The Inuit population of Nunavik (Canada) is exposed to immunotoxic organochlorines (OCs) mainly through the consumption of fish and marine mammal fat. We investigated the effect of perinatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) on the incidence of acute infections in Inuit infants. We reviewed the medical charts of a cohort of 199 Inuit infants during the first 12 months of life and evaluated the incidence rates of upper and lower respiratory tract infections (URTI and LRTIs, respectively), otitis media, and gastrointestinal (GI) infections. Maternal plasma during delivery and infant plasma at 7 months of age were sampled and assayed for PCBs and DDE. Compared to rates for infants in the first quartile of exposure to PCBs (least exposed), adjusted rate ratios for infants in higher quartiles ranged between 1.09 and 1.32 for URTIs, 0.99 and 1.39 for otitis, 1.52 and 1.89 for GI infections, and 1.16 and 1.68 for LRTIs during the first 6 months of follow-up. For all infections combined, the rate ratios ranged from 1.17 to 1.27. The effect size was similar for DDE exposure but was lower for the full 12-month follow-up. Globally, most rate ratios were > 1.0, but few were statistically significant (p
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.
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.
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.
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.
BackgroundObesity and insulin resistance are linked with mood disorders, and elevated concentrations of branched-chain (BCAAs) and aromatic amino acids (AAAs). Our study aimed to prospectively assess the relationship between childhood plasma BCAAs and AAAs, and behavioral problems in young Inuit from Nunavik.MethodsWe analyzed data on 181 children (with a mean age of 11.4 years at baseline) involved in the Nunavik Child Development Study. Plasma BCAA and AAA concentrations were measured in childhood (2005-2010). BCAA/AAA tertiles-the ratio of total BCAAs to AAAs-were considered as surrogate categorical independent variables. Behavioral problems were assessed with the Youth Self-Report (YSR) from the Child Behavior Checklist about 7 years later during adolescence (2013-2016). ANOVA ascertained relationships between BCAA/AAA tertiles and YSR outcomes.ResultsAscending BCAA/AAA tertiles were positively associated (Ptrend
Polychlorinated biphenyls (PCBs), methylmercury (MeHg), and lead (Pb) are environmental contaminants known for their adverse effects on cognitive development.
In this study we examined the effects of prenatal exposure to PCBs, MeHg, and Pb on cognitive development in a sample of Inuit infants from Arctic Qu?bec.
Mothers were recruited at local prenatal clinics. PCBs, mercury (Hg), Pb, and two seafood nutrients-docosahexaenoic acid (DHA) and selenium (Se)-were measured in umbilical cord blood. Infants (n = 94) were assessed at 6.5 and 11 months of age on the Fagan Test of Infant Intelligence (FTII), A-not-B test, and Bayley Scales of Infant Development-2nd Edition (BSID-II).
Multiple regression analyses revealed that higher prenatal PCB exposure was associated with decreased FTII novelty preference, indicating impaired visual recognition memory. Prenatal Hg was associated with poorer performance on A-not-B, which depends on working memory and is believed to be a precursor of executive function. Prenatal Pb was related to longer FTII fixation durations, indicating slower speed of information processing.
PCBs, MeHg, and Pb each showed specific and distinct patterns of adverse associations with the outcomes measured during infancy. By contrast, none of these exposures was associated with performance on the BSID-II, a global developmental measure. The more focused, narrow band measures of cognitive function that appeared to be sensitive to these exposures also provide early indications of long-term impairment in specific domains that would otherwise not likely be evident until school age.
Boucher O, Muckle G, Jacobson JL, Carter RC, Kaplan-Estrin M, Ayotte P, Dewailly ?, Jacobson SW. 2014. Domain-specific effects of prenatal exposure to PCBs, mercury, and lead on infant cognition: results from the Environmental Contaminants and Child Development Study in Nunavik. Environ Health Perspect 122:310-316; http://dx.doi.org/10.1289/ehp.1206323.
Cites: Child Dev. 1993 Feb;64(1):57-798436038
Cites: Public Health Rep. 2000 Nov-Dec;115(6):521-911354334
Prenatal exposure to an average of 0.5 oz absolute alcohol per day (the equivalent of 7 standard drinks per week) during pregnancy has been found to be associated with numerous adverse effects on pre- and postnatal development. In the animal model, concentrated alcohol exposure has been found to lead to more adverse effects than exposure to the same total quantity of alcohol ingested in smaller doses over a longer period of time. The primary aim of this study is to determine whether, in a population where binge drinking is common but total alcohol consumption across pregnancy is low, prenatal exposure to alcohol is associated with effects on prenatal growth, visual acuity and cognitive development during infancy. The second aim is to determine which of several indicators of alcohol consumption best predicts pre- and postnatal outcomes. Data were collected from 216 Inuit women and their infants living in Nunavik, the northern region of Québec. Maternal interviews were conducted during mid-pregnancy and at 1 and 6 months postpartum. Birth weight, length, and head circumference were assessed at delivery. Visual acuity and cognitive development were assessed at 6 months of age. In this population in which infrequent heavy episodic drinking is common, even occasional binge exposure was associated with reduced prenatal growth and poorer visual acuity at 6 months of age. A simple dichotomous measure of binge drinking during pregnancy provided the best predictor of fetal growth and 6-month acuity. The population studied here is unusual in terms of its pattern of binge alcohol consumption. To our knowledge, this is the first study to observe effects of binge drinking during pregnancy on infant growth and development in a sample where the average daily alcohol intake is low (
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.
