THE COHEN GROUP
  Environmental Health & Safety Consulting Services

The Cohen Group Newsletter - Volume 8  Issue 3, Article 2.  September, 2006

  Welding and Metals Exposure
Tim Bormann, CIH

The term "steel" encompasses many types of metals made principally of iron, but often containing other metals as well, including manganese, chromium, and nickel and non-metallic elements, such as carbon, silicon, phosphorus, and sulfur. Of these elements, manganese, chromium and nickel typically present the most significant health concerns. They are contained either in the base metal (mild steel or ferromanganese alloy) that is being welded or in the welding consumables (electrodes and rods).

In arc welding operations, manganese may be present in the electrode in amounts typically less than 5%. Manganese is also commonly found in steel at levels from less than 1% to 10%. Except for stainless steels and some "hard facing" materials, chromium, is typically present at levels less than 1%, as is nickel. It is important to examine the material safety data sheets for all products being used in the welding operation since individual metal constituents may vary widely in the steel alloy and the electrode. As the percentage of any one constituent metal increases, so does the potential exposure to that constituent during welding.

Cal/OSHA regulates exposure to welding fumes as both total particulates and as individual metal components in Section 5155 of Title 8 of California Code of Regulations, "Permissible Exposure Limits for Chemical Contaminants,". The Permissible Exposure Limit (PEL) for welding fumes is 5 milligrams of total particulates per cubic meter of sampled air (5 mg/m³). The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for total welding fume was the basis for the PEL, but was withdrawn in 2003. Interestingly, when the ACGIH recommended the 5 mg/m³ particulate welding fume limit, they were clear that the exposure limit was based on measurements made inside the welding helmet. This sample location requirement was not, and continues not to be, a stipulation of the Cal/OSHA PEL. The ACGIH has chosen not to have a welding fume TLV, but instead relies on the TLVs for individual metal constituents of the welding fume. When air monitoring is conducted for welding operations, the total particulate concentration may often be the only aspect of the welding fume analyzed. However, this overlooks the potentially harmful exposure to the individual elements.

It has been the experience of The Cohen Group that even though total particulate exposure levels during many welding operations may be below the PEL, exposures to individual metals (manganese, in particular) may actually be above the respective PEL. For example, the current Cal/OSHA PEL for manganese is 0.2 mg/m³, established to reduce the potential for health affects to the lungs and central nervous system. This level may be readily exceeded in some instances of welding when the amount of manganese in the metal being welded is significant and the total exposure to welding fumes is elevated but still below the PEL of 5 mg/m³.

When monitoring for welding fumes, consider having the lab perform a welding fume scan of individual metal components (in accordance with NIOSH analytical method 7300). This will provide information on the levels of cadmium, total chromium (various forms), copper, iron, manganese, nickel, silver and zinc in the sample.

Adequate ventilation will generally reduce exposure to the various metal constituents from welding. Ventilation is particularly important when welding is done in hard-to-reach or tight work spaces with limited air flow. Proper ventilation may be achieved by good natural (i.e., general dilution) ventilation or through use of a local exhaust system or blowers.