Direct measurement of Bisphenol A (BPA), BPA glucuronide and BPA sulfate in a diverse and low-income population of pregnant women reveals high exposure, with potential implications for previous exposure estimates: a cross-sectional study

Abstract

BackgroundBisphenol A (BPA) is a ubiquitous, endocrine-disrupting environmental contaminant that increases risk of some adverse developmental effects. Thus, it is important to characterize BPA levels, metabolic fate and sources of exposure in pregnant women.MethodsWe used an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytic method to directly and simultaneously measure unconjugated BPA (uBPA), BPA glucuronide and BPA sulfate in the urine of a population of ethnically and racially diverse, and predominately low-income pregnant women (n = 112) in their second trimester. We also administered a questionnaire on dietary and non-dietary sources of exposure to BPA.ResultsWe found universal and high exposure to uBPA and its metabolites: median concentrations were 0.25, 4.67, and 0.31 μg/g creatinine for uBPA, BPA glucuronide, and BPA sulfate, respectively. The median Total BPA (uBPA + BPA in glucuronide and sulfate forms) level was more than twice that measured in U.S. pregnant women in NHANES 2005–2006, while 30 % of the women had Total BPA levels above the 95th percentile. On average, Total BPA consisted of 71 % BPA in glucuronide form, 15 % BPA in sulfate form and 14 % uBPA, however the proportion of BPA in sulfate form increased and the proportion of uBPA decreased with Total BPA levels. Occupational and non-occupational contact with paper receipts was positively associated with BPA in conjugated (glucuronidated + sulfated) form after adjustment for demographic characteristics. Recent consumption of foods and beverages likely to be contaminated with BPA was infrequent among participants and we did not observe any positive associations with BPA analyte levels.ConclusionThe high levels of BPA analytes found in our study population may be attributable to the low-income status of the majority of participants and/or our direct analytic method, which yields a more complete evaluation of BPA exposure. We observed near-universal exposure to BPA among pregnant women, as well as substantial variability in BPA metabolic clearance, raising additional concerns for effects on fetal development. Our results are consistent with studies showing thermal paper receipts to be an important source of exposure, point to the difficulty pregnant women have avoiding BPA exposure on an individual level, and therefore underscore the need for changes in BPA regulation and commerce.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-016-0131-2) contains supplementary material, which is available to authorized users.

Variability and exposure classification of urinary phenol and paraben metabolite concentrations in reproductive-aged women

“…Human exposure is nearly ubiquitous and comes from diet, personal care products, and pharmaceuticals (Guo and Kannan, 2013; Moreta et al, 2015). Although rapidly metabolized, the common detection of phenols and parabens in U.S. adults indicates exposure is nearly continuous (Calafat et al, 2010, 2008, 2007a, 2007b; Gerona et al, 2016; Harley et al, 2016; Jukic et al, 2016; Meeker et al, 2013; Mortensen et al, 2014; Smith et al, 2012). The primary source of exposure may vary by source population.…”

Metabolism of bisphenol S in mice after oral administration

“…The UPLC working conditions were set as follows: column oven, 35°C; flow rate, 0.2 mL/min; and injection volume, 2.0 μL. A 2.0 mM ammonium acetate aqueous solution (solvent A) and methanol (solvent B) were used as the mobile phase . Gradient elution was as follows: 0.0–9.0 min, 5% to 50% B; 9.0–11.0 min, 50% to 100% B; 11.0–14.0 min, 100% B; 14.1–20.0 min, 100% to 5%B.…”

“…Waters Oasis HLB cartridges (1.0 mL) were preconditioned with 3.0 mL methanol followed by 3.0 mL water. 26 After loading the urine samples, the cartridges were washed with 3.0 mL of methanol/water (5:95, v/v) to remove salts and the target analytes were eluted with 5.0 mL of 100% methanol. The collected eluents were evaporated under a stream of nitrogen gas to dryness and re-dissolved in 100 μL of methanol/water (1:9, v/v).…”

An old culprit but a new story: bisphenol A and “NextGen” bisphenols

“…It also led to the development of new methodology for the direct analysis of BPA in human biospecimens (67) and the ability to reliably and accurately measure unconjugated BPA and its two major metabolites, BPA glucuronide and BPA sulfate. The ability to identify individual metabolites using direct detection methods makes it possible to detect metabolic differences among individuals, identify allelic variants (e.g., in metabolic enzymes) that affect BPA metabolism, and to determine whether specific genetic variants render an individual more vulnerable to the effects of exposure (67). This is particularly important in light of recent data suggesting that the glucuronidated form exhibits estrogenic bioactivity (68).…”