Document NeGwe9Le5dQd3kK8dEy1LKJQV

i i` ws-iswsn i I | PLAINTIFFS CAEXMHI-B3IT66 iiW ^ijasjs^safa Critical reappraisal of Balangero chrysotile and mesothelioma risk ; 1i | i ; i Edw ard B. Ilgren^, Frederick D. Pq o iey, Yumj M ICuwuya and John A. Ho sk n sw BACKGROUND: Balangero, 40 km northwest of Torino In the Pledmonte Region, was home to thB largest and most active chrysotile mine In Europa operating from 1916 -1990 and employed over 300 men at any one time. The chrysotile was thought to be pure. Despite this some claim Ithas been responsible for causing numerous mesotheliomas. This report refutes this claim on the grounds that It Is not pure but potentially contaminated by tremollte asbestos. In addition there are numerous alternate sources of naturally occurring and commercially available amphlbole asbestos In the region, METHODS: Geological studies Illustrate the presence of naturally occurring tremolUe and various anatyses have shown naturally occurring and commercially used amphlbole by Its presence In animal and human tissue. The diagnostic criteria used to study pleurat disease In the Balangero cohort were examlned.on a case by case basis. RESULTS: Several authors have searched available registries for post-mortem Information and listed possible mesothelioma cases. Cross matching these searches has been attempted and the strength of their diagnoses examined. CONCLUSIONS: There Is good evidence that croddotlta, amoslte and tremollte are responsible for the alleged mesothelioma cases at Balangero. Myriad sources of naturally occurring and commercial amphlbole asbestos exist in the region to account for the alleged cases. Regrettably, necessary Information Is Incomplete and Insufficient for the cohort which calls the diagnostic accuracy o f the cases Into quesUon.The problemls further compounded by confuslonsutroundlngloh titles andralses the question If any o f the cases actually occurred In `miners' per se. Key words: chrysotile, Balangero, Pledmonte, Casale Monferato, mesothelioma CO Fcrrnerly Faculty of Biological Sciences, Oxford UntDtrslly. Oxford, UK (2) Research professor Pathology Department Medical MicroscopySdcnceLaboratory, CardiffUniversity, Cardiff ' CDJPormsrlyBrynMam Conags,Pennsylvania, USA <0 ConxvltantToxicolcglfi,Easlsmere, Sum# tX CORRESrOimiNGAWHO&BdwardB Bgren, Formerly FacultyofBiologicalSciences, Oxford University, Oxford, UK *-maikdredtigrenQaoUom X>QI'1QJ427/10I2S Accepted on November /< 20X4 SUPPORT.DrBgrm mote thispaper wbtnaConsultantto companiesin asbestosHtlgaUon i I1 \I i i ! ; t EpidemiologyBiostnSsticHidPublicM ih -2015,Volume12,Hunta 1 INTRODUCTION Analytical Evidence Balangero Is ca. 40 km northw est of Torino in rise Pledmantc Region of Italy. It was hom e to th e largest and m ost active chrysotfle m ine in Europe operaring fixun 1916 - 1990 and em ployed over 300 m en at any one lim e. The chrysotfle w as thought to be pure. D espite its presumed, purity, some claim It has been responsible for causing numerous m esotheliomas. This report refutes the claims th at Balangero chrysotfle is able to produce m esotheliom a on the grounds that it is not pure but potentially contaminated by trem olite asbestos; because the diagnosis o f m ost of die allegedly attributable eases has not been proven; also numerous alternate sources of naturally occurring and commercially available amphlbole asbestos, and possibly other fibrous silicates can explain rim allegedly attributable m esotheliom a coses, QUESTIONS OF PURITY -.TREMOUTE: ' Geological Evidence The Balangero chrysotfle mine is situated in a serpentinite satellite body of the Lanzo M assif (Piedmont, Italy), the largest ultraroafic body of th e Western Alps [1}. Various areas w ithin the lanzo m assif are conducive to the form ation of trem olite asbestos as shown through direct sampling of rock, a ir and lung tissue. Fortune: c t al. (21 n oted that th e region is very rich In serpentine rocks, m any of them outcropping, and