Lowering reporting limit values for respirable crystalline silica analysis by X-ray diffraction in preparation of the 0.025 mg/m3 occupational exposure limit.

Internationally, respirable crystalline silica (RCS) occupational exposure limits (OELs) are being reassessed and, in some jurisdictions, lowered, putting pressure on the capabilities of the analytical techniques used to achieve robust analyses and reliable detection limits. In preparation of a lower OEL, options for lowering the limit of detection (LoD) for RCS analysis have been assessed. Using a Direct-on-Filter X-Ray Diffraction (XRD) analysis under reduced scan speeds in combination with low-noise RCS sampling filters, an LoD of 0.

Geographical variation of shoeprint comparison class correspondences.

The underlying principles involved in the interpretation of shoeprint comparisons have become a topical subject due to criticisms in the 2009 National Academy of Science (NAS) report on forensic sciences[1]. Difficulties in the application and understanding of these principles were also highlighted in a recent court ruling [2-5] and subsequent discussion of the ruling. We report here a survey that may inform some aspects of this interpretation and discuss the implications of findings from this survey in the light of that court ruling and more importantly the NAS report.