Maternal exposure to metals and time-to-pregnancy: The MIREC cohort study.

OBJECTIVE: To study the association between maternal exposure to arsenic, cadmium, lead, manganese and mercury, time-to-pregnancy (TTP) and infertility. DESIGN: Pregnancy-based retrospective TTP cohort study. SETTING: Hospitals and clinics from ten cities across Canada. POPULATION: A total of 1784 pregnant women. METHODS: Concentrations of arsenic, cadmium, lead, manganese and mercury were measured in maternal whole blood during the first trimester of pregnancy as a proxy of preconception exposure. Discrete-time Cox proportional hazards models generated fecundability odds ratios (FOR) for the association between metals and TTP. Logistic regression generated odds ratios (OR) for the association between metals and infertility. Models were adjusted for maternal age, pre-pregnancy body mass index, education, income, recruitment site and plasma lipids. MAIN OUTCOME MEASURES: TTP was self-reported as the number of months of unprotected intercourse to become pregnant. Infertility was defined as TTP longer than 12 months. RESULTS: A total of 1784 women were eligible for the analysis. Mean ± SD maternal age and gestational age at interview were 32.2 ± 5.0 years, and 11.6 ± 1.6 weeks, respectively. Exposure to arsenic, cadmium, manganese or mercury was not associated with TTP or infertility. Increments of one standard deviation of lead concentrations resulted in a shorter TTP (adjusted FOR 1.09, 95% CI 1.02-1.16); however, the association was not linear when exposure was modelled in tertiles. CONCLUSION: Blood concentrations of metals at typical levels of exposure among Canadian pregnant women were not associated with TTP or infertility. Further studies are needed to assess the role of lead, if any, on TTP.

Serum concentrations of legacy, alternative, and precursor per- and polyfluoroalkyl substances: a descriptive analysis of adult female participants in the MIREC-ENDO study.

BACKGROUND: Several legacy and emerging per- and polyfluoroalkyl substances (PFAS) have been regulated around the world. There is growing concern over the proliferation of alternative PFAS, as well as PFAS precursors. Biomonitoring data for PFAS are critical for assessing exposure and human health risk. METHODS: We collected serum samples from 289 adult female participants in a 2018-2021 follow-up study of the Maternal-Infant Research on Environmental Chemicals (MIREC) Canadian pregnancy cohort. Samples were analyzed for 40 PFAS using ultra-performance liquid chromatography-tandem mass spectrometry. For those compounds with > 50% detection, as well as the sum of these compounds, we describe serum concentrations and patterns of exposure according to sociodemographic and obstetrical history characteristics. RESULTS: 17 out of 40 PFAS were detected in > 50% of samples with 7 of these detected in > 97% of samples. Median [95th percentile] concentrations (µg/L) were highest for PFOS (1.62 [4.56]), PFOA (0.69 [1.52]), PFNA (0.38 [0.81]), and PFHxS (0.33 [0.92]). Geometric mean concentrations of PFOA and PFHxS were approximately 2-fold lower among those with more children (≥ 3 vs. 1), greater number of children breastfed (≥ 3 vs. ≤ 1), longer lifetime duration of breastfeeding (> 4 years vs. ≤ 9 months), and shorter time since last pregnancy (≤ 4 years vs. > 8 years). We observed similar patterns for PFOS, PFHpS, and the sum of 17 PFAS, though the differences between groups were smaller. Concentrations of PFOA were higher among "White" participants, while concentrations of N-MeFOSE, N-EtFOSE, 7:3 FTCA, and 4:2 FTS were slightly higher among participants reporting a race or ethnicity other than "White". Concentrations of legacy, alternative, and precursor PFAS were generally similar across levels of age, education, household income, body mass index, and menopausal status. CONCLUSIONS: We report the first Canadian biomonitoring data for several alternative and precursor PFAS. Our findings suggest that exposure to PFAS, including several emerging alternatives, may be widespread. Our results are consistent with previous studies showing that pregnancy and breastfeeding are excretion pathways for PFAS.

