Simultaneous Quantification of Bisphenol A, Its Glucuronide Metabolite, and Commercial Alternatives by LC-MS/MS for In Vitro Skin Absorption Evaluation

Suspension array for multiplex immunoassay of five common endocrine disrupter chemicals

A low cost and effective indirect competitive method is reported to detect five EDCs, 17-beta-estradiol (E2), estriol (E3), bisphenol A (BPA), diethylstilbestrol (DES), and nonylphenol (NP) simultaneously, based on suspension array technology (SAT). Five kinds of complete antigens (E2-BSA, E3-BSA, BPA-BSA, DES-BPA, NP-BSA) were coupled to different encoding microspheres using purpose-made solutions in our laboratory instead of commercially available amino coupling kits; the method was further optimized for determination and reducing  the cost. Encoding and signaling fluorescence of the particles are determined at 635/532 nm emission wavelengths. High-throughput curves of five EDCs were draw and the limit of detection (LOD) were between 0.0010 ng mL^-1 ~ 0.0070 ng mL^-1. Compared with traditional ELISA methods, the SAT exhibited better specificity and sensitivity. Experiments using spiked milk and tap water samples were also carried out, and the recovery was between 85 and 110%; the results also confirmed good repeatability and reproducibility. It illustrated great potential of the present strategy in the detection of EDCs in actual samples.

Skin Absorption of Bisphenol A and Its Alternatives in Thermal Paper

OBJECTIVES

Bisphenol A (BPA) is the most used colour developer in thermal paper for cashiers receipts, labels, and tickets. BPA can migrate onto the skin and be absorbed when handling these papers. BPA is a known endocrine disruptor and is therefore being replaced in thermal paper by some alternatives such as Bisphenol S (BPS), D-8, and Pergafast 201® (PF201). To our knowledge, no studies have characterized skin permeation of these BPA alternatives.

METHODS

We measured/characterized skin absorption for BPA, BPS, D-8, and PF201 through ex vivo human skin using flow-through diffusion cells according to OECD guideline 428. Skin samples were 7-12 per test substance from three different skin donors. Skin metabolism was studied for BPA. Dermal absorption was expressed as the amount of the BPA alternatives in the receptor fluid over applied dose in percent (%).

RESULTS

The absorbed dose after 24 h of exposure was 25% for BPA, 17% for D-8, 0.4% for BPS, and <LLOQ for PF201. The amount of BPA-glucuronide in the receptor fluid after 24 h was under the limit of quantification (LLOQ = 0.2 µg l-1). Despite the 10-fold lower concentration of the aq solution applied on the skin, D-8's permeation rate JMAX was 5-fold higher than the one for BPS (0.032 versus 0.006 µg cm-2 h-1). Neither D-8 nor BPS permeated readily through the skin (tlag = 3.9 h for D-8, 6.4 h for BPS). None of PF201's skin permeation kinetic parameters could be determined because this BPA analogue was not quantifiable in the receptor fluid in our test conditions.

CONCLUSIONS

Skin absorption was in decreasing order: BPA > D-8 >> BPS > PF201. These results are in agreement with their log Kow and molecular weights. We provided here the necessary data to estimate the extent of skin absorption of BPA analogues, which is a necessary step in risk assessment, and ultimately evaluate public health risks posed by D-8, BPS, and PF201.

Analytical challenges in human exposome analysis with focus on environmental analysis combined with metabolomics

Environmental factors, such as chemical exposures, are likely to play a crucial role in the development of several human chronic diseases. However, how the specific exposures contribute to the onset and progress of various diseases is still poorly understood. In part, this is because comprehensive characterization of the chemical exposome is a highly challenging task, both due to its complex dynamic nature as well as due to the analytical challenges. Herein, the analytical challenges in the field of exposome research are reviewed, with specific emphasis on the sampling, sample preparation, and analysis, as well as challenges in the compound identification. The primary focus is on the human chemical exposome, that is, exposures to mixtures of environmental chemicals and its impact on human metabolome. In order to highlight the recent progress in the exposome research in relation to human health and disease, selected examples of human exposome studies are presented.