Microbial decontamination of cosmetic raw materials and personal care products by irradiation

Abstract

Typical levels of sporadically occurring (dynamic) microbial contamination of cosmetic raw materials: pigments, abrasives and liposomes, as well as of final products for personal care: toothpaste, crayons, shampoos, cleansers and creams, were evaluated. In most cases the contamination was dominated by a single population of microorganisms, either Gram-negative bacteria or molds. The feasibility of microbial decontamination by irradiation was studied by determining the resistance to gamma radiation of contaminating microflora in situ. It was expressed as a dose required for the first 90% reduction, Dfirst90%red. The values in the range 1–2 kGy for molds and 0.1–0.6 kGy for Gram-negative bacteria were obtained. This relatively high susceptibility to irradiation allowed inactivation factors close to 6 to be achieved with doses generally not exceeding 3 kGy, and yielding endpoint contamination less than 10/g.