Reconstruction of Exposure of Reconstruction of Exposure of Skilled Craftsmen to Asbestos at Skilled Craftsmen to Asbestos at the Beaumont, Texas Refinerythe Beaumont, Texas Refinery

(1940 (1940 –– 2005) 2005)

Presented by: Pamela Williams, Dennis Paustenbach, and J. LeRoy Balzer

Presented to:American Industrial Hygiene AssociationChicago, ILMay 15-18, 2006

ChemChemRiskRisk

OutlineOutlineStudy purposeStudy purposeBackground informationBackground informationMethodsMethods

Task durationsTask durationsTaskTask--specific fiber concentrationsspecific fiber concentrationsRespirator use and effectivenessRespirator use and effectivenessTime spent working with asbestosTime spent working with asbestos

ResultsResultsStudy limitationsStudy limitationsConclusionsConclusions

Characterize historical 8Characterize historical 8--hr TWA asbestos hr TWA asbestos exposures for 12 types of craftsmen at exposures for 12 types of craftsmen at petroleum refinery in Beaumont, Texaspetroleum refinery in Beaumont, Texas

Use Monte Carlo modeling to account for Use Monte Carlo modeling to account for uncertainty and/or variability in datauncertainty and/or variability in data

Provide quantitative exposure estimates Provide quantitative exposure estimates for use in future risk assessments or for use in future risk assessments or epidemiology studies involving asbestos epidemiology studies involving asbestos

Study PurposeStudy Purpose

Mobil refinery constructed Mobil refinery constructed in 1902in 1902--19031903Example of an Example of an ““open airopen air””facilityfacilityApproximately 60% of the Approximately 60% of the piping systems and piping systems and vessels were insulated vessels were insulated AsbestosAsbestos--containing containing insulation was no longer insulation was no longer approved for use in 1972approved for use in 1972A A ““blueblue--bandingbanding”” program program was in place by 1974was in place by 1974

Background InformationBackground Information

AsbestosAsbestosCeramic fibers Ceramic fibers Mineral/Rock Mineral/Rock

woolwool

Asbestos Asbestos Ceramic fibers Ceramic fibers

Fiberglass Fiberglass Mineral/Rock Mineral/Rock

woolwool

AsbestosAsbestosFiberglass Fiberglass

Mineral/Rock Mineral/Rock woolwool

Rubber/FoamRubber/Foam

NANAInsulation Insulation TypeType

>800 >800 °°FF>280 >280 °°FFVariableVariableAmbientAmbientTemp. RangeTemp. Range

Process streamsProcess streamsSteam (high Steam (high pressure)pressure)

Process streamsProcess streamsSteam (low Steam (low pressure)pressure)

Chilled waterChilled waterLight Light

hydrocarbonshydrocarbons

ProductsProductsNitrogenNitrogen

Instrument airInstrument air

Typical Typical ContentsContents

20%20%25%25%15%15%40%40%DistributionDistribution

Very Hot Very Hot ServiceService

Hot Hot ServiceService

Cold Cold ServiceService

NonNon--InsulatedInsulated

Insulation Type at Refinery Insulation Type at Refinery (Prior to 1975)(Prior to 1975)

MethodsMethods88--hr TWA asbestos hr TWA asbestos exposures calculated exposures calculated using using ““time motiontime motion””analysisanalysisExposures estimated Exposures estimated for 12 crafts and 7 for 12 crafts and 7 time periodstime periodsMonte Carlo model Monte Carlo model used to characterize used to characterize distribution of distribution of asbestos exposuresasbestos exposures

TWA = TWA = ΣΣii(C(Cii x Dx Dii)/8 hrs/day x )/8 hrs/day x [1[1--(FR(FRwornworn x x FRFReffecteffect)] x FR)] x FRACMACM

TWATWA Estimated 8Estimated 8--hr TWA asbestos hr TWA asbestos exposure (fibers/cc)exposure (fibers/cc)

CCii TaskTask--specific fiber concentration specific fiber concentration (fibers/cc)(fibers/cc)

DDii TaskTask--specific duration (hrs/day)specific duration (hrs/day)FRFRwornworn Fraction of time a respirator is Fraction of time a respirator is

worn (unitless)worn (unitless)FRFReffecteffect Fraction of time the respirator is Fraction of time the respirator is

effective (unitless)effective (unitless)FRFRACMACM Fraction of time spent working Fraction of time spent working

with asbestos (unitless)with asbestos (unitless)

