DEC 1973INTERNATIONALLABOUROFFICE STUDIESANDREPORTS SeriesF(IndustrialHygiene)No.13 SILICOSIS RECORDSOFTHEINTERNATIONALCONFERENCE HELDATJOHANNESBURG 13-27AUGUST1930 GENEVA 1930 Publ i shedint heUni t edKi ngdom Fort heI NTERNATI ONALLABOUROFFI CE( LEAGUEOF-NATIONS* ByP.S.KI NG&SON.Lt d. OrchardHouse,14GreatSmithStreet,Westminster,London,S. W. 1 PRI NTEDBYALBERTKUNDI G GENEVA iCONTENTS Page I NTRODUCTI ON1 LI STOFMEMBERS5 LI S TOFOBSERVERS6 PARTI REP ORTOFPROCEEDI NGS Openi ngSi t t i ng,13 August1930,10 a.m9 Fi r stSi t t i ng,13 August1930,3.30p.m15 SecondSi t t i ng,15August1930,2.30p. m26 Thi rdSi t t i ng,16 August1930,9.45a.m32 Four t hSi t t i ng,18 August1930,9.30a.m44 FifthSi t t i ng,18 August1930,2.30p. m51 Si xt hSi t t i ng,19 August1930,9.30a.m59 Sevent hSi t t i ng,19 August1930,2.30p. m68 Ei ght hSi t t i ng,20August1930,9.30a.m72 Ni nt hSi t t i ng,20 August1930,2.30p.m80 Tent hSi t t i ng,23 August1930,9.30a.m85 El event hSi t t i ng,25August1930,9.30a.m86 TwelfthSi t t i ng,26 August1930,9.30a.m94 Thi r t eent hSi t t i ng,27 August1930,10 a.m102 PARTII P AP ERSPRESENTEDTOTHECONFERENCE Hi st ori calRevi ewof MiningConditionson t he Wi t wat er sr andandt he Changeswhi chhavet akenplacesincet heEar l yDaysof t heFi el ds. ByA.E.PAYNE,HANSPI ROWandFRANKG.A.ROBERTS. . . .107 TheNat ur eandSourceofDustinMineAir, t oget herwi t haBrief Referencet ot hoseOperat i onswhi chproduceDust .By A.F. MCE WE NandJ.BUI ST129 Met hodsforDet er mi ni ngt heDustinMineAir, aspract i sedon t he Wi t wat er sr and.BYJ AMESBOYD141 MeasuresforPr event i ngt heFor mat i onofDust ,andPr ecaut i ons designedt o Pr eventPersonsInhal i ngsuchDustas ma ybeformed, andt he Regul at i onsrel at i ngt her et o.ByMALCOLMFERGUSSON andWALTERSCOTT151 TheGeneralQuest i onofMineVent i l at i onand AirRenewal ,i ncl udi ng Referencest ot heHeatandHumi di t yPr obl ems.ByG.A. WATERMEYERandJ.P.R E E S172 ARevi ewof t he Hi st oryofSilicosison t he Wi t wat er sr andGoldflelds. ByL.G.I RVI NE,A.MAVROGORQATOandHANSP I ROW. . . .178 AetiologyofSilicosis(Dust -Pht hi si s).By A.MAVROGORDATO....209 APr el i mi nar ySt udyof t he Pat hol ogyof Silicosisas Seenon t he Wi t -wat er sr and.ByA.SUTHERLANDSTRACHANandF.W.SI MSON..223 TheClinicalPat hol ogy,Radi ol ogyand Sympt omat ol ogyofSilicosis.249 I.The ClinicalPat hol ogyofSilicosis.By L. G.I RVI NE, F.W.SIMSONandA.SUTHERLANDSTRACHAN. . . .251 I I .TheRadi ol ogyandSympt omat ol ogyofSilicosis. ByL.G.I RVI NEandW.STEUART269 IVCONTENTS Page SilicosisinAust ral i a.ByKEI THR.MOORE295 SilicosisinBelgium.By Dr. D.GLI BERT313 SilicosisinCanada.By J.G.CUNNI NGHAM317 SilicosisinGer many: I.Pr esentSt at eoft heSilicosisPr obl eminGer many. ByProf.A.B HME339 I I . TypesofDus tandSilicoticLungs:Compar at i ve St at i st i caland ClinicalRoentgenologicalResearchesin Bavar i a.ByProf.KOELSCHandDr.KAESTLE...369 SilicosisinGreatBri t ai n.By E. L.MI DDLETON384 Pneumoconi osi si nI t al y.By Prof.GI OVANNILORI GA481 Appendix: Pneumoconi osi sinMarbleWor ks.ByDr.GIACOMO BI ANCHI505 Pul monar yAsbest osi s.By Dr. D.LOVI SETTO506 ClinicalandRadiologicalNot esonPneumoconi osi sdue to Asbest os.ByDr.G.MUSSA509 Radiologicaland ClinicalSt udi eseffectedamongstt heCar r ar a MarbleWorkers.ByDr.L.TURANO509 Silicosisin t he Net herl ands.By Dr. W. R.H.KRANENBURG. . . .512 Silicosisin t he Uni t edSt at es.By Dr. ALBERTE.RUSSELL535 Appendix:Inhal at i onof Asbest osDust s:I t s EffectuponPr i mar y Tubercul ousInfectionByLEROYU.GARDNERandDONALD E.CUMMI NGS563 TheMedicalExami nat i onofNat i veLabourersonEngagementat t he GoldMinesoft he Wi t wat er sr and.By A.I.GI RDWOOD..566 Sanat or i umTr eat mentof Miners'Pht hi si sPat i ent s .By A. D. PRI NGLE572 PersonalExperi encesofMi ners'Pht hi si sont heRandfrom1903 to 1916.ByA.H.WAT T589 TheFunct i onsof t he Miners'Pht hi si sMedicalBureauand t he General Syst emofMedicalExami nat i onsConduct edundert heMiners' Pht hi si sAct .ByL.G.I RVI NE597 TheFunct i onsand Experi enceof t he MedicalBoar dof Appealappoi nt ed undert heMiners'Pht hi si sAct .ByMEMBERSOFTHEAPPEAL BOARD610 St at i st i calAccountof t he Incidenceand Progressionof Silicosisamongst t heGoldMinersoft heWi t wat er sr and.ByD.SPENCEFRASER andL.G.I RVI NE618 Revi ewoft heDevel opmentofSilicosisLegislationinSout hAfrica, wi t hPar t i cul arReferencetoCompensat i on.By A. B. DuTOI T, GEORGEE.BARRYandNORMANP.DALE648 TheAct uari alVal uat i onoft heOut st andi ngLiabilitiesundert he Sout hAfricanMi ners'Pht hi si sAct .By D.SPENCEFRASER..675 TheWor kof t he Mi ners'Pht hi si sBoardand of t he MiningI ndust r y in Provi di ngEmpl oymentfor SilicosisSufferersand t hei rDependant s. ByC.J.WI LLI AMS,C.S.RAATHandB.G. O.ORPEN687 INTRODUCTION TheInternationalLabourOfficehasneverunder-estimatedthe importanceofthesilicosisproblem,inwhich ithasmanifesteda livelyinterestsinceitsinception.Ithasinfactcarefullyfollowed scientific research effected,aswellasthereportsofpracticalmen in thedifferentcountries,andithasmadeeveryefforttoassemble andcollecttheextremelyscatteredscientificdatarelativetothe subject. Gradually, thanks to national and international meetings of doctors orexpertsinindustrialpathology,andthanksespeciallytoresults obtainedin thosecountries in which silicosis is legallycompensated asanoccupationaldisease,ithasbeenrenderedpossibleforthe Officetotabulatecompletely thedataobtained,andtodrawup aprogrammeofactivity.' Simultaneously the workers' organisations affectedhave inscribed thesilicosisproblemontheagendaoftheirmeetings.Notably isthistrueofthenationalstoneworkers'associationsandin particulartheirInternationalFederationwhich,since1921, hasat eachofitsmeetingsvotedresolutionsdemandingthatsilicosis shouldbeconsideredasanoccupationaldiseaseandcompensated as such.Otherworkers'organisationssuchas thoseof theminers, potteryworkers,etc.,havealsoadoptedmotionsinsupportof thisdemand.In1925theinternationalsecretariatofthestone-workers'organisationplacedbeforetheInternationalLabour Officea requestforinclusionofrespiratorydiseasesamongstthose entitlingtheworkertocompensation. OnreceptionofthisrequesttheHygieneServiceoftheOffice inJanuary1926 addressedtoacertainnumberofexpertsaques-tionnaireaccompaniedbyanoteexplainingtheobjectofthe enquiry.The replies obtained were embodied in a reportsubmitted totheCorrespondenceCommitteeonIndustrialHygieneduring itsmeetingatDsseldorfin1928.Theexpertsassembledbythe Officeengagedinalengthydiscussionontheproblemofsilicosis andadoptedaresolutioninwhichtheyrequestedtheOfficeto delay inscriptionof silicosis in the list of diseases to be compensated INTRODUCTION since, intheiropinion,theprobleminquestionwasonewhich presented special complication and difficulty.Two points especially were said to call forfurtherresearch, that is to say, precisediagnosis ofthedisease,anddeterminationof theindispensableelementsfor establishingthedegreeofcapacityof theworkertocontinuehis work.TheCommitteeaskedtheOfficetocontinuetheenquiry undertakenandtosubmittoitatafuturesessionthedata assembled. MeanwhileMr.Butler,Deputy-DirectoroftheOffice,during hisjourneyinSouthAfrica,discussedwiththoseinterestedinthe question thesuggestionmadebyDr.Orenstein,ofcalling anInter-nationalConferenceonSilicosisinJohannesburg. ThankstothegenerousaidoftheChamberofMinesitwas possibletocarryoutthisscheme,andthefirstproposalas tothe holdingofsuchaConferencewasmadetotheGoverningBodyin June1928.TheGoverningBodythenagreedthataConference ofexpertsshouldbeconvenedtostudythemedicalaspectsof silicosisandsuggestedthataConferenceheldatJohannesburg wouldaffordanopportunityforexpertsfromothercountries toexaminetheremarkableworkdonebytheMiners'Phthisis Bureau on theRand.The Governing Body also expressed thehope thatsuchaConferencemightbringaboutcloserinternational co-operation in the study of the disease and thatit wouldendeavour toorganiseaprogrammeofresearchonthesubject. In March 1929 the Governing Body approved a provisional agenda fortheConferenceasfollows: (a)Medicalaspectsofsilicosis(pathologicalandclinical); (b)Preventivemeasures; (c)Compensation. Scientificinvestigationsonthesubjectengagedinchieflyin GermanandinEnglishspeakingcountries,theworkeffectedby CommitteesappointedbytheBritishGovernmentinrecentyears, theresultsof thediscussion of thereportsubmittedto theInterna-tionalCongressofOccupationalDiseasesatLyons, 1929adiscus-sionwhichdealtchieflywiththeresearcheffectedbytheMedical ResearchBureauandtheMiners' Phthisis Bureau in SouthAfricaaswellasresearchengagedininGermany,allthesecontributed naturallytopavingthewayforthecallingofaConferenceexclu-sivelyconcernedwiththeproblemofsilicosis. This Conference, in accordancewith the decision of theGoverning Body,metinJohannesburgfrom13 to27 August1930. INTRODUCTION3 InviewofthelengthandcostofthejourneytoSouthAfrica thefundsavailableonlyallowedoftheappointmentofalimited numberof experts.In thecourse of consultationwith theGovern-mentsit,however,becameapparentthatcertainGovernments werewillingtopaytheexpensesofdelegateschosenbytheOffice inagreementwiththem,anditwasthereforepossibletoissuean additionalnumberofinvitationsandtoincreaseboththesize andtheauthorityoftheConference.TheOfficeisextremely gratefulto the delegates who acceptedits invitation, to the Govern-mentswhichboretheexpensesofcertaindelegates,andtothe BritishMedicalResearchCouncilwhichundertooktodefraythe expensesofProfessorKettle. TheOfficerecordswithinterestand appreciation that theUnited States, in accordance with its policy of participationin theactivities oftheInternationalLabourOrganisation,wasrepresentedby twodelegates,theexpensesofoneofthembeingbornebythe UnitedStatesGovernment. InorderthattheConferencemightsecurethefullestpossible informationontheworkdoneinSouthAfrica,therewerealso appointedanumberofSouthAfricanobservers, who were ableto bepresentatthemeetingsandtoassistintheelucidationof questionsinregardtowhichtheywerespeciallycompetent. Assoonasthedelegateshadbeenappointed,eachwasasked towriteapapereitherontheproblemofsilicosisorpneumonoco-niosisinhisparticularcountryoronthatparticularscientific aspectofthequestionwithwhichhewasspeciallycompetentto deal. CertainfirmsatJohannesburgalsokindlyassistedtheOffice bytheloanofmicroscopes,anepidiascope,andscreensforthe showingofradiographs,requiredfortheexhibitionoftheslides andotherspecimensbroughtbythedifferentexpertstoillustrate certainphasesoftheirwork. ThefirmofKodak,SouthAfrica,presentedthemembersofthe Conferencewithanalbumcontainingphotographsofanatomical-histologicalpreparationsandradiographspreparedbytheservices of the Miners' Phthisis Bureauand of the MedicalResearchBureau. Thedelegateswerealsogivenopportunitiesofvisitingthesetwo institutions,aswellasagoldmineandthesanatoriumforfibrotic patients,andofstudyingthesystemofmedicalexaminationin forcefornativeworkersbeforetheyarepassedforserviceinthe mines. * 4INTRODUCTION Mr.Phelan,ChiefoftheDiplomaticDivision,wasappointed bytheOfficetobeingeneralchargeoftheorganisationofthe Conference;Dr.Carozzi, ChiefoftheIndustrialHygieneSection, astechnicalexpertoftheOffice ;andMessrs.Weaver andLittle andMissMacrae toassistinthesecretarialwork.Thematerial workofthesecretariatwasperformedbymembersofthestaff of the Chamberof Mines who were generously placedatthe disposal oftheConferencebytheChamberandwhoworkedunderthe directionofthesecretarialstaffoftheOffice. LISTOFMEMBERS Australia Dr.CHARLESBADHAM,MedicalOfficerofIndustrialHygiene,New SouthWalesDepartmentofPublicHealth. Dr.W.E.GEORGE1,MedicalOfiicer-in-Charge,BureauofMedical Inspection,BrokenHill. Dr.KEITHR.MOORE^"Directorof theDivisionofIndustrialHygiene, CommonwealthDepartmentofHealth,MemberoftheCommittee onIndustrialHygieneoftheInternationalLabourOffice,t'' ""-' Canada Dr.GRANTCUNNINGHAM,DirectoroftheDivisionofIndustrial Hygiene,DepartmentofHealth,Ontario.