Association between toxic metals, vitamin D and preterm birth in the Maternal-Infant research on environmental chemicals study.

BACKGROUND: Toxic metals, like lead, are risk factors for preterm birth (PTB), but few studies have examined low levels found in most Canadians. Vitamin D, which may have antioxidant activity, protects against PTB. OBJECTIVES: In this study, we investigated the impact of toxic metals (lead, mercury, cadmium and arsenic) on PTB and examined if maternal plasma vitamin D concentrations modify these associations. METHODS: We investigated whether concentrations of metals in whole blood measured in early and late pregnancy were associated with PTB (<37 weeks) and spontaneous PTB in 1851 live births from the Maternal-Infant Research on Environmental Chemicals Study using discrete time survival analysis. We also investigated whether the risk of PTB was modified by first-trimester plasma 25-hydroxyvitamin D (25OHD) concentrations. RESULTS: Of 1851 live births, 6.1% (n = 113) were PTBs and 4.9% (n = 89) were spontaneous PTB. A 1 µg/dL increase in blood lead concentrations during pregnancy was associated with an increased risk of PTB (relative risk [RR] 1.48, 95% confidence interval [CI] 1.00, 2.20) and spontaneous PTB (RR 1.71, 95% CI 1.13, 2.60). The risk was higher in women with insufficient vitamin D concentrations (25OHD <50 nmol/L) for both PTB (RR 2.42, 95% CI 1.01, 5.79) and spontaneous PTB (RR 3.04, 95% CI 1.15, 8.04). However, an interaction on the additive scale was not present. Arsenic was associated with a higher risk of PTB (RR 1.10, 95% CI 1.02, 1.19) and spontaneous PTB (RR 1.11, 95% CI 1.03, 1.20) per 1 µg/L. CONCLUSIONS: Gestational exposure to low levels of lead and arsenic may increase the risk of PTB and spontaneous PTB; individuals with insufficient vitamin D may be more susceptible to the adverse effects of lead. Given our relatively small number of cases, we encourage testing of this hypothesis in other cohorts, especially those with vitamin D-deficient populations.

Cohort profile update: The Canadian Maternal-Infant Research on Environmental Chemicals Child Development study (MIREC-CD PLUS).

BACKGROUND: The pan-Canadian Maternal-Infant Research on Environmental Chemicals (MIREC) study was established to determine whether maternal environmental chemical exposures were associated with adverse pregnancy outcomes in 2001 pregnant women. OBJECTIVES: The MIREC-Child Development (CD PLUS) study followed this cohort with the goal of assessing the potential effects of prenatal exposures on anthropometry and neurodevelopment in early childhood. POPULATION: MIREC families with children between the ages of 15 months and 5 years who had agreed to be contacted for future research (n = 1459) were invited to participate in MIREC-CD PLUS which combines data collected from an online Maternal Self-Administered Questionnaire with biomonitoring and neurodevelopment data collected from two in-person visits. PRELIMINARY RESULTS: Between April 2013 and March 2015, 803 children participated in the Biomonitoring visit where we collected anthropometric measures, blood, and urine from the children. The Behavioural Assessment System for Children-2, Behaviour Rating Inventory of Executive Function, MacArthur-Bates Communicative Development Inventories and the Communication subscale of the Adaptive Behaviour Scale from the Bayley Scales of Infant and Toddler Development-III are available on close to 900 children. There were 610 singleton children who completed in-person visits for neurodevelopment assessments including the Social Responsiveness Scale, Wechsler Preschool Primary Scale of Intelligence-III and NEuroPSYchological assessments (NEPSY). Currently, we are following the cohort into early adolescence to measure the impact of early life exposures on endocrine and metabolic function (MIREC-ENDO). CONCLUSIONS: Data collection for the MIREC-CD PLUS study is complete and analysis of the data continues. We are now extending the follow-up of the cohort into adolescence to measure the impact of early life exposures on endocrine and metabolic function (MIREC-ENDO). MIREC-CD PLUS is limited by loss to follow-up and the fact that mothers are predominately of higher socioeconomic status and 'White' ethnicity, which limits our generalizability. However, the depth of biomonitoring and clinical measures in MIREC provides a platform to examine associations of prenatal, infancy and childhood exposures with child growth and development.