Key Information SourcesKey Information SourcesHistorical company records Historical company records

Policies and procedures Policies and procedures Safety manuals Safety manuals Asbestos air monitoring dataAsbestos air monitoring dataInsulation bulk sampling data Insulation bulk sampling data

InIn--depth interviews with former corporate IH depth interviews with former corporate IH and craftsman/plant managerand craftsman/plant managerTestimony of former refinery employees and Testimony of former refinery employees and contract workers contract workers Published and unpublished literature on task Published and unpublished literature on task descriptions and airborne fiber concentrations descriptions and airborne fiber concentrations Professional experiences over last 40 yearsProfessional experiences over last 40 years

Craftsmen of InterestCraftsmen of Interest

InsulatorsInsulatorsPipefittersPipefittersBoilermakersBoilermakersMasonsMasonsWeldersWeldersSheet metal Sheet metal workersworkers

MillwrightsMillwrightsElectriciansElectriciansCarpentersCarpentersPaintersPaintersLaborersLaborersMaintenance Maintenance workersworkers

Task DurationsTask DurationsEach craft estimated to Each craft estimated to perform 4 to 8 distinct perform 4 to 8 distinct taskstasks on weekly basison weekly basisTask durations Task durations characterized using a characterized using a uniform distribution in uniform distribution in the Monte Carlo modelthe Monte Carlo modelModel randomly selected Model randomly selected from available tasks so from available tasks so workday is 8 hrs/dayworkday is 8 hrs/dayDoes not include Does not include potential potential ““down timedown time””such as lunch, breaks, or such as lunch, breaks, or safety meetingssafety meetings

Duration (hr/day)Duration (hr/day)

MaximumMaximumMinimumMinimumTasks Performed by InsulatorsTasks Performed by Insulators

2.02.00.50.5Scoping work and travel to job sitesScoping work and travel to job sites

0.60.60.30.3CleanClean--up of insulation debrisup of insulation debris

1.01.00.50.5Removal of insulationRemoval of insulation

3.03.01.51.5Finishing of insulation Finishing of insulation

4.54.52.52.5Application of insulationApplication of insulation

0.50.50.30.3Mixing of cement and insulation materialsMixing of cement and insulation materials

1.51.50.40.4Prefabrication of insulation or working in shopPrefabrication of insulation or working in shop

Estimated Task Durations for Estimated Task Durations for InsulatorsInsulators

Airborne Fiber ConcentrationsAirborne Fiber ConcentrationsTaskTask--specific fiber concentrations estimated specific fiber concentrations estimated using varying approachesusing varying approaches

Prior to midPrior to mid--1960s, estimates based on 1960s, estimates based on literature literature for for asbestos dustasbestos dustFrom midFrom mid--1960s to mid1960s to mid--1970s, estimates based on 1970s, estimates based on literature literature for asbestos fibersfor asbestos fibersAfter the midAfter the mid--1970s1970s, estimates based on literature , estimates based on literature and company aand company air monitoring datair monitoring dataIf no data, extrapolations made from existing data If no data, extrapolations made from existing data sets or based on professional judgmentsets or based on professional judgment

Fiber concentrations characterized using a Fiber concentrations characterized using a lognormal distribution in the Monte Carlo modellognormal distribution in the Monte Carlo model

Limited Data Available for Most Limited Data Available for Most CraftsCrafts

88--hr TWA fiber hr TWA fiber concentrations concentrations calculated for calculated for insulators onlyinsulators onlyOther craftsmen Other craftsmen estimated to have estimated to have 88--hr TWA fiber hr TWA fiber concentrations some concentrations some fraction of insulators fraction of insulators Estimates for other Estimates for other crafts confirmed by crafts confirmed by available data when available data when possiblepossible

1/301/30thth

WelderWelderSheet metalSheet metalElectricianElectricianPainterPainter

1/251/25ththCarpenterCarpenter

1/201/20thth

PipefittersPipefittersBiolermakersBiolermakersMillwrightsMillwrights

1/151/15ththMasonsMasonsMaintenanceMaintenance

1/51/5ththLaborerLaborer

TWA Concentrations TWA Concentrations Relative to Relative to InsulatorsInsulators

CraftCraft

Dust Concentration Dust Concentration ((mppcfmppcf))

