Hex marks the spot
The road to protecting workers from hexavalent chromium has been long and not without complications. A metal particle found in nature and commonly produced in industrial processes, hexavalent chromium has been classified by NIOSH as a possible occupational carcinogen and linked to a score of health problems in workers.
A standard, which took a lawsuit to ensure its promulgation, was issued in 2006 and affects general industry (29 CFR 1910.1026), construction (29 CFR 1926. 1126) and shipyards (29 CFR 1915.1026). Two years in, lawsuits and petitions continue to be filed regarding the standard.
Full compliance does not need to occur until May 2010, when implementation of engineering controls for hex chrome exposures will be required. Until then, employers can rely on different types of personal protective equipment to comply with the new, lowered permissible exposure limits.
Workers exposed to hex chrome have shown an increased risk of lung cancer, damage to the throat and nose, and ulcers. Protecting workers is best done by engineering out the exposure to hex chrome completely, according to Dan James, environmental, health and safety manager at Chromalloy Component Services, based in San Antonio, TX. “The best protection is not to have to work with it,” he said. For example, James recommended using paints that do not contain hex chrome. If this is not possible, he said, try the next best thing: Separate the operator from the components through the use of robotics, or work in an area with good ventilation.
The new standard actu-ally requires employers to use engineering and workplace practices as the primary means to maintain exposures below the PEL, which is 5 micrograms of hex chrome per cubic meter of air over an eight-hour time-weighted average. When some industry groups petitioned OSHA that it would not be feasible to implement engineering controls to meet the PEL, a settlement was reached that allows respiratory protection to supplement the controls that are possible.
The action level – the level at which monitoring is required – is 2.5 micrograms of hex chrome per cubic meter of air as an eight-hour TWA. If the level is more than 2.5 micrograms, but less than the PEL of 5 micrograms, employers must monitor employee exposure at least every six months. Samples from a respiratory filter are sent to a lab to determine if the number of micrograms is within the limit for an eight-hour period.
“You almost never get a sample that’s truly eight hours,” James said. This is where the TWA comes in. If the sample is taken over a six-hour period, the results are divided by six and then multiplied by eight to get the average. It’s that number that must be below 5 micrograms.
But even that can have its problems, James said, especially considering if breaks are taken during the sampling period. “If you did a two-hour sample without a lunch break, it could look artificially too high. With a lunch, it could look too low,” he said.
To ensure accuracy, the goal should be to get as close to an eight-hour sample as possible. If done properly, James said, the results can be very accurate.
The action level could be considered a type of warning for employers. “If you’re half the PEL, there’s a good chance you’re approaching the PEL,” said Paul Puncochar, a certified industrial hygienist for St. Paul, MN-based 3M.
When reaching the action level, safety professionals “need to start being concerned for the exposure,” he said. Although not required when the action level is reached, it would be a good idea for employers to consider taking additional precautions and engineering out hex chrome, he said.
When exposure levels exceed the PEL, respirators are required in certain situations, including:
- During the development of workplace or engineering controls
- During maintenance or repair activities when workplace or engineering controls are not feasible
- When engineering or workplace controls do not reduce exposure below the PEL
- When no such controls are in place for employees who are exposed to the PEL fewer than 30 days each year
For many situations, a NIOSH-approved 95 class part filter will work, Puncochar said. In situations in which exposure is up to 50 micrograms, a full facepiece respirator (with appropriate filters) can be used when qualitatively fit tested, according to 3M. If it is quantitatively fit tested, the same respirator may be used up to 250 micrograms. In exposures of up to 125 micrograms, a loose-fitting facepiece may be used. In exposures up to 5,000 micrograms, use tight-fitting full facepieces, hoods and helmets with a supplied- or powered-air purifying respirator.
This is quite a change from what was previously req-uired, James said. “Under the old standards, the standard filter respirator worked. Under the new standards, to get the protective factor that you need, you need a supplied-air or positive-pressure mask or hood or full-face respirator,” he said.
Protective clothing must be provided by the employer, who is responsible for ensuring any hex chrome is removed, either through laundering or the use of disposable clothing, James said. Eating, drinking and smoking areas must be separate from where the work is being done. For employees exposed above the action level for 30 days or more in a single year, medical surveillance is required.