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Per. Mineral. (2008), 77, 2, 27-34 doi:10.2451/2008PM0010 http://go.to/permin

PERIODICO di MINERALOGIAestablished in 1930

An International Journal ofMINERALOGY, CRYSTALLOGRAPHY, GEOCHEMISTRY,ORE DEPOSITS, PETROLOGY, VOLCANOLOGYandappliedtopicsonEnvironment,ArchaeometryandCultural Heritage

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Abstract. — Calabrian ophiolitic deposits findindustrial uses in two areas depending on theconditions of the deposit: the first exploits thefriabilityof rocks, toobtain theaggregateused inlocalconcretes,whiletheseconduseconsistsoftheproductionofthemassiveblocksofstonesusedfordecorativeelements,frames,paving,flooring,lapidaryandjewelsart,etc.Weselectedthesetwominingandmillingmethods togainanunderstandingof theiroperationswiththeaimofassessingtheriskoftheworker’sexposuretoasbestosairbornefibers,andthepossibledispersionofsuchfibersinthesurroundingenvironment.Also,theworkingcyclerelativetotheproductionoflapidarymaterialwasinvestigatedinordertoassesstheriskoftheworker’sexposuretoairborneasbestosfibers.Furthermore,bothsquaresandstreetsoftheurbandistrictsneartheophiolitesquarriesandmillingplantswereinvestigatedbyairsampling to determine the possible dispersion ofasbestosfibersintothesepopulatedareas.Sampleswerecollectedontomembranefiltersandanalysedusing Scanning Electron Microscopy (SEM).ThequalitativecharacterisationofthefiberswascarriedoutbyEnergyDispersiveSpectroscopy(EDS).Theresults show that the highest values of the meantremolitefiberconcentrationsareobtainedduringthe

diamondwirecuttingoperation(0.071fiber/cm3)andthebroomingprocess(0.059fiber/cm3).Furthermore,about 42% of the respirable asbestos fibers arereleasedduringthecuttingoperations.Eventhoughthe worker’s exposure to tremolite fibers did notexceedtheregulatorylimitspecified,theyshouldbesuppliedwithsuitablepersonalprotectionequipmentinordertoreduceasbestosriskexposure.Furthermore,theworkersshouldbeeducatedandinformedabouttherisksrelatingtooccupationalexposuretoasbestosfibers.Theasbestosfiberconcentrationsobtainedbyenvironmental samplings performed in the urbandistrictsdonotexceedthelimitof1fiber/litre,asWorldHealthOrganizationrecommendsforurbanareas.However,inordertoreducethedispersionoftremolitefibersthebestavailable techniquesshouldbeadoptedandusedtoreduceexposure.

Riassunto.-IgiacimentiofioliticidellaCalabria,grazieallelorodiverseproprietà,vengonoutilizzatiin due particolari tipologie di lavorazioni. Taliattivitàsonostateesaminateal finedi identificareleprincipalifasidelciclolavorativo,letecnicheele apparecchiature utilizzate. La prima tipologia,sfruttandolafriabilitàdellerocce,consentediottenereilprodottousatoprincipalmentecomeinerteperlaproduzionedicalcestruzzoenelsettoredell’edilizia.La seconda invece, consiste nella produzione di

Calabrian ophiolites: dispersion of airborne asbestos fibers during mining and milling operations

aneta MaRia ZakRZewska 1,*,PietRo Paolo CaPone 1,antonino iannò 1,VinCenZo taRZia 1,antonella CaMPoPiano 2,egidio Villella 3andRenato giaRdino 3

1ISPESL,LaboratorioPolverieFibre,CentrodiRicerche,LameziaTerme(CZ)2ISPESL,DipartimentoIgienedelLavoro,MontePorzioCatone,Roma

3ASLn°6,S.P.S.A.L.,LameziaTerme(CZ)

*Correspondingauthor,E-mail:[email protected]

28 a.M. ZakRZewska, P.P. CaPone, a. iannò, V. taRZia, a. CaMPoPiano, e. VillellaandR. giaRdino

grossiblocchidipietracompattausatiperlavorazionipiùparticolari,qualiadesempio,elementidecorativi,cornici,pavimentazioni,artelapidea,monili.

