Low-Level Detection of Amphiboles In Talc: Fingerprint Kits as An Example

Talc deposits form in both contact metamorphic and hydrothermal environments. Within contact metamorphic environments, the temperatures are high enough for amphiboles to form, some of which can be asbestiform. There is a concern regarding exposure to asbestiform amphiboles within talc that form under such conditions. Recently, a consumer group surveyed hundreds of commercial products to determine asbestos content in everyday household items such as food, toiletries, drugs, hardware, toys, etc. The method used for this analysis was transmission electron microscopy (TEM). While this is the standard technique for determining the asbestos content for air samples in an occupational setting, it has limitations for analysis of bulk samples. One product they found to contain asbestos was the CSI: Crime Scene Investigation kits, which have since been removed from shelves due to the speculation of tremolite asbestos being present. The percentage of asbestos in the fingerprint kits, as determined by the consumer group's survey, is approximately 4.52%.

We used powder X-ray diffraction (XRD) to determine if three CSI, one forensics lab kit and two fingerprint kits, contain amphibole. A standard was first developed using a known amphibole-free commercial talc product spiked with acicular tremolite, to determine a detection limit for the XRD method. The talc samples were spiked with different amounts of acicular tremolite ranging from 0.01% to 10%. The detection limit for this method developed is on the order of 0.01-0.05%, or better. The detection limit, once determined could then be used in comparison with the fingerprint kits and the forensics lab kit to determine if they contain amphibole. Using this method we found no detectable amphibole in the three products we examined.