Urinary concentrations and determinants of glyphosate and glufosinate in pregnant Canadian participants in the MIREC study.

BACKGROUND: Glyphosate is the most widely applied herbicide in agriculture. Glufosinate is a broad spectrum herbicide used to manage glyphosate-resistant weeds. Despite the widespread use of these herbicides, biomonitoring data - which inform risk assessment and management - are sparse. OBJECTIVES: To identify determinants of urinary concentrations of these herbicides and their metabolites in pregnancy. METHODS: We measured urinary concentrations of glyphosate, glufosinate, and their primary metabolites aminomethylphosphonic acid (AMPA) and 3-methylphosphinicopropionic acid (3-MPPA) in a single spot urine specimen collected during the first trimester of pregnancy from the Maternal-Infant Research on Environmental Chemicals (MIREC) study. MIREC recruited about 2000 pregnant women from 10 Canadian cities between 2008 and 2011. We used UItra-Performance Liquid Chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) with sensitive limits of detection to quantify analyte concentrations. We examined urinary concentrations according to maternal sociodemographics, sample collection characteristics, reported pesticide use, and consumption of fruits, vegetables, legumes, and grain products. We used ANOVA models with specific gravity-standardized chemical concentrations as the dependent variable to determine associations with maternal and sample determinants. RESULTS: Among women with biobanked urine samples (n = 1829-1854), 74% and 72% had detectable concentrations of glyphosate and AMPA, respectively. In contrast, one and six percent of women had detectable concentrations of glufosinate and 3-MPPA, respectively. The specific gravity-standardized geometric mean (95% CI) concentrations of glyphosate and AMPA were 0.112 (0.099-0.127) µg/L and 0.159 (0.147-0.172) µg/L, respectively. We observed a dose-response relationship between consumption of whole grain bread and higher urinary glyphosate concentrations. Season of urine collection and self-reported pesticide use were not associated with increased concentrations of any analyte. CONCLUSIONS: We detected glyphosate and AMPA in the majority of pregnant women from this predominantly urban Canadian cohort. Diet was a probable route of exposure.

Prenatal and concurrent blood mercury concentrations and associations with IQ in canadian preschool children.

BACKGROUND: Prenatal and childhood mercury (Hg) exposures have been associated with negative impacts on child neurodevelopment. It is unclear if associations persist at the low Hg exposures typical in Western countries. OBJECTIVE: To examine associations between prenatal/childhood blood Hg concentrations and child IQ in Canadian male and female children while considering the potential modifying role of prenatal fish consumption. METHODS: We analyzed data from the Maternal-Infant Research on Environmental Chemicals study. Hg was measured in first trimester (n = 527), cord (n = 430), and child (at 3-4 years of age, n = 355) blood and examined sex-stratified associations between blood Hg and children's Full Scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ), and General Language Composite (GLC) scores (assessed with WPPSI-III). Prenatal Hg analyses were further stratified by prenatal fish consumption (low: 0-2, moderate: 3-7, or high: ≥8 times/month). RESULTS: Higher cord blood Hg concentrations were associated with lower PIQ (ß = -3.27; 95%CI: 6.44, -0.09) in male children with the lowest prenatal fish consumption. Progressively stronger positive associations were observed with PIQ in male children for moderate (ß = 1.08; 95%CI: 0.10, 2.26) and high (ß = 3.07; 95%CI: 1.95, 4.19) prenatal fish consumption. Cord blood Hg concentrations were positively associated with female children's FSIQ (ß = 1.29; 95% CI: 0.77, 1.81) and PIQ (ß = 2.01; 95% CI: 1.19, 2.83); however, when stratified only in the highest fish consumption subgroup. Among female children, higher child blood Hg concentrations were associated with an approximately 1-point increase in FSIQ, VIQ, and GLC. CONCLUSIONS: Prenatal exposure to low levels of Hg was associated with lower PIQ scores in male children with low prenatal fish intake. Positive associations between cord and child blood Hg concentrations and IQ were primarily observed in female children and may be due to beneficial effects of prenatal fish intake.