L’obiettivo del presente lavoro è di valutarel’eventualerischiodiesposizioneafibrediasbestoaerodispersedurante i processidi lavorazionedeimaterialiprovenientidagliaffioramentiofioliticielapossibiledispersionedi tali fibrenell’ambientecircostante.Atalfinesonostatieseguitiicampionamentipersonalidurantelalavorazionedeimaterialiofioliticiedalcunicampionamentiambientalinellevicinanzedellecaveedegliinsediamentiproduttivi.Icampionidiaria,raccoltisullemembranefiltranti,sonostatianalizzatiutilizzando ilMicroscopioelettronicoaScansionecorredatodiMicroanalisiaraggiXperlacaratterizzazionequalitativadellefibre.

La valutazione dell’esposizione professionalehaevidenziatochelaconcentrazionedellefibreditremoliteèinferioreailimitiprevistidallavigentenormativama è, tuttavia, necessario chevenganoadottate le norme di protezione indispensabili ailavoratoripotenzialmenteespostiarischioamianto.Inoltre,ènecessariocheglistessisianoformatiedinformati sui rischi connessi all’esposizione adamianto durante il lavoro. Dai risultati emergeche la concentrazione media di fibre respirabilidi tremolite è maggiore durante le operazioni deltagliodelle lastre con il filodiamantato (0,071 f/cm3) seguitodalprocessodibocciardatura (0,059f/cm3).È statoappurato, inoltre, checirca il 42%dellefibreriscontrateall’internodell’impiantovienerilasciatodurantelelavorazionideltaglio.Ivaloridelleconcentrazionidifibrediasbestoottenutidaicampionamenti ambientali effettuati nei comunisedidellecaveedegliinsediamentiproduttivinonsuperanoillimiteraccomandatodallaWorldHealthOrganizationparia1fibra/litroperlezoneurbane.Alfinedicontenereladiffusionedellefibrediamiantonell’ambiente devono essere adottate delle best available techniquesdisponibilisulmercatoperaltrerealtàproduttiveincuiilcontrollodelladispersionedifibreèessenzialesiapermotividiigienechedisicurezza.

key woRds: ophiolites, asbestos, tremolite, airborne fibers.

intRoduCtion

Theophiolites,agroupofbasicandultrabasicmagmaticassociationsofrocks,duetotheirtypical

dark greenish colours are called greenstones.InCalabria,inthesouthofItaly,thegreenstonefieldsoftheMountReventinohaveaconsiderableimportanceastheyareanimportantandeconomicresource.Thesematerialsareusedinbuildings,intheproductionof theornamentalstones,andasdecorative jewels.Unfortunately thesedepositscontainasbestosfibersthatmaybereleasedduringtheminingandmillingof thesegreenstones. Ifthesefibersarerespirabletheymaypenetrateintothelungtissueandconsequently,mayleadtoanasbestos-related disease (e.g., asbestosis, lungcancerormesothelioma)(SelikoffandLee,1978;McDonaldandMcDonald,1998;SuzukiandYuen,2002;Senyigit et al.,2004)

TheclassificationschemeofthegreenstonesandtheiruseinrelationtotheirofasbestoscontentaredefinedintheMinisterialDecreeof14May1996.Suchclassificationisbasedonthepetrographicinformation.TheophiolitesoftheCalabrianArcareconsideredtohavebeenpartoftheneo-TethysoceaniclithospherethatonceseparatedtheEuropeanandAfricanPlates(Guerrera et al., 1993;Cello et al., 1996).TheCalabrianPeloritanArclinksthesouthernApenninicchaintotheMaghrebianchain(Amodio-Morelli et al. 1976)andissubdividedinto northern (Sila and Catena Costiera) andsouthernsectors(Bonardiet al.,1980;Tortorici, 1982).ThenappesystemofthenorthernCalabrianPeloritanArcissubdividedintothreemaintectoniccomplexes:theApennineComplex,theLiguridecomplexand theCalabrideComplex (Ogniben, 1973). In the literature, theCalabrianLigurideComplexhasbeensubdividedintoseveraltectono-metamorphicunits:theDiamante-Terranovaunit,theMalvitounit,theGimigliano-MonteReventinounit and theFridounit (Amodio-Morelli et al., 1976). The Gimigliano-Monte Reventino unitconsistsofserpentinites,metabasalts,metagabbros/metadoleriteswithametasedimentarycovermadeup of marble alternating with calcschists andquarzites(Piluso et al., 2000).Theserpentinites(withcloselyassociatedophicalcites)aremainlycomposedbyserpentine,actinoliteandchloritewithminor relictsofspinel,orthopyroxeneandolivine.Themetabasitesaremainlyrepresentedbygreenishtogreyishepidote-chlorite-actinoliteschists.Themineralassociationincludeschlorite,epidote,actinolite,whitemica,albite,quartzandlawsonite.Thebandedtextureischaracterisedby