^- ., . Germany ProfessorDr.BHME,Director,AugustaHospital,Bochum. ProfessorDr.KOELSCH,StateIndustrialMedicalOfficer,Munich. GreatBritain Dr.S.W.FISHER,MedicalInspectorofMines. ProfessorARTHURJ.HALL,ProfessorofMedicineatSheffieldUni-versity,ChairmanoftheMedicalResearchCouncilCommitteeto investigatepulmonarydiseasesfromsilicaandotherdusts. ProfessorE.H.KETTLE,ProfessorofPathology,St.Bartholomew's HospitalMedicalSchool,UniversityofLondon. Dr.E.L.MIDDLETON3,MedicalInspectorofFactories. Italy ProfessorDr.GIOVANNILORIGA,ChiefMedicalInspectorofFactories, Member of the Committee on IndustrialHygiene of theInternational LabourOffice. Netherlands Dr.W.R.H.KRANENBURG,MedicalAdvisertotheLabourInspec-torate,MemberoftheCommitteeonIndustrialHygieneofthe InternationalLabourOffice. 1RepresentingNewSouthWalesGovernment. 2RepresentingFederalGovernment. 8RepresentingBritishGovernment. 6LISTOFMEMBERSANDOBSERVERS UnionofSouthAfrica Mr.A.B.DuTOIT,Chairman,Miners'PhthisisBoard. Dr.A.I.GIRDWOOD,ChiefMedicalOfficer,WitwatersrandNative LabourAssociation,Ltd. Dr.L.G.IRVINE,Chairman,Miners'PhthisisMedicalBureau. SirSPENCERLISTER,Director,SouthAfricanInstituteforMedical Research. Dr.A.MAVROGORDATO,FellowinIndustrialHygiene,SouthAfrican InstituteforMedicalResearch. Dr.A.M.MOLL,ChairmanoftheMiners'PhthisisMedicalAppeal Board. Dr.A.J.ORENSTEIN,SuperintendentofSanitation,Rand Mines, Ltd. Dr.HansPIROW,GovernmentMiningEngineer. Mr.F.G.A.ROBERTS,TechnicalAdviser,TransvaalChamberof Mines. Dr.W.STEWART. UnitedStatesofAmerica Dr.L.V.GARDNER,TrudeauSanatorium.' Dr.ALBERTE.RUSSELL1,UnitedStatesPublicHealthService. LISTOFOBSERVERS Dr.PETERALLAN,MedicalSuperintendent,NelspoortSanatorium, CapeProvince. Mr.G.E.BARRY,LegalAdviser,TransvaalChamberofMines. Mr.JAMESBOYD,Secretary,Anglo-AmericanCorporationofSouth Africa. Mr.J.BUIST,SeniorDustInspector,TransvaalChamberofMines. Dr.E.H.CLUVER,DepartmentofPublicHealth,Pretoria. Mr.NORMANP.DALE,Secretary,Miners'PhthisisBoard. Mr.MALCOLMFERGUSSON,ChiefInspectorofMines. Mr.D.SPENCEFRASER,ActuarytotheMiners'PhthisisBoard. Mr.W.GEMMILL,GeneralManager,TransvaalChamberofMines. Mr.G.R.HEYWOOD,Manager,RoseDeep,Ltd. Mr.H.R.HILL,ConsultingEngineer,UnionCorporation,Ltd. Mr.A.F.MCEWEN,ChiefChemist,TransvaalChamberofMines. Dr.A.J.MILNE,MedicalOfficerofHealth,Johannesburg. Dr.ALEXANDERMITCHELL,SecretaryofPublicHealth,Departmentof PublicHealth,Pretoria. Mr.B.G.ORPEN,NewConsolidatedGoldFieldsofSouthAfrica,Ltd. 1RepresentingUnitedStatesGovernment. LISTOFMEMBERSANDOBSERVERS / Dr.A.D.PRINGLE,MedicalSuperintendent,TransvaalMiners' PhthisisSanatorium. Mr.C.S.RAATH,Member,Miners'PhthisisBoard. Mr.J.P.REES,DustandVentilationOfficer,TransvaalChamberof Mines. Mr.F.G. A.ROBERTS, TechnicalAdviser, TransvaalChamberofMines. Mr.WALTERSCOTT,AssistantConsultingEngineer,RandMines,Ltd. Dr.F.W.SIMSON,Pathologist,SouthAfricanInstituteforMedical Research. Dr.J.M.SMITH,Miners'PhthisisMedicalAppealBoard. Dr.A.SUTHERLANDSTRACHAN,Pathologist,SouthAfricanInstitute forMedicalResearch. Dr.R.M.TRUTER,Miners'PhthisisMedicalAppealBoard. ProfessorG.A.WATERMEYER,ProfessorofMining,Universityof Witwatersrand. Dr.ANDREWH.WATT,MedicalOfficer,RandMutualAssurance Company,Ltd. Mr.C.J.WILLIAMS,DeputyChairman,Miners'PhthisisBoard. REPORTOFTHEPROCEEDINGS OPENINGSITTING Wednesday,13August1930,10a.m. Chairmen:SirWILLIAMDALRYMPLEandMr.E.J.PHELAN TheopeningsittingoftheInternationalSilicosisConferencewas heldintheSelborneHall,Mr.E.J.Phelan,ChiefoftheDiplomatic DivisionoftheInternationalLabourOffice,wasintroducedbySir WilliamDalrymple. Mr.E.J.Phelan :Myprincipalfunctionthismorningis toaskthe Minister,Mr.Sampson,toopenformallythisConference;butitmight beinterestingtoyou(anditwouldcertainlybefairtohim)ifIfirst indicatedbrieflywhytheInternationalLabourOfficeoftheLeagueof Nations in Geneva convened this Conferenceand what we expect it to do. TheInternationalLabourOfficeistheexecutivesecretariatofthe InternationalLabourOrganisation,.TheInternationalLabourOrganisa-tionisasocietyoffifty-fiveStates.Itis a purelyofficialbodywhichis theresultoffifty-fiveStatesintheworldhavingenteredintoacontract tocollaboratefortheimprovementofconditionsof labour.Itbeganas youprobablyknowatthesametimeastheLeagueofNations,andits Constitutionis tobefoundintheTreatiesofPeace.Oneofitsoriginal Members isSouthAfrica.TheOrganisationhastohaveasecretariatan executive to carryout its decisions; thatexecutive is theInternational LabourOffice,whichIhavethehonourtorepresenthereto-day. Now,theInternationalLabourOfficeis,asIhavesaid,anexecutive body.Itdoesnottakedecisions;decisionsaretakenbytheInter-nationalLabourConference,whichmeetsonceayearandtowhich everymemberoftheOrganisationthatistosay,everyoneofthe fifty-fiveMemberStatessendsadelegationcomposedofGovernment representatives,representativesof the workers andrepresentativesofthe employers.TheycomposetheannualConferenceinwhichisvested whatImaycall thesovereignpoweroftheOrganisationandtheyalone canformulatedecisions,whichlaterbecomeinternationaltreaties. Iwanttomakethatclear,becausetheconferencewhichMr.Sampson isgoingtoopeninafewminutesisnotthatConference;itisnotthe GeneralConferenceoftheOrganisationwhichcanadoptDraftConven-tionsandRecommendations. BeforethatGeneralConferenceactuallymeetstoformulatedecisions whichGovernmentsmusttakeintoconsiderationandwhichGovern-ments,iftheyratify,mustobserve,thefunctionoftheInternational Labour Officeis to see thatit shall have the fullestpossible informationat itsdisposal ; therefore,long beforetheInternationalLabourConference 10REPORTOFPROCEEDINGS considersthetakingofanydecisions,theOfficeinGenevaisbusy collecting,summarisingandanalysinginformation,translatinglaws andregulations, andattempting to make as complete a survey as possible of all the law and practice bearing on the question which, later, theInter-nationalLabourConferencewilldiscuss.Thispreparatoryworkofthe Officecovers the wholeareaof labourproblems.Theprogrammeofthe OrganisationwhichislaiddowninthePreambletoPartXIIIofthe TreatyofPeaceisofthemostcomprehensivecharacter. Iamnotgoingtodiscussthatprogrammethismorning;butitdoes contain,asyouwouldnaturallyexpectittocontain,averyspecific referencetoindustrialdisease ;andtherefore,amongthestudieswhich theOfficeis constantlycarryingon withtheultimateobjectofsomeday orothergoingtotheInternationalLabourConferencefordiscussion andadecision,is thequestionofindustrialdisease.Onesectionofthe organisationoftheOfficeisspeciallydevotedtothatwork,andasits headwewerefortunateenoughtosecuretenyearsagoaverydistin-guishedEuropeanauthority,Dr.Carozzi,whoiswithmeherein Johannesburg to-dayas the technicalexpertof theInternationalLabour Office.TheveryimportantworkwhichtheOfficehasalreadydonein the field of the studyof industrialdisease is due above all to Dr.Carozzi's vision, energyandintelligence.He has, in thecourse of tenyears,built upauniqueorganisation;hehascreatedanetworkofexpertsand techniciansscatteredallovertheworld,withwhomheisinconstant contactbycorrespondence;and,sincescienceneednotregardthe politicaldifferenceswhichsometimesseparatepoliticalunits,thatnet-workofmedicalcorrespondencecovers,notonlythemembersofthe InternationalLabourOrganisation,butcertainveryimportantunits whichlieoutsideit,liketheUnitedStatesofAmericaandRussia. Dr.Carozzi'sworktakesamaterialforminthepublicationeverythree orfourmonthsofabibliographyofeverythingheis able todiscover whichhasbeenpublishedonthesubjectofindustrialhygiene.Heis abletosupplytheGovernmentservicesofthedifferentcountriesand experts in industrialhygiene withsome two or three thousandreferences ayear,sothateachofthem,indealingwithhisownwork,cankeep abreastoftheworkwhichisbeingdoneelsewhere.Hehasalsobeen abletoundertaketheimmensetaskofcompilinganEncyclopaediaof Occupationand Health,thefirstvolumeofwhichwillappearinafew months.Togiveyousomeideaofthefieldcoveredandtheamount ofworkhehasperformed,itwillbeavolumeofsomethinglike2,200 pages. YouhaAre now,Ihope,some ideaoftheorganisationwhichlies atthe originofthisConference-theInternationalLabourOffice,withits generalresponsibilityforsecuringbetterconditionsoflabour,andthe IndustrialHygieneSectionwithitsparticularinterestinindustrial disease. ButtheOfficedoesnotbyanymeansworkonlyonpaper.We havehadthegreatadvantageofhavinghadattheheadoftheOffice agreatinternationalfigure,Mr. AlbertThomas, a man withoutstanding qualitiesofleadershipandauniquecapacityforachievement.He realisedfromthebeginningthedangeroftheOfficebecomingamere AcademyandthenecessitythattheofficialsoftheOffice,whenevert he occasionmightarise, should get away from purelypaper work and gainas muchdirect experienceof the problems with which we are dealing as possi-ble.Itwasin pursuanceofthis policy thatthree yearsago theDeputy-DirectoroftheInternationalLabourOffice,Mr.Butler,undertooka visit to South Africain order to become familiar with the labour problems OPENINGSITTING11 ofSouthAfrica,andwiththeobjectofintensifyingrelationsbetween SouthAfricaandtheInternationalLabourOrganisation.Duringhis visithereinJohannesburg,inconversationwithMr.Gemmiliand otherrepresentativesoftheChamberofMines,andDr.Orenstein, his attentionwasdrawntothe uniquecollectionofmaterialwhichhadbeen made by the Chamber and by the officialsof the Government in connection withsilicosis.He saw atonce the importanceof making thisknowledge internationallyavailableandhe accordinglydiscussedwithMr.Gemmili andDr.Orensteinthepossibilityofdiscoveringsomemethodwhereby t hescientistsandtheofficialsoftheothercountriesmightbeableto profitby the immense experience of thatdisease whichis centredinthis city.OutofthoseconversationsgrewthepresentConference:outof thoseconversationsgrewthesuggestionthatitmightbepossibleto conveneanInternationalConferenceofexpertstostudythemedical aspectsofsilicosisandthemeasuresforitsprevention. TheproposalwaslaidbeforeourGoverningBody,whichisthe executivecounciloftheInternationalLabourOffice,andwasapproved bythem;butSouthAfricabeingaverylongwayawayfromGeneva, andtheInternationalLabourOfficebeing afarfromrich body, itwould have beendifficultperhaps to have held this Conferenceif it hadnot been forthegenerosityoftheChamberofMines;andIshouldliketo-day, onbehalfoftheInternationalLabourOffice,formallytothankthe Chamberof Mines for the generous assistance which has made the holding ofthisConferencepossible.IshouldlikealsotoaskMr.Sampsonto convey to theGovernmentof theUnion ofSouthAfricatheappreciation of theInternationalLabourOfficeof the facilities which the SouthAfrican Governmenthasgiventous,andofthegenerouswayinwhich,assoon asitwasconsulted,itofferedtogiveeveryassistancetotheConference andtolaybeforeitallthematerialwhichithasinitspossession. ButbeforeIaskMr.SampsonformallytoopentheConference,the