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BACKGROUND: Vitamin D improves absorption of calcium; however, in animal studies vitamin D also increases the absorption of toxic metals, such as lead and cadmium. OBJECTIVES: We examined maternal and neonatal cord blood levels of lead, cadmium, manganese, and mercury after supplementation with vitamin D during pregnancy. METHODS: The Maternal Vitamin D for Infant Growth trial was a randomized, placebo-controlled, multi-arm study of maternal vitamin D supplementation during pregnancy in Dhaka, Bangladesh (NCT01924013). Women were randomized during their second trimester to blinded weekly doses of placebo or 4,200, 16,800, or 28,000 IU of vitamin D3 throughout pregnancy. Each group had 118–239 maternal blood specimens and 100–201 cord blood samples analyzed. Metals were measured using inductively coupled plasma mass spectrometry. Unadjusted estimates from linear regression models were expressed as percentage differences. Cord blood cadmium was analyzed as detectable or undetectable with log-binomial regression. RESULTS: Maternal cadmium, mercury, and manganese levels were nearly identical across groups. Maternal lead levels were 6.3%, 7.4%, and 6.0% higher in the treatment groups (4,200, 16,800, and 28,000 IU, respectively) vs. placebo; however, 95% confidence intervals (CIs) showed that differences from 4.1% lower to 20% higher were compatible with the data. In treatment groups (4,200, 16,800, 28,000 IU) vs. placebo, neonatal cord blood lead levels were 8.5% (95% CI: -3:5, 22), 16% (95% CI: 3.3, 30), and 11% (95% CI: 0.4, 23) higher and had higher risk of detectable cadmium, relative risk ðRRÞ= 2:2 (95% CI: 1.3, 3.7), RR = 1:4 (95% CI: 0.8, 2.5), RR = 1:7 (95% CI: 1.0, 2.9). DISCUSSION: Vitamin D supplementation from the second trimester of pregnancy did not influence maternal cadmium, mercury, or manganese levels at delivery. Vitamin D was associated with nonsignificant increases in maternal lead and with significant increases in cord blood lead and cadmium. These associations were not dose dependent. Given that there are no safe levels of metals in infants, the observed increases in cord blood lead and cadmium require further exploration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Certain phthalates and bisphenol A (BPA) show reproductive effects in animal studies and potentially affect human ovulation, conception, and pregnancy loss. OBJECTIVES: We investigated these chemicals in relation to follicular- and luteal-phase lengths, time to pregnancy, and early pregnancy loss (within 6 weeks of the last menstrual period) among women attempting pregnancy. METHODS: Women discontinuing contraception provided daily first-morning urine specimens and recorded days with vaginal bleeding for up to 6 months. Specimens had previously been analyzed for estrogen and progesterone metabolites and human chorionic gonadotropin. A total of 221 participants contributed 706 menstrual cycles. We measured 11 phthalate metabolites and BPA in pooled urine from three specimens spaced throughout each menstrual cycle. We analyzed associations between chemical concentrations and outcomes using linear mixed models for follicular- and luteal-phase lengths, discrete-time fecundability models for time to pregnancy, and logistic regression for early pregnancy loss. RESULTS: Higher concentrations of monocarboxyoctyl phthalate (MCOP) were associated with shorter luteal phase [2nd tertile vs. 1st tertile: -0.5 days (95% CI: -0.9, -0.1), 3rd vs. 1st: -0.4 days (95% CI: -0.8, 0.01), p = 0.04]. BPA was also associated with shorter luteal phase [2nd vs. 1st: -0.8 days (95% CI: -1.2, -0.4), 3rd vs. 1st: -0.4 days (95% CI: -0.8, 0.02),p = 0.001]. CONCLUSIONS: BPA and MCOP (or its precursors) were associated with shorter luteal phase. Menstrual cycle--specific estimates of urinary BPA and phthalate metabolites were not associated with detrimental alterations in follicular-phase length, time to pregnancy, or early pregnancy loss, and in fact, DEHP [di(2-ethylhexyl) phthalate] metabolites {MEOHP [mono(2-ethyl-5-oxohexyl) phthalate] and ΣDEHP} were associated with reduced early loss. These findings should be confirmed in future human studies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Extracellular vesicles (EVs), membrane-bound particles containing a variety of RNA types, DNA, proteins, and other macromolecules, are now appreciated as an important means of communication between cells and tissues, both in normal cellular physiology and as a potential indicator of cellular stress, environmental