som e that have been exploited in rite past during the quarrying of asbestos. "In areas such as Piedm ont, everyone is exposed to low doses o f airborne asbestos ...T he asbestos species commonly found in natural sources (Le. rocks) is asbestos tremolite and asbestos actinolite* (3], Many have noted this and in consequence parts of the Susa Valley are contam inated w ith trem olite. Many local talc mines Id] found near Balangero are contaminated w ith trem olite asbestos. One, 'Bmnetta1 w as thought to be the source of the trem olite asbestos found by Pooley In the lungs o f a Balangero w orker w ith m esothelioma "The presence o f trem olite la so il in the Susa and Chlsone Valleys (W estern Alps) Is a plausible explanation for the m ost w estern mesothelioma clusters....'1[3], Direct analysis of Balangero chrysotfle has shown the presence of tremolite. For example, Bader[6] foundtremolite In one offour Balangero samples he studied usingTEM- 30SD. Additional studies of a ir and lung Ghow trem olite. Short and long term air sam pling in the lanzo and Susa Valleys detected long trem olite and acrinolite fibres using SEM - EDS, Lung burden studies of cows grazing in both Lanzo and Susa valleys also show ed elevated concentrations of trem olite/ actinolite asbestos [2.?]. Similarly, hum an lung sam ples from those residing either in o r near Balangero la rite Lanzo Valley an d .others Hying in the Susa valley nearby also contained trem olite/acUnolite asbestos fibres (2,73. Urine sam ples from Individuals redding in Susa valley also contained trem olite (2,71. M irabelli e t aL (8] cite Fornero's animal lung burden w ork to support the alleged role o f Balangero chrysotfle la producing an environm ental' mesothelioma risk but foil to m ention Fomero's finding o f natural and commercial amphlbole asbestos In m any of rite samples taken. Pooley [91 demonstrated elevated tremolite concentrations in lung tissue from three Balangero workers (21% of fibres > 5 prolong: Table 42 In Dand nine control subjects (Table 1). The workers died of asbestosls, king cancer and mesothelioma; the controls from non asbestos related causes. Naturally occurring trem olite Is not surprising. The geology Is conducive to to formation. Why has its presence not been noted before? Sampling error is certainly one explanation as very few samples have been analyzed, the sample sizes have generally been, small, and rite analytical m ethods (XKD) may not have been sufficient to detect It. None, aside from Butler (3, ever tested samples using ad d digestion and TEM-XRD. The considerable mining area and heterogeneity, la the ore body created difficulties in obtaining representative samples over the nearly 75 years of Its operation. Relatively small percentages of trem olite can be biologically im portant representing substantial airborne fibre concentrations [10]. Therefore, the very high dust levels produced during mining [11-131, may have contained very high concentrations o f tremolite. ii ) i 1 I I-- e^vTg'ffs a r^r:: "'.ir,.Tr.w r7. E ffcislogy M tM s mifable Hsaifh - 2615, V o te 1%N um b 1 lif liililM r sw sisv ter." n~f r ^ .- ^ ,, u s O T r o ^ o c s ^ e s r /--j-& a ,~ i> c ,js a i i ! BALANGERO CHRYSOTIIE COHORT * DIAGNOSTIC ISSUES* Pioiatto ct aL [14] repotted the flist two mesotheBonlas in die -Balangero cohort, th e first case (1975) was diagnosed cytatoglcafiy; the other (1977) histologically, Neither used im m unohlstochem lstry (mC), CaUstl [12] reported a third mesothelioma In.the Balangero cohort whilst Browse (1992 pets commuiO said that as of 1992 there were at m ost four mesotheliomas repotted a t Balangero, "one In a manager, but they were suspect given the doubtful nature o f the occupational histories". Mote teccndy,the studies ofthe incidence of mesothelioma in Balangero chrysotlle "workers' (seebelow ) havebeen conductedby two groups in Torino. One, situated largely at the Institute fo r Occupational Medicine (COM) die other