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.

A descriptive analysis of first trimester urinary concentrations of 14 bisphenol analogues in the MIREC Canadian pregnancy cohort.

BACKGROUND: Concern over the health effects of BPA, particularly for the developing fetus, has led to an increasing use of bisphenol analogues in industrial and consumer products, which may be as hormonally active as BPA. Biomonitoring data for many bisphenol analogues, especially in pregnant populations, are limited. METHODS: We measured concentrations of 14 bisphenol analogues in 1st trimester urine samples (n = 1851) from the Maternal-Infant Research on Environmental Chemicals (MIREC) Canadian pregnancy cohort (2008-2011). We examined patterns of exposure according to sociodemographic and sampling characteristics as well as occupation and frequency of consumption of canned fish within the previous 3 months. RESULTS: BPA was detected in 89% of participants with a specific gravity standardized geometric mean concentration of 0.990 µg/L. Biphenol 4,4' (BP 4,4'), 4,4'-dihydroxydiphenyl ether (DHDPE), and bisphenol E (BPE) were detected in >97% of participants. Bisphenol F (BPF) and bisphenol S (BPS) were detected in >60% of participants. Specific gravity standardized geometric mean concentrations of these 5 compounds ranged from 0.024 to 0.564 µg/L. Nine bisphenol analogues were detected in <9% of participants. Concentrations of BP 4,4', DHDPE, and BPE were higher in younger women and those with higher pre-pregnancy BMI, lower household income, lower education, and among smokers. We found a similar pattern of differences in BPF for age, education, and smoking status while BPS similarly differed across categories of pre-pregnancy BMI. Participants who were unemployed or working in the service industry had higher molar sum of 7 bisphenol analogues than those working in healthcare, education, or an office setting. Canned fish consumption was not related to bisphenol analogue concentrations. CONCLUSION: BP 4,4', DHDPE, BPE, BPF, and BPS were highly detected in 1st trimester urine samples in this large pan-Canadian pregnancy cohort. This suggests widespread exposure to these analogues around 2008-2011 and warrants further investigation into associations with health outcomes.

Imputing accelerometer nonwear time in children influences estimates of sedentary time and its associations with cardiometabolic risk.

BACKGROUND: A limitation of measuring sedentary time with an accelerometer is device removal. The resulting nonwear time is typically deleted from the data prior to calculating sedentary time. This could impact estimates of sedentary time and its associations with health indicators. We evaluated whether using multiple imputation to replace nonwear accelerometer epochs influences such estimates in children. METHODS: 452 children (50% male) aged 10-13 were tasked with wearing an accelerometer (15 s epochs) for 7 days. On average, 8% of waking time was classified as nonwear time. Sedentary time was derived from a "nonimputed" dataset using the typical approach of deleting epochs that occurred during nonwear time, as well as from an "imputed" dataset. In the imputed dataset, each nonwear epoch was re-classified as being as sedentary or not using multiple imputation (5 iterations) which was informed by the likelihood of a wear time epoch being classified as sedentary or not using parameter estimates from a logistic regression model. Estimates of sedentary time and associations between sedentary time and health indicators (cardiometabolic risk factor and internalizing mental health symptoms Z-scores) were compared between the nonimputed and imputed datasets. RESULTS: On average, sedentary time was 33 min/day higher in the imputed dataset than in the nonimputed dataset (632 vs. 599 min/day). The association between sedentary time and the cardiometabolic risk factor Z-score was stronger in the imputed vs. the nonimputed dataset (ß = 0.137 vs. ß = 0.092 per 60 min/day change, respectively). These findings were more pronounced among children who had < 7 days with ≥10 h of wear time. CONCLUSION: Researchers should consider using multiple imputation to address accelerometer nonwear time, rather than deleting it, in order to derive more unbiased estimates of sedentary time and its associations with health indicators.

Estimating sleep efficiency in 10- to- 13-year-olds using a waist-worn accelerometer.

