Comparison of the Analysis of Respirable Crystalline Silica in Workplace Air by Direct-on-Filter Methods using X-ray Diffraction and Fourier Transform Infrared Spectroscopy.

A comparison of the analysis of respirable crystalline silica direct-on-filter methods using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy was undertaken using 253 real workplace air samples from road construction and tunnelling, coal mining, and kitchen benchtop manufacturing in Australia. Using pure α-quartz standards, XRD and FT-IR direct-on-filter analyses produced identical test results, however, the real workplace samples showed a clear discrepancy between FT-IR and XRD results with on average a 9% positive bias of the FT-IR results. The cause of the positive bias was due to matrix interferences which was confirmed by using synthetic mixture air samples. Approximately a third of the data by direct-on-filter method using FT-IR was assessed to be invalid based on the peak height ratio criterion due to excessive interferences and weight overload limitations. The XRD method showed better results due to less interference from the common matrices. XRD could handle up to twice the sample loading and at higher loadings up to 7 mg when a correction was applied. It was also able to achieve a lower limit of detection of 2 µg filter-1 when a slower scan condition was utilized.

[Iatrogenic non uremic calciphylaxis: A case report]. / Calciphylaxie non urémique iatrogène : une nouvelle observation.

Calciphylaxis is a rare and severe condition, characterized by calcification and thrombosis of small vessels, mainly affecting the skin. It is most often described in patients with end-stage renal disease on dialysis. Rarer cases of non-uremic calciphylaxis are reported. The prognosis is grim and the treatment is not well codified. Sodium thiosulfate has been used for more than a decade in the treatment of uremic calciphylaxis and has been shown to be effective. Its use in non-uremic cases has been reported in a few rare observations. Rheopheresis is a technique very recently used as an adjuvant treatment in uremic calciphylaxis. We describe a case of non-uremic calciphylaxis in a patient with normal renal function and with calcium supplementation. Sodium thiosulfate was introduced, then discontinued due to the patient's poor tolerance for this treatment. Rheopheresis was then used and allowed the acceleration of healing process and a significant reduction in pain. These two treatments are promising, larger studies are needed to establish their effectiveness in non-uremic calciphylaxis.