Dallaire Renée, Dewailly Eric, Ayotte Pierre, Muckle Gina, Laliberté Claire, Bruneau Suzanne
Public Health Research Unit, Laval University Medical Research Centre-Centre Hospitalier, Universitaire de Québec, Québec City, Québec, Canada.
Environ Res. 2008 Nov;108(3):387-92. doi: 10.1016/j.envres.2008.08.004. Epub 2008 Sep 23.
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.
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.
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.
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.
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.
多项前瞻性研究表明，孕期接触多氯联苯（PCBs）和其他有机氯化合物（OCs）会影响婴儿期的神经发育。PCBs可能干扰神经发育的机制之一是甲状腺激素（TH）浓度不足。
我们调查了经胎盘接触PCBs和六氯苯（HCB）对来自两个偏远沿海人群的新生儿TH浓度的潜在影响，这两个人群通过食用海产品接触OCs。
从努纳维克（n = 410）和圣劳伦斯河下游北岸（n = 260）（加拿大魁北克）的新生儿脐带采集出生时的血样，用于甲状腺参数[促甲状腺激素（TSH）、游离T4（fT4）、总T3（tT3）和甲状腺素结合球蛋白（TBG）]及污染物分析。
在多变量模型中，主要的PCB同系物PCB 153的脐带血血浆浓度与两个人群的TH和TSH水平均无关联。孕期接触HCB与两个人群出生时的fT4水平呈正相关（努纳维克，β = 0.12，p = 0.04；圣劳伦斯，β = 0.19，p < 0.01），而在圣劳伦斯队列中，TBG浓度与PCB 153浓度呈负相关（β = -0.13，p = 0.05）。
OCs水平与我们两个人群新生儿的TH降低无关。海产品中的碘等必需营养素可能预防了OCs在胎儿发育期间对甲状腺系统的负面影响。