exposures, and early disease pathogenesis. Extracellular signaling through EVs is a growing field of research for understanding fundamental mechanisms of health and disease and for the potential for biomarker discovery and therapy development. EVs are also known to play important roles in mediating the effects of exposure to environmental stress. OBJECTIVES: This seminar addresses the application of new tools and approaches for EV research, developed in part through the National Institutes of Health (NIH) Extracellular RNA Communication Program, and reflects presentations and discussions from a workshop held 27–28 September 2021 by the National Institute of Environmental Health Sciences (NIEHS) and the National Center for Advancing Translational Sciences (NCATS) on “Extracellular Vesicles, Exosomes, and Cell-Cell Signaling in Response to Environmental Stress.” The panel of experts discussed current research on EVs and environmental exposures, highlighted recent advances in EV isolation and characterization, and considered research gaps and opportunities toward identifying and characterizing the roles for EVs in environmentally related diseases, as well as the current challenges and opportunities in this field. DISCUSSION: The authors discuss the application of new experimental models, particularly organ-on-chip (OOC) systems and in vitro approaches and how these have the potential to extend findings in population-based studies of EVs in exposure-related diseases. Given the complex challenges of identifying cell-specific EVs related to environmental exposures, as well as the general heterogeneity and variability in EVs in blood and other accessible biological samples, there is a critical need for rigorous reporting of experimental methods and validation studies. The authors note that these efforts, combined with cross-disciplinary approaches, would ensure that future research efforts in environmental health studies on EV biomarkers are rigorous and reproducible. [ABSTRACT FROM AUTHOR]

BACKGROUND: Parabens, found in everyday items from personal care products to foods, are chemicals with endocrine-disrupting activity, which has been shown to influence reproductive function. OBJECTIVES: This study investigated whether urinary concentrations of methylparaben, propylparaben, or butylparaben were associated with the urinary metabolome during the periconceptional period, a critical window for female reproductive function. Changes to the periconceptional urinary metabolome could provide insights into the mechanisms by which parabens could impact fertility. METHODS: Urinary paraben concentrations were measured in paired pre- and postconception urine samples from 42 participants in the Early Pregnancy Study, a prospective cohort of 221 women attempting to conceive. We performed untargeted and targeted metabolomics analyses using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. We used principal component analysis, orthogonal partial least-squares discriminant analysis, and permutation testing, coupled with univariate statistical analyses, to find metabolites associated with paraben concentration at the two time points. Potential confounders were identified with a directed acyclic graph and used to adjust results with multivariable linear regression. Metabolites were identified using fragmentation data. RESULTS: Seven metabolites were associated with paraben concentration (variable importance to projection score >1, false discovery rate-corrected 푞-value<0.1). We identified four diet-related metabolites to the Metabolomics Standards Initiative (MSI) certainty of identification level 2, including metabolites from smoke flavoring, grapes, and olive oil. One metabolite was identified to the class level only (MSI level 3). Two metabolites were un-identified (MSI level 4). After adjustment, three metabolites remained associated with methylparaben and propylparaben, two of which were diet-related. No metabolomic markers of endocrine disruption were associated with paraben concentrations. DISCUSSION: This study identified novel relationships between urinary paraben concentrations and diet-related metabolites but not with metabolites on endocrine-disrupting pathways, as hypothesized. It demonstrates the feasibility of integrating untargeted metabolomics data with environmental exposure information and epidemiological adjustment for confounders. The findings underscore a potentially important connection between diet and paraben exposure, with applications to nutritional epidemiology and dietary exposure assessment [ABSTRACT FROM AUTHOR]