| Hexavalent Chromium, also known as Cr(VI), is a known carcinogenic fume given off when welding or cutting is performed on stainless steel. In addition, other heavy metals are released through these processes; including lead, manganese (Mn), and molybdenum. In March 2006 the Occupational Safety and Health Administration (OSHA) implemented a new Cr(VI) standard, lowering the Permissible Exposure Limit (PEL) from 52 microg/m3 to 5 microg/m3.;In recent years, an emphasis has been made on an additional metal fume, manganese. Recent studies have shown that individuals exposed to high levels of Mn can develop neurological problems. The American Conference of Governmental Industrial Hygienists (ACGIH) proposed a change of the Mn Threshold Limit Value (TLV) in the 2010 edition of the ACGIH TLVs and BEIs from 0.2 mg/m 3 to 0.02 mg/m3.;This study evaluated the exposure to Cr(VI) and Mn associated with shielded metal arc welding (SMAW) on stainless steel and the migration of Cr(VI) and Mn in a fossil fuel generation facility. The facility is composed of eight different maintenance crews, which are responsible for the maintenance of a specific area of the facility. The crew evaluated is composed of twelve mechanics and works primarily with stainless steel material.;Results showed detectable concentrations that were below the occupational exposure limit of Cr(VI) in two of the personal breathing zone samples and detectable concentrations below the occupational exposure limit in one of the general area trials 10 feet away from the work area. Mn concentrations below the occupational exposure limit were detected in all four trials in the personal breathing zone samples and general area samples 10 feet away from the work area. None of the general area samples collected in the hallway or breakroom detected a measurable concentration of Cr(VI) or Mn. Wipe samples collected showed concentrations of Mn in all of the trials but Cr(VI) was not observed in any of the wipe samples.;While the study showed a lack of migration of Cr(VI) and Mn through the area air samples, Mn was detected in all of the breakroom wipe samples. It is postulated that migration occurred through the transfer of particles from the employees clothing to the breakroom. It is suggested the welders do utilize local exhaust ventilation and practice good hygiene. Welders are encouraged to wash their work clothes frequently, as well. |
