Effects of prenatal exposure to organochlorines on thyroid hormone status in newborns from two remote coastal regions in Québec, Canada.

BACKGROUND: Several prospective studies have revealed that prenatal exposure to polychlorinated biphenyls (PCBs) and other organochlorine compounds (OCs) affect neurodevelopment during infancy. One of the mechanisms by which PCBs might interfere with neurodevelopment is a deficit in thyroid hormone (TH) concentrations. OBJECTIVES: We investigated the potential impact of transplacental exposure to PCBs and hexachlorobenzene (HCB) on TH concentrations in neonates from two remote coastal populations exposed to OCs through the consumption of seafood products. METHODS: Blood samples were collected at birth from the umbilical cord of neonates from Nunavik (n=410) and the Lower North Shore of the St. Lawrence River (n=260) (Québec, Canada) for thyroid parameters [thyroid-stimulating hormone (TSH), free T4 (fT4), total T3 (tT3), and thyroxine-binding globuline (TBG)] and contaminants analyses. RESULTS: In multivariate models, umbilical cord plasma concentrations of PCB 153, the predominant PCB congener, were not associated with TH and TSH levels in both populations. Prenatal exposure to HCB was positively associated with fT4 levels at birth in both populations (Nunavik, beta=0.12, p=0.04; St. Lawrence, beta=0.19, p<0.01), whereas TBG concentrations were negatively associated with PCB 153 concentrations (beta=-0.13, p=0.05) in the St. Lawrence cohort. CONCLUSION: OCs levels were not associated to a reduction in THs in neonates from our two populations. Essential nutrients derived from seafood such as iodine may have prevented the negative effects of OCs on the thyroid economy during fetal development.

Neonatal vitamin A deficiency and its impact on acute respiratory infections among preschool Inuit children.

OBJECTIVE: To assess if vitamin A concentration in umbilical cord blood is associated with incidence and severity of respiratory infections in preschool Inuit children from Nunavik (Québec, Canada). METHOD: The medical charts of 305 children were reviewed from 0 to 5 years of age. The association between vitamin A concentration in umbilical cord plasma and the incidence rates of acute otitis media (AOM), lower respiratory tract infections (LRTIs) and hospitalization rates for LRTIs was evaluated using Poisson regression. RESULTS: Compared to children with vitamin A concentration > or =20 microg/dl, adjusted rate ratios (RR) for children below 20 microg/dl ranged between 1.06-1.62 for AOM, 1.12-1.34 for LRTIs, and 1.09-1.43 for hospitalization for LRTIs. Most RRs were statistically significant for AOM and LRTIs, but not for hospitalization for LRTIs. CONCLUSION: Neonatal vitamin A deficiency appears to be a significant risk factor for AOM and LRTIs in this population.

Portrait of outpatient visits and hospitalizations for acute infections in Nunavik preschool children.

OBJECTIVE: Inuit children from around the world are burdened by a high rate of infectious diseases. The objective of this study was to evaluate the incidence rate of infections in Inuit preschool children from Nunavik (Northern Québec). METHODS: The medical chart of 354 children from a previously recruited cohort was reviewed for the first five years of life. All outpatient visits that led to a diagnosis of acute infection and all admissions for acute infections were recorded. RESULTS: Rates of outpatient visits for acute otitis media (AOM) were 2314, 2300, and 732 events/1000 child-years for children 0-11 months, 12-23 months, and 2-4 years, respectively. Rates of outpatient visits for lower respiratory tract infections (LRTI) were 1385, 930, and 328 events/1000 child-years, respectively. Rates of hospitalization for pneumonia were 198, 119, and 31 events/1000 child-years, respectively. CONCLUSION: Inuit children from Nunavik have high rates of AOM and LRTI. Such rates were higher than that of other non-native North-American populations previously published. Admission for LRTI is up to 10 times more frequent in Nunavik compared to other Canadian populations.

Effect of prenatal exposure to polychlorinated biphenyls on incidence of acute respiratory infections in preschool Inuit children.

OBJECTIVE: We set out to assess whether environmental prenatal exposure to polychlorinated biphenyls (PCBs) is associated with incidence of acute respiratory infections in preschool Inuit children. STUDY DESIGN: We reviewed the medical charts of 343 children from 0 to 5 years of age and evaluated the associations between PCB-153 concentration in umbilical cord plasma and the incidence rates of acute otitis media (AOM) and of upper and lower respiratory tract infections (URTIs and LRTIs, respectively). RESULTS: The incidence rates of AOM and LRTIs were positively associated with prenatal exposure to PCBs. Compared with children in the first quartile of exposure (least exposed), children in fourth quartile (most exposed) had rate ratios of 1.25 (p<0.001) and 1.40 (p<0.001) for AOM and LRTIs, respectively. There was no association between prenatal PCB exposure and incidence rate of URTIs or hospitalization. CONCLUSION: Prenatal exposure to PCBs could be responsible for a significant portion of respiratory infections in children of this population.

Gestational age and birth weight in relation to n-3 fatty acids among Inuit (Canada).

