PO 117: Exposure Assessment Strategies 117: Exposure Assessment Strategies AIHce 2006 13-18th May ... (HSE, 1994) MDHS 14/3 (HSE, ... PETRONAS Dr. Sean Semple

PO 117: Exposure Assessment Strategies

AIHce 200613-18th May

at theMcCormick Place

Chicago, Illinois

Norhazlina Mydin1 , Dr. Sean Semple21 Industrial Hygienist, PETRONAS, Malaysia

2 Senior Lecturer, University of Aberdeen, Scotland

Development And Validation Of A Model To Estimate Welding

Fume Exposure

Malaysia: Truly Asia

Population : 26.13 million (as 2nd Quarter 2005)

Independence Date : 31st August 1957

Capital City : Kuala Lumpur

Language : Malay (English widely used)

Aim & ObjectivesIntroduction of WeldingWelding FumeHealth Effects of Welding FumeExposure AssessmentStudy MethodologyFindingsConclusions

Content

Aim & Objectives

Development And Validation Of A Model To Estimate Welding Fume Exposure

Aim & Objectives

To measure welding fume concentrations in the identified occupational settingsTo identify the factors influencing the levels of exposureTo develop an exposure model to estimate fume exposuresTo validate the exposure model

Introduction to Welding


Introduction of Welding

What is welding?Welding – principal joining process in the fabrication of numerous metal products by fusion or coalescence of the interface

Giachino et. al., 1978

Introduction of Welding cont’d

Variety of welding processes include:

Arc welding

Oxy-acetylene welding

Resistance welding

Brazing

Thermal cutting

Introduction of WeldingArc Welding

Arc welding and oxy-acetylene welding are the common types of welding applied

Different Arc processes:Metal inert gas (MIG)Manual metal arc (MMA)Tungsten inert gas (TIG)

Introduction of WeldingSub-arc welding

Introduction of WeldingArc Welding – MIG Welding

Introduction of WeldingArc Welding – FCAW

Introduction of WeldingArc Welding – TIG Welding

Introduction of WeldingOxy-acetylene Welding

Introduction of WeldingArc Welding – TIG Welding

Introduction of WeldingArc Welding – MMA Welding

Introduction of WeldingVariations in Arc Welding

Process variations in arc welding types depending on:

ApplicationsProcess requirement

Base metalsWelding rodsFluxShield gas

Introduction of WeldingApplicability

Shipping industry

Oil & gas industry

Construction industry

Automotive & repair

Electronics (soldering)

Etc.

Welding Fume


Welding FumeHealth & Safety Hazards

Toxic fumesDustGasesNoiseVibrationHeatRadiationElectrical currentErgonomics

Referred as “particulate emissions intrinsic to the various welding processes”

International Agency Research for Cancer, 1990

Welding Fume

Fe, Mn, Ca, Si, F, K, Ti, Cr, NiMMA/SSFe, Mn, Ca, K, Si, F, TiMMA/MSNi, Fe, BaMMA/NiFe, Mn, Si, KMIG/MSFe, Mn, Cr, NiMIG-MAG/SSFe, Mn, SiMIG-MAG/MSNi, FeMIG/NiAlMIG/Al

Elements (Fume Compositions)Welding Process – Metal

Welding FumeWelding Fumes Components

Welding FumeSources

Sources of welding fume are:

1. Vaporisation of wire, rod, coatings

2. Decomposition and vaporisation of the flux

3. Spatter from the arc regions and weld pool

4. Evaporation from the molten weld pool

Based on:ACGIH – USCOSHH – UKUSECHH – Malaysia

5 mg.m-38 hr TWA

Welding FumeWhat is the OEL ?

Health Effects of Welding Fume


Due to Mn, Al, CdFirst stage - psychiatric symptoms such as emotional lability, compulsive behaviourSecond stage – neurological symptoms such as impaired speech, tremor, muscular weeknessA risk factor to “Parkinsonism”. Welders had a younger age of onset of PD vs. control

(Hudson et al., 2001, Annals of Occ. Hyg.)(Sjogren et al., 1996, Occ. & Env. Med.)