Blood metals and vitamin D status in a pregnancy cohort: A bidirectional biomarker analysis.

Low 25-hydroxyvitamin D (25OHD), a biomarker of vitamin D status, is associated with reduced immune function and adverse pregnancy outcomes, such as preterm birth. Observational studies indicate that long-term, high level exposure to metals such as cadmium (Cd) and lead (Pb) can impact a person's vitamin D status. However, the directionality of the association is uncertain, particularly for low-level exposures. We used three distinct longitudinal data analysis methods to investigate cross-sectional, longitudinal and bidirectional relationships of Cd and Pb biomarkers with 25-hydroxyvitamin D (25OHD) in a Canadian pregnancy cohort. Maternal whole blood Cd and Pb and plasma 25OHD concentrations were measured in the 1st (n = 1905) and 3rd (n = 1649) trimester and at delivery (25OHD only, n = 1542). Our multivariable linear regression analysis showed weak inverse associations between Cd and 25OHD concentrations cross-sectionally and longitudinally while the latent growth curve models showed weak associations with Pb on the 25OHD intercept. In the bidirectional analysis, using cross lagged panel models, we found no association between 1st trimester metals and 3rd trimester 25OHD. Instead, 1st trimester 25OHD was associated with 9% (-15%, -3%) lower 3rd trimester Cd and 3% (-7, 0.1%) lower Pb. These findings suggest the 25OHD may modify metal concentrations in pregnancy and demonstrates the value of controlling for contemporaneous effects and the persistence of a biomarker over time, in order to rule out reverse causation.

Heavy metal blood concentrations in association with sociocultural characteristics, anthropometry and anemia among Kenyan adolescents.

OBJECTIVES: To measure heavy metal concentrations among Kenyan youth and quantify associations with sociocultural, demographic, and health factors as well as anthropometry. METHODS: Using data from a study of semi-nomadic pastoralists in Samburu County, Kenya, we measured blood concentrations of lead (Pb), mercury (Hg), and cadmium (Cd) in 161 adolescents. We identified sociocultural, demographic and health characteristics associated with each metal and quantified the association between metals and adolescent anthropometry. RESULTS: Median blood concentrations of Pb, Cd, and Hg were 1.82 µg/dL, 0.24 µg/L and 0.16 µg/L, respectively. Place of residence (highlands vs lowlands) was a determinant of metal concentrations. Hg was inversely related to anemia, and metals were not associated with anthropometry. CONCLUSIONS: In this population of Samburu adolescents, median Pb and Cd blood concentrations were higher than other North American or European biomonitoring studies. These findings motivate further investigation into the environmental sources of metals in this community.

Navajo Nation Stores Show Resilience During COVID-19 Pandemic.