Crushing scrap asbestos is not a steady routine operation (8 hrs a month to about 12 hours a week)

27.514.8Feeding scrap into crusher by shoveling broken pieces into hopper

Crushing scrap asbestos is not a steady routine operation (8 hours a month to about 12 hours a week)

NA10.2Breaking up scrap asbestos insulation by hand prior to crushing

No fibers observed in any of the dust samples from dismantling operations; after a few weeks or months service, insulation on hot lines dries out/disintegrates

5.92.3Removing and dismantling of insulation from old cracking coil 4" tar line by cutting with hatchet or small hand axe and prying loose with hands

Tubing is held in place by fine copper wire7.83.4

Cutting of 2" asbestos tubing (85% magnesia/15% asbestos) with hand saw and pounding tubing into place with open hand during insulation of cracking coil hot oil lines

Blocks or sections of pipe cover are held in place by wrapping #16 gauge galvanized wire about each oneNA0.8Cutting "Sponge Felt" with hand saw during

insulation of treating plant acid suction line

The dustiness of handling these materials has been reduced considerably

NA4.5Applying and plastering blocks of "Fire Felt" to 750-pound cracking coil accumulator

Dust concentrations considered too high for working without adequate protection

23.812.6Applying asbestos "Sponge Felt" to 12" steam line

Work often performed on scaffolds 12-15 feet above ground with men lying on their backs under the line

18.16.9Tapping blocks of 85% magnesia into place during insulation of 12" steam lines

CommentsComments

MaximumMaximumAverageAverage

Job TaskJob Task

Dust Samples Collected for Insulators Dust Samples Collected for Insulators Reported in Literature Reported in Literature (Bonsib 1939)(Bonsib 1939)

aRepresents dust counts (units of mppcf)

Concentration Concentration (fibers/cc)(fibers/cc)

Number Number SamplesSamplesJob TaskJob TaskSample Sample

TypeTypeSample Sample

DurationDurationAnalysis Analysis MethodMethodIndustryIndustryReferenceReference

Range Range (min/max)(min/max)

Arithmetic Arithmetic MeanMean

0.1 0.1 -- 22.922.94.84.81616CleaningCleaning

0.2 0.2 -- 10.710.72.62.62222MixingMixing

0.2 0.2 -- 26.326.38.98.91717RemovalRemoval

0.1 0.1 -- 24.424.42.72.73131Finishing Finishing

0.1 0.1 -- 61.661.66.46.44545Application Application

0.1 0.1 -- 24.324.38.58.52222PrePre--fabricationfabrication

PersonalPersonal0.50.5--3 hr3 hrPCMPCMCommericalCommericalBuildingsBuildings

BalzerBalzer and and Cooper, Cooper,

19681968

0.8 0.8 -- 1010aa

Removing 85% Removing 85% Magnesia/15% Magnesia/15% amositeamosite blocks blocks and pipe sections and pipe sections

1.46 1.46 -- 6.06.0aa

Installing 85% Installing 85% Magnesia/15% Magnesia/15% amositeamosite blocks blocks and pipe sectionsand pipe sections

AreaAreaKonimeterKonimeterU.S. Navy U.S. Navy and Contract and Contract YardsYards

Marr, 1964Marr, 1964

0 0 -- 4.74.7aa0.01 0.01 -- 3.13.1aa2525Cement mixingCement mixing

0.10 0.10 -- 12.812.8aa0.12 0.12 -- 6.196.19aa77BandBand--saw cuttingsaw cutting

0.01 0.01 -- 4.34.3aa0.23 0.23 -- 2.182.18aa1818Layout/cuttingLayout/cutting

AreaAreaKonimeterKonimeterU.S. Navy U.S. Navy ShipyardShipyard

Fleischer et Fleischer et al., 1946al., 1946

Dust and Fiber Samples Collected for Dust and Fiber Samples Collected for Insulators Reported in LiteratureInsulators Reported in Literature

Concentration Concentration (fibers/cc)(fibers/cc)

0.2 - 1.517

Outdoor insulation removal or installation operations

0.6 - 3.37Indoor cutting or mixing operations

Personal2.5-219 minPCMRefineryHervin et

al., 1973

7.6 (standard)

1.5 (improved)

Cutting materials for later use

5.2 (standard)

2.5 (improved)

Cutting and applying insulation block or sections of pipe covering

2.5 (standard)

