Welding Fume Exposure Assessment of Welders Working in Isolation
Laurel Berman, Ph.D.
with Serap Erdal, Ph.D., Lorraine Conroy, Ph.D., John Franke, Ph.D., Ernesto Indacochea, Ph.D., Peter Scheff, Ph.D., and Daniel Tessier, Ph.D.,
all at University of Illinois at Chicago
American Industrial Hygiene Association Conference and Exposition
May 13-16, 2006Chicago, Illinois
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Introduction: Welding• Over ½ million workers
in the U.S. are involved with welding and related processes
• Fume is a complex mixture of metals, silicates, oxides– About 90% respirable,
< 1 µm aerodynamic diameter
– Exposures are complex: e.g., heavy metals, fine particulates, gases
• Focus: SMAW, MIG
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Health Effects, Regulatory LimitsExposure to welding fume has been associated with a variety of adverse health effects, including:
• Respiratory effects (MFF, bronchitis)• Cancer (Cr, Ni)• Effects on reproductive organs• Neurological effects – Manganism?
– Welding fume• ACGIH TLV-TWA is 3 mg/m3, respirable, 10 mg/m3 total• OSHA PEL (PNOC) is 5 mg/m3 respirable, 15 mg/m3
total • (NIOSH REL, PNOR is also 5 and 15 mg/m3, respirable
and total)
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Study Question/Objectives:
• What are the exposures of welders under isolated conditions?
• Challenge: – A population that works alone – isolation of
exposure • Solution:
– Artists/metal sculptors• Typically work alone• Use processes common to industry/production welding• Special population at risk (NORA)
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Methods: Personal Exposure, Respirable Fume and Fume Components
• Personal samples: breathing zone, respirable
• Cyclone samplers, 4.0 µm cut-point• 2.5 lpm, pumps• 37-mm Teflon filters• Wisconsin State Laboratory of Hygiene
(WSLH) for analysis– Filters pre and post-weighed by WSLH (robotic)– Gravimetric analysis– ICPMS analysis
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Methods: Subjects/Processes Monitored
• Artist A: SMAW/SS, E308H-16, 18 days• Artist B: MIG/MS, ER100S-1, 6 days• Artist C: SMAW/MS, E6011, 16 days• Typical workday: 4 hours, 8+ under deadline• Exposures to respirable and elemental
components measured under both field and laboratory conditions– Studio– Exposure chamber
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Artist A’s Studio Space: SMAW/SSPole barn, well-ventilated: box fan/door, large public art, 40 yrs exp.
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Artist B’s Studio Space: MIG/MSWithin large warehouse facility, dilution ventilation: dock doors/exits.
Large public art, 35 yrs exp.
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Artist C’s Studio Space: SMAW/MSOld industrial facility, now studios and business, 13X40 feet. Small,
“human” forms, private collections/exhibitions, 10 yrs exp.
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SMAW/MS Work Process
• Scavenged/found metals– Including painted
floor panels (Pb) • Two ventilation
conditions• Exposures were
from welding and cutting (no grinding)
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Personal Exposure Concentrations – Respirable Fume, Descriptive Statistics
0.880.180.762.03SD
3.190.752.31** (SuperMIG)
7.72Max
1.540.560.702.98Mean
0.610.360.210.54Min
C #2: SMAW/ MS Conc(mg/m3)
C #1: SMAW/ MS Conc(mg/m3)
B: MIG/MS Conc (mg/m3)
A: SMAW/ SS Conc(mg/m3)
Statist. Descrip-tor
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Personal Exposures to Respirable Particles
• SMAW/SS, Artist A: highest exposures, most variable (SD)– 8 of 18 near or over PEL (PNOC, resp.)
• MIG/MS, Artist B: exposures < PEL • SMAW/MS, Artist C:
– exposures < PEL (fan)– 3 near or > ½ PEL (no fan)
• All artists: not a full workshift– TWA: some zero exposure times unless
maximum production conditions
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Personal Exposure Concentrations: Elemental Composition
• ICPMS: 42 elements for the three processes• Restricted to metals > 0.1% of total metal
mass • Iron greatest component for all three fume
types (as expected)• SMAW/SS – 33% of fume metal• MIG/MS – 22% of fume metal• SMAW/MS – 22 –26% of fume metal
• Remainder: silicates, oxides
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Results –Elemental Fume Composition, Personal Samples
• Fe major component of all fume types – Cu, Mn, Ti also present in all fume types
• Day-to-day variability both gravimetric and elemental– Activity based
• Average elemental concentrations did not exceed individual metals TLVs – View use of TLVs with caution
• a mixture of metals vs. individual metals• fume component interactions• Samples were not full shift
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Results – Composition, Chamber Samples• Samples also exhibited
variability (not expected)– Controlled conditions – However, blanks were also
variable
• Chamber sample mean metal concentrations typically exceeded TLV for individual components– Mn– Cr, Ni (SS) – Fe (MS/6011)– Interpret with caution – only a
few minutes of welding, very intense
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Chamber Sample Fume Composition vs. Personal Sample Fume Composition
• Chamber and personal samples differed:
– Different metals
– Different % of total metal mass
– Different % of total fume mass
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Fume Composition: Field vs. Chamber Samples e.g. SMAW/SS
Studio SMAW/SS:12 Metals > 0.1% of Total Metal Mass
05
101520253035
Mg Mo Al Na Ca Cu Ti Ni Mn Cr K Fe
Metal
Perc
ent T
otal
Met
al
Mas
s (%
)
Fe: 32%, Cr:14%, Mn: 13%, Ti: 6%
Fe and Mn: 22%, Cr: 20%, Ti: 10%
Chamber SMAW/SS14 Metals Comprising > 0.1% of Total Metal Mass
0
10
20
30
Sn V Ca Cu Mg Zn Al Na Ni Ti K Cr Mn Fe
Metal%
Tot
al M
etal
Mas
s
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Fume Composition: Field vs. Chamber Samples e.g. MIG/MS
9 Metals Comprising > 0.1% of Total Metal Mass, Excluding Fe (65%)
05
1015202530
Sn Mo Mg Na Ni Cu Zn Mn
Metals
% T
otal
Met
al M
ass
Fe: 73%, Mn: 10%, Zn: 0.8%
Fe: 65%, Mn: 24%, Zn: 7%
Studio: 14 Metals Comprising > 0.1% of Total Metal Mass, Excluding Fe (73%)
0
10
20
30
As Sn Ti Mo Cr Mg Zn Cu Na Ni Ca K Mn
Metal
Perc
ent T
otal
M
etal
Mas
s
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Conclusions• Field activities are critical when assessing welding fume
exposures– e.g. plasma/oxy-cutting: vaporization of base metal– e.g. grinding: at least 30% respirable– e.g. arc time, 20 – 25%
• This means 2 h of 8 h day
• Field-based activities are critical to understanding real exposures– Laboratory data is useful but for “welding only”– Better if conditions can be matched
• e.g. # of electrodes, sampling time– Laboratory-based studies typically neglect these true
field conditions (arc time, grinding, cutting), leading to over-estimations of exposure
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Acknowledgements• The artists• NIOSH Training Grant
Number T42/CCT522954
• 2004 NIOSH Education Program in Occupational Safety and Health Pilot Project Research Grant
• The contents are solely the responsibility of the author(s) and do not necessarily represent the official views of NIOSH
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QUESTIONS?
Contact Information:Laurel Berman, Ph.D.Boelter and Yates, Inc.
[email protected]@gmail.com