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Inuit communities in Northern Quebec (Canada) are exposed to environmental contaminants, particularly to mercury, lead and polychlorinated biphenyls (PCBs). Previous studies reported adverse associations between these neurotoxicants and memory performance. Here we aimed to determine the associations of pre- and postnatal exposures to mercury, lead and PCB-153 on spatial navigation memory in 212 Inuit adolescents (mean age = 18.5 years) using a computer task which requires learning the location of a hidden platform based on allocentric spatial representation. Contaminant concentrations were measured in cord blood at birth and blood samples at 11 years of age and at time of testing. Multivariate regression models showed that adolescent mercury and prenatal PCB-153 exposures were associated with poorer spatial learning, whereas current exposure to PCB-153 was associated with altered spatial memory retrieval at the probe test trial. These findings suggest that contaminants might be linked to different aspects of spatial navigation processing at different stages.

Through their marine-based diet, the Inuit of Nunavik (Quebec) are exposed to neurotoxic environmental contaminants that impact cognitive development. Mercury levels in Nunavik Inuit mothers and newborns were higher than in U.S. and Canadian populations but lower than in previous Arctic samples. Lead, polychlorinated biphenyls, chorinated pesticides, and possibly protective substances (selenium and N-3 polyunsaturated fatty acids) were also measured. (SV)

Objectives. We examined the relation of household crowding to food insecurity among Inuit families with school-aged children in Arctic Quebec. Methods. We analyzed data collected between October 2005 and February 2010 from 292 primary caregiver--child dyads from 14 Inuit communities. We collected information about household conditions, food security, and family socioeconomic characteristics by interviews. We used logistic regression models to examine the association between household crowding and food insecurity. Results. Nearly 62% of Inuit families in the Canadian Arctic resided in more crowded households, placing them at risk for food insecurity. About 27% of the families reported reducing the size of their children’s meals because of lack of money. The likelihood of reducing the size of children’s meals was greater in crowded households (odds ratio = 3.73; 95% confidence interval = 1.96, 7.12). After we adjusted for different socioeconomic characteristics, results remained statistically significant. Conclusions. Interventions operating across different levels (community, regional, national) are needed to ensure food security in the region. Targeting families living in crowded conditions as part of social and public health policies aiming to reduce food insecurity in the Arctic could be beneficial. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are food-chain contaminants that have been shown to induce adverse developmental effects in humans. In the course of an epidemiologic study established to investigate neurodevelopmental deficits induced by environmental PCB exposure in the Inuit population of northern Québec (Nunavik, Canada), we compared three biomarkers of prenatal exposure and models to predict PCB plasma concentration at 6 months postpartum. Concentrations of 14 PCB congeners were measured by high-resolution gas chromatography with electron capture detection in lipids extracted from maternal plasma, cord plasma, breast milk (collected at ∼1 month postpartum), and 6-month-old infant plasma samples. Similar congener profiles were observed in all biologic samples, and PCB-153, the most abundant and persistent PCB congener, was strongly correlated with other frequently detected PCB congeners in all biologic media. When expressed on a lipid basis, maternal plasma, cord plasma, and milk concentrations of this congener were strongly intercorrelated, indicating that PCB concentration in any of these biologic media is a good indicator of prenatal exposure to PCBs. A multivariate model that included maternal PCB153 plasma lipid concentration, breast-feeding duration, and the sum of two skin-fold thicknesses (an index of infant body fat mass) explained 72% of PCB-153 plasma concentration variance at 6 months postpartum (p < 0.001). By contrast, based on the product of breast-feeding duration times the concentration of PCBs in plasma lipids, which was used as an index of postnatal PCB exposure in several studies, only 36% of infant plasma concentration was explained. [ABSTRACT FROM AUTHOR]

The Inuit population residing in Nunavik (northern Québec, Canada) relies on species from the marine food web for subsistence and is therefore exposed to high doses of environmental contaminants such as polychlorinated biphenyls and methylmercury and to a lesser extent lead. In view of the neurotoxic properties of these substances following developmental exposure, we initiated a study on infant development in this remote coastal population. Here we report the magnitude of prenatal exposure to these contaminants and to selective nutrients in Inuit mothers and their newborns who were recruited on the Hudson Bay coast. We conducted interviews during the women's pregnancies and at 1 and 11 months postpartum and collected biological samples for mercury, lead, polychlorinated biphenyls (PCBs), and chlorinated pesticides analyses as well as selenium and N-3 polyunsaturated fatty acids (n3-PUFA). Cord blood, maternal blood, and maternal hair mercury concentrations averaged 18.5 µg/L, 10.4 µg/L, and 3.7 µg/g, respectively, and are similar to those found in the Faroe Islands but lower than those documented in the Seychelles Islands and New Zealand cohorts. Concentrations of PCB congener 153 averaged 86.9, 105.3, and 131.6 µg/kg (lipids) in cord plasma, maternal plasma, and maternal milk, respectively; prenatal exposure to PCBs in the Nunavik cohort is similar to that reported in the Dutch but much lower than those in other Arctic cohorts. Levels of n3-PUFA in plasma phospholipids and selenium in blood are relatively high. The relatively low correlations observed between organochlorine and methylmercury concentrations may make it easier to identify the specific developmental deficits attributable to each toxicant. Similarly, the weak correlations noted between environmental contaminants and nutrients will facilitate the documentation of possible protective effects afforded by either n3-PUFA or selenium against neurotoxic contaminants. Key... [ABSTRACT FROM AUTHOR]