Calabrian ophiolites: dispersion of airborne asbestos fibers during mining and milling operations 29

thinalternating layersofalbiteandsubordinatequartz together with epidote, amphibole andchlorite(Piluso et al., 2000).

Method and teChniques

Thegreenstones,duetotheirdifferentproperties,areusedintwoparticularmanufacturingprocesses.Thefirsttypeexploitstherocksfriabilityallowingit to be used principally as the inert filler forconcreteproduction.Theseconduseconsistsoftheproductionofthelargeblocksofstonesusedmainlyfordecorativeelements,frames,pavements,indoorflooring,lapidaryandjewels.Andinturntherearetwodifferentmillingprocessused.

The production of the friable material issubdivided in two phases, the first takes placedirectlyinthequarrywithselectionofrawmaterialandthesecondoccursatthecrushingandsieveingplant where the material, transported from thegreenstonequarry,isunloadedinsidethehopperandcrushed.Nextitismovedbyaconveyorbelttovibrating-sieveswhere it is subdivided in tohomogeneoussizeclasses.Thefinalprocessingphaseconsistsofloadingthematerialontrucksfortransport.Itisworthnothingthatthecrushingandsizingplantisequippedwithaclarificationsystemofrecycledwaterandmud.

The ophiolitic site, where the rock is moremassive, situated, for example, near the urbandistricts of Conflenti, are characterized by aquarryingactivityofthelargeblocksofstone.Theworkingcycle,inthiscase,differssomewhatasafunctionoftheenduseoftheproduct.Regardless,oftheproduct,thefirststepiscuttingtheblocksandtransportingthemoutofthequarry.Recalltheblocksarecutintoslabsbyeitheradiamond-wireordiamond-blades.

Basedon the thickness,hardness, colourandveinswithin the slabs, a series of thedifferentsuperficial treatments are performed to obtaindifferentproducts.Thepolishingprocessproducesa product used for pavements and decoration.The brooming process is obtained by rotatingplatesequippedwithWidia-tips,thatgivesslapsa rough and irregular look.Theseproducts areusedforstreetpavementsandoutdoordecoration.Theslapsobtainedbythepolishingorbroomingprocess are cut with diamond blades to obtain

tiles which represent the finished product. Forsomeapplications, theslapsareglued together.Theseworkingprocessesareperformedinawetabatementsystem,exceptforthestone-masonorstone-breaker,whichareperformeddirectlyontheblocksandslabswithchisels.

The working cycle relative to production oflapidary material was investigated in order toassesstheriskoftheworker’sexposuretoasbestosairbornefibers.

In order to verify the presence of asbestosboth bulk and air samples were characterized.AnalysesoffibrousmineralswerecarriedoutonnaturalsamplesoftheophioliticrocksoccurringintheneighbouringPlataniaandConflentiareas.Fig.1showtheGeologicalmapoftheCalabrianPeloritanArc,northernsector(Piluso et al., 2000),andthelocationoftheareaofstudy.

The personal exposure data were collectedbypersonalsamplingsaccordingtoItalianLawDecree277/91.TheportablesamplersAcquariaAcquaria(mod.Personal)and metallic selectors were usedandmetallicselectorswereusedwithaflowrateofonel/min.Polycarbonatefilterswithaporesizeof0.8µmandadiameterof25mmwereused,andthevolumeofairwasestablishedinrelationtothequantityoftheairbornedust.

