Welding Operations and Manganese

The Division of Occupational Safety and Health’s Health Effects Advisory Committee (HEAC) is meeting March 6 to discuss new permissible exposure limits (PELs) for manganese, hydrogen sulfide, 2 butoxy ethanol and 2-butoxyethyl acetate.  I am most interested in manganese due to the potential impact reducing the PEL will have on welding operations. Manganese is a component of most mild steel, which is commonly welded.  Manganese is also found in many welding rods and filler metals to promote hardness.

DOSH is proposing a PEL of 0.1 mg/m3 total (inhalable) particulate and 0.01 respirable particulate for this substance.  The current PEL is 0.2 mg/m3 for total particulate with no PEL for respirable.  The American Conference of Industrial Hygienists (ACGIH) current threshold limit value (TLV) is 0.1 mg/m3 inhalable particulate and 0.02 mg/m3 respirable particulate.  Interesting to note; the federal OSHA PEL for manganese has remained at 5.0 mg/m3.

According to DOSH, “neurological effects are the most sensitive toxicological endpoints for manganese exposure”.  The Cohen Group has conducted many welding surveys, where manganese is component of the welding fume. In our experience we have found exposure concentrations approaching or exceeding the current Cal/OSHA PEL of 0.2 mg/m3 and the ACGIH TLV for welding mild steel.  This is particularly true for “production” welding operations, where the worker is primarily engaged in actual welding activities over the course of the work day.  Many welding operations are more short term, where the worker may be engaged on other non-welding tasks.  Short-term welding operations have not typically been of concern to exceed the PEL.  However, with the proposal to lower the PEL, some short term operations may now exceed the PEL. Assuming the new PEL as proposed will be adopted, The Cohen Group can assist you in evaluating your welding operations and assist in recommending potential exposure controls such as local exhaust ventilation and personal protective equipment so that you will maintain compliant with OSHA.