Given that their traditional lifestyle and diet still relies on fish and other marine species for sustenance, the Inuit are highly exposed to polychlorinated biphenyls (PCBs) and PCBs are increasingly linked to obesity. However, evidence is not consistent regarding which periods of exposure are most relevant. In this study, we examine whether in utero, childhood, and adolescent exposure to PCBs are related to physical growth at adolescence. Inuit adolescents from Canada (N=212) enrolled in a prospective longitudinal cohort study since birth were assessed for height, weight, body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI) at 18 years of age. PCB 153 concentrations were quantified in blood samples obtained at birth (umbilical cord), 11, and 18 years of age. Maternal anthropometrics were measured and those for the newborns collected from medical records. Data on biological mothers and participants' sociodemographic characteristics and food security were collected using interviews. Multiple linear regression analyses were used to test associations between PCB 153 concentrations and adolescent anthropometric measures. Cord PCB 153 was not related to height or FFMI at adolescence. By contrast, analyses showed that cord PCB 153 was related to higher BMI, FMI and marginally to weight in girls but not boys. Child PCB 153 was not related to height, weight or FFMI in adolescence. Child PCB 153 was related to lower BMI and FMI at adolescence in both sexes, particularly among those considered overweight or obese during childhood. Adolescent PCB 153 was not associated with any outcome. This study suggests that prenatal exposure to PCBs may have a long-term effect on growth in early adulthood among girls and identifies the peri-pubertal period as another window of sensitivity for the action of PCBs. Our findings also suggest that exposure to PCBs and body size be documented in multiple time periods from infancy to adulthood. • Prenatal exposure to PCBs may have a long-term effect on growth among girls. • Peri-pubertal period identified as a window of sensitivity for PCBs. • Exposure to PCBs and body size be documented in multiple time periods. [ABSTRACT FROM AUTHOR]

Background: Frequency and quantity of alcohol consumed by women are two important indicators of the risks associated with drinking during pregnancy. Some studies have compared the validity of maternal alcohol report obtained during and after pregnancy. However, to date none have examined alcohol use in a Native Canadian population, such as the Inuit. Effective measurement methods are necessary to better understand why children from some communities seem at increased risk of alcohol-related neurodevelopmental disorders., Methods: Prospective and retrospective drinking interviews were obtained from a sub-sample of 67 women included in the Nunavik Child Development Study (NCDS), Nunavik, Canada (1995-2010; N=248). Number of days of alcohol consumption and binge drinking (five drinks or more per episode) across pregnancy as well as ounces of absolute alcohol per day and per drinking day among users were collected using timeline follow-back interviews administered both during pregnancy and again 11years after delivery. Consistency of alcohol reports over time, as well as significant differences for alcohol quantities described by users between interviews were examined. Sociodemographic characteristics associated with alcohol use reports were also assessed., Results: The proportion of positive reports of alcohol and binge drinking during pregnancy was higher when women were interviewed prospectively during pregnancy than retrospectively. We observed a fair to moderate agreement of alcohol report between interview periods. By contrast, the number of binge drinking days during pregnancy was slightly higher among alcohol users when documented retrospectively., Conclusions: Our findings endorse the conclusion that prospective alcohol measures provide more reliable ascertainment and likely generate more valid information about the proportion of children prenatally exposed to alcohol in the Inuit population., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Chronic exposure to methylmercury (MeHg), lead (Pb) and polychlorinated biphenyls (PCBs) has been associated with a range of attention deficits in children, but it is not known whether selective spatial attention is also altered. We modified the classic Posner paradigm, which assesses visuospatial attention, to also assess vigilance and impulsivity. This paradigm is based on the well-documented findings that a target will be detected more quickly if a visual cue indicates beforehand where it will appear, and more slowly if the cue indicates a false spatial location. In our task, visual distractors were introduced, in addition to the classic Posner trials, to assess impulsivity, and a central smiley face, whose eye-movement cued the location of the targets, to measure spatial attention. This task was administered to 27 school-age Inuit children (mean age = 11.2 years) from Nunavik (Arctic Quebec, Canada), in which pre- and postnatal exposures to environmental contaminants had been documented from birth. After controlling for the impact of confounding variables, multivariable regressions revealed that prenatal exposures to PCBs and Pb were significantly associated with greater inattention and impulsivity, respectively, while current exposure to Pb was significantly associated with longer reaction times. Although a significant correlation was observed between cord blood PCB concentration and decreased visuospatial performance, no significant association was found after adjustment for confounders. No effect was found for Hg exposures. These results suggest that our adapted Posner paradigm is sensitive in detecting a range of attention deficits in children exposed to environmental contaminants; implications for future studies are discussed., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objectives: Inuit in Canada experience alarming levels of food insecurity, but nutritional and physiological consequences are poorly documented, especially in school-age children. The objective of this study was to assess the relation of food insecurity to iron deficiency and stature in school-aged Inuit children from Nunavik (Northern Quebec)., Methods: Food insecurity, iron deficiency, and stature were assessed in a cohort of children. Food insecurity was determined by interviewing the children's mothers. Multiple logistic regression was used to evaluate the association of food insecurity to iron deficiency and short stature. We defined short stature as a height in the lowest tertile for age and sex, based on Canadian growth charts. The relation of food insecurity to height (cm) was analyzed with a general linear model. Statistical models controlled for age, sex, normal/overweight/obese status, prenatal lead exposure and postnatal polychlorinated biphenyls exposure., Results: Half of the children (49.7%, n=145) were food insecure, while one third were iron depleted, 12.6% had anaemia, and 8.7% had iron-deficiency anaemia. The multivariate odds ratio of anaemia was 1.82 (95% CI: 0.97, 3.42, p=0.06) for food-insecure children. Prevalence of short stature was 18.7%. Food-insecure children were an average of 2 cm shorter (95% CI: -0.48, -3.17) than food-secure children (p<0.01)., Conclusion: In this population, food-insecure children have greater burdens of nutritional deficiencies and slower linear growth. Considering the high prevalence of food insecurity among Inuit children in Nunavik, nutritional deficiencies and adverse effects on development should be carefully monitored.