at the University of Turin In collaboration with the Institute for Pharmacological Research, 'Mario Negri*, (MN) who Investigated die health o f the Balangero workershasedupon analyses ofdeath certificates found through searching company records. Since the IOM had very lim ited access to hospital records and pathology m aterial first hand diagnostic confirmation was generally n o t possible. Blra e t al. [151 said: "The ose of death certificates Instead of cancer registries In occupational cohorts investigating cancer risk has inherent limitations due to the inadequacy of available information1'. Apparently, on rare occasions P in e t ah 0 5 ] could identify cases o f m esothetioma using means other than death certificate since they said "One case of pleural m esotheliom a was Identified in the cohort but lung cancer as a cause of death was reported in die death certificate. Since the diagnosis o f mesothelioma is still complex, this is not surprising". The methods used to Identify die I l  ` - - ------ "K>y'rat>| | :]SXh>'.5jKS8.S;|; y ,,| ftfK }ci'W jS!^ jjaj^ j r*5B$* ii m esotheliom a case v e rs not discussed. A nother group, the Unit of Cancer Epidemiology, (CPO) celled principally upon th e Registry ofMalignantMesotheliomas (RMM) [8,11,16). This only coveted infbnnation from 1980 onwards b u t cases among mine employees could b e Identified in some Instances In the hospital records and other Registry materials. The most recent updates of tee Balangero chiysotfle workers were done by Pita et ah [15) a t the IOM-MN and by AfitabdB et ah [8] at the RMM. Plra et al [151 compared their results 'on pleural and peritoneal cancer to those reported in another analysis conducted in tee sam e area, based on tee Piedmonts registry of m alignant mesotheliomas'. Pin. et al [15) found 4 'deaths from pleural and 1 from peritoneal cancer as compared to 6 deaths from pleural mesothelioma during tee same period la tee registry based study. They concluded that 'despite the 'different sources of data (death certificate versusregistry Information) the results for pleural cancer are in substantial agreement!. Despite (he effortsto compare the findings o f te e IOM and the RMM, the individual cases have never been matched. Prof Xa Vccchia, D r Negd an d Dr Pducchl have provided tee available undedying rtetait on tec six o res reported by Pita etah 115] to compare with, the nine 'occupational' cases reported by MlrabelH et al. [8). Poll analysis of the complex, cross-matching Is given in the supplemental data to this papec Sylvestri. e t ah (11) also assessed th e incidence of m esotheliom a in th e cohort, `on te e basis of a search o f the literature and o f tee files o f the Mesothelioma Registry of Piedtnonf. They said 'Three additional cases o f m alignantm esotheliom a o f the pleura w ere found w ith past exposure In the m ine, and no evidence of other occupations entailing exposure to asbestos'. Also, life lo n g workhistory was known for two with"no evidence of other occupations entailing exposure to asbestos. Case 1 w as a technical clerk (tee study w as lim ited to blue-collar w orkers) w ho died after te e end of follow-up. Case 2 w orked in the Balangero m ine horn 1936 to 1944. Case 3 w as included In tee study by Piolatto et ah but died after tee end o f follow up.' Therefore, case 1 can b e dism issed. Case 3 appears to be one of tee cases reported by Piolatto show n In Table 2 (supplem ental data) . Case 2, on tee basis of the dates of h ire and reparation, m ay be te e sam e as th at reported by Callstl e t al [12] Since histology w ith 1HC is tee currently recognized standard for the diagnosis of mesothelioma, no m ore than two o f tee cases reported to date have used te e technique an d so ate potentially confirm ed. However, th e exactpanel of IHC m arkers used, tee adeqoacy o f negative and positive controls, and te e staining patterns and intensities for th o se stains ate not known and so confirmation Is not