Quantification of bisphenols in Korean urine using online solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry
Introduction
Bisphenol A (BPA) is a high-volume industrial chemical used for the global production of polycarbonate (PC) plastics and epoxy resins used in the coating of food and drink containers (Buscher et al., 2015; Huang et al., 2018; Lehmler et al., 2018; Park et al., 2016). Additional applications of BPA include paints, varnishes, glues, and thermal paper used for receipts (Covaci et al., 2015). Due to the prevalence of BPA in plastics and other consumer products, exposure to this compound is inevitable for every individual (Covaci et al., 2015). Unfortunately, BPA is a known endocrine-disrupting chemical (EDC) and increasing evidence suggests it is medically harmful (European Chemicals Agency ECHA, 2018; Lehmler et al., 2018; Rochester and Bolden, 2015). Scientists, regulators, and the general public have raised concerns about the use of BPA, particularly because of its ubiquitous nature and high potential for continuous exposure.
Thus, over the past decade, bisphenol F (BPF) or bisphenol S (BPS) have been used as an alternative to BPA (Li et al., 2019; Peinado et al., 2020). BPS is primarily employed in industrial products and thermal papers, while BPF is used for epoxy resins and coatings, especially for systems needing increased thickness and durability (Rochester and Bolden, 2015). Emerging toxicological evidence suggests that BPF and BPS pose similar potential health hazards to BPA owing to their similar structures, metabolism, and mechanisms of action, although there is insufficient evidence at this time to estimate these toxic effects in humans (Wang et al., 2019).
In 2010, the Ministry of Food and Drug Safety (MFDS) set the tolerable daily intake (TDI) of BPA to 50 μg/kg bw/day (Choi et al., 2010). Following a re-evaluation in 2014, the TDI was reset to 20 μg/kg bw/day (Park et al., 2016). However, no TDI values have been established for BPF and BPS due to a lack of information concerning their toxicity.
BPA, BPF, and BPS are rapidly metabolized by mammalian uridine 5′-diphosphate-glucuronosyltransferases (UGTs) to the corresponding glucuronides, which are quickly eliminated in the urine of rats and humans (Lehmler et al., 2018). Total urinary glucuronide levels, typically determined after deconjugation with β-glucuronidase/sulfatase, are considered a robust biomarker for exposure to bisphenol analogues (Lehmler et al., 2018). Urinary concentrations of total bisphenols (free and conjugated) have been used to evaluate their exposure from all sources (Vandenberg et al., 2007). Previous population-based studies using human biomonitoring data have primarily focused on BPA (Lehmler et al., 2018; Park et al., 2016). We reported that the geometric mean of unadjusted and creatinine-adjusted urinary BPA concentrations for all ages in the general Korean population were 1.83 μg/L and 2.01 μg/g creatinine, respectively (Park et al., 2016). BPF and BPS biomonitoring has recently been investigated using convenience samples, including infants, children, and adolescents, to determine the exposure levels in the Korean population.
This study sought to develop an efficient and accurate method for the simultaneous analysis of bisphenol analogues and to provide analytical data essential for the overall risk assessment of these compounds. An online solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry (online SPE-HPLC-MS/MS) method was used to measure three bisphenol analogues in human urine samples with high sensitivity. Data were analyzed for demographic associations based on bisphenol exposure levels in the Korean population using 2017–2018 nationally representative data.
Section snippets
Analytical standards and reagents
BPA, BPF, and BPS standards and a BPA-d16 internal standard were purchased from Sigma-Aldrich (St. Louis, MO, USA). Chemicals used for the preparation of synthetic urine (potassium chloride, sodium chloride, urea, citric acid, ascorbic acid, potassium phosphate, creatinine, sodium hydroxide, sodium bicarbonate, and sulfuric acid) and β-glucuronidase/sulfatase (Helix pomatia, H1) used in the enzymatic degradation reaction were obtained from Sigma-Aldrich (St. Louis, MO, USA). SRM 3673 was
Method validation
The analytical method was validated for linearity, accuracy, and precision (Table 2). The calibration curves were highly linear over the calibration range for all compounds, with r2 > 0.997. The MDLs were 0.24 μg/L, 0.19 μg/L, and 0.13 μg/L for BPA, BPF, and BPS, respectively. Intra- and inter-day accuracies were 98.3–113.4% and 99.4–108.4%, respectively, while intra- and inter-day precision were <9.2 %RSD and <8.5 %RSD, respectively. All compounds were thus within the acceptable limits for
Discussion
Bisphenol analogues, particularly BPA, are ubiquitous in the environment, with human exposure occurring through dietary and non-dietary sources (Geens et al., 2012; Vandenberg et al., 2007). Previous risk assessments have shown that the BPA exposure level is currently safe (Park et al., 2016); nevertheless, consumers are still concerned about BPA exposure.
If a nationally representative sample collecting system were available, biomonitoring could be used to investigate the level of exposure of
Conclusion
This is the first study to report urinary BPA, BPF, and BPS concentrations in a nationally representative population of Korea. In this nationally representative study, we estimated the bisphenol analogue exposure levels of the general Korean population and demonstrated a relationship between bisphenol analogue concentrations and demographic characteristics. This study revealed that the most abundant bisphenol analogue was BPA, while BPF was rarely detected. There was no strong correlation
Funding sources
This study was supported by the Ministry of Food and Drug Safety, Republic of Korea (grant no. 18161 MFDS101).
CRediT authorship contribution statement
Min Jeong Jo: Investigation, Writing - original draft, Software, Visualization. Jae-Hong Park: Writing - review & editing. Kyung-A An: Data curation. Heeju Choi: Data curation. Yun-sook Kang: Supervision. Myungsil Hwang: Conceptualization, Methodology.
Declaration of Competing Interest
The authors report no declarations of interest.
References (32)
- et al.
Quantitative analysis of unconjugated and total bisphenol A in human urine using solid-phase extraction and UPLC-MS/MS: method implementation, method qualification and troubleshooting
J. Chromatogr. B Anal. Technol. Biomed. Life Sci.
(2015) - et al.
Urinary bisphenol analogues and triclosan in children from south China and implications for human exposure
Environ. Pollut.
(2018) - et al.
Urinary BPA measurements in children and mothers from six European member states: overall results and determinants of exposure
Environ. Res.
(2015) - et al.
A review of dietary and non-dietary exposure to bisphenol-A
Food Chem. Toxicol.
(2012) - et al.
Bisphenol A concentrations in human urine, human intakes across six continents, and annual trends of average intakes in adult and child populations worldwide: a thorough literature review
Sci. Total Environ.
(2018) - et al.
The EuroMix human biomonitoring study: source-to-dose modeling of cumulative and aggregate exposure for the bisphenols BPA, BPS, and BPF and comparison with measured urinary levels
Environ. Int.
(2020) Low dose mixture effects of endocrine disrupters and their implications for regulatory thresholds in chemical risk assessment
Curr. Opin. Pharmacol.
(2014)- et al.
Factors affecting interpretation of national biomonitoring data from multiple countries: BPA as a case study
Environ. Res.
(2019) - et al.
Pharmacokinetics of bisphenol S in humans after single oral administration
Environ. Int.
(2018) - et al.
Risk assessment based on urinary bisphenol A levels in the general Korean population
Environ. Res.
(2016)