originofwhichIhavedescribed,Iwouldliketodrawattentiontoan aspectof it whichis notpurelymedical.This Conference,distinguished asitisbythescientistswhohavecomefromdifferentcountriesin Europe,Africa,Canada,AustraliaandtheUnitedStatesofAmerica, representsperhapsamoreremarkablebodyofexpertopinionthanhas evercometogethertodealwiththequestionofanindustrialdisease; but,importantandremarkableasitmaybeinthatrespect,itisstill more importantand more remarkable in another respect.We inGeneva oftenfeelthatwe area long wayfromthedistantcountries,andIhave no doubtthatSouth Africansoftenfeel theyare a long way fromGeneva andthatGenevais dealing withproblemswhichareremotefromSouth Africanpreoccupationsandthat,toputitquitefrankly,theLeagueof NationsspendsthegreaterpartofitstimediscussingpurelyEuropean problems.Thatisonlyahalftruth.ItistruethattheLeagueof NationsandtheInternationalLabourOrganisationdospendagreat dealoftimediscussingproblemswhichareofmajorEuropeaninterest; butitisnottruethattheseproblems,orthesolutionofthem,hasnot adirectinteresttothemoredistantcountries.Itisunfairtomake theseobservationsasacriticismoftheLeagueofNationsorofthe InternationalLabourOrganisation.TheLeagueofNationsisnotan internationaldictator;theLeagueofNationsisnotasuper-State;the LeagueofNationsis notsome Martianbody which meets inGenevaand decideswhatisgoodforFrance,orItaly,orSouthAfricaorAustralia. TheLeagueofNationsisexactlyliketheSouthAfricanParliamentor the British Parliament or the German Parliament.It is in nowisedifferent fromthememberswhichcomposeit;andwhenitmeetsinGeneva,its 12REPORTOFPROCEEDINGS activitiesaredictatedbythe influenceofits mostactivemembers.The LeagueofNationsdoespreciselywhataParliamentwoulddowhena majorityintheParliamentdecidesonacertaincourseofaction,and thereforeitisnotajustcriticismoftheLeagueofNationstosaythat itsactivitiesaretooEuropean.Butitisperhapsaregrettablefactafact,however,forwhichthelessactivemembersoftheLeagueare themselvesresponsibleandnotsomesuper-body. Now,whatis thecorrectivetothat?Whatisthewayinwhichthe LeagueofNationscanbeledtopaymoreattentiontonon-European questions and to become really in its activities a more world-wide organisa-tion?Theonly way in which thatcan be done is for thenon-European StatestobringtheirproblemstoGenevaandinsist,astheEuropean Statesdo,thattheirproblemsshallbedealtwith.SouthAfricahas now takenthe lead byfurnishingan example of how this can be done. ThefactthatthisConferenceismeetinginSouthAfricaistherefore ahistoricoccasion.Itis thefirstConferenceconvenedbytheLeague ofNationswhichhasmetoutsideofEurope.Itistruethatthefirst InternationalLabourConferencemetinWashington,intheUnited StatesofAmerica;butthefirstInternationalLabourConferencewas notconvenedbytheInternationalLabourOrganisationnorbythe LeagueofNations.ItwassettledintheTreatiesofPeace,andithas notmetinWashingtonsince,forthesimplereasonthattheUnited StatesdidnotjointheLeagueofNationsortheInternationalLabour Organisation;andwiththedisappearanceoftheUnitedStatesof America, the balance between theEuropeanandthe non-Europeansides oftheLeaguewasperhapsweightedinfavourofEurope,so thatEuro-peanproblemshaveplayedapredominantpartinthediscussionsof Geneva. To-day,forthefirsttime,Mr.SampsonisgoingtoopenanInter-nationalConferenceofficiallyconvenedbytheInternationalLabour OfficeoftheLeagueofNations,meetingoutsideEuropeandhavingas itsobjectthestudyofaproblemthatisnotbyanymeanswholly Europeaninitsinterest.Forthatreason,IthinkthatImaysaythat thisConferencemarksahistoricpointinthedevelopmentofthe League'smachinery.Itshows,Ithink,too,thattheSouthAfrican GovernmenthasunderstoodtherealmeaningofMembershipofthe League.TheCovenantisnotafinalnoranabsoluteguaranteeofthe world'speaceorof industrialprogressorofanythingelse.TheLeague is,andcanbe,nothingmorethanitsMembersmakeit.Butthe differencebetweentheLeagueworldandthepre-Leagueworldisthis: thatinthepre-LeagueworldeveryStateguideditspolicyinitsown purelyselfishinterest.IntheLeagueworldwehopethatStates will moreandmoreconsider,notwhattheycangetoutofthe League,but whattheycanputintotheLeagueforthecommongoodofthewhole; andthisConferenceisagestureofthatkind.SouthAfricahasasked theseexperts,throughtheintermediaryoftheInternationalLabour Office,tocome toJohannesburginorder tosee whatcontributionSouth Africacanmaketowardsthesolutionofagravemedicalproblem. Icannotspeakfor theexperts, butmy impressionis thatSouthAfrica hasmoretogivethanshecanhopetoreceive.Shehashadalonger experienceandshehasaccumulatedagreatercollectionofmaterial going backfora longer periodthanperhapsanyothercountry.Butthe essenceofSouthAfrica'sgestureisherdesiretoputatthedisposalof humanityasawholethepeculiarknowledgewhichshehastoofferfor thesolutionofaverypressingproblemintheindustrialworld.Ican assureMr.SampsonthatthatgestureisappreciatedinGenevatoits OPENINGSITTING13 fullest;andthoughpossiblySouthAfricamaygainlittledirectbenefit fromthis Conference,her rewardis thatshe will havecontributedtothe goodofhumanityasawhole.Ihavenowgreatpleasureinasking Mr.SampsontoopenformallythisInternationalSilicosisConference. (Applause.) The Hon.H.W.Sampson,M.P.(MinisterofPostsandTelegraphs) : TheproblemofsilicosishasbeenoneofconsiderablegravityinSouth Africa,andtheGovernmentoftheUnionhasthereforespecialreason towelcomethassemblyinJohannesburgofthisInternationalSilicosis Conference. Our Chairman, Mr. Phelan, has dealt very minutely with theparticulars of thepreliminariesthatled uptothisConference,andhassavedmethe necessityofrepeatingthosematters.Iwanttothankhimverymuch forhisexpositionofthereasonsforwhichtheLeagueofNationsexists. Afterall,aswegetfurtherandfurtherfromthewartimeofthepast, commercialismwillsometimesask:whatdo we getoutoftheLeague of Nations?Itiswellwehaveoneinourmidstthismorningwhohas explainedtothisassemblythespiritwhichleduptotheformationof thatbodyandthespiritinwhichthisworkistobecarriedoninthe future.Iamquitesurethatthisaudienceisparticularlyinterestedin thatmatter,andI amsure theyrealise the necessityof getting theworld closertogetherindealing withworldproblemsapartfromtheproblems inregardtotheirownspecialcountries.Hehasexplainedveryfully how you,Gentlemen,come tobe here thismorning,anditis mydutyto extendto youall a verycordial welcome in the nameof theGovernment oftheUnionofSouthAfrica.Iwelcomeespeciallythosewhohave come long distancestoattendthisConference.Theirpresencehereisa signalproofofthegreatinternationalfellowshipinscientificinvestiga-tionandresearchwhichoverridesall nationalboundaries,andaffordsso hopefulamanifestationofthatgrowinginternationalspiritwhichthe InternationalLabourOrganisationembodies. Thepresenceoftherepresentativesofso manycountriesandthehigh standingofthemembersoftheConferenceaffordsalsoanindication ofthewidespreaddistributionof the menace of silicosis and of theserious light in which itis regardedby the healthauthoritiesof manycountries. Silicosis is indeed,Isuppose, individuallyperhapsthemostimportant ofalloccupationaldiseasesandonewhich,asweknow,isadangerto healthandlifeinmanyindustriesbesidesthat, ofmetalmining.The problemof" silicarisk" andhow itis tobecounteredformsto-dayone ofthemostimportantpreoccupationsofindustrialhygiene. Tothemetalminerwhoworksincertainkindsofhardsiliceousrock thedisease has everywherebeena specialdanger,andwe inSouthAfrica fullyrealise thatour local problemis only partofa world-wideproblem. Werealisethattheprominencewhichthediseasehasattainedinthis country has been due primarily to the greatextentand uniquegeograph-icalconcentrationofthegreatgold-bearingreefoftheWitwatersrand, andtotheextraordinarilyrapiddevelopmentoftheminingindustry whichisbaseduponit,andthemagnitudewhichthatindustryhas attained. Theproblemhasthusbeenwithusatoncelargerandmoresharply concentratedandthedeathsandsufferingcausedbythatdiseasehave beenmoreclearly apparentthanmight haveunderothercircumstances beenthecase. Itis impossible tostate withanydegree of dfinitenesswhattheentire ramificationofthediseasehere has been.Statistics(andmanyofthem 14REPORTOFPROCEEDINGS notcomparative)areonlyavailablesince1911.Buttheenormous burdenwhichtheindustryhastobearofnearly1,000,000perannum, totalling,I believe, some 15,000,000forcompensationclaims since1911 andarisingchieflyfromanaverageof21,000 to30,000 whitesemployed undergroundduring thatperiod,will convey to yourminds thesuffering tothevictimsandloss totheindustry. It tooka good many years before the gravityof the situationinrespect ofsilicosiswasfullyrecognisedinthiscountry;butonemay,Ithink, fairlystatethatfromthetimethatitwasfullyrealisedneitherthe GovernmentoftheUnionnortheminingindustryhaverelaxedtheir effortstocontrolthesituation. TheUnionGovernmentdefinitelyrecognised" miners'phthisis"as anoccupationaldiseasein1911, andsince t hatdatenofewerthannine Actsof Parliamenthave beenpasseddealing with thematterofcompen-sationtominersaffectedbysilicosis,ortothedependantsofdeceased miners.Fromtimetotimealsotherehavebeenincorporatedinthe MiningRegulationsa largeandincreasing numberofdetailedprovisions aimingatthepreventionofthedisease. Theminingindustryhascloselyco-operatedwith theDepartmentof Mines in the investigationand trialof preventivemeasures,and thisfact has greatly facilitatedthe developmentof a systematic preventivepolicy. Formanyyears one seemed tosee no verymarkedameliorationofthe situation,althoughonerealisesthatwithsuchadiseaseassilicosisit takes a considerable time beforechanges in occupationalconditionsshow theirfulleffect. IamgladnowtolearnfromtheChairmanoftheMedicalBureau thattheannualnumberofthecasesofsilicosis whicharearisingto-day inonlyaboutone-thirdofthenumberthatwerearisingfourteenor sixteenyearsago,andthatasubstantialimprovementinthesituation hasoccurredwithinthelastthreeyears.Thisisverywelcomenews, butweshouldwishforsomethingevenbetter,andifyou,Gentlemen, canhelpustodobetterweshallbeverygrateful. Itis perhaps toomuchtohopeforthatyourdeliberationswill leadto anyverygreatreductionintheincidenceofsilicosis;onlyalarger expenditureinpreventivemeasuresthanmanyofourolderminesare abletoaffordandcontinuetoworkcandothat;butitwillsavemany livesandmuchsuffering,besidesbeingofgreatfinancialassistanceto the industry, if means can be foundof arresting thedisease or ofprevent-ingsilicoticsufferersfrominfectionwiththetuberculargerm.Thiswe havehithertotriedtodobythearbitrarymethodofforcingamanto leaveundergroundwork;buttheproblemoffindinghimalternative employmentis a difficultone, ranking,as hedoes,among theunfit,and leadstoconstantdemandsformorecompensation. Iobservefromtheprovisionalprogrammeofyourdiscussionst hat everyaspectofthesilicosisproblemwillbedealtwith.Iamsuret hat this conjunctionof the trainedmindsof many countries, each of you with adiverseandvariedexperienceofthequestion,maybeexpectedto havefruitfulresults.IhaveeveryconfidencethatthisConferencewill advancetheknowledgeofthecausationandpreventionofsilicosistoa greatdegree.Afterall, it is preventionthatcounts mostof all, and itis tothemedicalexpertsthatwelookforwisecounselinthatdirection. Iwishyou,Gentlemen,everysuccessinyourimportanttask, the results of which, I am sure, will markan importantstage in the ultimatesolution of this grave question.I have pleasure in declaring this Conferenceopen. (Applause.) [ FIRSTSITTING15 