definite. There is tee fo rth question that none of tee cases are specifically called 'm iners'. Por example, Mlrabelli e t 1 [8) claims to have found a `cluster o f 14 mesothelioma cases among workers who w ere active in fije mine' but only list 9 such cases in Table 1 of th eir report and none are called 'miners*. Confusion on the point also concerns th e workers studied by tee IOM and MN. Rubino et al, [13] said `tee work force has num bered about 300 m en. At present some 350 m en are employed to tee mine and its associated milling, crushing, screening and bagging plant*, Their cohort consisted o f 952 m ale workers with at least 30 days employment betw een 1 Jan 1930 an d 31 Dec 1945. Their cohort data are not broken down Into those w ho worked at the m ine and/ or tee mUl/piant as opposed to those who only worked a t tee m ine versus those who only worked at tee "m lll/plan. Enigmatically, Rubino e t ah [131 said "almost all w orkers had changed their job during their w orking life at tee facioiy", and Piolatto e t ah [14) said their study is an 'update o f cancer'm ortality among chxysotfle asbestos litters' b u t 'the cohort comprised m en who had w orked for a t least one year a t the factory betw een 1945 and 1987. 'What Is meant by `factory* is not explained. Similarly, Pita et ai. [15] said they `obtained employm ent data from personnel records at tee factory and ascertained vital status and causes o f death through population registers and copies o f death certificates from municipal registration offices.1 So it looks like the IOM - MN has been studying factory workers' rather th an 'm iners'. The te n a 'p la engenders fo rth confusion. Specific data for millers are also n o t provided though reference is frequently m ade to work to tee m ill. Therefore, taking tee strictest view of the data presented to the Hteratune to date by the IOM. and the RMM, including tee recently obtained unpublished data from MN, n o m ote vi , ^ > a %s , v ^ s i ^ s | jf y w m s a a x |itf i xsasaa& sxrer- ^dsirioSoBVEtelisfc andPublicU h -2015, IM M M Jl& K v 'K -.i'C 'ts.r r j a E 8 as-j3 .T nsyawBwessTBisai than two c u e s alleged to be mesothelioma would begin to m eet present day diagnostic standards. However, neither case can b e said to be, w ith a high degree of certainly, a Balangero asbestos m iner. BALANGERO CHRYSOTILE COHORT SOU RCES OF ALTERNATE CAUSATION General Considerations Piedm ont was home to many asbestos industries 0.7), T he'region around and la Turin, a n d Balangero historically housed an extensive asbestos industry w ith many, form er asbestos factories and plants. In consequence, amphiboles were the 'common urban environm ental pollutant In Turin' [12]. Amphiboles first arrived horn South Africa, at the factory at Basse dl Dora fCaplam lanto') in Torino w hich made 'a ll kinds of w hite, blue, and araositc asbestos' articles and specialised in w hite and blue asbestos textiles (18). O ther factories in the area also used South African blue (croddoiiie) asbestos and amosite [19). All crude asbestos for Italy was initially delivered to Genoa and some men from (he Piedm ont would commute to w ork from the m ines and plants to fire port to w o rk in shipyards and steel mills [IB,20). Piedm ont was hom e to the greater part of the Italian asbestos industry 21,22) The extensiveuse of amphlbole asbestos is reflected in the significantly elevated incidence of m esotheliom a in Turin and the surrounding province and has been demogcaphtcally dem onstrated for (his region {20,22} with respect to the location o f die main asbestos Industries and die residences o f mesothelioma cases. Clusters of pleural cancers in different parts o f th e Province w ere also found in other 'high-risk, areas due to a wide range of asbestos manufacturers (mainly textile [231, and the production of brakes and dutches) and Industrial use of asbestos products [20], A population based case control study of two Industrialized areas