Seafood consumption during pregnancy carries both benefits (high n-3 FA intake) and risks (exposure to environmental contaminants) for the developing fetus. We determined the impacts of marine n-3 FA and environmental contaminants on gestational age (GA) of Nunavik women and the anthropometric characteristics of their newborns. FA and contaminant (polychlorinated biphenyls and mercury) concentrations were measured in cord plasma of Nunavik newborns (n = 454) and compared with those of a group of newborns (n = 29) from southern Québec. Data were collected from hospital records and birth certificates. In Nunavik newborns, arachidonic acid (AA) was two times lower (P < 0.0001), whereas DHA concentration, the sigman-3 / sigman-6 ratio, and the percentage of n-3 highly unsaturated FA (HUFA) (of the total HUFA) were three times higher (P < 0.0001) compared with southern Québec newborns. After controlling for confounders, GA and birth weight were higher by 5.4 d [95% confidence interval (CI): 0.7-10.1] and 77 g (95% CI: -64 to 217) in the third tertile of percentage of n-3 HUFA (of the total HUFA) as compared with the first tertile. There was no evidence that contaminants had negative effects on GA or birth weight. In this seafood-eating population, an increase in the proportion of n-3 HUFA (of the total HUFA), measured in umbilical cord plasma phospholipids, was associated with a significantly longer GA.

Otitis media and hearing loss among 12-16-year-old Inuit of Inukjuak, Quebec, Canada.

OBJECTIVES: Chronic otitis media (COM) and associated hearing loss is a frequent problem for many Inuit children in Canada. In this study, we evaluated individuals aged 12-16 years living in Inukjuak, to determine the prevalence of middle ear disease and hearing loss, and the effect of hearing loss on academic performance. METHODS: Otological examination, hearing test, medical and school file review were performed in November 1997. 88 individuals were seen. RESULTS: Otological examination revealed maximal scarring in 1.8%, minimal scarring in 34.9%, normal eardrums in 49.1% and chronic otitis media in 16.9%. There were 62 individuals whose ear exams could be directly compared with a previous exam done in 1987. Of those, there were three ears that had developed COM and 4/13 ears with COM in 1987 that had healed. Hearing tests found bilateral normal hearing in 80% (PTA <20dB), unilateral loss in 15% and bilateral loss in 5%. Hearing loss was associated with poorer academic performance in Language (p<.05). A similar trend was found in Mathematics but not in Inuttitut. CONCLUSION: Chronic otitis media remains a significant problem among the Inuit, with a prevalence of 16.9% in individuals aged 12-16 years. One in five in this age group has hearing loss, and this hearing loss impacts on academic performance.

Vitamin A concentration in umbilical cord blood of infants from three separate regions of the province of Québec (Canada).

BACKGROUND: Inuit women from Northern Québec have been shown to consume inadequate quantities of vitamin A. This study was conducted to evaluate the prevalence of blood vitamin A deficiency in newborns from 3 distinct populations of the province of Québec. METHODS: 594 newborns were included in this study (375 Inuit newborns from northern Québec (Nunavik), 107 Caucasian and Native newborns from the Lower Northern Shore of the Saint-Lawrence River (LNS) and 112 newborns from Southern Québec where clinical vitamin A deficiency is uncommon). Mothers were recruited at delivery and vitamin A (retinol) was analyzed from umbilical cord blood samples by reversed-phase high-pressure liquid chromatography. RESULTS: Nunavik and LNS newborns had significantly lower mean vitamin A concentrations in cord blood compared to Southern Québec participants (15.7 microg/dL, 16.8 microg/dL and 20.4 microg/dL respectively). The differences observed were similar when adjusted for sex and birthweight. Results also showed that 8.5% of Nunavik newborns and 12.2% of LNS newborns were below 10.0 microg/dL, a level thought to be indicative of blood vitamin A deficiency in neonates. CONCLUSION: These data suggest that a carefully planned vitamin A supplementation program during pregnancy in Nunavik and LNS might be indicated to promote healthy infant development.

Contribution of Selected Traditional and Market Foods to the Diet of Nunavik Inuit Women.

Food composition data were determined for food consumed by 226 Inuit women in Nunavik, estimating the relative contribution of traditional and market food for energy, protein, lipid, carbohydrate, vitamin A, vitamin D, iron, calcium, magnesium, phosphorus, selenium, zinc, and eicosapentaenoic and docosahexaenoic acids. Traditional Inuit food was an important source of protein, vitamin D, iron, selenium, and phosphorus, as well as the main source of eicosapentaenoic and docosahexaenoic acids. The mean contribution of traditional and market food to energy and nutrients was analyzed according to age groups (18-39 and 40-74). Analysis of Inuit women's nutrient intake showed that the contribution of traditional food was greater in the older group than in the younger group, for whom the contribution of market food was greater. Market food contributed the most to Inuit women's energy intake, while 40% of the intake of several nutrients, including protein, vitamin D, iron, phosphorus, and zinc, was derived from traditional food. Inuit women had low vitamin A and calcium intakes. Traditional food had low calcium and vitamin A concentrations, and the Inuit infrequently consumed market food such as milk, dairy products, and yellow and green vegetables. Thus, even though the present study showed that traditional food was the major source of many nutrients in the Inuit diet, market food was also important for the nutritional status of this population, particularly young women. In promoting safe nutritional habits among the Inuit, dietitians must help them maintain traditional food use, which has provided some health advantages (e.g., a lower incidence of cardiovascular disease); encourage consumption of nutritious market foods; and consider the societal values reflected in the traditional diet.