Exposure to Free and Conjugated Forms of Bisphenol A and Triclosan among Pregnant Women in the MIREC Cohort

Abstract

Background:Bisphenol A (BPA) and triclosan (TCS) are two nonpersistent chemicals that have been frequently measured in spot urine samples from the general population but less so in pregnant women; however, data are limited on the free (bioactive) and conjugated forms of these phenols.Objectives:The Maternal-Infant Research on Environmental Chemicals (MIREC) Study addressed these data gaps by utilizing stored maternal urine samples from a large multicenter cohort study of Canadian pregnant women.Methods:Concentrations of free and conjugated forms of BPA and TCS were measured in about 1,890 first-trimester urine samples by ultra performance liquid chromatograpy–tandem mass spectrometry using isotope dilution.Results:The glucuronides of BPA and TCS were the predominant forms of these chemicals measured (detected in 95% and 99% of samples, respectively), whereas the free forms were detected in 43% and 80% of samples, respectively. The geometric mean urinary concentrations for glucuronides of BPA and TCS were 0.80 μg/L (95% CI: 0.75, 0.85) and 12.30 μg/L (95% CI: 11.08, 13.65), respectively. Significant predictors of BPA included maternal age < 25 vs. ≥ 35 years, current smoking, low vs. high household income, and low vs. high education. For TCS, urinary concentrations were significantly higher in women ≥ 25 years of age, never vs. current smokers, and women with high household income and high education.Conclusions:The results from this study represent the largest national-level data on urinary concentrations of free and conjugated forms of BPA and TCS in pregnant women and suggest that maternal characteristics predicting elevated urinary concentrations of these phenols largely act in opposite directions.Citation:Arbuckle TE, Marro L, Davis K, Fisher M, Ayotte P, Bélanger P, Dumas P, LeBlanc A, Bérubé R, Gaudreau É, Provencher G, Faustman EM, Vigoren E, Ettinger AS, Dellarco M, MacPherson S, Fraser WD. 2015. Exposure to free and conjugated forms of bisphenol A and triclosan among pregnant women in the MIREC cohort. Environ Health Perspect 123:277–284; http://dx.doi.org/10.1289/ehp.1408187

Temporal trends in bisphenol A exposure in the United States from 2003–2012 and factors associated with BPA exposure: Spot samples and urine dilution complicate data interpretation

“…However, the pvalue for the multiple test for association for daily smokers over the five periods based on Fisher's method for combining independent p-values is .04. This suggests an association between urinary BPA and smoking which is in accordance with some other reports (He et al, 2009;Arbuckle et al, 2015;Geens et al, 2014). It is not clear why the association did not hold when using number of cigarettes smoked over the previous five days but it is possible that smoking is a surrogate for some other type of behavior or demographic factor which would render the number of cigarettes smoked moot.…”

Female exposure to phenols and phthalates and time to pregnancy: the Maternal-Infant Research on Environmental Chemicals (MIREC) Study

“…Compared with the few studies available worldwide that have assessed concentrations of TCS in pregnant women, MIREC reported the highest urinary concentration of TCS (6,784 mg/L) but had considerably lower median concentrations than the other international studies (30). Higher socioeconomic class and older age were determinants of TCS exposure in the MIREC cohort (30).…”

“…Higher socioeconomic class and older age were determinants of TCS exposure in the MIREC cohort (30). The MIREC population tended to be more highly educated than the population of women giving birth in Canada (27).…”

“…The potential confounders were maternal age, smoking, education, and household income, which have been identified as predictors of exposure to BPA, TCS, and phthalates in the MIREC cohort (28,30). In addition to the covariates that also impact fecundity, body mass index (BMI) was included in the adjusted models (3).…”

The small GTPases Ras and Rheb studied by multidimensional NMR spectroscopy: structure and function

“…The main source for human exposal to bisphenols is based on the uptake through food and drinks (Vandenberg et al, 2007). Therefore, bisphenols are found in human serum (Ribeiro-Varandas et al, 2013), urine (Matsumoto et al, 2003), adipose (Ben-Jonathan et al, 2009), and placental tissues (Arbuckle et al, 2015). Outside the human body, significant amounts of bisphenols can be found in drinking and wastewater, air, as well as dust (Vandenberg et al, 2007).…”