dose to th e City of Torino also demonstrated large numbers o f m esothdlom as in relation to the many industrial activities found in the area [24], 7he spatial mortality studies also found a circular d u ster around Turin that reached th e lanzo Valley where Balangero Is situated 20). Sources in the mine and th e mill Pooley [91 identified significantly elevated concentrations o fcrorldolite iu the lungs ofthree workers and four out o f nine control subjects living in the vldnity o f the mine (see above) (Table 1), In addition to foe treroolite/acttaollte noted shovecowand human lung tissuefrom the Lanza valley also contained amosite whilst those from Susa had both am osite and ctoridollfe, Ah sanqiHag found long croddolite fibres in both Lanza and Susa valleys. Thenurneroussoarcesofcomtnetdalamphlbde asbestos exposure Inand aroundBalangero explain foe Jungburden findings. Production had inermsed during foe postwar reconstoicfioa period and technological Improvements in the mid-1950swere mainly in mining methods and only marginally in diy control During foe sixties production in foe mitt increased to between 100,003 and 150,000 tonnes pecyear. [t<SJ, Some 'm ine' workers also worked outside Balangero w ifopossible exposure to othertypes o f asbestos [17), in railw ay coach construction, fas an iron foundry and in a motor vehicle assembly p lan t Purther alternate, exposures in the mine may have come from foe use of croddolite asbestos cement from Casale. Croddolite. was also apparendy used la the Balangero mine foe 'shot? periods in small amounts for m aterial testing and preparing mixtures [15], and In different parts o f foe Balangero mine and m ill foe longer' periods for various purposes. Croctdoltte was also at rimes added to foe Balangero duysotile ore; [25). Croddolite and amosite were transferred to foe mine by Balangero subcontractors from different asbestos firm s. Amphlbole asbestos cement coverings in th e new part of the Balangero nnK" [12] w ere said to contain croddolite from Casale. Croddolite and amosite were also transferred to Balangero la jute bags [U]. These are known to create a significant mesothelioma risk (e.g. see 2(3) Other exposure to airborne asbestos can result from buildings constructed on setpendnidc cocks which may contain manufactured tu to rials containing arisestos. Occupations at Risk of Mesothelioma In the Pledmonte Many job titles end occupations have i l ^ " - '" -- w -------------- r o w * 1 v^r:? I I 1 been reported to b e a t risk o f mesothelioma In (Mkabelll e t ai, X7), their Table 2)]: All three tb e Piedmonts [20,22,24,27-29], Most of these cases "of malignant m esothelioma in workers com port well with, the 'alternate exposures* never employed at the Balangeto mining site, noted in m ost of M tobefii e t al'a [177 cases but occupationally exposed to chrysotile from said to b e attributable to Balangero chrysotile the mine", ore m arked w ith an V , MIrabeUI et exposure. Rublno et al [22] ldeDtlfied 22 fades al [171 said 'coses 15 and 17 m ay also have been a t risk. Room e t a l [24] identified several exposed to fibrous tremoUte* a t a mill outside Industries as welt as trades a t risk. Nesti. et ah the mining rile not owned by Amiantifcca [29] found, on the basis of the Registryanalysis, treating Balangeto ore. Case 1<5 likewise since high risk categories to indude bricklayers, plum bers, carpenters, electricians and others. Mirabel!! et a l [28] also noted that `Other Industries producing asbestos-containing m aterials, such as asbestos textiles, finings for brakes and dutches, and asbestos cardboard and packing, were mainly located in Piedmont1. he analysed ore to rn the Balangero mine and bufit/monaged pilot plants for ore exploitation. These could have used croddolite in their construction. All 3 cases had significant sources of alternate exposure. "Cases o f m alignant m esotheliom a due j 1ll i I i \ Mauhie et a l [20] found cases in the tortile to