Chemical and radiological characterization of clay minerals used in pharmaceutics and cosmetics

Radiological assessment of pharmaceutical clays

“…The pH of the presented samples were generally lower than that reported by Lopes-Galindo et al [14] and Silva et al [34] for clays used for therapeutic and cosmetic purposes.…”

Radium depletion and 210Pb/226Ra disequilibrium of Mar^|^iacute;taro hydrothermal deposits, Los Azufres geothermal field, Mexico

“…4a and b) are probably related to different capacity of retention on the mineral surface of their parent elements, 238 U and 232 Th. Experimental studies showed for example that white clays (kaolinite) are more enriched with 228 Ra over 226 Ra than the green clays and 228 Ra shows a pronounced enrichment over its parent nuclide, 232 Th (Silva et al, 2011). In our core, 210 Pb activity shows a rough trend with the amount of kaolinite in the sample (Fig.…”

“…Observed associations of quartz + cristobalite + alunite + zeolite + clay-minerals (montmorillonite, kaolinite) suggest a temperature between 100°C and 250°C and acidic to strongly acidic environments (Hayashi, 1973). Several episodes of geothermal fluid percolation and min-may indicate that lead is partially retained in this mineral phase which is well known for having enhanced adsorption capacities for radionuclides (e.g., Ames et al, 1983a;Beneš et al, 1985;Hidaka et al, 2007;Komarneni et al, 2001;Silva et al, 2011). The observed trends between radionuclides activities and element/mineral phases (Figs.…”

Trace element content and morphological characteristics in microscale of commercially available clays used as cosmetic products

“…Because of their high specific surface area, optimum rheological characteristics and/or excellent sorptive capacity which are being studied by many researchers, clay minerals have been used in several health care formulations (Patel et al, 1986;Christidis et al, 2006;López-Galindo et al, 2007;Viseras et al, 2007;Rathossi et al, 2011;Christidis, 2012). This is because when dispersed in polar solvents, they possess enough viscosity to remain in contact with the application area (Murray, 2000;Carretero, 2002;Silva et al, 2011).…”

“…Specifically, they must have low or zero toxicity. Their high adsorption capacity can cause the accumulation of trace elements and some of them are considered as potentially toxic (López-Galindo et al, 2007;Silva et al, 2011). Cosmetic clays are available in various colours (white, green, red, pink, yellow etc.…”