OBJECTIVE: In field settings, wrist- and waist-worn accelerometers are typically used to assess sleep characteristics and movement behaviors, respectively. There has been a shift in movement behavior studies to wear accelerometers 24 h/d. Sleep characteristics could be assessed in these studies if sleep algorithms were available for waist-worn accelerometers. The objective of this study was to develop and provide validity data for an algorithm/sleep likelihood score cut-off to estimate sleep efficiency in children using the waist-worn Actical accelerometer. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty healthy children aged 10-13 years. MEASUREMENTS: Children wore an Actical on their waist and an Actiwatch 2 on their nondominant wrist for 8 nights at home in their normal sleep environment. Participants were randomized into algorithm/sleep likelihood score "development" and "test" groups (n=25 per group). Within the development group, we assessed sleep efficiency with the Actical using the same algorithm that the Actiwatch 2 uses and selected the sleep likelihood score cut-off value that was the most accurate at predicting sleep efficiency at the nightly level compared with the Actiwatch 2. We applied this algorithm and cut-off value to the test group. RESULTS: Mean (SD) sleep efficiency estimates for the test group from the Actical and Actiwatch 2 were 89.0% (3.9%) and 88.7% (3.1%), respectively. Bland-Altman plots and absolute difference scores revealed considerable agreement between devices for both nightly and weekly estimates of sleep efficiency. CONCLUSION: A waist-worn Actical accelerometer can accurately predict sleep efficiency in field settings among healthy 10- to 13-year-olds.

Associations between weight-related teasing and psychosomatic symptoms by weight status among school-aged youth.

OBJECTIVE: Weight-related teasing (WT) is associated with poor mental health. This study examined whether weight status moderates the relationship between WT and psychosomatic symptoms within a representative sample of school-aged youth. METHODS: Data are from the Canadian 2013/2014 Health Behaviour in School-aged Children Survey, a nationally representative sample of youth in Grades 6-10. WT, psychosomatic symptoms and body mass index (BMI) were self-reported. RESULTS: The final sample consisted of 20,277 youth (mean age = 14.2 years; 50.2% female). The prevalence who reported being WT at least once a week was 4.6%, 8.1% and 17.3% among youth with normal weight, overweight, and obesity, respectively (p < 0.001). There was a gradient relationship between the frequency of WT and psychosomatic symptoms (p < 0.001). By comparison to youth that were not WT, psychosomatic symptom z-scores were significantly (p < 0.05) higher in youth that were WT one to two times in the past few months (0.47, 95% CI: 0.41-0.53), two to three times per month (0.65, 0.52-0.77), about once a week (0.82, 0.71-0.93) and several times a week (0.98, 0.84-1.12). However, the WT * BMI category interaction term was not significant (p = 0.86). CONCLUSIONS: Victims of WT experienced more psychosomatic symptoms independent of BMI category; however, BMI category did not moderate the association between WT and psychosomatic symptoms.

Comparison of ActiGraph GT3X+ and Actical accelerometer data in 9-11-year-old Canadian children.

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Objectively measured physical activity, sedentary time and sleep duration: independent and combined associations with adiposity in canadian children.

OBJECTIVE: To examine independent and combined associations among objectively measured movement/non-movement behaviors (moderate-to-vigorous-intensity physical activity (MVPA), total sedentary time and sleep duration) and adiposity indicators in a sample of Canadian children. METHODS: A cross-sectional study was conducted on 507 children aged 9-11 years from Ottawa, Canada. Movement/non-movement behaviors were assessed using an Actigraph GT3X+ accelerometer over 7 days (24-h protocol). Outcomes included percentage body fat (bioelectrical impedance) and waist-to-height ratio. RESULTS: After adjustment for age, sex, ethnicity, maturity offset, fast food consumption, annual household income and highest level of parental education, MVPA was inversely and sedentary time positively associated with adiposity indicators, whereas sleep duration was not. However, only MVPA remained significantly associated with adiposity indicators after additional adjustment for the other movement/non-movement behaviors. Combined associations using tertiles of the three movement/non-movement behaviors showed that higher levels of MVPA were associated with lower adiposity indicators, irrespective of total sedentary time and sleep duration. CONCLUSIONS: Higher levels of MVPA were associated with lower adiposity in this sample of children regardless of sedentary time and sleep duration. Although correlational in nature, these findings suggest that future efforts of obesity reduction should focus more on increasing MVPA than on reducing sedentary time or increasing sleep duration to maximize the effectiveness of interventions.