househoid/eavirounentsl exposure* (5 sector, cement and a foundry) synlhedofibre textile plants, and local railway carriage cases) (MirahelK et a t [17], their Table 3): Of the five "cases of m alignant mesothelioma due l `{ construction. to household or environmental exposure", four of the five merely lived in 'proximity o f the \ mine site*. However, num erous other sources i Case Specific Alternate Sources of Exposure of commercial, ampHbole asbestos exposure Outside the Mine and the MiU were present in the area immediately around Balangero. (Details in the supplemental data.) M irabelli et al [8] believe Balongeco chrysotile also significantly contributed to the "Cases o f m alignant m esotheliom a production of mesothelioma found in 13 other among persons exposed to m ine tailings ru ed people exposed to Balangero chrysotile outside of th e workforce. They considered 17 cases outside mine* (5 Cases). QdliabeUt e t aL [17], their Thbte 4)i Of the five 'coses of malignant 1 in four exposure categories, m arked with a mesothelioma among persons reposed to mine superscript V On their table legends) to denote tailings need outside mine?, three are marked `possible exposure to other types o fasbestos*. with an V . Using asbestos contaminated Jute bags by Case 23 was not discounted as a "Cases o f m alignant m esotheliom a potential cause in their series [171 "Besides am ong w orkers em ployed by sub-contractors chrysotile asbestos o f different fibre length, the at th e Balangeco m ining site" (5 Cases) mill produced by-products of different specific (Mfcabefii et al [17], their Table IB): Of the weight end crushed stone (gravel shingles) five "cases of malignant mesothelioma among to be used as ballast" [11], Exposure to mine w orkers employed by sub-contractors at the Balangeto m ining`site', one is marked V as tailings used as ballast may hare involved tremolite exposure w hen it was from other l having possible exposure to other types of asbestos. Three others worked in facilities mining areas outride Balangero and processed a t rise Balangero m ill [17). In ail, at least three I i and/or had Job titles a t potential high risk of the five cases claimed to h e due to Balangero for mesothelioma. Case 10 was also probably exposed to ctocidofite transported to and used in the construction of the asbestos m ill chrysotile bad potential arppUbole exposures. I i Therefore, four o f the five cases had significant Conclusion potential sources o f alternate exposure. fourteen of foe 17 mesothelioma cases ! i "Cases o f m alignant m esotheliom a in reported by M kahdll et a l [17] attributed to 1 w orkers never em ployed a t th e Balangeto Balangero chrysotile w orked in occupations m ining site, b u t occupationally exposed to chrysotile team th e m ine" 0 Cases) a t high risk for mesothelioma from potential arapblbole asbestos exposure. l/ Eternlt Casaie Monferato Asbestos Cement Plant Balangcro is an open pit strip m ine ca 25 miles north-west of Ruin. Winter snow and th e rainy season would prerent the miners from w orking in the mine for several months a year. A substantial amount of moonlight w ork w as therefore done in other nearby facilities. There w ere myriad opportunities for exposure to am phlbole asbestos in these facilities, One o f the most Important o f these sources of potential alternate exposure was the Eternlt Asbestos Cement plant in the town o f Casaie M onfetrato one of the hugest asbestos cement pipe factories In the world. It operated m ote or less contemporaneously (1906 - 1986) with the Badangero mine site (1915 - 1998) being relatively near the mining area itself. Since the Casaie asbestos cement factory was an im portant source of nocidolite and amosite exposure, and Bslangero and Casals were both ow ned by EtetniC, an exchange of workers could have taken place between these two facilities w hen Bslangero ceased mining. Whilst foe company records a t Casaie do n o t list many Baiangeco workers, they would not have recorded relatively brief eg . 