0.5 (improved)

Mixing and applying cement and cloth covering to insulation

PersonalPCMConstructionNicholson, 1971

0 -14.01.016Cleaning

0.1 - 19.43.117Mixing

1.2 - 49.38.48Removal

0.1 - 6.30.619Finishing

0.2 - 18.32.036Application

1.6 - 19.46.623Pre-fabrication

Personal0.5-2 hrPCMLight/Heavy Industrial Buildings

Cooper and Balzer, 1968

Range Range (min/max)(min/max)

Arithmetic Arithmetic MeanMean

Number Number SamplesSamplesJob TaskJob TaskSample Sample

TypeTypeSample Sample

DurationDurationAnalysis Analysis MethodMethodIndustryIndustryReferenceReference

Concentration (fibers/cc)Concentration (fibers/cc)

----------------00Scoping work and travel to job sitesScoping work and travel to job sites

1.2501.2500.0100.0100.4960.4960.2420.24266CleanClean--up of insulation debrisup of insulation debris

9.7609.7600.0020.0021.5531.5530.7650.7658383Removal of insulationRemoval of insulation

----------------0.00.0Finishing of insulation Finishing of insulation

2.0002.0000.0040.0040.4090.4090.1920.1923636Application of insulationApplication of insulation

----------------00Mixing of cement and insulation materialsMixing of cement and insulation materials

0.3410.3410.0490.0490.1630.1630.1530.15333Prefabrication of insulation or working in shopPrefabrication of insulation or working in shop

MaxMaxMinMinStd DevStd DevMeanMeanSample Sample

SizeSize

TaskTask

Company Asbestos Air Monitoring Company Asbestos Air Monitoring Data for Insulators (1970Data for Insulators (1970––2005) 2005)

Respirator Use and EffectivenessRespirator Use and Effectiveness

According to company safety manuals, respiratory According to company safety manuals, respiratory protection programs were in place since the 1940sprotection programs were in place since the 1940s

Former IH personnel and employees indicated that Former IH personnel and employees indicated that respirators were required since the 1950s, but may respirators were required since the 1950s, but may not have been strictly enforced until the 1970snot have been strictly enforced until the 1970s

Respirator training and fit testing appeared to have Respirator training and fit testing appeared to have been in place since at least the 1980s been in place since at least the 1980s

Even when worn, respirators would likely have been Even when worn, respirators would likely have been only partially effective only partially effective

These parameters were These parameters were characterized using an uniform characterized using an uniform distribution in the Monte Carlo modeldistribution in the Monte Carlo model

Respirator Use (%)Respirator Use (%)

7575--1001007575--1001007575--1001007575--10010019941994--20052005

7575--1001005050--1001005050--1001005050--10010019861986--19931993

5050--75755050--1001005050--1001005050--10010019761976--19851985

1010--505000--10101010--25251010--252519721972--19751975

1010--505000--10101010--20201010--202019661966--19711971

1010--505000--5500--101055--101019511951--19651965

1010--505000--5500--101055--101019401940--19501950

Respirator Respirator Effectiveness Effectiveness

(%)(%)Others CraftsOthers CraftsLaborerLaborerInsulatorInsulator

Time Time PeriodPeriod

Estimated Respirator Use and Estimated Respirator Use and Effectiveness When Working With Effectiveness When Working With or Around Asbestos or Around Asbestos

Time Spent Working With Time Spent Working With AsbestosAsbestos--Containing MaterialsContaining Materials

Literature indicates that insulators spent 60% Literature indicates that insulators spent 60% and 45% of time working with asbestosand 45% of time working with asbestos--containing materials in the late 1930s and late containing materials in the late 1930s and late 1960s, respectively 1960s, respectively

AsbestosAsbestos--containing insulation was used containing insulation was used primarily on very hot (and to a lesser extent hot) primarily on very hot (and to a lesser extent hot) services at refineryservices at refinery

Substitutes for asbestos and a blueSubstitutes for asbestos and a blue--banding banding program were in place by the early to mid 1970sprogram were in place by the early to mid 1970s

Estimated Time Spent Working Estimated Time Spent Working With or Around AsbestosWith or Around Asbestos

Fraction of Time (%)Fraction of Time (%)

0.00010.0001--0.0010.0010.10.1--0.50.50.10.1--0.50.511--5511--5519941994--20052005

