Suzanne Bruneau

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.

Exposure of the Inuit Population of Nunavik (Arctic Quebec) to Lead and Mercury

Abstract The authors conducted a survey during 1992 to evaluate blood levels of lead and mercury in Inuit adults of Nunavik (Arctic Québec, Canada). Blood samples obtained from 492 participants (209 males and 283 females; mean age = 35 yr) were analyzed for lead and total mercury; mean (geometric) concentrations were 0.42 μmol/l (range = 0.04–2.28 μmol/l) and 79.6 nmol/l (range = 4–560 nmol/l), respectively. Concentrations of omega-3 fatty acid in plasma phospholipids–a biomarker of marine food consumption–were correlated with mercury (r = .56, p < .001) and, to a lesser extent, with blood lead levels (r = .31, p < .001). Analyses of variance further revealed that smoking, age, and consumption of waterfowl were associated with lead concentrations (r 2 = .30, p < .001), whereas age and consumption of seal and beluga whale were related to total mercury levels (r 2 = .30, p < .001). A significant proportion of reproductive-age women had lead and mercury concentrations that exceeded those that have been reportedly associated with subtle neurodevelopmental deficits in other populations.

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 Nuvavik 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 Σn−3/Σn−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.

Arctic air pollution and human health: what effects should be expected?

Persistent contaminants such as heavy metals and organochlorine compounds are transported from distant sources to the Arctic by oceanic and atmospheric currents. Natives inhabiting the Arctic can be exposed, because they exist at the highest trophic level of the arctic aquatic food chain, along which biomagnification of contaminants occurs. We reviewed the data available on heavy metal and organochlorine body burden in natives from different regions of Nunavik (northern Québec) and assessed the potential risk of health effects. In addition, we investigated the relationship between each contaminant plasma level and omega-3 fatty acid content of plasma phospholipid, a surrogate measure for aquatic food consumption. Cadmium exposure appears to be unrelated to the consumption of species from the aquatic food chain (r = 0.0004; P = 0.99), whereas PCBs and mercury were (r = 0.49 and 0.52, respectively; P < or = 0.0001). Mean blood mercury levels measured in northern Québec natives were below those associated with significant neurological disorders. Typical daily intakes of dioxin-like compounds, PCBs, DDE, and dieldrin were estimated from the mean concentration in milk fat and pharmacokinetic models. The calculated PCB intake (0.3 microgram/kg/day) exceeds the acceptable daily intake, with effects on reproduction and development being the most relevant to assess in future epidemiological studies.

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.

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 4/13ears 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.