TheConferencewasalsoaddressedbyDr.KeithMoore(Australia), Dr.GrantCunningham(Canada),ProfessorBhme(Germany),Dr. Middleton(GreatBritain),ProfessorLoriga(Italy),Dr.Kranenburg (Netherlands)andDr.Gardner (U.S.A.)whoexpressedtheirthanksto theSouthAfricanGovernmentforthewelcomewhichithadoffered. (TheConferenceadjournedat12noon.) FIRSTSITTING Wednesday,ISAugust1930,3.30p.m. Chairmen:MR.E.J.PHELANandDR.L.G.IRVINE Mr.E.J.Phelan:ThefirstpointistheelectionoftheChairmanof theConference. ELECTI ONOFCHAIRMAN Dr.MiddletonproposedtheelectionofDr.IrvineasChairman. Dr.Gardner secondedthisproposal. Dr.Irvinewasunanimouslyelected Chairman. TheChairmanreadthefollowingtelegramreceivedfromMr.Albert Thomas.DirectoroftheInternationalLabourOffice: PleaseconveyheartygreetingstoDelegatesandwarmestwishes fora successiulandfruitfulconference.ALBERTTHOMAS. HealsoreadthefollowingletterreceivedfromMr.Thomas: LEAGUEOFNATIONS.INTERNATIONALLABOUROFFICE, GENEVA. SIR, Onthis,thefirstoccasionuponwhichtheInternationalLabour OfficehasconvenedaConferenceoutsideEurope,Iventuretoask youtoconveytoitsmembersmywarmestwishesforitssuccess, andtoexpresstotheChamberofMinesmygratitudeforthe assistancewhichismakingtheholdingoftheConferencepossible. Ifeelconfidentthatthelaboursofexpertsdrawnfromfourconti-nentscannotbutresultinasubstantialandvaluablecontribution towardsthesolutionoftheproblemofindustrialsilicosis.The InternationalLabourOfficeishappytobeassociatedwiththe TransvaalChamberofMines in thisattempttoincreasetheprotec-tionof mine workersand workers in other silicotic industriesagainst thedangerstowhichtheyareexposedfromthisdisease. Ishallbegratefultoyou,Sir,ifyouwillbegoodenoughto conveymygreetingsandgood wishestothemembersoftheCon-ferenceandtoassurethemthatI shall watchtheprogressoftheir workwiththedeepestsympathyandinterest. Ihavethehonourtobe, Sir, YourobedientServant, (Sgd.)ALBERTTHOMAS. ThePresidentofthe InternationalSilicosisConference, Johannesburg. 16 REPORTOFPROCEEDINGS TheChairmanproposedthatthistelegramandlettershouldbe insertedintheMinutesoftheConference.Dr.Orensteinmovedthat receipt of this telegram and letter should be acknowledgedand thethanks oftheConferenceexpressedbycable. TheConference unanimouslyadopted thisproposal. ELECTIONOFVICE-CHAIRMEN Dr.LorigaproposedtheelectionofDr.RussellasVice-Chairman. Dr.Pirowsecondedthisproposal. Dr.RussellproposedSirSpencerListerassecondVice-Chairman. ProfessorKettleandDr.Lorigasecondedthisproposal. Dr.RussellandSirSpencerListerwereunanimouslyelectedVice-Chairmen. PUBLICITYOFPROCEEDINGS Mr.Phelan:TheConferenceshoulddecideatoncewhetheritspro-ceedingsweretobepublicorprivate.Hebelievedthatthemedical expertsmightprefertoconducttheirdiscussionswithoutthepresence oflaymen, buttheymightconsider whethertheclosing sessionatwhich thesuggestionsandrecommendationsmightbeadoptedshouldbe public. Dr.Middletonproposedthatallproceedingsshouldbeprivate. Dr.Lorigaagreed. TheChairmanaskedwhethermedicalmennotmembersofthe Conferenceandrepresentativesofthemedicalprofessionshouldbe excluded. Dr.Middleton:Hewasoftheopinionthatallsittingsshouldbe privateunless theConferenceotherwiseresolved.Itmightatmoments beusefultoholdtheirdiscussions beforeawiderpublic, butanad hoc procedurewouldallowthistobedone. Mr.PhelanaskedwhetherDr.Middletonhadanyobjectiontothe issueofPresscommuniqustokeepthepublicinformedoftheprogress oftheConference. Dr.Middleton:AnycommuniquesshouldbeapprovedbytheCon-ferencebeforetheywereissued. Mr.Phelan:ItwouldbedifficulttoconsulttheConferencedailyfor approvalofcommuniqus,andhesuggestedthatthestaffmightbe allowedtoissue communiqusto informthePressof theprogressmade, butthatwhereanyreferencesweremadetodifferencesofopinion,the Conferenceshouldfirstbeconsulted. Dr.Macrogordato suggestedthata publicitycommitteebeappointed. Dr.Orenstein:TheResolutionsCommitteecouldfulfilthisfunction. Dr.Cluver:WhatwouldbethepositionofthemedicalPress?He washimselfbothanobserverandtherepresentativeoftheBritish MedicalJournal,andtheJournalofIndustrialHygiene. Dr. Orenstein proposed thatthis question be referredto theResolutions Committee. TheChairmansubmittedthefollowingtexttotheConference: 1.TheConferenceassuchshouldberegardedasprivateand themeetingsconfinedtomembersandobservers,andanypublicity FIRSTSITTING17 given to its proceedings should be agreed to ad hoc by theConference withtheexceptionthata shortresume of thedaily proceedingsmay be issued tothePress by theSecretariat. 2.Dr.Orenstein'sproposalthatDr.Gluver'sproposal,"a resumoftheproceedingsmightbedrawnuponbehalfofandfor publicationinthemedicalPresssubjecttotheapprovalofthe ResolutionsCommittee",bereferredtotheResolutionsCommittee forarecommendation,isaccepted. TheConferenceunanimouslyadopted theseproposals. NOMINATIONOFREPORTERSANDOFRESOLUTIONSCOMMITTEE Mr.Phelan:HeproposedthattheResolutionsCommitteeshould consistofDr.Irvine(Chairman),Dr.RussellandSirSpencerLister (Vice-Chairmen),Dr.Moore,Dr.Kranenburg,Dr.Bhme,and Dr.Orenstein. Healsoproposedthatreportersshouldbeappointedforthethree groupsintowhichthesubjectwasmosteasilydividedasfollows: (1)Prognosis,AfterCareandCompensation:Dr.Cunningham, Dr.Koelsch, ProfessorHall. (2)PreventiveMeasures:Dr.Loriga,Dr.Badham,Mr.Roberts. (3)Medical Aspects (to cover Pathologyand other subjectsseparately ifnecessary,buttosubmitasinglereport):Dr.Orenstein, Dr.Gardner,Dr. Middleton,Dr.Steuart. TheChairmanputtothevotetheappointmentofaResolutions CommitteeconstitutedasproposedbyMr.Phelan. TheConferenceunanimouslyappointedtheResolutionsCommitteeas proposed. Dr.CunninghamproposedthatSouthAfricashouldberepresented byareporterupon" Prognosis,After-CareandCompensation". Dr.Fishersecondedthisproposal. Dr.Orenstein:TheSouthAfricanpointofviewwasthatitwouldbe betterforthereporttobedrawnupuninfluencedbySouthAfrican opinion. Dr.Cunningham:ItwouldbeserioustoomitallSouthAfrican experience. Mr.Phelan:Thediscussionwouldbeopentoallthemembers,and allthatwasproposedbytheSouthAfricanmemberswasthatitshould besummarisedimpartially byoverseas members. Dr.CunninghamandDr.Fisherwithdrewtheirproposal. TheConferenceunanimouslyappointedthereportersasproposedby Mr.Phelan. Dr.Orenstein:Dr.Steuart,whohadbeenappointedoneofthe reporterson" MedicalAspects",wasanobserverandnotamember oftheConference. Mr.Phelan :TheInternationalLabourOfficewaspreparedtoinvite Dr.SteuarttobeamemberoftheConference. ProfessorKettlemovedthatDr.Steuartshouldbeinvitedtobecome amember. TheConference unanimouslyadopted thisproposal. 2 18REPORTOFPROCEEDINGS REPORTSOFTHEPROCEEDI NGSOFTHECONFERENCE Mr.Phelan:Asummaryoft hediscussionsoft heConferencewould bepreparedbyt heSecretariatandroneoed,andmemberscouldhand inanycorrectionswhicht heydesiredt omake.Thereport ssubmi t t ed t ot heConferencebyt hereportersfort het hreegroupswouldevent ual l y bepublishedinavolume,whichwouldincludet hevariousreport s submi t t edt ot heConferencebeforehand,andanaccountoft heproceed-ings.ThisvolumewouldalsobepublishedinFrenchatal at erdat e, andpossiblyinotherlanguages.Thenon-technicaldiscussionswould bereportedbyt heSecretariat.Fortechnicaldiscussionshesuggested t hatspeakersshouldprepareasummaryoftheirownobservationsand handi tint ot heSecretariat.Insuchcasesdelegatescouldhandina summaryintheirownlanguages. TheChairmanaskedwhet hert heSecretariatwouldprepareasummar y whent hetechnicaldiscussionwasmoreint henat ur eofadebat et han ofaseriesofspeeches. Mr.Phelan: Insuchcasesa stenographic notet akerwould beprovi ded, andt heSecretariatwouldalsot akenotes.Int hi swayasufficiently accuratereportwouldbeobtained,whichdelegateswouldalsohavet he opport uni t yofcorrecting. Dr.Middletonaskedwhethert hereporterswouldberequiredt ot ake notesoft hewholediscussion. Mr.Phelan:Adistinctionshouldbedrawnbetweenreportsoft he discussionandt hereportseventuallydraftedt o summarise t hediscussion. Nodisagreementwaslikelyt oariseovert hesummaryoft hediscussion,. butt hereportsthemselvesmi ghtbecontroversial.Itwastherefore desirablet hatt hereportersshouldt akesomenotes. TheChairmansuggestedt hatspeakers'summariesshouldbehanded t ot heSecretariatwithintwenty-fourhours. PROGRAMMEOFTHECONFERENCE TheChairman:Theprogrammeproposedfollowedalogicalsequence, viz.(1)PreventiveMeasures,(2)MedicalAspects,(3)Prognosis,After CareandCompensation.TheSouthAfricanreport swerei nt endedt o serveasst art i ngpointsfordiscussion,andt herelevantpart sofot her report swouldbet akenatt hesamet i me.Thesubjectmat t err at her t hant hepapersthemselveswouldbediscussed.Papers1t o6were moreoccupationalincharactert hanmedical;anyt hi ngbearingont he medicalaspectcouldbediscussedundert hesecondheading,andanyt hi ng bearinguponprognosisandcompensationundert het hi rd. THECHAIRMAN' SSPEECH TheChairmant henaddressedt heConferenceasfollows: Gentlemen,Ihavet ot hankyoumostdeeplyfort hesignalhonouryou havebeengoodenought oconferuponmeinnomi nat i ngmeasChai rman ofthisInt ernat i onalSilicosisConference.ItisanhonourwhichIam veryproudt oacceptbecauseIview i tasarecognitionoft heplacewhich t heMiners'PhthisisMedicalBureau,whoseworkIhaveatt hemoment t heprivileget odirect,hasgainedforitselfasapioneeri nst i t ut i oni n FIRSTSITTING19 thefieldofindustrialhygiene.Iamonlysorrythatmypredecessor Dr.WatkinsPitchford,whofoundedandorganisedtheBureaufourteen yearsagoduringatimeofstressanddifficulty,andwhodirectedits activitiesfora periodof ten years thereafter,is not here tooccupyinmy placeapositionwhichhemightsoadequatelyhavefilled. FormyselfIacceptthishonourwithmuchdiffidence.AlthoughI havebeenincontactwiththesilicosisproblemforeightandtwenty yearsIambutahumblemusket-bearerinthearmyoftheLord,and, whenIfaceas Ido now thisfriendlybutcriticalgatheringof thechosen expertsinindustrialmedicineofmanycountries,Ifeelmuchlikea companycommanderinabattalionofthelinewhoissuddenlycalled upontoleadacompositeforceofallarmsinahighlymechanisedpost-wararmy.Happily,littleornoleadingwillbecalledfor.Butsince youhavebeengoodenoughtoplacemehereIshalldomybestto dischargethegreatprivilegewhichyouhaveconferreduponme,and which1 esteemmosthighly. Myfirstdutyis to welcomeour visitorsin thenameof theminingand medicalprofessionsofSouthAfricaascolleaguestomeetwhomis tous averygreatpleasureandauniqueopportunity.Theotherdaywhen asolitarymalehippopotamuswhichhadwanderedfromZululandalong thecoastalmarginofNatalintothenativeterritoriesbeyond,alonely tourofmorethantwohundredmiles,reachedanativekraalandrested withthecattle,theheadmanofthevillagegaveordersthatanox shouldbeslaughtered.Thisisthecustomarywayinnativecirclesto honouradistinguishedvisitor.Gentlemen,weherebyfiguratively slaughterouroxinyourhonour.Ihopethatweshallestablishat ourmeetingsacloseandfriendlycontactwitheachotherwhichwill makethisConferencealandmarkforeachofusofgoodfellowshipand goodworkdone, andwill makeitalso a notablelandmarkin thehistory ofthesilicosisproblem. ThattheInternationalLabourOfficehascalledthisConferenceto meetatJohannesburg is to us a greatsatisfaction.But it is achastened satisfaction.Forwhilewewelcometheopportunityofhavingthe benefitintheconsiderationofourlocalproblemsoftheadviceofso manytrainedminds, whose experiencemustinmanyrespectshavebeen differentfromourown,yetthatsatisfactionistemperedbytheknow-ledgethatprobablythemainreasonwhyyouhavecometous