0.0010.001--0.010.010.50.5--110.50.5--1122--151522--101019861986--19931993

0.010.01--0.10.111--5511--101055--202055--202019761976--19851985

0.10.1--1122--101033--10101010--30301515--353519721972--19751975

0.10.1--3355--101055--15152525--40404040--505019661966--19711971

0.10.1--5555--151555--20202525--40404545--606019511951--19651965

0.10.1--5555--151555--20202525--40404545--606019401940--19501950

Sheet Metal Sheet Metal Welder Welder

Electrician Electrician Carpenter Carpenter

PainterPainter

PipefitterPipefitterBoilermaker Boilermaker Millwright Millwright

MaintenanceMaintenanceMasonsMasonsLaborer Laborer InsulatorInsulator

Time PeriodTime Period

ResultsResultsInsulators were estimated to have experienced Insulators were estimated to have experienced the greatest 8the greatest 8--hr TWA exposures to asbestos hr TWA exposures to asbestos relative to the other craftsmen relative to the other craftsmen Laborers were the second highest exposure Laborers were the second highest exposure group, with estimated 8group, with estimated 8--hr TWA asbestos hr TWA asbestos exposures 1/5exposures 1/5thth to 1/10to 1/10thth that of insulators that of insulators The next highest estimated exposures were for The next highest estimated exposures were for (1) masons; (2) maintenance workers; (3) (1) masons; (2) maintenance workers; (3) pipefitterspipefitters, boilermakers, and millwrights; and , boilermakers, and millwrights; and (4) carpenters (4) carpenters The remaining craftsmen (welders, sheet metal The remaining craftsmen (welders, sheet metal workers, electricians, and painters) had workers, electricians, and painters) had negligible estimated exposuresnegligible estimated exposures

Estimated 50Estimated 50thth (and 95(and 95thth) Percentile ) Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos Exposures

----

----

----

----

----

----

----(0.002)(0.002)

1986 1986 ––19931993

------------0.0020.002(0.007)(0.007)

0.010.01(0.03)(0.03)

0.010.01(0.04)(0.04)

WelderWelderSheet MetalSheet MetalElectrician Electrician PainterPainter

------------0.0030.003(0.008)(0.008)

0.010.01(0.04)(0.04)

0.020.02(0.04)(0.04)

CarpenterCarpenter

--------0.0040.004(0.007)(0.007)

0.020.02(0.04)(0.04)

0.10.1(0.1)(0.1)

0.10.1(0.2)(0.2)

PipefitterPipefitterBoilermakerBoilermakerMillwrightMillwright

--------0.0050.005(0.01)(0.01)

0.020.02(0.1)(0.1)

0.10.1(0.2)(0.2)

0.10.1(0.2)(0.2)

MaintenanceMaintenance

--------0.0050.005(0.01)(0.01)

0.030.03(0.1)(0.1)

0.10.1(0.3)(0.3)

0.10.1(0.3)(0.3)

MasonMason

----0.0010.001(0.004)(0.004)

0.050.05(0.09)(0.09)

0.30.3(0.7)(0.7)

11(2)(2)

11(2)(2)

LaborerLaborer

----0.0050.005(0.02)(0.02)

0.30.3(0.5)(0.5)

22(5)(5)

88(13)(13)

9 9 (16)(16)

InsulatorInsulator

1994 1994 ––20052005

1976 1976 ––19851985

1972 1972 ––19751975

1966 1966 ––19711971

1951 1951 ––19651965

1940 1940 ––19501950

CraftCraft

Insulators

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc PEL= 2

f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Laborers

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/ccPEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresInsulators and LaborersInsulators and Laborers

Masons

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/ccPEL= 0.2 f/cc PEL=

0.1 f/cc

Maintenance

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc

PEL= 2 f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresMasons and Maintenance WorkersMasons and Maintenance Workers

Pipefitter

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/ccPEL= 0.2 f/cc PEL=

0.1 f/cc

Boilermaker

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc

PEL= 2 f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresPipefittersPipefitters and Boilermakersand Boilermakers

Millwright

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc

PEL= 2 f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Carpenter

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresMillwrights and CarpentersMillwrights and Carpenters

Welder

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc PEL= 2

f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Sheet Metal

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresWelders and Sheet Metal WorkersWelders and Sheet Metal Workers