On April 8, 2020, the Navajo Nation issued an administrative order limiting business operations. Facing high coronavirus disease 2019 (COVID-19) rates and limited food infrastructure, a survey was conducted among Navajo Nation store managers to assess: (1) COVID-19 adaptations; (2) challenges; (3) changes in customer volume and purchasing; and (4) suggestions for additional support. Purposive sampling identified 29 stores in Navajo communities. Representatives from 20 stores (19 store managers/owners, 1 other; 7 grocery, and 13 convenience/other stores) were interviewed by phone or in-person to reach saturation (new information threshold < 5%). Responses were coded using frequencies and inductive thematic analysis. All 20 stores implemented COVID-19 guidelines (Centers for Disease Control and Prevention [CDC]/Navajo Nation) and most received orientation/support from local chapters, community organizations, or health centers. Stores implemented staff policies (50%, handwashing, vaccinations, protective personal equipment (PPE), sick leave, temperature checks), environmental changes (50%, hand sanitizer, checkout dividers), customer protocols (40%, limit customers, mask requirements, closed restrooms), and deep cleaning (40%). Most stores (65%) reported challenges including stress/anxiety, changing guidelines, supply chain and customer compliance; 30% reported infection or loss of staff. Weekday customer volume was slightly higher vs. pre-COVID, but weekend lower. Stores reported consistent or more healthy food purchases (50%), more nonfood essentials (20%), or shelf-stable foods (10%). Desired support included further orientation (30%), leadership support (20%), overtime/time to learn guidelines (20%), and signage/handouts (15%). Despite a high COVID-19 burden and limited food store infrastructure, Navajo Nation stores adapted by implementing staff, environmental and customer policies. Local support, staffing, and small store offerings were key factors in healthy food access.

Implementation of Indigenous Food Tax Policies in Stores on Navajo Nation.

In 2014, the Navajo Nation Healthy Diné Nation Act (HDNA) was enacted and permanently approved in 2020; HDNA places a 2% surtax on unhealthy foods and beverages, while other 2014 legislation exempted healthy food items from the 6% regular sales tax. Little is known about Navajo Nation store manager/owner perspectives toward the HDNA and how best to support stores to implement the legislation. Purposive sampling was used to ensure a balanced sample of correct HDNA implementers, incorrect HDNA implementers, and stores which made healthy store changes over the past 6 years. Three community-based interviewers collected surveys by phone or in-person. Frequency of closed-ended questions was quantified, and open-ended responses were coded using thematic analysis. Of 29 identified sample stores, 20 were interviewed to reach saturation. Eleven of 20 stores made changes improving their healthy food environments. Barriers included lack of equipment (6/20) and low consumer demand (5/20). Facilitators included consumer awareness and increased produce supply options (5/20). Sixteen of 20 stores supported HDNA continuation. Facilitators to HDNA implementation included orientation and informational materials (6/20) and promotion of tax-free items (5/20). Barriers included confusion about the tax (6/20) and tax exemption (5/20). Suggestions for support included printed materials (6/20) and store training (5/20). HDNA benefits included greater awareness of healthy choices among staff (7/20) and customer-community members (2/20). Most managers and owners expressed receiving support for healthy store changes and HDNA, but also identified a need for added resources and support. Findings inform legislative action to promote timely and appropriate uptake of HDNA, and support equitable, healthy food systems.

Association between arthritis treatments and ovarian reserve: a prospective study.

RESEARCH QUESTION: How do anti-Müllerian hormone (AMH) concentrations in women with and without arthritis compare? Is there an association between AMH and arthritis drug regimen? DESIGN: In this prospective cohort study, AMH was measured at two time points (T0 and T1) in 129 premenopausal women with arthritis. AMH at T0 was compared with that from a bank of serum samples from 198 premenopausal women without arthritis. Primary outcomes were: (i) diminished ovarian reserve (DOR) (AMH <1.1 ng/ml) and (ii) annual rate of AMH decrease. Univariate, multivariable and Firth logistic regression identified variables associated with annual AMH decrease in excess of the 75th percentile. RESULTS: Median time between T0 and T1 was 1.72 years. At time T0, median age-adjusted AMH in women with arthritis was significantly lower than that of women without arthritis (median 2.21 ng/ml versus 2.78 ng/ml; P = 0.009). Women with arthritis at highest risk for DOR had a history of tubal sterilization or were over the age of 35. Those with highest odds of having an annual AMH decrease in excess of the 75th percentile (over 28% decrease per year) were those: over the age of 35 or who sought care for infertility. Women with arthritis taking methotrexate alone (OR 0.08, 95% CI 0.01-0.67) or methotrexate plus tumour necrosis factor-alpha antagonists (OR 0.13, 95% CI 0.02-0.89) were less likely to be in the highest quartile of annual AMH decrease than women with arthritis not taking medication. CONCLUSIONS: Women with arthritis had lower AMH than healthy controls. Long-term methotrexate use was not associated with an annual AMH decrease.