Although an extensive literature has documented a broad range of cognitive performance deficits in children with prenatal alcohol exposure, little is known about how the neurophysiological processes underlying these deficits may be affected. Event-related potentials (ERPs), which reflect task-specific changes in brain electrical activity, provide a method for examining multiple constituents of cognitive processing at the neural level.
We recorded ERPs in 217 children from Inuit communities in Arctic Quebec (M age = 11.3 years) during 2 different tasks-Go/No-go response inhibition and continuous recognition memory. Children were classified as either alcohol-exposed (ALC) or controls (CON) depending on whether the mother reported binge drinking during pregnancy.
Both groups performed comparably in terms of accuracy and reaction time on the tasks, and both tasks elicited the expected effects on ERPs when responses were compared across conditions. However, the ALC group showed slower P2 latencies on Go/No-go, suggesting an altered neurophysiological response associated with initial visual processing of the stimuli. On the memory task, the ALC group showed reduced FN400 amplitude to New items, known as the familiarity effect, and reduced amplitude for the late positive component, possibly reflecting impairment in memory retrieval.
These findings show that, even in tasks in which alcohol-exposed children exhibit behavioral performance that is comparable to controls, fetal alcohol exposure is associated with altered neurophysiological processing of response inhibition and recognition memory. The data suggest that fetal alcohol exposure is associated with reduced efficiency in the initial extracting of the meaning of a stimulus, reduced allocation of attention to the task, and poorer conscious, explicit recognition memory processing.
Because of their geographical location and traditional lifestyle, Canadian Inuit children are highly exposed to polychlorinated biphenyls (PCBs) and lead (Pb), environmental contaminants that are thought to affect fetal and child growth. We examined the associations of these exposures with the fetal and postnatal growth of Inuit children.
We conducted a prospective cohort study among Inuit from Nunavik (Arctic Québec). Mothers were recruited at their first prenatal visit; children (n=290) were evaluated at birth and at 8-14 years of age. Concentrations of PCB 153 and Pb were determined in umbilical cord and child blood. Weight, height and head circumference were measured at birth and during childhood.
Cord blood PCB 153 concentrations were not associated with anthropometric measurements at birth or school age, but child blood PCB 153 concentrations were associated with reduced weight, height and head circumference during childhood. There was no association between cord Pb levels and anthropometric outcomes at birth, but cord blood Pb was related to smaller height and shows a tendency of a smaller head circumference during childhood.
Our results suggest that chronic exposure to PCBs during childhood is negatively associated with skeletal growth and weight, while prenatal Pb exposure is related to reduced growth during childhood. This study is the first to link prenatal Pb exposure to poorer growth in school-age children.
In 1999, the Government of Canada regulated the use of lead shot for hunting. Concurrently, the Nunavik Regional Board of Health and Social Services (NRBHSS) was informed of the results of an isotope study that pointed to lead ammunition as a likely source of lead exposure in Nunavik. Rapidly thereafter, a coalition for the banning of lead shot was implemented by the NRBHSS as well as by regional/local partners and by Inuit hunters in order to disseminate this information to the public.
The purpose of this article is to describe the intervention conducted in the winter of 1999 by the NRBHSS and to assess the combined impact of national legislation and an awareness campaign on blood lead levels in Nunavik.
Impact assessment of the intervention for the banning of lead shot conducted in 1999 in Nunavik using blood lead levels data before and after the intervention.
Data on blood lead levels in Nunavik describing foetal exposure as well as during childhood and in adults published between 1992 and 2009 were compiled. Blood lead levels in Nunavik prior to and after the interventions were compared. To assess the current situation, the most recent blood lead levels were compared with those from surveys conducted during the same period in North America.
Analysis of blood samples collected from umbilical cord and from adults show that blood lead levels in Nunavik significantly declined between 1992 and 2004. Nevertheless, lead exposure in Nunavik still remains higher in comparison to that observed in other North American surveys.
The current situation regarding lead exposure in Nunavik has significantly improved as a result of the implemented intervention. However, according to recent data, a gap still subsists relative to other North American populations.
The beneficial effects of prenatal and early postnatal intakes of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) on cognitive development during infancy are well recognized. However, few studies have examined the extent to which these benefits continue to be evident in childhood.
The aim of this study was to examine the relation of n-3 PUFAs and seafood-contaminant intake with memory function in school-age children from a fish-eating community.
In a prospective, longitudinal study in Arctic Quebec, we assessed Inuit children (n = 154; mean age: 11.3 y) by using a continuous visual recognition task to measure 2 event-related potential components related to recognition memory processing: the FN400 and the late positive component (LPC). Children were also examined by using 2 well-established neurobehavioral assessments of memory: the Digit span forward from Wechsler Intelligence Scales for Children, 4th edition, and the California Verbal Learning Test-Children's Version.
Repeated-measures analyses of variance revealed that children with higher cord plasma concentrations of docosahexaenoic acid (DHA), which is an important n-3 PUFA, had a shorter FN400 latency and a larger LPC amplitude; and higher plasma DHA concentrations at the time of testing were associated with increased FN400 amplitude. Cord DHA-related effects were observed regardless of seafood-contaminant amounts. Multiple regression analyses also showed positive associations between cord DHA concentrations and performance on neurobehavioral assessments of memory.
To our knowledge, this study provides the first neurophysiologic and neurobehavioral evidence of long-term beneficial effects of n-3 PUFA intake in utero on memory function in school-age children.
Cites: Toxicol Lett. 2000 Mar 15;112-113:119-2510720720