is,that, owingtothemagnitudeandtheuniqueconcentrationofthemining industryoftheWitwatersrand,andtoitsrapidandintensivedevelop-mentwithinthespaceofageneration,theproblemofsilicosishasbeen withusatonceofgreatergravity,andhashadresultswhichhavebeen moreclearlyapparentthanmighthavebeenthecase inothercountries, inwhichtheminingcommunitiesmaybeofolderstandingandindi-viduallyperhaps relatively smaller and more scattered.Oursatislaction is temperedalso bythefactthatalthoughaftermanyyearsofintensive effortwe can claima very considerable measure of success, we haveas yet reachedno final practicalsolutionof thedifficultproblemofthepreven-tionofsilicosis. Itissignificantofthelocalattitudetoward" miners'phthisis"t hat theinitialsuggestiontoholdthisConferenceatJohannesburgshould havecomefromDr.Orensteinonbehalfoftheminingindustryofthe Witwatersrand,andthattheTransvaalChamberofMineshasactively co-operatedwiththeInternationalLabourOfficeandtheGovernment of theUnionofSouthAfricain making this meeting possible.Sincethe timethatthe gravityof the menaceof silicosis was fullyrecognisedthere hasbeen manifesta close co-operationbetween theDepartmentofMines 20REPORTOFPROCEEDINGS of the UnionGovernmentand the gold mining industryin the investiga-tionandapplicationofpreventivemeasures.Thiswholesomespirit animatedtheworkof thefirstMiners'PhthisisPreventionCommittee, towhichweinthiscountrylookbackashavingsetonfootareally energeticandsystematicpolicyofprevention.Our presentmeeting is theoutcomeofthesamespirit,whichalonecanrenderpossiblea satisfactorysolutionofthisgravequestion. Ido not wishtodetainyouoverlongwithpreliminaries.Youhave comeheretosee thingsforyourselvesandnottolisten.Butperhaps youwill bearwithme ifIofferat the outseta few verygeneralremarks upon the subject-matterof our programme, as viewedparticularlyin the lightof our South Africanexperience, inasmuchas this is the only aspect* of the generalproblemof silicosis of whichI haveany directknowledge. Thepaperswhichhavealreadybeencontributedtotheproceedings of theConferenceare in yourhands.Thosepreparedby localmining and medical men may appearto bulklargely in the programme, but they are designedtoservesimplyasanintroductionto the generaldiscussions ontheseveralaspectsofoursubject.Theywillbe takenas read,and willthusprovideashortandhappymethodofdisposingofthelocal contributors,andofopeningthe way todiscussions,which,as isplain fromthe contributionsfromothercountrieswhich havealreadyreached us,willbeenrichedbytheresultsofwideandintensivestudiesof the generalproblemelsewhere. Thecontributionsalreadyreceivedfromothercountries, togetherwith otherswhich may be forthcoming,will fit naturallyand mostprofitably intothe courseof the relevantdiscussionsof the differentaspectsof our subject,and will be of especialvaluein wideningtheirscope.InSouth Africa,so far, the silicosis problem has been practically a mining problem, andthelocalcontributionsareaccordinglypracticallyconfinedtothe subjectofthesilicosisofthegoldminer.Therecordofexperience derivedfromotherindustriesandothercountrieswillservetocorrect thisapparentlimitation.Itrust,however,thatyou willforgiveme if thefew remarksIhavepersonallytooffermay alsoappeartohavean undulylocalcolour. 1.The topics set down for our discussion follow a logical sequence. Thefirstmainsubdivisionofourprogrammedealswiththecausation andpreventionof silicosis.The first six papers deal accordingly with the physicalandchemicalcharactersof thegold-bearingconglomerateand thecontiguouscountryrockof the Witwatersrandreef,withthehistory oflocaloccupationalconditions,thenatureofthepreventivemeasures whichhavebeenadopted,andwiththegeneralhistoryofsilicosison theWitwatersrand. Theproblemof whatconstitutes" silicarisk" and of how itis to be counteredisobviouslyfundamentalsinceifthatcanbesolvedthe pathologyof silicosis becomesof no moreand no less specialsignificance thanthatof any otherdisease,and the matterofcompensationmay be leftto lookafteritself.The questionof the aetiologyand prevention of silicosis is plainly primarily a medical one, and I trust that thisConference will be able to contributeto the formulationof some definitelead in this respect,sincewithoutawell-informedandconvincingleadfromthe medicalside,theminingengineeror theindustrialistmustremainata loss.As a world-famousengineer said at a recent Empire Mining Congress : "Let the physiologists tell us plainly whatthey wantdone, and we shall findwaysofdoingitfor them."Hithertothephysiologistsandother medicalpeoplehavethemselvesbeenpursuingapainfulprocessof self-education.Are we now in a position to do better? L FIRSTSITTING21 Weknowthatcertaindustswhichcontainfreesilicaarephthisis-producingdusts,andthatotherdustswhichalsocontainfreesilicaare not,andtheacceptedviewatpresentisthatthedifferenceliesinthe presenceinthelatterkindsofdustofotherconstituents,whichnullify theharmfulpotentialitiesofsilica.Thefactsarethere, buttheirexpla-nationisstillsomewhatobscure,althoughwecanpictureseveral possibilities.Andcanthefactsbeappliedinapracticalwaytothe preventionofsilicosis,eitherinmining,or,ifnotinmining,inother industriesinwhich" silicarisk"exists,andinwhichdilutionwith other"antidote"dustsmightbepossible ?Thelinehithertotakenin SouthAfricahasledfarawayfromanyattemptinthisdirection, althoughDr.J.S.Haldanehasmorethanoncecalledourattentionto itspossibilities. The history of silicosis in South Africa,and indeed in all other countries, makessadreading,andtothosewhohaveworkedinclosecontactwith thediseasethroughout,thepersonalexperiencehasbeenmoresad. To theactualsufferersithas meantcasesofdisablementordeathwhich haverunintothousands.Ithinkthatthoseofyouwhohavereadthe severallocalcontributionstothehistoryofthesubject,towhichI havereferred,musthavebeenimpressedbythemanifestcandour ofthewriters.Ourtenyearsofignorance,ourfurthertenyearsof partialrealisation,hesitationandtentativeimprovements,oureighteen yearsofincreasinglyenergeticefforttodealwiththeproblemhave beenset down withoutextenuation,and make up, I suppose, thecommon storyofsuchthingstheworldover,exceptthatwithusthatstoryhas beencondensedintotheperiodofone generationinsteadof beingspread outoverseveralormany. Theslowawakeningtothegravityofthesituationandtothefact thatwehaveinsilicosisaconditionwhichisindividuallythemost importantofalloccupationaldiseases,andonemostdifficulttodeal with,particularlyundermining conditions, is faithfullyreflectedinthese papers.Attheoutsetthiscircumstancewasdueinparttosimpleignor-anceof thecharacterandextentofthedanger, in partto thedominance ofthemetalminingtraditionofthosedays.Thecoalminingtiadition stoodthen,asnow, forampleventilationtocombatthedangerof mine gases.The metalmining tradition,exemptas most metal minesarefrom anysuchobviousandimmediaterisks,wasstillcontenttorelyupon naturalventilation.Andthereisanimmenseinertiaintraditionthe moresowhenithasbecomeextensively.embodiedinactualmaterial structure whetheraboveor belowground. Themainlessonofthehistoryofsilicosisappearstobethatinmetal mineswhichcreateaphthisis-producingdusttherearejustascogent reasonsforampleventilationasexistincoalmines,sinceinthelast resort we are dealing, in an atmosphere laden with impalpablesilicadust, withwhatisforpracticalpurposesadangerousgas,perhapsmore extensivelydangeroustolifeinitsremoteeffectsthanarefiredampor blackdampwiththeirimmediateandobviousrisks.Hadthisbeen generallyrealised thirtyor fortyyears ago we shouldhave been sparedat leastalargepartofourtroubles.Andalthoughmineventilationhas formanyyearsreceivedgreatandincreasingattentiononthesefields wearestillto-dayinthisrespecthamperedandhandicappedbythe heritageof theold tradition,as embodied in the original layout andmode of working of theolder mines. Itwas notuntil thereportof the Miners'Phthisis MedicalCommission waspublishedin1912thatthewidespreadcharacterofthemenaceof silicosisandtherealgravityofthesituationwererecognisedinthis 22REPORTOFPROCEEDINGS country,andthatyearmarksthebeginningofthereallyenergetic measuresforthepreventionofsilicosiswhichhavesincebeentaken. Evenso,medicalmenandengineerswerestillagreedthatwaterwas the mainremedy. Sincethatdatepreventivepolicyhasbeenincreasinglysystematised in the measures summarisedin several of the papers beforeyou ; measures whichhaveincorporatedandextendedthemanyimportantpreventive methodswhichhadalreadybeenintroduced. Theyformto-dayalargeandcomplicatedsystem.Therearethe "medicalmethods"ofstrictexaminationofrecruits,andofthedetec-tionandremovalofthesubjectsofactivetuberculosis;andthereare the" engineeringmethods",suchas provisionforadequateventilation, andtheregulationofshiftsandblastingandalsothosemethodswhich dependupontheuseofwatertopreventtheescapeofdustintomine air,or to lay it when actually in suspension.The success of thiscombina-tionofmeasureshasundoubtedlybeengreat.Onemayclaim,Ithink with truth, thatthe numberof cases of silicosis which are arisingannually to-dayisonlyaboutone-thirdofthenumberwhichwerearisingfour-teenorsixteenyearsago.Duringtbepastthreeyearstherehasbeen acontinuousdropintheproductionratesofthedisease.NordoIthink thatthepotentialitiesofour" presentday" methodsarebyanymeans exhausted.Withinthe last tenyears, to takeone featureonly, the whole practiceof rockdrill workhas beencompletelyandfavourablyrevolutio-nised,andsuchthingstaketimetoshow theirfulleffect.Theimprove-mentattainedthereforehas beensubstantial,andthere is reasonedhope forfurtherimprovementinthefuture.But,althoughwearesatisfied sofar,wearealsodisappointed.Wehavescotchedthesnake,butwe havenotkilledit.Werealiseinparticularthatalthoughwaterwill takeone a large partof the way, it will not takeone all the way,andthat itsusehascertainpositivedisadvantagesbothhygienicandeconomic. Hence theminds of medical menandengineersare turningto-daytothe question:havewenotbeenoverdoingwater?Couldwenotdobetter withlesswater,andagreaterextensionofalternativemethods?On thispointtheexperienceofothercountrieswillbewelcome. 