Evaluation of Quality of Life in Adult Individuals With Cleft Lip and/or Palate.

OBJECTIVES: The purpose of the present study was to systematically review literature relating to the quality of life (QoL) in adult individuals with cleft lip and/or palate (CLP) and identify which aspect of QoL adults with CLP find to be the most problematic, in comparison to a general non-cleft population. DESIGN: Different databases were searched for this review including the Cochrane Central Register of Controlled Trials, Ovid MEDLINE and Embase. Five domains of QoL were identified to evaluate the overall results of these QoL measures. These domains were; physical function, physical pain, psychological implications and self-esteem, self-perception in relation to facial aesthetics, and social function. The studies included underwent critical appraisal and different types of bias were assessed based on the Cochrane handbook for systematic reviews of interventions. RESULTS: Ten studies were included in this review. The total number of participants was 541. The most common QoL measure for adults with CLP was Short-Form (SF-36). Seven studies out of 10 reported statistically significantly worse scores (P < 0.05) in the psychological implications and self-esteem domains of QoL in adults with CLP, indicating lower QoL in terms of these domains. The least affected QoL domain was physical function. A high heterogeneity was found among the studies, including variation in the QoL measures, types of orofacial clefts, types of treatment and comparison groups. CONCLUSION: The presence of CLP did seem to negatively affect the QoL for adults with CLP, mainly in terms of psychological implications and self-esteem.

The 3G Multigenerational Cohort of Nova Scotian women and their mothers and offspring.

BACKGROUND: The negative impact of exposures such as maternal obesity, excessive gestational weight gain, and hypertension in pregnancy on the health of the next generation has been well studied. Evidence from animal studies suggests that the effects of in utero exposures may persist into the second generation, but the epidemiological literature on the influence of pregnancy-related exposures across three generations in humans is sparse. OBJECTIVES: This cohort was established to investigate associations between antenatal and perinatal exposures and health outcomes in women and their offspring. POPULATION: The cohort includes women who were born and subsequently had their own pregnancies in the Canadian province of Nova Scotia from 1980 onward. DESIGN: Intergenerational linkage of data in the Nova Scotia Atlee Perinatal Database was used to establish a population-based dynamic retrospective cohort. METHODS: The cohort has prospectively collected information on sociodemographics, maternal health and health behaviours, pregnancy health and complications, and obstetrical and neonatal outcomes for two generations of women and their offspring. PRELIMINARY RESULTS: As of October 2018, the 3G cohort included 14 978 grandmothers (born 1939-1986), 16 766 mothers or cohort women (born 1981-2003), and 28 638 children (born 1996-2018). The cohort women were generally younger than Nova Scotian women born after 1980, and as a result, characteristics associated with pregnancy at a younger age were more frequently seen in the cohort women; sampling weights will be created to account for this design effect. The cohort will be updated annually to capture future deliveries to women who are already in the cohort and women who become eligible for inclusion when they deliver their first child. CONCLUSIONS: The 3G Multigenerational Cohort is a population-based cohort of women and their mothers and offspring, spanning a time period of 38 years, and provides the opportunity to study inter- and transgenerational associations across the maternal line.

The Navajo Nation Healthy Diné Nation Act: A Two Percent Tax on Foods of Minimal-to-No Nutritious Value, 2015-2019.

