The purpose of these studies is to identify possible candidate industries, labor unions and workplaces with occupational exposures to welding fumes (WF) with special emphasis on manganese (MN) and recruit their participation in an exposure assessment study. NIOSH has identified a specific need for assessing the neuropsychiatric effects of WF, as concern was noted for the potential of manganese (Mn) in welding fume to cause neurotoxicity in exposed workers. This study will measure workplace exposures of welders, especially those exposed to appreciable levels of Mn, often associated with mild-steel and stainless steel welding operations. Manganese in WF complexes with many other metal elements, chiefly iron, oxides, and fluoride and may exist in several valence states. A literature review and initial field surveys are ongoing to assemble the information necessary to more thoroughly develop the study design and exposure monitoring strategy. Selection of sites will depend on the: industrial sector;welding process(es);production rates;number of welders and other workers exposed;previous exposure records;anticipated exposure levels (preferably with a range of exposures);and work place conditions. NIOSH established a contract for assistance recruiting study sites and industrial hygiene field data collection. Background information for selection of possible candidate companies is being evaluated and suitable companies will be recruited to participate in the study. Selection will depend on the: industrial sector;welding process(es);production rates;number of welders and other workers exposed;previous exposure records;anticipated exposure levels (preferably with a range of exposures);and work place conditions. Six companies agreed to partner with NIOSH. Literature was reviewed relevant to formulate the rationale and design of industrial hygiene monitoring strategies and supporting analytical method development. Current methods do not distinguish between the specific Mn compounds within WF which have different valence states and solubility, factors which could affect bioavailability and resultant health effects. Analytical chemistry exploratory research was initiated in the laboratory to investigate the viability of several alternative analytical approaches. A sequential extraction procedure was evaluated for it's ability to differentiate different valence states and solubilities using different Mn compounds. X-ray defraction (XRD) analysis was also performed which was able to distinguish between different valence states. Welding fume field samples were analyzed using scanning and transmission electron microscopy (S/TEM). Bright field and Z-contrast imaging were determined to be crucial in obtaining the most information possible. Furthermore, elemental information was obtaining using energy dispersive x-ray analysis (EDXA) along with x-ray mapping. These combined techniques show promise for characterizing the welding fumes in regards to Mn speciation;thus air sampling surveys were conducted applying these methods. An important objective of this project will be to determine if these analytical techniques can be applied to samples collected in workers'breathing zones where contaminant mass loading may be low. A NIOSH e-news internet site solicited partnerships with the private sector to allow NIOSH access to their sites where welding activities occur to evaluate exposures to welding fume with emphasis on Mn. Several companies showed interest. Contact was initiated and site visits were conducted at 5 facilities in September 09 and FY10. The purpose of these walk through surveys was to collect supporting information, introduce the project to plant and union representatives, and collect a series of ?screening? samples to aid in the analytical method development. Furthermore, research on particle size distributions was conducted. To date, a total of 4 sampling surveys have been conducted and over 90 full-shift worker days of exposure have been collected. Six additional monitoring surveys are scheduled.