Electrician

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)PEL=5 f/cc PEL= 2

f/cc

PEL= 0.2 f/cc PEL=

0.1 f/cc

Painter

0.001

0.01

0.1

1

10

100

1940 -1950

1951 -1965

1966 -1971

1972 -1975

1976 -1985

1986 -1993

1994 -2005

Con

cent

ratio

n (fi

bers

per

cc) 50th Percentile

95th Percentile

TLV = 5 mppcf (~30 f/cc)

PEL=5 f/cc PEL= 2

f/ccPEL= 0.2 f/cc PEL=

0.1 f/cc

Estimated 50th and 95th Percentile Estimated 50th and 95th Percentile 88--hr TWA Asbestos Exposureshr TWA Asbestos ExposuresElectricians and PaintersElectricians and Painters

Sensitivity AnalysisSensitivity Analysis

The most The most ““sensitivesensitive”” input parameters to the input parameters to the exposure model varied by time periodexposure model varied by time period

Dust to fiber conversion factor (1940Dust to fiber conversion factor (1940--1965)1965)

TaskTask--specific fiber concentrations (1966specific fiber concentrations (1966--1971)1971)

Respirator use and effectiveness (1976Respirator use and effectiveness (1976--2005)2005)

Fraction of time working with asbestos (1972Fraction of time working with asbestos (1972--2005)2005)

The type of distribution used to characterize The type of distribution used to characterize fiber concentrations had little impact on 8fiber concentrations had little impact on 8--hr hr TWA exposures (uniform, triangular, lognormal)TWA exposures (uniform, triangular, lognormal)

Key FindingsKey FindingsDue to their job tasks, insulators likely experienced the Due to their job tasks, insulators likely experienced the greatest exposures to asbestos at this refinery compared greatest exposures to asbestos at this refinery compared to the other craftsmen to the other craftsmen

Estimated exposures for all craftsmen decreased Estimated exposures for all craftsmen decreased substantially over time (more than 1,000substantially over time (more than 1,000--fold)fold)

The 8The 8--hr TWA exposures estimated for these craftsmen hr TWA exposures estimated for these craftsmen did not exceed contemporaneous occupational exposure did not exceed contemporaneous occupational exposure limits for asbestoslimits for asbestos

The amount of time spent working with asbestosThe amount of time spent working with asbestos--containing materials (and to a lesser extent respirator containing materials (and to a lesser extent respirator use) had a significant impact on the estimates of use) had a significant impact on the estimates of exposure exposure

Estimated 8Estimated 8--hr TWA asbestos exposures were consistent hr TWA asbestos exposures were consistent with estimates reported in the published literature for with estimates reported in the published literature for selected craftsmenselected craftsmen

Study LimitationsStudy LimitationsLack of data for many crafts, job tasks, Lack of data for many crafts, job tasks, and time periodsand time periodsReliance on dust samples and air Reliance on dust samples and air monitoring data collected from other monitoring data collected from other industriesindustriesExtensive reliance on professional Extensive reliance on professional judgment to fill data gapsjudgment to fill data gapsLimited knowledge of asbestos type used Limited knowledge of asbestos type used in various locations within the refinery in various locations within the refinery ((chrysotilechrysotile, , amositeamosite, or mixed fibers) , or mixed fibers)

ConclusionsConclusionsTo the best of our knowledge, a retrospective To the best of our knowledge, a retrospective exposure assessment of this kind has not been exposure assessment of this kind has not been performed in any occupational setting involving performed in any occupational setting involving historical exposures to asbestos historical exposures to asbestos The quantitative exposure estimates generated The quantitative exposure estimates generated for this facility can be used in future risk for this facility can be used in future risk assessments or epidemiology studies involving assessments or epidemiology studies involving asbestos asbestos The methodology and results presented here are The methodology and results presented here are likely to be applicable to some other refineries, likely to be applicable to some other refineries, chemical plants, or industrial facilitieschemical plants, or industrial facilities

AcknowledgmentAcknowledgment

Assistance in interpreting and Assistance in interpreting and understanding the company air monitoring understanding the company air monitoring data, the tasks performed by craftsmen, data, the tasks performed by craftsmen, and the refinery production processes and the refinery production processes were provided by Bruce Larson (former were provided by Bruce Larson (former corporate IH) and Johnny corporate IH) and Johnny CasmoreCasmore(former craftsman and plant manager)(former craftsman and plant manager)This work was funded by ExxonMobilThis work was funded by ExxonMobil