Our study summarizes tax revenue and disbursements from the Navajo Nation Healthy Diné Nation Act of 2014, which included a 2% tax on foods of minimal-to-no nutritional value (junk food tax), the first in the United States and in any sovereign tribal nation. Since the tax was implemented in 2015, its gross revenue has been $7.58 million, including $1,887,323 in 2016, the first full year. Revenue decreased in absolute value by 3.2% in 2017, 1.2% in 2018, and 4.6% in 2019, a significant downward trend (P = .02). Revenue allocated for wellness projects averaged $13,171 annually for each local community, with over 99% successfully disbursed and more rural areas generating significantly less revenue. Our results provide context on expected revenue, decreases over time, and feasibility for tribal and rural communities considering similar policies.

Initial management and long-term follow up after the rehabilitation of a patient with severe dentoalveolar trauma: A case report.

Dental trauma is common and for patients who suffer significant oral injuries, rehabilitation can be challenging to the clinical team. This case report describes the successful prosthetic replacement of multiple missing teeth lost due to severe dentoalveolar trauma, using iliac crest bone grafting, an implant-retained removable dental prosthesis and implant-supported crowns. Good functionality and aesthetic outcome were achieved.

Blood metal levels and early childhood anthropometric measures in a cohort of Canadian children.

Fetal exposure to some toxic metals has been associated with reduced fetal growth, but the impact of contemporary, low-level metals on anthropometric measures in childhood is not well understood. Our primary objective was to quantify associations between childhood levels of toxic metals and concurrently measured body mass index (BMI) in a population of Canadian preschool-aged children. We collected biomonitoring data and anthropometric measures on 480 children between the ages of two and five years in the Maternal-Infant Research on Environmental Chemicals (MIREC) Child Development Plus study. Concentrations of four toxic metals (lead, arsenic, cadmium, and mercury) were measured in whole blood collected from pregnant women and their children. Blood levels of key essential elements were also measured in children. Children's weight, height, and BMI z-scores were calculated using the World Health Organization growth standards. We used a series of linear regression models, adjusted for potential parental confounders, concurrently measured metals and elements, and prenatal blood metal levels, to evaluate associations between tertiles of each toxic metal and anthropometric measures. We tested for effect modification by sex. Of the 480 children, 449 (94%) were singleton births and had complete biomonitoring and anthropometric data. The majority of children had detectable concentrations of metals. In the adjusted models, girls with blood lead concentrations in the highest tertile (>0.82 µg/dL) had, on average, 0.26 (95% Cl: -0.55, 0.03) lower BMI z-scores than those in the referent category. In contrast, boys with lead levels in the highest tertile had, on average, 0.14 higher BMI z-scores (95% Cl: -0.14, 0.41) (p-value heterogeneity = 0.04). In this population of Canadian preschool-aged children with low-level blood lead concentrations, we observed effect modification by sex in the association between Pb and BMI but no statistically significant associations in the sex-specific strata. Child blood levels of As, Cd, and Hg were not associated with childhood BMI, weight, or height in boys or girls.

Associations between maternal triclosan concentrations in early pregnancy and gestational diabetes mellitus, impaired glucose tolerance, gestational weight gain and fetal markers of metabolic function.