Bothsquaresandstreetsnearthequarriesandthe greenstone processing plants of the urbandistricts of Decollatura, Platania and Conflentiwere sampled. Temperature, relative humidity(R.H.)andwindvelocity(W.V.)weredeterminedbyathermoigrometer(mod.Testo445).

Thesamplefilterswerepreparedaccordingtothe analysis method specified by a MinisterialDegree 6/9/94: Quantitative determination of airborne asbestos fiber concentrations in indoor environments. A portion of each filterwas transferred onto an aluminium stub, andthencoatedwithathinlayerofgoldtoincreasetheconductivity,andanalysedwithaScanningElectronMicroscope(Leo1430).ThequalitativecharacterizationofthefiberswerecarriedoutbyEnergy Dispersive X-ray Spectroscopy (EDS,IXRFSystemsmod.500).BasedonthePoissoniandistribution,themethodvariabilitywasestimated.


Results

T h e f i b r o u s v a r i e t y o f t r e m o l i t eCa2Mg5Si8O22(OH)2,arelativelycommonmineralin metamorphic rocks, was found in the bulkmetamorphic rocks, was found in the bulk rocks, was found in the bulksamplesfromthegreenstoneoutcrops(Figs.2-3).Fig.4showsanSEMphotographofanairborneasbestos fiber deposited on the surface. Thepresenceofthevarietyoftremolitewasconfirmedbyaqualitative fiberanalysis.Fig.5 showsanexampleoftheEDSspectraofatremolitefiber.

The values of personal exposure and thecorresponding values of the upper and lowerconfidencelimits,forthePoissoniandistribution,obtained for each duty during the lapidaryproductionareshowninTable1.Theresultsshow

Fig.1–GeologicalsketchmapoftheCalabrianPeloritanArc,northernsector(Piluso et al., 2000),andthelocationofthestudiedarea.1.ApennineUnitsComplex;2.OphioliteUnits;ContinentalcrustUnits;3.Castagnaunit;4.CalabrideUnits;5.sedimentarycoveroftheCalabrideUnits;6.LigurideComplexoftheCalabrian-Lucanianboundary;7.Miocene-Oligocenesedimentarysequences.

Fig.2–SEMmicrographofthebulksampleusingx2000magnification.


thatthehighestvaluesofthemeanasbestosfiberconcentration are obtained during a diamondwirecuttingoperation(0.071fiber/cm3)andthebroomingprocess(0.059fiber/cm3).Furthermore,about42%of the respirable asbestos fibers arerespirable asbestos fibers areasbestos fibers arefibers arearereleasedduring thecuttingoperationsasFig.6indicates.Last, the resultsof the air samplingsperformed in urban districts of Decollatura,PlataniaandConflentiareshowninTable2.ThehighestmeanconcentrationofasbestosfiberswasfoundinurbandistrictofDecollatura(0.18fiber/

litre)andassumedtooccurbecauseofthepresenceofthegreenstoneworkingplantinthatarea.

disCussion

Our sampling showed that both types ofgreenstone outcrops contain fibrous tremolite.Thepresenceofamphibolesgivesthegreenstonesparticular physical properties that make themsuitable fordifferent industrial applications. In

Fig.3–EDSspectrumofabulksample.

Fig.4–SEMmicrographofairbornetremolitefiberusingx7000magnification.


fact, theoutcropswitha lightgreencolour arerichinamphiboles, fragile, and easily broken intoamphiboles, fragile, and easily broken intofragile,andeasilybrokenintopieces; forthisreasontheyareused forconcreteproductionandasaggregate.Therockswithadarkgreencolourcontain feweramphibolesandaremoredurable;theyareusedinpavements,indoorflooring,andlapidaryproduction.

The estimation of the airborne asbestosconcentrationconfirms that the fibersdiffusiongeneratedduringquarryingactivitiesdependsonthetypeofthematerialextracted(Falcone et al.,2005).Thefiberconcentrationsarehigherinthequarrycharacterizedbyfriablematerialthaninthequarrywiththepresenceofthemassiveblocks;however,duringnaturalweatheringthediffusionofasbestosfibersisverylow.

