Phthalate and bisphenol A exposure among pregnant women in Canada--results from the MIREC study.

Bisphenol A (BPA) and phthalates are endocrine disruptors possibly linked to adverse reproductive and neurodevelopmental outcomes. These chemicals have commonly been measured in urine in population surveys; however, such data are limited for large populations of pregnant women, especially for the critical first trimester of pregnancy. The aim of the study was to measure BPA and phthalate metabolites in first trimester urine samples collected in a large national-scale pregnancy cohort study and to identify major predictors of exposure. Approximately 2000 women were recruited in the first trimester of pregnancy from ten sites across Canada. A questionnaire was administered to obtain demographic and socio-economic data on participants and a spot urine sample was collected and analyzed for total BPA (GC-MS/MS) and 11 phthalate metabolites (LC-MS/MS). The geometric mean (GM) maternal urinary concentration of total BPA, uncorrected for specific gravity, was 0.80 (95% CI 0.76-0.85) μg/L. Almost 88% of the women had detectable urinary concentrations of BPA. An analysis of urinary concentrations of BPA by maternal characteristics with specific gravity as a covariate in the linear model showed that the geometric mean concentrations: (1) decreased with increasing maternal age, (2) were higher in current smokers or women who quit during pregnancy compared to never smokers, and (3) tended to be higher in women who provided a fasting urine sample and who were born in Canada, and had lower incomes and education. Several of the phthalate metabolites analyzed were not prevalent in this population (MCHP, MMP, MiNP, MOP), with percentages detectable at less than 15%. The phthalate metabolites with the highest measured concentrations were MEP (GM: 32.02 μg/L) and MnBP (GM: 11.59 μg/L). MBzP urinary concentrations decreased with maternal age but did not differ by time of urine collection; whereas the DEHP metabolites tended to be higher in older women and when the urine was collected later in the day. This study provides the first biomonitoring results for the largest population of pregnant women sampled in the first trimester of pregnancy. The results indicate that exposure among this population of pregnant women to these chemicals is comparable to or even lower than that observed in a Canadian national population-based survey.

Arbuckle TE ，Davis K ，Marro L ，Fisher M ，Legrand M ，LeBlanc A ，Gaudreau E ，Foster WG ，Choeurng V ，Fraser WD ，MIREC Study Group ... -  《-》

Exposure to phthalates, bisphenol A and metals in pregnancy and the association with impaired glucose tolerance and gestational diabetes mellitus: The MIREC study.

Studies from several countries report increases in rates of gestational diabetes mellitus (GDM) over recent decades. Exposure to environmental chemicals could contribute to this trend. To determine the associations between plasticisers and metals measured in early pregnancy with impaired glucose tolerance (IGT) and GDM in a Canadian pregnancy cohort. Women enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study were included if they had a singleton delivery and did not have pre-existing diabetes. Eleven phthalate metabolites and total bisphenol A (BPA) were measured in first-trimester urine samples, and four metals (lead, cadmium, mercury and arsenic) were measured in first-trimester blood samples. IGT and GDM were assessed in accordance with standard guidelines by chart review. Chemical concentrations were grouped by quartiles, and associations with outcomes were examined using logistic regression with adjustment for maternal age, race, pre-pregnancy BMI, and education. Restricted cubic spline analysis was performed to help assess linearity and nature of any dose-response relationships. Of 2001 women recruited into the MIREC cohort, 1274 met the inclusion criteria and had outcome data and biomonitoring data measured for at least one of the chemicals we examined. Elevated odds of GDM were observed in the highest quartile of arsenic exposure (OR = 3.7, 95% CI = 1.4-9.6) in the adjusted analyses. A significant dose-response relationship was observed in a cubic spline model between arsenic and odds of GDM (p < 0.01). No statistically significant associations were observed between phthalates or BPA or other metals with IGT or GDM. Our findings add to the growing body of evidence supporting the role of maternal arsenic exposure as a risk factor for gestational diabetes.

Shapiro GD ，Dodds L ，Arbuckle TE ，Ashley-Martin J ，Fraser W ，Fisher M ，Taback S ，Keely E ，Bouchard MF ，Monnier P ，Dallaire R ，Morisset A ，Ettinger AS ... -  《-》

Exposure to free and conjugated forms of bisphenol A and triclosan among pregnant women in the MIREC cohort.

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 ... -  《-》

Biomonitoring of phthalate metabolites in the Canadian population through the Canadian Health Measures Survey (2007-2009).