5 to 4 week, work periods particularly for workers in foie pipe section. Casaie produced foe 'famous Halit brand of asbestos cement shingles, sheathing and pipes' and became th e first to manufacture asbestos cement for water mains. The water m ain division of their business expanded within, a very short time a little m ore than 20 years after it began In 1907, to `unbelrevabie proportions', resulting in brandies and agents in practically every European counfry, India and other p u ts of the world. It became In turn foe second largest distributor o f asbestos cement roofing'. (30). T he Casaie facility is a major risk factor fo r mesothelioma in th e Piedm onts. This results from its vast scale and extensive use o f croddoltce and amosite. The Casaie Plant has been said to have an 'overwhelming' influence on the epidemiological situation o f th e Piedmonts and causative o f large num bers mesotheliomas [171. Mauhle et ah [20] in their study o fth e spatial map o f pieural cancers o f the Piedmonte said: T he m ost striking mortality excess appears foe both m en and women in the area around Casaie M onfetrato (their Fig. 2). The clusters stretch south, In the surroundings of Alessandria, w here occupational exposure to asbestos w as mainly due to the chemical Industry. Pot m en, the d u ster is m ore elongated and, w ithout solution o f continuity, reaches areas w here it was common fo r workers to commute to and from Genoa to w ork in shipyards and ste d m ills. A sim ilar picture characterized pleural cancer In women' BALANGERO CHRYSOTILE COHORT ASCERTAINMENT BIAS Different methods of ascertainment may have created bias. Variation fn cohortstarting dates Euhlno e ta l 1131Includedmen who started wotk in 1930. Piolatto e t a! [141 appear to only indude those who started working in 1946, Pita e t al [151 included those who 'started working betw een 1930 and 1975* bot said, somewhat confusingly Hhdr follow up began In 1946'. OjHsti [12] said workers Vorldng in Bslangero from 1939 to 1944 were not infolded in the cohort of Belangers miners and millers studied by Rnblao et al [13] and by Piolatto et al [14). Case 3 w as indnded to the study b y Piolatto 61 aL b u t died after foe end of follow-up.' [12] Variation in CohortInclusion CriteriaMinimum work duration Bubtoo e t a l [13] included all m en who w orked a t least one month. Piolatto et aL [14! excluded those who worked less than one year. This dearly affected outcome. Pira e t a l [15] noted this and said exduslon caused one case of pleural mesothelioma to b e m issed as h e was engaged for a `short period (<1 year).* SHU, there appears to be overall 'agreem ent' to. foe number of alleged cases. This would seem to Indicate that between foe IOM and foe EMM roost if not all mesotheliomas have been identified regardless of the variation in minimal w ork duration, Historical Recall Bias Reliance on second handinterviews created recall bias and m uch opportunity to miss many l V . 2015 12 1Epidstrbgy Bfetnfisfc andFiiHcHmI - , Vsbis , Humber other important sources of exposure due to 'retrospective interview of closest relatives* llli, Rubino [22] also said T h e conclusion thus seems w arranted that the data regarding an unequivocal o r probable exposure in the m esothelioma group should be considered conservative*. R ath er difficulties with the accurate assessment o f alternate exposures results from the apparent Inability to classify workers as miners, 'millers' or 'combinations'. Uhls goes to the fact that Rublno et al [13] said "alm ost aX workers had changed their Job during their working life at the factory*. That means all of the Balangero weakens could b e susceptible to the same types of alternate exposures died above in the mill not withstanding exposures potentially Incurred in the town and the surrounding municipalities. O ther exposure information on the working and environmental conditions in the Balangero mine