Physico-chemical behaviour and microbiological suitability of residual smectitic soils mixed with two mineralized waters for therapeutic and dermocosmetic applications

Peloid is a matured mud with healing and/or cosmetic properties, composed of a complex mixture of mineral or seawater with a clay-based material, that requires quality control prior to its application in therapeutic and dermocosmetic treatments. In this research, physico-chemical and biological analyses were performed to assess influence of the two mineralized waters on three residual smectitic soils. Seawater increased the electrical conductivity values of peloids (from 0.3 to 0.5 mS/cm to 68.0-73.8 mS/cm) and their organic matter content (from 2.6 to 4.7% to around 7%), whereas thermo-mineral water enhanced the cation exchange capacity (from 38.4 to 70.0 meq/100 g to 55.2-86.6 meq/100 g). The pH of peloids remained alkaline, and zeta potential values were stable throughout the maturation period. The concentrations of Pb, Co, Ni and V in samples exceed the acceptable limits established for cosmetic and pharmaceutical products, hence further dermal bioacessibility assessment are required to substantiate their clinical safety before therapeutic use. Moreover, fecal indicator bacteria were not detected in the peloids, however thermo-mineral water peloids showed fungal contents slightly above recommended microbiological limits. The physico-chemical and microbiological characterization suggests that these peloids have potential therapeutic values, although further thermal and rheological characterization are required to assess their suitability.