Risk factors influencing contamination of customized cosmetics made on-the-spot: Evidence from the national pilot project for public health

Abstract

Customized cosmetics made by consumers or sellers on-the-spot have several safety issues, and therefore require a preventative approach to their safety management. The present study aimed to identify potential factors affecting the safety of customized cosmetics made on-the-spot. Heavy metals and microbial contaminants in customized cosmetics were analyzed in 120 samples. It was revealed that the transfer of cosmetics to new containers during the production process is a significant risk factor for cross-contamination and that heat treatment is crucial for reducing the number of microorganisms in the products. For instance, cosmetics made with heat and with no transfer showed relatively low microbial counts ranging from not detected to 440 CFU/ml. The high pH (>pH 10) of samples did not guarantee the microbial safety of the freshly made cosmetics (with a rinse-off product having 2,830 CFU/ml and a pH of 11.2). There was no significant difference in microbial counts among cosmetic types (P > 0.05); however, semisolid types, especially creams and rinse-off products, were susceptible to contamination (maximum 2,710 and 2,830 CFU/ml, respectively). Most microorganisms in the customized cosmetics (40.8%) decreased to non-detectable levels during 60 days of storage. None of the samples harbored heavy metals. Sequencing analysis of isolates revealed some bacteria and mold that could cause human infections. The results of this study suggest that the regulation of customized cosmetics should consider the risk factors revealed in this study, as the products made on-the-spot are also final products sent directly to consumers.

Figure 1

Box plots of (A) total bacterial counts, (B) total mold and yeast counts, and (C) total aerobic microbe counts of nine types of customized cosmetics (n = 120): perfume (n = 10), skin or mist (n = 12), lotion (n = 12), essence (n = 10), cream (n = 24), oil (n = 3), lip product (n = 16), rinse-off product (n = 28), and the others (n = 5). Square means of the interquartile range for each data point, and the black and blue lines indicate the median and mean values, respectively. The error bars above and below the square denote the 90^th and 10^th percentiles, and the black circles represent outliers. Values (%) on the bars indicate the detection rate of each microorganism in the samples, and ND indicates no detection of microorganisms.

Figure 2

Box plots of (A) total bacterial counts, (B) total mold and yeast counts, and (C) total aerobic microbe counts of different formulations of customized cosmetics (n = 120): liquid (n = 40), semisolid (n = 64), and solid (n = 16). Square means of the interquartile range for each data point, and the black and blue lines indicate the median and mean values, respectively. The error bars above and below the square denote the 90^th and 10^th percentiles, and the black circles represent outliers. Values (%) on the bars indicate the detection rate of each microorganism in the samples, and ND indicates no detection of microorganisms.

Figure 3

Box plots of (A) total bacterial counts, (B) total mold and yeast counts, and (C) total aerobic microbe counts of rinse-off products according to the preparation methods, M1 to M5. Square means of the interquartile range for each data point, and the black and blue lines indicate the median and mean values, respectively. The error bars above and below the square denote the 90^th and 10^th percentiles, and the black circles represent outliers. Values (%) on the bars indicate the detection rate of each microorganism in the samples, and ND indicates no detection of microorganisms.

Figure 4

Dot plots of microbial populations of nine types of customized cosmetics (n = 120) according to pH: (A) perfume, (B) skin or mist, (C) lotion, (D) essence, (E) cream, (F) oil, (G) lip product, (H) rinse-off product, and (I) the others. The arrow indicates cosmetic samples that did not comply with the standard microbial limits.

Figure 5

Pie chart representation of the genera of (A) bacteria and (B) mold and yeast isolated from the customized cosmetics. Microorganisms presented in the gray box indicate the isolated species of each genus.

Figure 6

Survival of bacteria, mold and yeast, and aerobic microbes in microbiologically positive customized cosmetic samples (n = 49) after storage up to 60 days at 22 °C. Values (%) on the graph indicate the detection rate of each microorganism in the samples.