According to the American Chemistry Council (ACC) consultants, lowering the permissible exposure limit (PEL) for crystalline silica would cost employers billions of dollars a year and make accurate measurements difficult. Never mind how many lives the lowering of the PEL would save. Let’s not let something like that get in the way of lost revenue.

Let me address the second issue first. Most labs have no problem currently analyzing silica down to 10ug. They would not have to lower their detection limit to meet the new standard – recommended by NIOSH and ACGIH at 50ug/m3.If the accuracy of the method is ok for the current PEL - then it would be fine for the proposed PEL. Sampling at 1.7LPM for 8 hours would give you a detection limit of 12 ug/m3– well below the 50ug/m3.

As for the first part, as a Health & Safety Professional, how can you ignore the fact that exposing workers to levels of silica at the current allowable limit will cause numerous cases of silicosis. I do not have the numbers, but I am sure someone can find them to support this. Is the tradeoff of human life worth the revenue savings?

I say no.

For the past several years evidence has been accumulating that occupational exposure to manganese may lead to early-onset Parkinson’s disease. Symptoms of Parkinson’s include unsteady body movements, stiff limbs, poor balance, and tremors. This seems to be the result of neurological damage to particular cells located in the midbrain that are responsible for producing dopamine. The damage results in an excess production of dopamine, causing the observed symptoms. One widely cited study of 20,000 welders found the incidence of Parkinson’s disease to be ten times higher then a similar population of non-welders. Some studies indicate that neurobehavioral problems may occur to exposures less than 0.2 mg/m3.

The current OSHA PEL for manganese is a ceiling limit of 5 mg/m3. The current NIOSH REL is 1 mg/m3 and the current ACGIH TLV is 0.2 mg/m3, measured as an inhalable fraction. The ACGIH has published a “notice of intended change” for manganese to TWA’s of 0.2 mg/m3 as an inhalable fraction and 0.02 mg/m3 measured in the respirable fraction. Given the small particle size of most welding fumes, it can be expected that the vast majority of manganese exposures during welding will be within the respirable range. There is some evidence that current control technologies may have a difficult time keeping exposures below the new respirable TLV. As a result, the use of respirators, powered air respirators (PAPR), or supplied air may be needed along with classic local exhaust to achieve adequate exposure control to the proposed levels.

According to an ASSE practice specialty article on welding fumes, approximately 10,000 welders nationwide have filed suit on grounds that welding fume exposure have caused them to suffer from manganese-induced parkinsonism. Some legal experts believe that eventual litigation efforts could rival those of asbestos. Given the metallurgical value of manganese to the production of steel, it is unlikely that its use will be phased out. If your production processes result in the generation of manganese fume, it is in your company’s best interest to formulate an exposure control strategy that demonstrates exposure controls below the proposed limits.

For more information, see the following links:
http://www.asse.org/practicespecialties/articles/weldingfumes.php
http://www.cdc.gov/niosh/topics/welding/