2.Thesecondmainsubdivisionofourprogrammeisconcerned withthestrictlymedicalaspectofsilicosis. Inthissectiondiscussionwill beopenedbythepaperson the" Aetio-logy of Silicosis" and on"ExperimentalSilicosis" by Dr.Mavrogordato. Thepathology,radiologyandsymptomatologyofsilicosisasmetwith inSouthAfricaaredealt within threefurtherpapers.Thefirstofthese, contributedbyDrs.StrachanandSimson,iswrittenfromthestrictly pathologicalstandpoint.Thesamewritershaveco-operatedwith membersof theMedical Bureauinthepreparationofthetwosucceeding paperson" TheClinicalPathology,RadiologyandSymptomatology ofSilicosis", inwhichthatconditionis consideredparticularlyfromthe standpointofitspracticaldiagnosisasanoccupationaldisease.These twopaperspresenttheconclusionsdrawnfromacarefulcorrelation oftheresultsofpathological,radiographicandclinicalexamination inaconsecutiveseriesof400individualcasesofsilicosisoccurring amongstEuropeanminers,ineachof whicha postmortemexamination was performed,and in each of whicha radiographicandclinicalexamina-tionhadbeencarriedoutwithinthesixmonthsprecedingdeath.Itis uponthistriplecorrelationthatthestandardsofdiagnosisandclassifi-cationadoptedbytheMedicalBureauarebased.Itformsatoncethe frontlineandthelastditchinourtrenchsystemofdiagnosis. Itis commongroundthatitis thehighpotentialpredispositiontothe FIRSTSITTING23ultimatedevelopmentofanactivetuberculosisthatisthechieffactor inmakingsilicosistheseriousconditionwhichitinmostcasesis.The relationbetweensilicosisandtuberculosishas beenrepeatedlydiscussed, andwill,onepresumes,beoncemorethoroughlydiscussedatthis Conference. Theviewtakeninthesepapersisthatanon-tuberculousnodular fibrosisofthelungdue tothearrestofsilicadustvvithin thatorganisa definiteanddistinctpathologicalprocess, andis the predominantfeature ofthegreatmajorityofcasesofwhatisclinicallytermed"simple silicosis" particularlyinitsearlierstages,andfurtherthatthatprocess mayadvanceassuchuptoapoint,buttoaveryconsiderabledegree without the interventionof tuberculousor other infection,evenalthough theaffectedmanisremovedfromundergroundwork. On the other hand, notonly are a numberof cases of silicosisobviously complicatedfromtheoutsetbyactivetuberculousinfection,butpatho-logicalobservationleadsonetotheviewthatthereexistsinmanyand probablyinmostcasesofclinically" simple"silicosis,fromthetime thatitbecomesdefinitelydetectable,somelatentcircumscribedfocus orfocioflow-gradetuberculousinfectioninassociationwithcertain ofthesilicoticlesions. Somesuchinfectivelesionsmayoriginatefrompersistentactive focidatingbackoriginallytoaprimaryinfectionduringearlylife: some may be due to a limited re-infectionoccurring during andassociated with theearlydevelopmentof thesilicotic process. Thisfeatureformsonefactorintheexplanationofthetendency totheultimatedevelopmentofactivetuberculosiswhichismanifest insomanycasesofsilicosis.Thefuturehistoryofthecasewilldepend onwhethersuchfociremaininactive,orbecomeactiveandprogressive orwhetheragainafurtherinfectionoccursfromasourceoutsidethe lungs.Otherfeaturesinthesituationhoweverheightenthatpredispo-sition.Thesitesofthesilicoticlesionsofferpossiblepointsofarrestof bacteriainthelymphaticsystemofthelung.Andprobablythemost importantfactorofallis thecircumstance,ashasbeenshowninparti-cularbyGyeandKettle,thatfinelydividedsilicaactsasasolublecell poisonandhasinconsequenceaspecificeffectindeterminingthe selectionbyatuberculousinfectionofsiteswheresilicaisaggregated. Thelocaltoxicactionofsilicamayalsogofartoexplainthecharac-teristicmodificationofthesilicoticprocessbychronicinfections,and particularlybyachronictuberculousinfection,withtheproduction ofslowlyprogressiveinfectivelesionsofcomparativelylowvirulence, accompaniedbyanexcessivefibroidreaction,whichformsostriking a featureof manycases of the disease.To this characteristicmodification of silicosis thegeneral term" infectivesilicosis " or in the morerestricted sense" tubrculo-silicosis" has beenapplied. Itwouldappearthatthetypicaleffectofsilicadustwheninhaledin excessivequantitiesoverlongperiodsis,generallyspeaking,firstto causea" dustbronchitis",thentoproducethesimplenodular"dust fibrosis"whichis" silicosis",andfinallytoleadontoaconditionof "infectivesilicosis"andatrue" dustphthisis".Buttherearein individualcasesmanyvariationsinthecourseofthisdevelopment, determinedmainlybytherelativepreponderanceofthe dust factoror of theinfectivefactor,andbytheearlierorlatermanifestationofthe latter. AtthispointIwouldcallyourattentiontothephotographicAtlas ofthePathologyandRadiographyofSilicosiswhichliesbesideeach of you.It contains a reproductionof the original illustrations to thethree 2 4REPORTOFPROCEEDINGS papersI have justmentionedandhas been preparedforandis presented tothemedicalmembersofthisConferencethroughthecourtesyand generosityofKodak,SouthAfrica.Itwillform,wehope,auseful additiontotheliteratureoftheConference,andIamsureyouwill desirethatthecordialthanksofthemembersoftheConferenceshould beconveyedtothedonors,Kodak,SouthAfrica,fortheirhandsome gift-book.ToDr.Steuartandmyselfitisespeciallypleasing,because theendeavourtosecuresatisfactoryreproductionsofradiographic negativesofchestconditionshashithertobeenastandingheart-break; thereproductionsachievedbytheprinterconveyingforthemostpart nothingofanyvalue,eithertotheirauthorsortootherpeople.This isparticularlyunfortunateinthecaseofsuchaconditionassilicosis, inthediagnosisofwhichradiographyformssoessentialanelement. ButtheAtlasinyourhandshas,Ithink,madegoodthisdeficiency inaverysatisfactorymanner,sofaratleastasthematerialwhichit containsisconcerned. IfI may beso boldas toofferthesuggestion,Ishouldwishtoseethis Conferenceconsiderparticularlythreepointsinconnectionwiththe pathologyanddiagnosisofsilicosis. First:Canweagreefromthefundamentalpathologicalstandpoint upona definitionof whatconstitutessilicosis regarded as adefinite conditionofdisease,thepresenceofwhichrenderstheaffected mancapableofbeingcertifiedassufferingfromaspecificand identifiableoccupationalmalady,whichmayconstituteavalid basisforapossibleclaimforcompensationinthatrespect? Second :Can we agree upona terminologywhich will rendera descrip-tionofthecharacteristiclesionsandvarietiesandpossiblythe "stages" of silicosis mutually intelligible toobservers indifferent countries? Third:Canweagreeuponaterminologydescriptiveofthevarious typesofradiographfoundincasesofsilicosis,orotherconditions ofpulmonaryfibrosis,whichmaysimilarlybemutuallyintelli-gibletodifferentobservers?TheMedicalBureauhasinthis regardtentativelyputforwarditsownprivateconventional terminologyfortheconsiderationoftheConference.Suggestions forimprovementwillbewelcome. Ithinkitwouldbeamatterofrealvalueifsomeagreementcouldbe reachedonthesethreepointswhichwouldfacilitatemutual understandinginthefuture. 3. The thirdsubdivisionof our programmedeals with theincidence andprogressionofsilicosis, withthelegalaspectof thedisease,andwith thequestionofcompensation. Thereare includedhereseveral papers, mainlyfromtheadministrative side, on the workof the Medical Bureauand the Medical Boardof Appeal, on thesanatoriumtreatmentof silicosis andon theexaminationofnative minelabourers. Finallytheprogrammeconcludeswiththreepaperswhichdealwith thedevelopmentofminers'phthisislegislationinSouthAfrica,withthe questionofcompensationandofotherameliorativemeasuresundertaken by the Miners'Phthisis Board,and with the great monetary burden,past, presentandprospectivewhichthediseasehasplaceduponthemining industry.Yetgreatas this burdenhas beenitrepresentsonlyaportion oftheveryseriouseconomiclosswhichhasbeenoccasionedinSouth Africabythis" scourgeofthemetalminer" FIRSTSITTING25 Miners'phthisis,wearetoldinthesepapers,hasbeeninthiscountry thesubjectoffiveGovernmentCommissions,theearliesthavingbeen appointedin1902,oftenParliamentarySelectCommittees,andofnine ActsofParliament,thefirstofwhichwasenacted in 1911 and the last,or whatisforthepresentthelast,in1925.Thesubjecthasthusoccupied agreatdealoftheattentionandtimeofthelegislatureduringthepast nineteenyears.IngeneraleachsuccessiveActhasbeenmarkedbyan increaseintheamountoftheawardspayabletofreshcases,andby additionalprovisions for surviving beneficiariesunder previous Acts orfor thedependantsofdeceasedminers,andonecannotsaywhetherfinality intheserespectshasyetbeenreached.Legislationonthesubjecthas inthiswaygrowntobeextremelycomplicated.Ifearthatthosewho approachthestudyofthepresentActwillfindinitanextraordinary mazeof" sageprovisos,sub-intents,andsavingclauses"whichonly those who know its historycanhope to understandwithouta guide. Suchalegislativehistoryinitselfproclaimsthattheproblemof compensation has proved to be a difficultone.And the standingdifficulty asyouwillwellunderstandis,that,viewingsilicosisasanindustrial "injury",the" injury"inflictedisinthemajorityofcasesnota stationaryone, butone which tendstoget worse, yetwhichdoesso very erraticallyandin generalover a periodofa goodmanyyears.As Ihave saidelsewheretheimportantpointaboutanearlycaseofsilicosisisnot whatheis atthemomentbutwhathe maybecome.Mr.SpenceFraser has computed the average expectationof life of an early case of thedisease when first notified,to be about fourteenyears, with a wide variationabove and below thataverage.In the earlier stages of silicosis in whichdisabil-ity may be absent and is at all events not serious, the real crux of the ques-tionisnotsomuchmedicalaseconomicitisalmostwhollythatof securingalternativeemploymentby themenaffected.Inthe laterstage itisoneofdefiniteandpermanentinvalidity.Thequestionofserious invalidityhasbeenmetsince1919bythepaymentofalife pensionto thosewhosuffergraveincapacitationfromthe disease ; the earlierstages aredealtwithbysinglelumpsumawards.Thepracticalproblemis complicated by the fact that in this country, in which most of theunskilled labour is done by the native, alternativeavenues of employment especially forpartiallydisabledmenareprobablylesseasytofindthaninother morefullyindustrialisedcommunitieswithahomogenouspopulation. Itmaybesuggestedalsothattheterm" miners'phthisis"itselfhas unfortunatelyactedasadeterrentintheobtainingofemploymentby beneficiariesandhasalsohad,perhaps,inagoodmanyinstances,a subtlepsychologicaleffectinthisandotherdirectionsuponthebenefi-ciaryhimself.Itseemsunfortunatethereforethatthistermappears tohavebecomeentrenchedinthetitlesofthelocalActsalthoughitis nowherementionedintheirsubstance.Thisis not,one wouldsuggest, anexampletobefollowed. Onewordinconclusion.TheMedical Bureaubythesanctionofthe MinisterofMineshasrecentlyinstalledanewthree-phraseX-ray generatorfromwhichwehopeformuchandofwhichweinviteyour inspection. MayIalso venturetocallyourattentiontotheplansoftheproposed newMedicalBureauwhichadornthesewalls.TheBureauhaolong outgrowntheswaddlingclothes generously presentedat itsbirthbythe SouthAfricanInstituteforMedicalResearchandhasindeedlongbeen hamperedandevenendangeredbyinsufficientaccommodation.These plans are a vision of a larger future.They are an earnest of how seriously thepresentGovernmentoftheUnionregardsthematterofsilicosisin 2 6REPORTOFPROCEEDINGS South Africaand of the high standardof efficiencyfor which it is prepared toprovidethemeansandof whichitexpectstoobtaintherealisationin thedetectionand investigationof the disease. MayIbepermittedtoofferafinalsuggestion,namely,thatthis Conferenceshouldnotterminatewithoutmakingarrangementsfor futureinternationalintercommunicationuponthisveryimportant matterofsilicosisandallieddustdiseasesbytheestablishmentand maintenanceforexampleofcentrallibrariesoftheliteratureofthe subjectundertherelevantGovernmentdepartmentofeachcountry, andpossibly byformulatinga provisionalprogrammeoffuturedesirable linesofresearch,andbyendeavouringtosecureagreaterinternational co-operationincarryingoutsuchaprogrammethanatpresentexists. Theexperienceofdifferentcountriesanddifferentindustriesdiffersin importantrespects,andsomesystematicmeansofcollatingand comparingthatexperiencemightbefound. Andnow,Gentlemen,Ihavedone.Imustthankyoufor hearingme sopatiently.Ihaveattemptedmerelytoofferyouaverygeneral perspectiveofthesilicosisquestioninSouthAfrica.Iamwellaware thatthisisbutoneofmanyaspectsofthegeneralproblemwhichwill occupyourdiscussions,andthatithasmanyotheraspects.Butitis besttospeakofwhatoneknows. VISITINGMEMBERS'EXHIBITS Aftersomediscussionitwasagreedthattheexhibitsbroughtby visiting membersshould beshownat8.15 p.m. on Friday,15 August. (TheConference adjournedat5.55p.m.) SECONDSITTING Friday,15August1930,2.30p.m. Chairman:DR.L.G.IRVINE TheChairmanproposedthatthemembersoftheMiners'Phthisis MedicalBureauandthemedicalstaffoftheSouthAfricanInstitutefor