ofnational epMraieSogtcsi Isvesiigatiou oapamtmncaaloMk (1946-1986) (in Odrase). TUt China: Ministry of Public ilhshh. 1992. AddietmJ. MMmMng foe health hazards associatedwithdwogmd products contalBing staysoty asbestos. 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Hxnigm M, Msw S. Begin R_ F&sts in lung tissues of mssotUioaM cases smuts tolnsni and miliars of foe township of Asbestos, Quebec. American Journal of Industrial Modieine 1995:27381-92. DuSosne A, Begin R. Duftosme CM, Cooaeraewanich P, Prnmnl( Q. foateuian of asbestos fibers in lungs of wotkers with sbastoais and lung etnoar, sad mesothelioma ia Asbestos township. Occupational and Environmental Medicine |99d;S3:801--7. European CommunWaa: Commission Directive 1999/77/EC. On the marketing and usn of certain dangerous substances and preparations (asbestos). Brussels, 1999. Fiokelatetn MM, Dnfnws; A. Infonatcea os the kinetics of aabesioe deptwitkas And clearance among chrysotiie mittens and millet*- Americaa Jourwai of Industrial Medtcioc 199935-401-12Gteen HY. Hadley R, Vallysthaa V, Allhouse R, FtA G, Dement 3, Midi* R. Fooley F. Bxpranss and miacralogicsl cemdatss ofpulmonary fibrosis in chrysolite asbestos work- era. C*cetgtlofi*l and Hnvunmnsninl Medicine 1997;54:549-59. 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