The evaluation of the worker’s exposure toasbestosfibersduringlapidarymaterialproductionshowedthattherespirablefiberconcentrationsoftremolitearelowerthanthelimitof100fiber/litrecurrentlyrecommended.Evaluatingtheprincipalphasesoftheworkingcycle,thecuttingoperationproducedthelargestofrespirablefibers.Inthisprocess about 42% of the asbestos respirablerespirablefibers were released; during both diamond bladewerereleased; during both diamond blade;duringbothdiamondbladecutting (13%)anddiamondwirecutting (29%)operations.The appropriate abatement systemsshouldbeused todecrease thefibersdiffusion;for example the continuous use of water jetsduringthevariousworkingphasescontributestothereducingofworker’sexposure.Theasbestosfibersconcentrationsobtainedbyenvironmental

table 1 — Mean asbestos fiber’s concentrations obtained by personal samplings during lapidary production

DutyNo.of Conc. LCL UCL

samples Meanvalue(fiber/cm3) (fiber/cm3) (fiber/cm3)

Diamondwirecuttingoperator 5 0.071 0.042 0.093Diamondbladecuttingoperator 6 0.036 0.021 0.049Stone-breakeroperator 5 0.029 0.006 0.064Brooming 6 0.059 0.042 0.087Polishing 5 0.040 0.025 0.074Gluing 5 0.030 0.023 0.042

Urbandistrict No.ofsamplesConc.

LCL(fiber/L) UCL(fiber/L)MeanValue(fiber/L)

Decollaturaa 8 0.18 0.06 0.92

Conflentib 4 0.03 0.00 0.40

Plataniac 3 0.00 0.00 0.40aTemp.21.1°C;R.H.56.1%bTemp.21.5°C;R.H.51.0%;W.V.1.9m/s.W.V.0.9m/s.cTemp.17.5°C;R.H.63.5%;W.V.1.0m/s.

table 2 — The respirable fiber concentration of tremolite obtained by environmental samplings carried out in urban district next to the quarries and greenstone working plants


samplings carried out in the urban districts ofurban districts ofDecollatura,PlataniaandConflentidon’texceedthe limit of one fiber/litre, as World HealthOrganization (WHO “Air quality guidelines for Europe”, 1987) recommendsforurbanareas.

ConClusions

Theresultsofthisstudyshowthatthepersonalexposures to airborne asbestos fibers are keptbelowthecurrentlimitvaluesinItaly;however,theworkersshouldbesuppliedwithsuitablepersonalprotectionequipmentinordertoreduceasbestosriskexposureevenfurther.Inordertoreducethedispersionof tremolite fibers thebestavailabletechniquesshouldbeadoptedandusedinotherproductionareaswherefibercontrolisessential

for hygiene and industrial safety. Furthermore,the workers should be educated and informedabouttherisksrelatingtooccupationalexposuretoasbestosfibers.Thepresenceoftheophioliticsitesdoesnotseemtoplacethelocalpopulationatanelevatedrisk;however,furtherstudyisneededonthedispersionofthefibers,particularlyinthedistrict of Decollatura where, unlike the otherareas,agreenstonemillingplantissituatedintheurbancentre.

Examinations of the asbestos fibers by SEManalysisshowthattheirdimensionsarevariable.Further examination is necessary to determinethe dispersion of finest asbestos fibers. Thesefiberscancrossthepulmonary-pleuralbarrierandthereforemayleadtoincreasesinmesotheliomaandotherbenignpleuralmanifestationsasrecent

Fig.5–EDSspectrumofairbornetremolitefiber.

Fig.6–Percentagesoftremolitefibersfoundduringprincipalworkingphases.


researchesdemonstrate(Chiappino,2006;Tomatiset al.,2006).

aCknowledgeMents

Wewish to expressourdeepest appreciation toprof.R.Cirrincioneandprof.M.E.Gunterfortheirconstructive reviews, that greatly improved thispaper.

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