Exposure estimates of parabens from personal care products compared with biomonitoring data in human hair from Northeast China

Inhibitory effects of parabens on human and rat 17β-hydroxysteroid dehydrogenase 1: Mechanisms of action and impact on hormone synthesis

Parabens are commonly used preservatives in cosmetics, food, and pharmaceutical products. The objective of this study was to examine the effect of nine parabens on human and rat 17β-hydroxysteroid dehydrogenase 1 (17β-HSD1) in human placental and rat ovarian cytosols, as well as on estradiol synthesis in BeWo cells. The results showed that the IC50 values for these compounds varied from methylparaben with the weakest inhibition (106.42 μM) to hexylparaben with the strongest inhibition (2.05 μM) on human 17β-HSD1. Mode action analysis revealed that these compounds acted as mixed inhibitors. For rats, the IC50 values ranged from the weakest inhibition for methylparaben (no inhibition at 100 μM) to the most potent inhibition for hexylparaben (0.87 μM), and they functioned as mixed inhibitors. Docking analysis indicated that parabens bind to the region bridging the NADPH and steroid binding sites of human 17β-HSD1 and the NADPH binding site of rat 17β-HSD1. Bivariate correlation analysis demonstrated negative correlations between LogP, molecular weight, heavy atoms, and apolar desolvation energy, and the IC50 values of these compounds. In conclusion, this study identified the inhibitory effects of parabens and their binding mechanisms on human and rat 17β-HSD1, as well as their impact on hormone synthesis.

Biomonitoring of parabens in wild boars through hair samples analysis

Parabens are compounds widely utilized in the industry as preservative additives to personal care products, cosmetics and food. They pollute the environment and penetrate to the living organisms through the digestive tract, respiratory system and skin. Till now the knowledge about exposure of terrestrial wild mammals to parabens is extremely scarce. Therefore, this study for the first time assessed the concentration levels of five parabens commonly used in industry (methylparaben-MeP, ethylparaben-EtP propylparaben-PrP, benzylparaben -BeP and butylparaben-BuP). Substances have been analyzed in hair samples collected from wild boars using liquid chromatography-mass spectrometry (LC-MS) method. The hair is a matrix, which allows to study long-term exposure of organisms to parabens. During this study MeP was noted in 96.3% of samples with mean 88.3±72.9 pg/mg, PrP in 87.0% of samples with mean 8.5±3.3 pg/mg, BeP in 44.4% of samples with mean 17.2±12.3 pg/mg and EtP in 11.1% of samples with mean 17.2±4.8 pg/mg. In turn BuP was noted only in 3.7% of samples with concentration levels below limit of quantification (2.6 pg/mg). Statistically significant intragender differences in parabens levels have not been noted. Only BeP concentration levels depended on industrialization and density of human population of area, where the animals lived. This study indicates that wild boars are exposed to parabens, especially to MeP and PrP, and analysis of the hair seems to be a useful tool of biomonitoring of parabens in wild mammals.