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Welding Exposures in Construction, 30 Years of OSHA Data

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Pam Susi , Mike Flynn
CPWR - The Center for Construction Research and Training , University of North Carolina at Chapel Hill
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Summary Statement

This presentation by Mike Flynn at the AIHA conference in May 2013, co-authored by Pam Susi of CPWR, was an analysis of an impressive data set of 30 years of welding sampling results from OSHA compliance inspections. The data set included 100,000 measurements collected on 30,000 welders from 1978 to 2008. The results indicated that heavy construction and structural steel erection had elevated risks of overexposure to manganese and lead jointly.
May 2013

Welding Exposures in Construction - 30 Years of OSHA Data

Michael R. Flynn

University of North Carolina Chapel Hill

mike_flynn@unc.edu

PO 136 Construction

Construction Worker Performing Welding Work

Acknowledgements

  • Co-author: Pam Susi, MSPH, CIH - Center for Construc8on Research and Training (CPWR)
  • Funded in part by coopera8ve agreement OH009762 from Na8onal Ins8tute for Occupa8onal Safety and Health (NIOSH)
  • Thanks to OSHA for providing the data set

Objectives

  • Use OSHA data to characterize 8hr-TWA exposures to airborne contaminants associated with welding in the construc8on industry, with a focus on Mn.
  • Explore mixed exposures with addi8ve effects especially Mn and Pb
  • Test for any exposure trends in 8me over the 30 year period

OSHA DATA SET

  • Data set obtained in 2008; over 100,000 measurements; ~30,000 welders in a wide variety of industries, from 1978-2008.
  • A subset for the Construc8on Industry was extracted based on SICs (15xx, 16xx and 17xx) (N~2500).

Types of Data in the OSHA File that were used in this analysis

Exposure Type Inspection Type Sample Type
Ceiling Complaint Personal
Peak Follow Up Bulk
TWA Referral Wood
Dose Other Blood
ND Fatality Urine
Not analyzed Monitoring Area
Short Term Exposure Variance  
Not Valid Unprogrammed  
  Programmed  

Agents Ranked by Sample Size

Substance Count (N) Zeros (<LOD)
Pb 455 239
Fe 418 14
Zn 293 36
Cu 238 41
Cr 238 92
Ni (ins) 201 115
Mn 182 27
Cd 149 115
Total 112 7
CrVI 6 1

Select Exposures: Mean/ OEL > 0.5

  Mean PEL TLV REL Mean/ PEL Mean/ TLV Mean/ REL
Mn 0.10 5.0 0.1 1.0 0.02 1.0 0.1
Cu 0.12 0.1 0.2 0.1 1.2 0.6 1.2
Pb 0.22 0.05 0.05 0.05 4.5 4.5 4.4
Ni ins 0.045 1.0 0.2 0.015 0.05 0.2 3
CrVI 0.006 0.005 0.01 0.001 1.2 0.6 6
Cd 0.013 0.005 0.01 Ca 2.5 1.3 NA
Zn 2.67 5.0 NA 5.0 0.5 NA 0.5

2 digit SIC codes

Ironworkers rehabilitating a steel bridge

Ironworkers rehabilitating a steel bridge (could fall under 16XX or 17XX steel erection)

SIC CODE DESCRIPTION EXAMPLES
15xx Building General Contractors Includes residential, commercial, industrial buildings
16xx Heavy Construction Includes roads, bridges, tunnels, water, sewer, power & communication lines
17xx Special Trade Contractors Includes sub specialties - e.g. steel erection, plumbing, HVAC, & sheet metal work

Welding Crafts in Construction

Boilermakers work on boiler tubes

Boilermakers work on boiler tubes during power plant rehab/ maintenance

Pipe fitter and welder working on HVAC piping

Pipe-fitter/ welder working on HVAC piping during new construction of a university building

Manganese by 2 digit SIC

Mn 15xx 16xx 17xx
Mean 0.08 0.19 0.07
Median 0.04 0.06 0.03
Std. Dev. 0.10 0.35 0.10
Maximum 0.34 1.66 0.58
Count 19 52 111
Fraction > TLV* 0.32 0.37 0.25

*Inhalable Mn TLV = 0.1 mg/m3 2013

Lead by 2 digit SIC

Pb 15xx 16xx 17xx
Mean 0.06 0.48 0.14
Median 0.00004 0.007 0.00004
Std. Dev 0.14 2.75 1.16
Maximum 0.70 28 19.06
Count 44 123 288
Fraction > TLV* 0.18 0.29 0.17

*Pb TLV = 0.05 mg/m3 2013

Descriptions of some 4 digit SIC

SIC CODE DESCRIPTION EXAMPLES
1629 Heavy Construction not elsewhere classified Petrochemical plant; power plant; pile driving, boilermakers
1791 Structural Steel Erection Iron work, structural-contractors; Storage tanks
1799 Special Trade Contractors, NOC Welding contractors, operating at site of construction: Lead burning contractors

Manganese by 4 digit SIC

Mn 1629 1791 1799
Mean 0.22 0.17 0.05
Median 0.05 0.13 0.01
Std. Dev. 0.40 0.16 0.10
Maximum 1.66 0.58 0.35
Count 29 16 17
Fraction > TLV* 0.41 0.75 0.18

*Inhalable Mn TLV = .01 mg/m3 2013

Lead by 4 digit SIC

Pb 1629 1791 1799
Mean 0.58 0.10 0.13
Median 0.00004 0.03 0.00004
Std. Dev. 3.63 0.23 0.49
Maximum 28 1.45 2.9
Count 61 51 56
Fraction > TLV* 0.11 0.33 0.20

*Lead TLV = 0.05 mg/m3 2013

Additive exposures Pb and Mn: SIC 1791 86% > 1; SIC 1629 50% > 1

SAMPLE Mn/ TLV Pb/ TLV SUM
1 2.00 0.66 2.66
2 1.48 0.32 1.80
3 1.10 2.40 3.50
4 3.40 0.74 4.14
5 3.34 0.64 3.95
6 1.18 0.00 1.18
7 0.06 0.00 0.06
AVERAGE= 1.79 0.68 2.47
NUMBER > 1 6 1 6 (86%)

Iron Exposures vs. Year SIC 1799

Graph of Iron Exposures versus Year SIC 1799

 

Conclusions

  • Welders in construction have been exposed to a wide variety of substances at levels in excess of current OELs.
  • Lead, cadmium, copper, zinc, and hexavalent chrome were exposures with mean values over the PEL.
  • Mean exposure of Mn was over the current TLV
  • Heavy Construction NOC and Structural Steel Erection had elevated risk of overexposure (TLV) to Mn and Pb jointly. A neurological health concern.
  • Limited evidence of declines in exposures over time; one detected - Fe in Special Trade Contractors

Recommendations

  • Reduce the PEL for Mn.
  • Increase the use of local exhaust ventilation.
  • Target joint exposures e.g. Mn and Pb
  • Target carcinogens: Cd, CrVI.

Summary of Select Exposure Data

Substance Count (N) Zeros (F) Mean Median
Mn 182 27 0.10 0.04
Fe 418 14 1.77 0.74
Total 112 7 3.28 1.97
Cu 238 41 0.12 0.005
Pb 455 239 0.22 0
Ni (ins) 201 115 0.045 0
Cd 149 115 0.013 0
CrVI 6 1 0.006 0.00006
Cr 238 92 0.056 0.002
Zn 293 36 2.67 0.03

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