w as taken horn legal proceedings. One m ust therefore question the thoroughness of this source of data [11] (citing the Preturn di Torino I??6) [15]. Further confounding could arise from reliance on 'ad hoc* examination of the files from the Mesothelioma. Registry of Piedmont and o f the compensations in cases of asbestosds [11], BALANGERO CHRY50T1LE COHORT B A IA N G E R O IT E The role of balangeroiie as y e t another alternate cause of the mesotheliomas found at Balangero is undear, lhareeentstudy,TO icietal. [31] said 'Considering foe profound differences betw een foe structure o f baiangeiote and amphiboles, previous results and observations on the poox ecpperslstence of balangerolte, and foe present data, w e conclude thatbalangerolte traces may contribute to the overall toxldry of the airborne fibres h r Balangero, but may not b e compared, to tremolite cm considered foe sole responsible for foe excess ofmesothelioma found in Balangero*. It would therefore appear to be'm ore likely than not that balangerolte is a not a major contributor to mesothelioma risk but foe data are stilt insufficient to categorically exclude a causal role for this flbtc. CONCLUSIONS All foe evidence suggests that croddolite, amoslte and trem olite are responsible for the alleged mesothelioma cases at Balangero. MlrabelU et al IB) admit their `assessm ent was based on 'incomplete data'. They regard foe association between Balangero chrysotile and mesothelioma only as possible'. They `had no access to the individual records of th e cohort members alive in 1987* and Inform ation on exposure (was only) available for 5094 of all cases in the RMM*. Myriad sources of naturally occurring and commercial amphibole asbestos exist to account for foe alleged Balangero cases. The diagnostic accuracy of foe cases can also be questioned and amfuston surrounding Job tides rises foe question if any of fo e cases actually ever occurred in 'miosis' per se, ACKNOWZBDSEtCBNISrBttnmolbanhsto Professors tiro, Romano, Tlelotlo, U Ytabto, ou tNctifa r provision o fdata aiut rUiamtan i f sam son various oenastons aver thepastJhirytars. References {1} CompifcnDoifc, Etoaiir O, Som L BaJaufiennie, a oevr Bbsow xSictt relaxedto gagetteJrom Balaagcto* Italy. tacdoAMfeenlosltt, P I 5om ao E,bdkao E, OpdU.S,Bdlis .Eaviraomatd exponueto Vbestos udo& ettac*& tilttues ustafm tasl luqg add- d ita iE a ti a W 1`40?&):X0W- tO ie. 3] Bdiuro. ^ c trv ti G. New dii* on briaagetotte ftad cu lo stu n ate bom fiplac scq?cQtlpJtcs, BuropJ (41 D ariaJMG, AddlioaJ, M dntaiii Q >QkrBG, Nfcea K. Vadtilm la the ardnogenldtf of tranollic dust sim ple? o fdifficjdgDOiybbgf.Aon. N X AemS. S d WU&45it&i90. 0] UUaBdilD|C^aift.^rotttfiQr*fflO0spxtlcotsirith learris d peritooeal tmacx la.AltVaBt 01 SuoJ (In. D*UtnJJ$?IdtjaJtaher. 7m Ncrr*ec6:2StMS. f I i 1i j\ i I SX -S ' p^&s&mw&w&i&l iS ^ f t^ M M ii^ V l n* Addftionat referencess forSuppUmentat data Q2\ Bruno C, CombtFt Innocratt G, H igain} c ; VfooiBK w ul Zanca} R (199ty Studio di m ortella dellapopoinione (erigesse n d communiubicatiIn prosdmlts.detti c a la ta d i cdiotlio diB alsngero.iMcxtaiirp itody ofth jeridcnt pepulatbn in communzlci located tome cheyaotG t ratea afB aiaajera A no. tatiam <S^}deodo)o]a, A ci dell* Xyi adoni in su le (V entili), >5. (abito) 3 3 ) Rubino GB, Cocotti E.S cansati G, (XJ>68>**Ricerca,nella popofedone dd )t pUccbo pleuriche ca ld ftrtc carne segue, radiologico di t&poB&one uto (cdsottto). A tti d d convegno cttstad isuo* patologia de asbesto CTorioo). p e s ta rti iota odlotogkal ctudr o f odSeA piena! pltupes la thepopubdonas foliows, ng. uba* tos dtuiG oa (duysotle).tooceedS&gi o fth e meaiog of th nudy on asbesto Iflatsa] 5* HuUoo GB,Scam ati G, D oluto G, F in R The card* nogenic eflfcet oftrem ule am lrux n epideatioiogtcal icudjr on (he tale o fotololdlao and -racthyleat b lr (2*nabyiinllinc} In Icdudng bUdder cancec In man. Batfron Rcs l9 & F r.U l~ 2tf doUO.lOlS/DOlS- 5 U W W t PMZD.7084156