Lead Paint Removal >> Lead Paint Exposure To Workers In California

Occupational Safety and Health Administration (OSHA) Welding Safety Orders for hot work on painted steel structures require that lead-based paint be stripped back "a sufficient distance from the area to be heated to ensure that the temperature of the unstripped metal will not be appreciably raised." 
For enclosed spaces, this distance must be at least four inches from the weld or cut line, or Lead Paint Exposure To Workers In California workers must wear supplied-air respirators. 

(1) The somewhat stricter Cal/OSHA Construction Safety Order requires that all surfaces covered with toxic preservatives be stripped at least four inches from the weld or cut line (no mention of enclosed spaces), or Lead Paint Exposure To Workers In California workers must wear supplied- air respirators. The (2) The California Department of Health Services (DHS) Occupational Lead Poisoning Prevention Program received anecdotal evidence that iron workers performing hot work on previously stripped steel may encounter high airborne lead levels. These exposures may be caused by a failure to meet the four-inch- minimum OSHA requirement, Lead Paint Exposure To Workers In California or by hot work so intense that excessive lead fumes are created even when the paint is stripped back. 

The lead source may be residual paint on the surface or possibly lead in the base steel. To investigate this issue, DHS industrial hygienists conducted air sampling of an iron worker's exposure to lead fumes during two days of hot cutting 3/4-inch steel for a major seismic retrofit job on a bridge. The general contractor had Lead Paint Exposure To Workers In California purportedly stripped the lead- based coating back four inches from both sides of the cut lines prior to cutting. 

Background Very few task-based exposure assessments of iron workers engaged in the hot cutting of painted steel exist. A 1988 Canadian study of a demolition project that included the oxy-acetylene torching of an old water purification system Lead Paint Exposure To Workers In California demonstrated that sandblasting a six- to eight-inch strip from the painted metal prior to cutting significantly reduced breathing zone air levels from a mean of 21,330 ¹g/M3 to mean values of 1300 ¹g/M3 and 1100 ¹g/M3 . 

(3) A recent task-based exposure assessment evaluated oxy-acetylene torch cutting on stripped steel associated with a bridge renovation project and Lead Paint Exposure To Workers In California with an elevator demolition project. The study explored the practical technical and management problems of completing paint removal prior to torch cutting.

(4) Methods In November 1998, Lead Paint Exposure To Workers In California DHS industrial hygienists conducted two consecutive days of task-based personal exposure monitoring of an iron worker cutting 3/4-inch steel on the western span of the San Francisco-Oakland Bay Bridge. The Bay Bridge was constructed in 1936, and the existing paint is known to contain high levels (approximately 20–40%) of lead.

(5) The work consisted of hot cutting 40 one-inch by 24-inch segments from existing painted 3/4-inch steel forms (Figure 1). These steel forms were being trimmed to accommodate installation of additional outer steel braces for Lead Paint Exposure To Workers In California earthquake retrofit. The iron worker used a Lincoln Arc Iron worker CIV-25 with carbon arc electrode rods (Copper clad Arcair) on the first day, and an oxygen/propane torch on the second day. 

Actual hot-cutting time consisted of 166 minutes on day one, and 154 minutes on day two. For the eight- hour time-weighted average (TWA) calculation, Lead Paint Exposure To Workers In California zero exposure was assumed for the remainder of each shift. The paint had been stripped back from the cut line by the general contractor previously using open sandblasting. 

A tape measure was used to record the actual distance that the paint had been stripped back from each of 12 cut lines, Lead Paint Exposure To Workers In California on both front and back surfaces. Direct readings of lead levels on both stripped and unstripped steel were taken using a Niton XL-309 X-ray fluorescence (XRF) analyzer. A bulk sample of the paint was collected and analyzed. 

Personal samples in the operator breathing zone inside the welding helmet were taken on both days. On day two, Lead Paint Exposure To Workers In California separate filter samples were collected for (1) exposure when cutting on stripped steel (91 minutes) and (2) exposure when making five corner cuts on steel that had not been stripped of paint (63 minutes). 

A laboratory accredited by the National Lead Laboratory Accreditation Program performed the analyses, using Environmental Protection Agency method #SW-846 for analysis of metal in paint chip samples, Lead Paint Exposure To Workers In California and NIOSH method #7300 for analysis of airborne lead particulates. Results Content of Lead and Other Metals in the Paint Laboratory analysis of the bulk paint chip showed 4.2 percent lead by weight in the bridge paint at this location. 

This result is much lower than the 20 to 40 per- cent levels of lead typically found in bulk samples taken on San Francisco Bay Area bridges of this era. Analysis for three other metals showed 1900 ppm (0.19%) chromium, <50 ppm arsenic, Lead Paint Exposure To Workers In California and <2 ppm cadmium. At the work site, XRF analyzer readings confirmed a positive reading for lead (mean of 52 mg/cm2 for 28 readings of unstripped areas). 

The depth indicator on the XRF demonstrated that the lead was concentrated in the deepest, Lead Paint Exposure To Workers In California bright- orange layers. The Niton XRF Spectraview L-shell spectrum was analyzed to determine whether other elements were presentin the paint. The model used gave qualitative, but not quantitative, results for metals other than lead.

The spectrum proved that iron and zinc were both present above the detectable limit (DL) of 500 ppm. Furthermore, it indicated that the following elements that are often found in paint were not present above the DL of 500 ppm: arsenic, chromium, manganese, and nickel; and mercury was not present above the DL of 100 ppm. 

However, the Niton XRF was unable to provide information about cadmium or beryllium, Lead Paint Exposure To Workers In California as these elements were not detectable due to interference by the XRF's cadmium source. Stripping XRF readings revealed no detectable levels of lead (detection level of 0.05 mg/ cm2 ) on the steel that had been stripped (mean of <0.07 § 0.02 mg/cm2 for 23 readings of stripped areas). These low readings indicate that the stripping method, open abrasive blasting, was effective in removing paint.

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