AN ANALYTICAL XRAY SERVICES LABORATORY
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XRD sample holders are easily the most common items we’re asked to machine. Sometimes it’s because they’re no longer available, but usually, it’s to accommodate some special application. Sometimes it’s as simple as making them from Aluminum to allow for cleaning with acetone or other harsh solvents. Other times it has more to do with the clients preferred style of loading or sample volume. The end result is that there’s very little consistency so our process needs to be as versatile as possible. This video highlights the most recent process. It’s hard to see exactly what’s going on through the coolant, but this is a test run of a program to cut special holders for 25mm filter membrane holders for respirable silica measurements (or anything else one might want to deposit onto a 25mm filter). It’s cutting the bottom of one holder and the top of another (each on its own side of the fixture).  A full load of these produces 6 complete holders for every run.

XRD is the preferred analytical method of testing free crystalline silica in workplace atmospheres.   At Texray, we offer respirable silica testing using the NIOSH 7500 method, so we thought those of you in industries such as concrete, construction, glass, milling, mining, hydraulic fracking and sandblasting will find it important to know that OSHA has proposed an update to the current rules.  The most notable change is a decrease in OSHA’s Permissible Exposure Limits (PEL) from 100 mg/m3 of air for general industries and 250 mg/m3 of air for construction industries to 50 mg/m3 of air for all industries.  OSHA, along with other independent occupational health institutions, feel the current PELs are outdated and inadequate, and rightfully so, considering limits were last set in 1971 and based on 1960s research.  However, most of these industries may not feel an impact from such as change, as many employers already use preventative measures to reduce dust exposure.

Would this rule change affect the analytical testing procedure?

Photo Courtesy of New Jersey Department of Health

Photo Courtesy of New Jersey Department of Health

No, XRD limits of detection (LOD) for NIOSH 7500 are 0.005 mg/m3 for an 800 L air sample.  This rule change would not affect the testing method, since the LODs for silica in the form of quartz and cristobalite are well below the newly proposed PEL.  However, the rule change may increase the number of industrial sites needing to test their work environments for respirable silica.

According to OSHA, “The proposed rule is expected to prevent thousands of deaths from silicosis, lung cancer, other respiratory diseases, and kidney disease. OSHA estimates that the proposed rule will save nearly 700 lives and prevent 1,600 new cases of silicosis per year once the full effects of the rule are realized.”  The rule change was proposed last September and the hearing was recently concluded at the beginning of April.  Final decision will be coming soon. We will keep you posted.