(Racette et al., 2001, Neurology)

Health Effects of Welding FumeNeurological Effects

Lung function The presence of fibrosis and emphesema among heavily exposed welders who work in poorly ventilated areas are transparent

(Meo et al., 2003; Barbee & Prince, 1999; Beckett et al., 1996)

Lung cancerBased on 17 cohort and 16 case-control studies, IARC concluded welding fume as “possibly human carcinogen (Group 2B)”Studies have confounded effects of smoking and asbestos exposure

(IARC, 1990)

Health Effects of Welding FumeRespiratory Effects - 1

Metal fume fever Acute respiratory illness of welders occurred during and after dutiesResolves within 24-48 hours after onset

(Antonini, 2003; Liss, 1996)

AsthmaCaused by inhalation of specific sensitizing agents in the workplaceCr-III and Ni are possible airway sensitizers in SS welding

(Palmer & Eaton, 2001; Howden et al., 1988)

Health Effects of Welding FumeRespiratory Effects - 2

Fume contain metal with reproductive toxicity effects such as Cr(VI), Ni, Mn

Cr(VI) – mutagenic effects in somatic and germ cells

Mn – causes degeneration of testes in animal

Health Effects of Welding FumeReproductive Effects

Exposure Assessment


Exposure Assessment

Why do we need exposure assessment?

⌦Welding is widely used worldwide (more than 3 million workers

⌦Fumes generated is expected to be higher than the OEL

⌦Severe impact of health hazards

Important to have a thorough, accurate and representative welding fume exposure assessment

To obtain accurate and precise estimate of the distribution and determine factors affecting human health in the mostefficient and cost-effective manner

Vermeulen et al., 2002, Scand.J. of Work, Env.& HealthNieuwenhuijsen, 2003, Exposure assessment in occupational and environmental epidemiology

Exposure Assessment – ModelPurpose

Exposure AssessmentStrategy

Personal sampling Stats analysis++

8 fabrication companies in Aberdeen, Scotland participated in the study

63 personal and 13 background welding fume samples of TIG, MIG, MMA, FCA, sub-arc and oxy-acetylene welding processes were collected using method as per the EH54 procedure

Potential determinants of exposure were observed and recorded throughout sampling duration

Samples were analysed:Gravimetrically for total fume concentration

Chemically for Mn and Ni content

Statistical analysis were used to discuss the findings and develop the exposure model

Exposure AssessmentStudy Methodology

SKC Sampling pumpIOM sampler25mm glass fibre filters

Reference:BS EN ISO 10882 – Part 1MDHS 70 (HSE, 1994)MDHS 14/3 (HSE, 2000)

Exposure AssessmentSampling - 1

Welder wearing a sampler

Exposure AssessmentSampling - 1

*sampler placed behind welding shield

Findings


5.0 / 7.9%

3.0 / 4.8%

16.0 / 25.4%

7.0 / 11.1% 13.0 / 20.6%

19.0 / 30.2%

Oxy-Acetylene

Sub-arc

FCAW

MMA MIG

TIG

Number of welding samples by welding processes

FindingsFume Data

Log Normal of Welding Fume Concentration

FindingsPersonal Exposure Distribution

GM = 3.63 mg.m-3, GSD = 3.74 mg.m-3Log normal of conc

4.003.50

3.002.50

2.001.50

1.00.50

0.00-.50

-1.00-1.50

-2.00

Freq

uenc

y

12

10

8

6

4

2

0

Std. Dev = 1.32 Mean = 1.29N = 63.00

Boxplot – Fume Concentration

FindingsPersonal Exposure Distribution

531671319N =

Type of welding processes

OXYSub-arcFCAWMMAMIGTIG

Wel

ding

fum

e co

ncen

trat

ions

(mg.