BACKGROUND: Triclosan is a phenolic biocide used in a multitude of consumer products and in health care settings. It is widely detected in the American and Canadian populations and has been shown in animal models to act as an endocrine disrupting agent. However, there has been little examination to date of the effects of triclosan exposure in pregnancy on perinatal metabolic outcomes in human populations. METHODS: Using data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a Canadian pregnancy cohort, we measured associations of first-trimester urinary triclosan concentrations with total gestational weight gain, gestational diabetes mellitus and impaired glucose tolerance in pregnancy, and fetal markers of metabolic function. Leptin and adiponectin were measured in plasma from umbilical cord blood samples in term neonates and categorized into low (< 10th percentile), intermediate (10th-90th percentile) and high (> 90th percentile) levels. Triclosan concentrations were grouped into quartiles and associations with study outcomes were examined using logistic regression models with adjustment for maternal age, race/ethnicity, pre-pregnancy BMI, education and urinary specific gravity. Restricted cubic spline analysis was performed to help assess linearity and shape of any dose-response relationships. All analyses for leptin and adiponectin levels were performed on the entire cohort as well as stratified by fetal sex. RESULTS: Triclosan measures were available for 1795 MIREC participants with a live born singleton birth. Regression analyses showed a non-significant inverse association between triclosan concentrations and leptin levels above the 90th percentile that was restricted to female fetuses (OR for highest quartile of triclosan compared to lowest quartile = 0.4 (95% CI 0.2-1.1), p-value for trend across quartiles = 0.02). Triclosan concentrations in the second quartile were associated with elevated odds of adiponectin below the 10th percentile in male fetuses (OR for Q2 compared to Q1 = 2.5, 95% CI 1.1-5.9, p-value for trend across quartiles = 0.93). No significant linear associations between triclosan concentrations and leptin or adiponectin levels in overall or sex-specific analyses were observed from restricted cubic spline analyses. No significant associations were observed in adjusted analyses between triclosan concentrations and gestational diabetes mellitus, impaired glucose tolerance or gestational weight gain. CONCLUSIONS: This study does not support an association between triclosan concentrations in pregnancy and fetal metabolic markers, glucose disorders of pregnancy, or excessive gestational weight gain.

Maternal Concentrations of Perfluoroalkyl Substances and Fetal Markers of Metabolic Function and Birth Weight.

Perfluoroalkyl substances (PFAS) are ubiquitous, persistent chemicals that have been widely used in the production of common household and consumer goods for their nonflammable, lipophobic, and hydrophobic properties. Inverse associations between maternal or umbilical cord blood concentrations of perfluorooctanoic acid and perfluorooctanesulfonate and birth weight have been identified. This literature has primarily examined each PFAS individually without consideration of the potential influence of correlated exposures. Further, the association between PFAS exposures and indicators of metabolic function (i.e., leptin and adiponectin) has received limited attention. We examined associations between first-trimester maternal plasma PFAS concentrations and birth weight and cord blood concentrations of leptin and adiponectin using data on 1,705 mother-infant pairs from the Maternal Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada birth cohort study that recruited women between 2008 and 2011. Bayesian hierarchical models were used to quantify associations and calculate credible intervals. Maternal perfluorooctanoic acid concentrations were inversely associated with birth weight z score, though the null value was included in all credible intervals (log10 ß = −0.10, 95% credible interval: −0.34, 0.13). All associations between maternal PFAS concentrations and cord blood adipocytokine concentrations were of small magnitude and centered around the null value. Follow-up in a cohort of children is required to determine how the observed associations manifest in childhood.

Air Pollution Exposure During Pregnancy and Fetal Markers of Metabolic function: The MIREC Study.

Previous evidence suggests that exposure to outdoor air pollution during pregnancy could alter fetal metabolic function, which could increase the risk of obesity in childhood. However, to our knowledge, no epidemiologic study has investigated the association between prenatal exposure to air pollution and indicators of fetal metabolic function. We investigated the association between maternal exposure to nitrogen dioxide and fine particulate matter (aerodynamic diameter ≤2.5 µm) and umbilical cord blood leptin and adiponectin levels with mixed-effects linear regression models among 1,257 mother-infant pairs from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, conducted in Canada (2008-2011). We observed that an interquartile-range increase in average exposure to fine particulate matter (3.2 µg/m(3)) during pregnancy was associated with an 11% (95% confidence interval: 4, 17) increase in adiponectin levels. We also observed 13% (95% confidence interval: 6, 20) higher adiponectin levels per interquartile-range increase in average exposure to nitrogen dioxide (13.6 parts per billion) during pregnancy. Significant associations were seen between air pollution markers and cord blood leptin levels in models that adjusted for birth weight z score but not in models that did not adjust for birth weight z score. The roles of prenatal exposure to air pollution and fetal metabolic function in the potential development of childhood obesity should be further explored.