MedicalResearchshouldbepermittedtoattendthesittingsofthe Conference. TheConference unanimouslyadoptedthisproposal. OCCUPATIONALCONDITIONSANDMETHODSOFDUSTPREVENTION Dr.Middleton : The scheme prepared by him and circulated tomembers of the Conferencedid not attempt to cover silicosis throughout theworld, butonlyasitoccurredinGreatBritain.By" tiology"inthetitle ofhisfirstheadingheintendedtocoverallthefactorsinthecausation of thediseasesilicosis. Thefirstfactorwas exposureto silica dust,by whichhe meantdioxide ofsiliconinafreestate,andnotchemicallycombinedintheformof silicate.Britishlegislationwasbasedontheviewthatdiseasewas SECONDSITTING27caused bysilica dust,anda precise definitionof whatwas silica dustwas thereforenecessary.During hisown investigationsintosilicaprocesses hehadneverbeenable todeterminethestandardof air dustinesswhich producedsilicosis.HewasawarethatinSouthAfricaandinSydney, Australia, a figure was laid down in connection with preventive measures. Ttwashoweverimpossibletodiscussafigureuntilallthefactswere known.HesuggestedthattheConferencemightusefullylaydowna basisforthecomparisonofresults. InEnglandtheapparentexposuretosilicadustnecessarytoproduce silicosis had beenshort; there was a case offatalresultfromtuberculosis withevidencethatit hadbeenproducedbysilicosis aftertwoanda half years'exposure. Athirdfactorwhichmustbetakenintoaccountwastheextentof exposure period plus latent period, and the relation of these to eachother. Theinfluenceofintermittencyofexposurebyalternationofoccupa-tionshadpreventivebearing.Whendustwasreducedbycertain hygienicconditionssilicawasstillpresent,butintermittentemploy-mentmightsavetheworkerfrompulmonarydiseaseoratleastfrom disablement.Thishadalreadybeenattemptedinsomefactoriesin GreatBritain. Anotherimportantaspectwastheinfluenceofthepresenceofother dustsontheoccurrenceandcourseofsilicosis.Somedustswere referredtoasrestrainingsilicosis; thiswassaidtobeduetocolloidalor tochemicalaction.Otherdustshadaphysicalactioninpreventing inhalationbyaggregation.Somerockscontainingclay,forinstance, producedlargeaggregationsof .particlestoolargetobecarriedtothe alveoli. Asregardsdustsotherthansilicawhichmightproduceevidenceof lungchangesimilartosilicosis,hepointedoutthataworkermight worsenhisconditionbypassingfromone industrytoanother.Asbestos damagedmorerapidlythansilica.Sandstonegrindingwasvery largelyreplacedbythenewformsofgrinding,suchasbyemery;there was not yetsufficientevidence to indicate theeffectson thehealthofthe workersoftheseprocesses. Differentindustriesproduceddifferenttypesofpulmonarydisease. Workersintherefractoriesindustriesandpottersdiedalikeofsilicosis, butthetypeofsilicosiswasdifferent.Livingconditionsmighthave some influence,but in highlyskilled trades, such as thatofstone masons, wherethestandardoflivingwasgood,themortalitywashigh. Finally,asregardstheoccurrenceofinfectiveprocesses,heaskedthe Conferencetoexpressanopiniononthestatementthatsilicosiswasnot developed in a healthy lung, butmust be preceded byinflammation. Dr.Russell : In the UnitedStates the proportionof silica dust in various industriesvariedfrom1upto90percent.Themediumbetweenthe twowasprobablytheaveragetypeofdust.Granitedustin theUnited Statescontainedlesssilicadustandahigherpercentageofother chemicals,towhichitsinhibitoryactionhadbeenattributed.The developmentofsilicosis in thegraniteindustryvariedindirectpropor-tionto theextentofexposure(30-35 percent.). Dr.Moore:Theperiodofexposurenecessarytocontractsilicosis dependedprimarilyontheindividual.IntheBendigominesthesilica contentwasover90percent.OntheWestCoastofTasmaniaitwas about60 per cent, and in Kalgoorliea little more.The Bendigostatistics werenotverytrustworthy,sincetheminerswerelothtobeexamined, butabouttenyearsseemedto be theaverageperiodtoproducesilicosis. 28REPORTOFPROCEEDINGS InKalgoorlieitwasnearersixteenyears.Silicosisseemedtodepend prettyaccuratelyon thesilicaaverage in thecountryrock. Dr. Bhme : German experience showed thatsand blasters andgrinders hadwell-developedsilicosissometimesafterthreeyears.Generally silicosisdeve'opedafternearlytenyears.Comparablestatisticswere requiredinordertodistinguishbetweenvariousdusts.Hedidnot believethatcoaldusthadanyinhibitoryeffect.Therewerecasesof workersemployedonhardrockforthreeyearsandthenworkingten yearsascollierswhowerestilldevelopingsilicosisandwerenomore protectedthanthose who hadnever workedas colliers. Dr.Koelsch:Inhisshortreportjust distributed,thequestionunder discussionhadbeenalreadyemphasised,aswellasthedecisive influenceoffreesilicicacid,andattenuationoftheeffectof silicicacid bycombinationwithothersubstances,etc.Asregardedtheperiodof timerequiredtodevelopthedisease,hehadseentwocasesofsevere silicosisaftertwo-and-a-halfyearsofemploymentonsand-blasting; theworkersinquestionwereagedtwenty-fiveandthirtyyears respectively.Timely suspension of work might in the earlier states bring aboutretrogressionofthesilicoticchanges.Yetinthisinstance,as likewiseinthedevelopmentofsilicosis, theindividualconstitutionand theresistancecapacityof thetissuesis ofcapitalimportance. Dr.Fisher:Threefactorsweretobeconsidered:(1)concentrationof dust;(2)time:(3)percentageoffnesilica.Itwasdesirabletouse thesamekonimeterthroughout,preferablythatwhichgavethemost de'icateresults.InGreatBritaintherewasupto60percent,free silicainmines.Hewouldliketoknowwhetherthis wasa safefigure. HealsoaskedtheConferencetoexpressanopinionastothebest konimeter.Twopreventivemeasureswerewateranddusttraps.He wouldliketoseeanefficientmaskinvented;amaskwhichdidnot obstructrespiratinwouldkeepbackhalfthedust,andthismight besufficientif300particlespercubiccentimetrewasasafecount. Dr.Badham: TheairofpartsoftheRandmineswhichhehadseen didnotcontain 4 milligrams of dustpercubicmetresincedustwasnot visibleunderthatfigure.Atabout400particlespercubiccentimetre (usingOwen'skonimeter)dustparticlesbelow10micronswitha sizefrequencyratioof3didnotformavisiblecloud. Thesizefrequencyratioofparticleswasimportant,forbyitsstudy it could be seen thatin a dust such as thatreferredto, though the 1 micron particleswereverynumerous,the2micronparticlescontributedthe greatestpercentageof surface;for thisreasonhe didnotsubscribe tothe beliefthatultra-microscopicparticleswereculpableinproducing silicosis.He thoughtthatfurtherworkshould be done in dustcounting toascertaindefinitelytheamountofsilica whichcouldproducesilicosis. ItappearedthattheaverageexposureontheRandwas|about1milli-grampercubicmetre,andifthiswassothentheprospectsoftheir attackonthediseasebyreducingtheamountofdustinhaledseemed ratherhopeless. HehopedthatfurtherattemptswouldbemadeinSouthAfricato correlatethekonimetercountswiththesugar-tuberesults.Hethought thatOwen's konimeter was capable of doing all the work now being done ontheRandwithanotherinstrumentandstatedthatitproduceda recordfromwhichcarbonparticlesandwater-solublesaltscouldbe eliminatedbyselectivecounting. Hethoughtthatmoreattentionshouldbegiventotheparticulate SECONDSITTING29 countandurgedSouthAfricanstotrymorerecentmethodsofdust estimation. Dr.Kranenburg:Itwasnecessarytoknowhowmuchsilicawas containedindifferentkindsofstone.Inmarble,forinstance,silica wasalwayspresent.Italianmarblehad6.7percent, freesilicaand Belgianmarble1.2percent.Thefiguresforsamplesoflimestonewere: Belgian,1.1percent.,1.5percent.,0.1percent., 0.5per cent. ; French, 0.6percent.,0.4percent.,0.6percent.;German,0.2percent. Dr.Pirow(inreplytoDr.Fisher):Thekonimeterstandardmust dependon thepercentageoffreesilica present.Hehadfoundwiththe Randpercentagesthat300 particlespercubic centimetrecouldbetaken asastandard,buthewasnotconvincedthatitwassafe.Waterand ventilationweretheonlypreventivesinSouthAfrica.Dusttrapshad beentried,butthegeneralopinionwasthattheyweremuchtoo dependenton thepersonalelementandcouldbeappliedonlyinisolated cases.Uptothepresentnofool-proofandpracticalmaskshadbeen produced.HedidnotagreewithDr.Badhamontherelationbetween micronsandthecountofparticlespercubiccentimetre;400or500 particlespercubiccentimetrecouldbefound;itdependedonthe finenessofthedust.Hand-drillingproducedmuchcoarserdustthan machinedrilling.Itwasusualtostatethepercentageofcoarsepar-ticles(thoseabove5and10microns).Owen'skonimeterwasusedby theMinesDepartmentasacheck,butrequiredtoomuchcaretobe practicalforroutinework.HeregardedtheSouthAfricanresults asonlycomparative.Effortstocorrelatekonimeterandsugar-tube resultshadnotbeenverysuccessful.Theconcentrationentirely dependedonthepercentageoffreesilicainthedust.Thepresent concentrationwas known to be dangerousandattentionwas beinggiven tothehighestconcentrations.Attemptswerebeingmadetostandar-dise konimeterpractice. Dr.Cunningham:InOntariogoldminestheexposurenecessaryto produceante-primarysilicosiswasninetotenyears.Thepercentage offreesilicawasaboutthirtytothirty-five.Thisperiodseemedshort comparedwithSouthAfricanexperience.Itwasperhapsimpossible tocorrelatethevariousdust-countinginstrumentsusedindifferent countries. SirSpencerLister:Therewassomeconfusionintheterm"silica content ", which mightrefer to rock ortodust.Onlythesilicacontent andamountoftheatmosphericdustmatteedandthesizeofthepar-ticles.Ifverysmallparticleswereproducedtheweightstandardwas ofsmallsignificancesincethelargeparticleswereinnocuous. Dr.Mavrogordato :HehopedtheConferencewouldinitiatean epidemiologyofsilicosis.Theyneededtoknowwhereitoccurred,what wasitscomparativeincidence,andwhatwerethecomparativecondi-tions.Freesilicaincountryrockwasaveryimportantfactor,but theymustknowthepercentageoffreesilicaintheair,andalsowhat otherdustswerepresent.Ofthesedusts,whichincreasedliability tosilicosis?InGreatBritainthereweretwokindsoffirebrickwith thesamesilicacontent,buttheincidenceofthediseasewasvery different. Itwaseasytoremoveallvisibledust,leavingallthedangerous dust, so thatsize frequencywas of great importance. A method which was effectiveforcoarseparticlesmightbeuselessforfinedust.Water wouldkeepdowndust,buthowwasdusttoberemovedwhenitwas 30 REPORTOFPROCEEDINGS onceintheair?Inrapidcases of thedisease what part was playedby thesizeoftheparticles ? Masksweremostlikelytobesuccessfulwithasystemofpositive pressure,buthedidnotbelievethatothertypesofmasksatpresent availablecouldstopthedustwithoutstopping theairwhenthesvearer wasatwork. SouthAfricansusedadarkgroundkonimetercountandbelieved thattheresultswereasgoodaswithoil immersionandalightground. Heagreedthat500particlespercubiccentimetrewithadarkground amountedto1milligram.Whenthecountwasdownto300itmeant adarkgroundcountinSouthAfrica. Dr.Kranenburgaskedwhetheritwaspossibletofreeairofinvisible dustbyprecipitation(flocculation). Mr.Boyd:SouthAfricandustcountswereregardedasempirical. Thesugar-tubemethodhadbeenretainedforpurposesofhistorical comparison.Finalityhadnotbeenreachedwiththekonimeter. It had neededmuchexperiment to reach the presentmethodofcounting, which hadnow beeninusefortwoyears.A Committeewasatpresent sittingtoinvestigatemethodsandtodeviseastandard.Owen's konimeterwastoodelicateforroutinework.Insize classificationthe largestparticleswerefoundintheore-bins,nextinhand-drilling,and theninmachine-drilling, which producedthefinestdust exceptblasting. Dr.Middleton:Workingconditionsinfactoriessometimesmade theuseof wateror exhaustdraughtimpossibleandmaskswerethere-forerequired.Nostandardmask