m^-

3) 60

50

40

30

20

10

0 41

25

36

FindingsBackground Fume Concentration

GM = 3.63 mg.m-3, GSD = 3.74 mg.m-3

LN (Concentration)

Std. Dev = .90

LNCONC

1.00.500.00-.50-1.00-1.50-2.00

Freq

uenc

y

5

4

3

2

1

0Mean = -.36N = 13.00

Boxplot – Background Fume Concentration

FindingsBackground Fume Concentration

25114N =

Type of welding processes

OXYFCAWMMAMIGTIG

Wel

ding

fum

e co

ncen

trat

ions

(mg.

m^-

3)

3.0

2.5

2.0

1.5

1.0

.5

0.0

FindingsModel Development

32 personal fume data were used in model development31 of the remaining data were used for model validationAdditional of 835 data from The Welding Institute database (Cambridge, UK) were used in model developmentRecalculated the GM and GSD of the welding fume concentrationsCombined with the potential determinants of exposure in the mathematical model

FindingsDeterminants of Exposure

Types of welding processes:TIG/ MIG/ MMA/ FCAW/ sub-arc/ oxy-acetylene

Welder’s position relative to work pieceVertical/ horizontal/ mixed vertical and horizontal

Location of welding activity:Open workshop/ open air/ confined space

Type of ventilationNatural/ general indoor ventilation/ LEV

FindingsStatistical Analysis

Fume concentration data together with the determinants of exposure were entered into SPSS 11.5 for statistical analysis

Multiple linear regressions were utilized to identify the factors significantly contributed to the exposure (p< 0.05)

The determinants of exposure became modifiers to the basic equation of fume exposure

4 models with appropriate R2 value were finalizedand validated with the remaining 31 welding

fume concentration data

Coefficient of each determinant were determined through the trial-an-error method

R12 = 0.4724

R32 = 0.8285

R22 = 0.3355

R42 = 0.7996

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140Measuremed fume concentration (mg.m-3)

Pred

icte

d fu

me

conc

entr

atio

n (m

g.m

)-3

model1 model3 model2 model4Linear (model1) Linear (model3) Linear (model2) Linear (model4)

FindingsCorrelation of Fume Concentration

Model 3 provides the best estimates !!

Correlation between the predicted and measured welding fume levels (validation dataset)

FindingsWelding Fume Exposure Model

Model 3(Predicted (WF) = WFw X p X v X a X f)Where:

WFw is the weighted welding fume concentration (mg.m-3)P is the modifier for welder’s positionV is the modifier for ventilationA is the modifier for the air movementF is the modifier for the fuming factor

Able to predict fume concentration with R2 value of 0.83 and % variation of 16% between the predicted and measured welding fume concentration

Conclusions & Way Forward


Conclusions

This study has developed a model to help with the quantitative assessment of worker’s exposure to welding fume based on subjective exposure assessment

The model was based on the mean welding fume concentration and significant determinants of exposure

Guidance values of the modifiers were proposed and models were validated with the best achieving R2

value of 0.83

The Way Forward

This findings shall assist occupational hygienists to carry out comprehensive welding fume exposure assessment by looking at the contributing factors

To aid medical practitioners and researchers carrying out retrospective exposure assessment to aid more epidemiological studies among arc welders

To improve the controlling factors to reduce the welders’ exposure to the fume

Acknowledgement

PETRONAS

Dr. Sean Semple, University of Aberdeen, Scotland

The Welding Institute, Cambridge

The Institute of Occupational Medicine (IOM), Edinburgh

UK HSE/HSL

Participating industries

Thank You

Norhazlina [email protected]

PETRONAS, MALAYSIA


Documents

PO 117: Exposure Assessment Strategies 117: Exposure Assessment Strategies AIHce 2006 13-18th May ... (HSE, 1994) MDHS 14/3 (HSE, ... PETRONAS Dr. Sean Semple