The Inuit from Nunavik (Northern Québec) are one of the most highly exposed populations to environmental contaminants in North America mainly due to the bioaccumulation of contaminants in fish and marine mammals that constitute an important part of their diet. This follow-up study aimed to assess the impact of exposure to contaminants on visual brain development in school-age Inuit children (mean age=10.9 years). Concentrations of polychlorinated biphenyls (PCBs), mercury (Hg), and lead (Pb) were measured in umbilical cord blood and again in blood samples at the time of testing, reflecting pre- and current exposure, respectively. Pattern-reversal visual evoked potentials (VEPs) were scalp-recorded at the occipital cortex. Visual stimulation consisted of achromatic gratings presented at four visual contrast levels: 95%, 30%, 12% and 4%. The relation between environmental contaminant body burdens and VEPs was examined by regression analysis controlling for confounding variables, including fish nutrients and other toxicants. No significant association was found for PCB exposure after statistical adjustments. Cord blood mercury level was associated with a reduction of the N75 amplitude at the highest contrast level and with a delay of the N75 latency at the 12% contrast level. Prenatal exposure to lead was associated with a delay of the N150 latency at most contrast levels. This study suggests that heavy metal exposure, in particular during the gestational period, can impair the development of visual processing., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Studies conducted in the Faeroe Islands and Japan suggest a negative impact of mercury on heart rate variability (HRV) among children while the results regarding blood pressure (BP) are less consistent., Objective: To assess the impact of mercury on HRV and BP among Nunavik Inuit children., Methods: A cohort of 226 children was followed from birth to 11 years old. Mercury concentration in cord blood and in blood and hair at 11 years old were used as markers of prenatal and childhood exposure, respectively. HRV was measured using ambulatory 2 h-Holter monitoring while BP was measured through a standardized protocol. Simple regression was used to assess the relationship of mercury to BP and HRV parameters. Multiple linear regressions were performed adjusting for covariates such as age, sex, birth weight, body mass index (BMI), height, total n-3 fatty acids, polychlorinated biphenyls (PCB 153), lead, selenium and maternal smoking during pregnancy., Results: Median cord blood mercury and blood mercury levels at 11 years old were 81.5 nmoL/L (IQR:45.0–140.0) and 14.5 nmol/L (IQR: 7.5–28.0), respectively. After adjusting for the covariates, child blood mercury was associated with low frequency (LF) (b = 0.21, p = 0.05), the standard deviation of R–R intervals (SDNN) (b = 0.26, p = 0.02), the standard deviation of R–R intervals measured over 5 min periods (SDANN) (b = 0.31, p = 0.01) and the coefficient of variation of R–R intervals (CVRR) (b = 0.06,p = 0.02). No significant association was observed with BP., Conclusion: Mercury exposure during childhood seems to affect HRV among Nunavik Inuit children at school age.