existed, andthoseon themarket were notofknownvalue.TheHomeOfficewas investigatingthepossibility ofa masktoprotectagainstfinesilicadust,whileat thesametime pro-vidingforanairpressurewhichwouldallowamantowearitsome timewithoutfatigue. HethoughtthattheConferenceshouldadoptaresolutionofapro-gressivekindonthesubjectofcorrelatingtheresultsofdustcounting. Thepercentageoffreesilicaseemedtobeinrelationtothesilicosis inducedinthelungs, butthiswasanunprovedassumption.Hehoped thattheConferencewoulddrawupaschemefortheexchangeofviews andknowledge.Thedustcountswhichhehadreproduced inhispaper lednowhere.HehadalwaysusedOwen'skonimeterandfoundit useful,butitwasimpossibletoreachastandardforasafe dustfigure. InSouthAfricaconditionsfromminetominewerefairlycomparable, anditwasthereforeeasiertoarriveatafigure,thoughhewasaware ofthedifficulties,partlyduetothechangeininstrumentsandunder-groundconditions.Hedidnotpersonallyfavourdarkgroundillumi-nation,becauseitdidnoteliminatecarbonparticles,whichwerevery numerousinmostdustsamplesinGreatBritain.Silicadusttended toremaindiscrete,butitwasimpossibletosayhowfarthesame mixtureofdustoccurredintheatmosphereasinthesmear.Where moisture was used to lay dustthe numberof particles below twomicrons inadropletmightbeover800.Heurgedthatauniformmethod shouldbeadoptedsoastorenderresultscomparable. ProfessorHallproposedthatasub-committeeshouldbeappointed toconsiderthepossibilityofstandardisingdustcounts. Mr.Roberts:Asub-committeewouldnothavesufficienttimeto reacha satisfactoryconclusion.AJointCommitteeofthe Mines Depart-mentandtheChamberofMineshadbeenworkingatthequestionfor morethanayear. SECONDSITTING31 Thesugartubehadgivengoodresults,butitshowedweightand notnumbers.Anattemptwasnowbeingmadetoreducenumbers withthehelpofOwen'sandotherkonimeters.Miningengineerswould endeavourtocarryoutwhateverthesilicosisexpertsrecommended. Itwaspossiblethatventilationoughttobeincreasedandhumidity decreased,evenattheriskofmoredust. Dr.Loriga:Hehadnothingtoaddascasesofsilicosisarerarein Italy,andsuchashaveoccurredhavenotbeenrecordedindetail. Hehadthereforenocommunicationtomakeinregardto thedisease, butwouldliketoaskthemembersoftheConference,inviewofthe factthatuptillnowexclusivementionhasbeenmadeofsilicosis: weretherenototherdustswhichproducedformsofpneumoconiosis otherthansilicosis ? Referencehasbeenmadetotheoutbreakofthediseaseafteralapse often,fifteen,andtwentyyears.Howwasitpossibletomeasuresuch periodswithanyaccuracy?Silicosisdidnotresembleanacutedisease occurringatagivenmoment,butitwasadiseasewithslowprogressive evolution.Whatstageinthediseasewasconsideredtoconstituteits commencement?Hebelieveditwaswhenthelungscouldnolonger eliminatethedustsothatthediseaseeitherincreased,wasarrested, orledontodeath,buthewouldliketoknowwhatcriterionwasused instatingthata workerwasnow no longerhealthybutmustbe|regarded assilicotic. Firstly,whatdustsfavouredorretardedtheactionofsilica?And whatdustscouldreachthelungsandgetfixedthere?Neitherthe Sub-CommitteenortheConferencecouldsolvetheseproblems.It wouldneverbepossibletosaypreciselywhatquantityofdustwould provokesilicosissinceitwasnotabsolutequantityorqualityt hat matteredbuttherelativequantity.Oneindividualmightresista proportionof100particlespercubiccentimetre,whileanotherwould reactunfavourablyto50particlespercubiccentimetre;therewas furtherthe wholequestionof therateof inhalation.A medicalinspector whowasinactivewouldinhalemuchlessthanaworkerengagedin heavyphysicallabour.Acceleratedrespirationwouldinthelatter casecauseinhalationofparticleswhichtheformercouldnotinhale. Thespecialpathologicalaspectseemed,therefore,incapableofsolution, butthegeneralpathologicalsideoftheproblemwasalreadysolved. Ineachcaseitwasnecessarytodirectattentiontothesizeofthe particles,therateofinhalationandpossiblepenetrationandfixation thatwasineachgivencase,butageneralestimationoftheseto meetallcaseswasimpossible. TheSub-Committeewasthereforeobligedtoconfineitsattention tothehygienicandpracticalissue,thatwas:(1)todeterminethe standardamountofdusttolerableintheairofamineforanindividual ofaveragehealth;(2)todeterminemeansofassuringreductionofdust tothisamountbyanalysingtheairandtodeterminethebestmethods ofestimatingthedustpresentintheatmosphere. Inregardto(1)thestandardwoulddependonsuchfactorsas qualityandadmixturewithotherdusts. Indealingwiththehygienicaspectsecondaryquestionsmustbe leftoutofaccount.Theproblemwasthatofreachingagreementasto astandardlimitforallcountriestobedeterminedby futureresearch. Dr.Orenstein:Twodifferentquestionswereansweredbythedust count:(1)inagivenindustryitdeterminedhowconditionsvaried (whereconditions,asontheRand,werealwayscomparable);and(2) 32REPORTOFPROCEEDINGS forcriticalscientificstudyaninternationalstandardcouldbelaid down. About100,000samplesweretakenannuallyontheRand,sothat alaboriousprocedurewasimpossible. Headdedthat" darkgroundillumination"wasnotthetruedark groundofthemicroscopist. Hesuggestedthatthereportersmightco-optoneortwoexperts toconsiderarecommendationforaninternationalstandardindust countsforscientificresearch,andtheResolutionsCommitteeshould recommendtheexpertsinquestiontothereporters. TheConference unanimouslyadopted thisproposal. (TheConferenceadjournedat5.10p.m.) THIRDSITTING Saturday,16August1930,9.45a.m. Chairman:DR.L.G.IRVINE PREVENTIVEMEASURESANDUNDERGROUNDCONDITIONS TheChairmansuggestedthatthediscussionshouldbebrokeninto specificsubjects. I.TheRelativeValueoftheUse ofWaterandofVentilation inthePreventionofSilicosis. DrMavrogordato:Waterhadthreeuses:(1)Tokeepdustoutof theairatthesitewherethestonewasbroken;water was veryefficient, butthefinestdustwouldpassanyformofwater.(2)Togivea"fly-paper " effect ; this hadbeen foundless effective ; testsmade on theRand in1912and1913provedthatotherpreparationse.g.Mr.Ussher's treaclewerenobetterthanwater;itwasdoubtfulhowmuchhad beengainedbykeepingtheplacecontinuallywet,sincetheairwas thusverygreatlyhumidified;whenadevelopmentendhaddriedfor twodaysitmaintained80 percent, relativehumidity,butwhenwashed i twentupto100percent,almostimmediately;itwouldtherefore bedesirabletoreverttothe"fly-paper"effectwithsomeotherprepa-rationthanwater.(3)Toremovedustfromtheair.LordListerhad saidatBerlinintheearlyeightiesthathewasashamedofeverhaving suggestedthatspraycouldaffectobjectsofthesizeofmicro-organisms intheair.TheCommissionon theventilationoftheHouseofCommons cametotheconclusionthatfineparticlescouldbeblownthroughany "water-screen.Withahightemperaturehighrelativehumiditywas agreatinconvenience;organismskeptalivemoreeasilyinawet atmosphereandthiswasverydisadvantageousasregardsinfective silicosis.Eventhoughthedustwasnothighlyconcentratedintheair, silicosiswasstillproducedinavirulentform.Theinfectiveelement, therefore,playedaconsiderablepart. THIRDSITTING33Theeffectofdustdidnotendwithinhalation.Hehadproduceda microscopicfibrosisinsevenmonthswithfinesilicadust(flint). Progresscontinuedovernineyears,however,mustbeduetosome elementsuperimposedonthedust.Thedropletof800particlesto whichDr.Middletonhadreferredwasbombardingthelungwith shrapnelinsteadofriflefire.Itwasdifficulttoinfectananimalby blowingdryorganisms,but90percent,positiveresultswereobtained fromspraying.Waterfacilitatedtheentryintothelungsofparticles in theairanditwasthereforepreferabletodeal withdustbyventilation. Hedoubtedwhetheraneffectiveventilationsystemwaspossible. SilicosiswasmadeintwelveyearsontheRand,andinaboutten yearsinCanadaandAustralia.ButinEnglishpotteriesandgrinding atwenty-fiveyearexposurewasfound.Drymethodsofcontrol thereforemade silicosis much more slowly.In English collieries there were probablymanyabnormallungs, buttheyhadbeenatworktwenty-five yearsormore.Wetsurfacesshouldbekeptdownasmuchaspossible andthere shouldbe all possible ventilation.Mines withaconcentration ofdustlike theRandwouldbemuchmorehealthyifthisconcentration weresecuredbydrymethods.Itwashoweverimpossibletoavoidthe useofwaterontheRandandthereforethesurfacemustbekeptdown byavoidingleaksindrillsanddiminishingallspraying;waterwould keepdustoutoftheairwithoutgreatsurface. Dr.Middleton:Infactorieswaterandlocalisedexhaustdraught werethetwomainmethodsofdustprevention.Watershouldbeused forthesuppressionofdustatitspointoforigin,andinsomeprocesses couldbeeffectivelyuseduponthisprinciple.Ifsufficientwaterwas useddustneverarose,butamplewatersupplywasessential.Ifno watercouldbeusedattheactualmomentoffractureofrocksteam had been foundefficient,but it must be in a saturatedcondition.If steam wasallowedtofallonadustcloudatitspointofformation,thedust wouldformaggregatesandfall.Argillaceousmatterinthedust facilitatedtheformationofaggregates. Theproblemofhightemperaturesdidnotariseinfactories,sothat humidityanddissociationdidnotoccur.Grindingwithsandstone wheelsof2 to7 feetdiametergave workingfacesof2or 3t*18 inches. Theideaatonetimeprevailedthatdustwasnotproducedatwet grindingbutthatifsparksescapedintotheatmospheredustwould also.InGreatBritaintherevolvingstoneoftendippedintoawater trough,butOwen'skonimeterhadprovedthatthemetalcutthrough thewetsurfaceandgaverisetofinedustfromthestone. Drygrindinghadoncebeenthemostdangerousindustry,Calvert Holland,ofSheffield,hadshownthatnodrygrindersinthe middleoflastcenturyreachedforty-fiveyearsofage.Itwasstill carriedon,butwithanexhaustdraughtandtheincidenceofsilicosis wasnowmuchless thanamong' wetgrinders.Therewasthusastrong argumentfortheuseofexhaustdraught. Britishregulationsrequiredthesuppressionofdustas nearas possible toitspointoforigin,eitherbywaterorbylocalisedexhaustdraught. Thedustfigurewassometimesverylittlereducedbyexhaustdraught perhapsby25 percent.Thefailureofthelocalisedexhaustdraught wasduetotheideathatithadsomeselectiveeffect.Thiswasnot thecase.Thesystemoughttobesuchas toremoveasufficientvolume ofairfromthepointoforiginofthedustandtoensureadirectional current.Theadditionofbafflesatthesidesoftheworkplacewould enormouslyreducetheamountofairtoberemoved.Itwasaspecial 3 34REPORTOFPROCEEDINGS engineeringproblemtocorrelatethesizeandspeedofthefan,the capacityoftheduct,andthevolumeofair tobemoved. Processesweresometimesimproperlycarriedonbetweenthepoint oforiginofthedustandtheexhaustsystem.Generalventilation shouldneverbecombinedwithalocalisedexhaustdraughtsystem unlessthetwocouldcorrelatedbysomemeans.Thepullofthefans causeddirectionalcurrentstowardsthemandthetwosystemstogether alwaysproducededdies.Dustcommonlyescapedfromthehoodand passeddirectlyupwards andwasthendiffusedgenerallythroughoutthe room,sothathighconcentrationscouldbecounted. Itwashardtodeterminetherelativevalueofwaterandexhaust draught;therewasaplaceforeach.Waterwasefficientwhereit couldbeeasilyandsufficientlyused,generallyoutsidetheworkroom; otherwiseexhaustdraughtwasnecessary.Itwasimpossibletolay downfiguresforefficientlocalexhaustdraught;alinearvelocity of200feetatthethroatoftheductwasusuallyenoughtoremove 80 per cent, ofthedust.Wherethesourceof dust was a rapidlyrevolv-ingobject,asintowingearthenware,therewasmuchmoredifficulty incollectingall thedust.Watercouldnotbeusedinthevastmajority offactoryprocesses. HehadbeenmuchimpressedbythehumidityintheCrownMines. Ifevenwiththeuseofwaterminuteparticlesofdustcouldstillbe determinedintheatmospherethiswasadefiniteargumentagainst theuseofwaterinconfinedspaces. Dr.Badham:Intex