Talc products are of interest both in the context of consumer and occupational exposure to asbestos and toxic metals. One product that has not been investigated in detail is talc crayons used for marking in manufacturing. An unopened box of talc based industrial crayons originating from China were analyzed. Twenty crayons were manually powdered, then examined using basic powder X-ray diffraction (XRD). All twenty crayons were subjected to inductively coupled plasma mass spectroscopy (ICP-MS) and selected samples were analyzed with scanning electron microscopy (SEM). XRD indicates that talc is the primary component of the crayons and do not have extreme mineralogical variation such as calcite or dolomite content, enabling a straightforward interpretation of ICP-MS geochemical data. From ICP-MS it was documented that potentially hazardous elements V, Ni, Cr, and Co were low in concentration with an average of only a few parts per million (ppm). Ca concentrations and P are highly correlated (r2 = 0.978) and rare earth elements (REEs), (Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) are also highly correlated (approximately r2>0.800 for REEs) to the concentration of Ca. Although Ca appears to be mainly controlled by apatite, SEM indicates some potential countable particles consistent with tremolite that occur in the talc matrix material which have dimensions of 200 nm x 650 nm. SEM also indicates that Fe is present in some talc particles. Both Fe and Al are common amongst samples and at concentrations of an average of 4106 ppm for Fe and 1370 ppm for Al. SEM indicates that Fe is present in some talc particles. These initial findings suggest these products may have a distinct geochemical fingerprint and should be further evaluated for asbestos content. There initially appears to not be significant concentrations of many elements of environmental or occupational concern, however the occurrence of asbestos in these products is an open question and will be investigated further. Asbestos is well understood and documented to cause mesothelioma, and while there is much research looking at cosmetic products, attention should also be given to other commercial or industrial materials to provide mineralogical and geochemical context for health professionals.
Author(s): Belak, Ethan., Wudke, Hannah., Lytle, Marion., Shaulis, Barry., Mcleod, Claire., Krekeler, Mark
Advisor(s): Mark Krekeler, Department of Geology
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