Human exposure to phthalates occurs through multiple sources and pathways. In the Canadian Health Measures Survey 2007-2009, 11 phthalate metabolites, namely, MMP, MEP, MnBP, MBzP, MCHP, MCPP, MEHP, MEOHP, MEHHP, MnOP, and MiNP were measured in urine samples of 6-49 year old survey respondents (n=3236). The phthalate metabolites biomonitoring data from this nationally-representative Canadian survey are presented here. The metabolites MEP, MnBP, MBzP, MCPP, MEHP, MEOHP and MEHHP were detected in >90% of Canadians while MMP, MCHP, MnOP and MiNP were detected in <20% of the Canadian population. Step-wise regression analyses were carried out to identify important predictors of volumetric concentrations (μg/L) of the metabolites in the general population. Individual multiple regression models with covariates age, sex, creatinine, fasting status, and the interaction terms age×creatinine, age×sex and fasting status×creatinine were constructed for MEP, MnBP, MBzP, MCPP, MEHP, MEOHP and MEHHP. The least square geometric mean (LSGM) estimates for volumetric concentration (μg/L) of the metabolites derived from respective regression models were used to assess the patterns in the metabolite concentrations among population sub-groups. The results indicate that children had significantly higher urinary concentrations of MnBP, MBzP, MEHP, MEHHP, MEOHP and MCPP than adolescents and adults. Moreover, MEP, MBzP, MnBP and MEOHP concentrations in females were significantly higher than in males. We observed that fasting status significantly affects the concentrations of MEHP, MEHHP, MEOHP, and MCPP metabolites analyzed in this study. Moreover, our results indicate that the sampling time could affect the DEHP metabolite concentrations in the general Canadian population.

Saravanabhavan G ，Guay M ，Langlois É ，Giroux S ，Murray J ，Haines D ... -  《-》

Urinary concentrations of bisphenol A, parabens and phthalate metabolite mixtures in relation to reproductive success among women undergoing in vitro fertilization.

We have previously investigated whether urinary concentrations of bisphenol A (BPA), parabens, and phthalate metabolites were individually associated with reproductive outcomes among women undergoing in vitro fertilization (IVF) treatment. However, humans are typically exposed to many man-made chemicals simultaneously. Thus, investigating one chemical at a time may not represent the effect of mixtures. To investigate whether urinary concentrations of BPA, parabens, and phthalate metabolite mixtures are associated with reproductive outcomes among women undergoing IVF. This prospective cohort study included 420 women contributing 648 IVF cycles who provided up to two urine samples per cycle prior to oocyte retrieval (N = 1145) between 2006 and 2017 at the Massachusetts General Hospital Fertility Center, and had available urine biomarker data. Urinary concentrations of BPA, parabens, and phthalate metabolites were quantified using isotope-dilution tandem mass spectrometry. Intermediate and clinical end-points of IVF treatments were abstracted from electronic medical records. Principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) were used to identify main patterns of BPA, parabens, and phthalate metabolites concentrations. We used generalized linear mixed models to evaluate the association between PCA-derived factor scores, in quartiles, and IVF outcomes, using random intercepts to account for multiple IVF cycles and adjusting for known confounders. Because of temporal trends in exposure, we conducted a sensitivity analysis restricted to women who underwent IVF cycles in the earlier years of study (2006-2012). Urinary concentrations of BPA, parabens, and most phthalate metabolites were significantly lower during the second half of the study period (2013-2017) than during the first half (2006-2012). None of the three factors derived from the PCA [di(2-ethylhexyl) phthalate (DEHP), non-DEHP, and paraben] was associated with IVF outcomes in the main analyses. Similarly, BKRM analyses did not identify any associations of individual urinary concentrations of BPA, paraben and phthalate metabolites with IVF outcomes while accounting for correlation between exposures. However, in sensitivity analyses restricted to women who underwent IVF cycles from 2006 to 2012, where concentrations of most phthalates and phenols were higher, there were decreases in implantation, clinical pregnancy, and live birth across quartiles of the DEHP factor. Specifically, women in the highest quartile of the DEHP factor had, on average, lower probabilities of implantation (-22% p, trend = 0.08), clinical pregnancy (-24% p, trend = 0.14), and live birth (-38% p, trend = 0.06) compared to women in the lowest quartile. Among this group of women, BKMR results did not identify any single contributor driving the decreased probabilities of live birth within the DEHP factor. We confirmed that women undergoing IVF are concurrently exposed to multiple endocrine disrupting chemicals (EDCs). While we found no overall significant associations, we observed diminished pregnancy success with specific clusters of chemicals among women who underwent IVF cycles in earlier years of study, when urinary concentrations of these EDCs were higher.

Mínguez-Alarcón L ，Messerlian C ，Bellavia A ，Gaskins AJ ，Chiu YH ，Ford JB ，Azevedo AR ，Petrozza JC ，Calafat AM ，Hauser R ，Williams PL ，Earth Study Team ... -  《-》