Infections et exposition aux organo-chlorés chez les enfants du Nunavik

Authors: Dallaire, Frédéric
Advisor: Dewailly, ÉricDe Serres, Gaston
Abstract: Inuit children from Nunavik are prenatally exposed to immunotoxic organochlorine substances (OCs) and display plasma concentrations several times higher than their counterparts from Southern Québec. This exposure tends to decrease over time but remains significantly high and could potentially alter certain immune functions. We calculated that the plasma concentration of polychlorinated biphenyls (PCB) decreased by almost 8% annually between 1994 and 2001 in Nunavik newborns. Several substances can modulate immune system functions and a wide variety of methods are available to evaluate their effects. Among them, variation in the incidence of acute respiratory infections in a given exposed population is a valid and clinically significant endpoint. To estimate the impact of exposure to OCs on the incidence of respiratory infections, we reviewed the medical charts of two cohorts of Nunavik children (n = 199 and n = 354). The calculated incidence of respiratory infections from the medical chart review during the first 5 years of life underlined a higher frequency of acute otitis media (AOM), of lower respiratory tract infections (LRTIs), and of admissions for respiratory infections, compared to most non- Inuit North-American populations. In order to determine the effect of prenatal exposure to OCs on the incidence of respiratory infections, we calculated the statistic association between plasma concentration of PCB congener 153 in umbilical cord blood or maternal blood at delivery and the incidence of diagnosed respiratory infections using Poisson regression. Results from the first cohort of children followed from 0 to 12 month of age showed a positive association between exposure to OCs and respiratory infections. However, the association was present only for children under 6 months of age and the statistical power was insufficient to reach statistical significance. Nevertheless, results from the second cohort showed a positive, statistically significant association between prenatal exposure to OCs and incidence of AOM and LRTIs. A dose-response relationship was present for AOM. Globally, these results support the hypothesis of a significant portion of respiratory infections in preschool children from Nunavik being due to prenatal exposure to OCs.
Document Type: Thèse de doctorat
Issue Date: 2006
Open Access Date: 12 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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