BACKGROUND Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined. METHODS Participants (mean corrected age = 6.6 months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n = 429) and the visual evoked potentials in a sub-group (n = 63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses. RESULTS We observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values < 0.1) between cord blood lead and mercury and electrophysiological visual acuity, whereas PCB and PBDE showed no association. When adding breastmilk selenium concentration to the mercury models, this association became statistically significant for cord concentrations (β = - 3.41, 95% CI = - 5.96,-0.86), but also for blood levels at 1st and 3rd trimesters of pregnancy (β = - 3.29, 95% CI = - 5.69,-0.88). However, further regression models suggested that this change in estimates might not be due to adjustment for selenium, but instead to a change in the study sample. CONCLUSIONS Our results suggest that subtle, but detectable alterations of infant electrophysiological visual acuity can be identified in a population prenatally exposed to low mercury concentrations. Compared to behavioural visual acuity testing, electrophysiological assessment may more sensitive in detecting visual neurotoxicity in relation with prenatal exposure to mercury.

中文翻译：

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产前暴露于加拿大婴儿中的遗留污染物和视力：母婴环境化学研究（MIREC-ID）。

背景技术产前暴露于环境污染物可能会对儿童发育产生有害影响。虽然已经研究了与慢性暴露有关的心理运动，认知和行为结局，但与视觉功能的关联仍不清楚。本研究的目的是评估加拿大婴儿出生前暴露于传统持久性有机污染物和重金属的视力与视力的关系。还检查了硒对汞毒性的潜在保护作用。方法参与者（平均年龄校正为6.6个月）是“环境化学母婴研究”（MIREC）研究的一部分。在怀孕期间，对母体血液中的多氯联苯（PCB），多溴联苯醚（PBDEs），铅和汞的浓度进行了测量，以及脐带血。柜员视力卡测试（TAC）（n = 429）和亚组的视觉诱发电位（n = 63）分别用于评估行为和电生理视敏度。使用多变量线性回归模型研究每种污染物的暴露量与视敏度之间的关系，同时控制潜在的混杂因素。在水银模型中，作为探索性分析，还考虑了母乳硒（可用于TAC和VEP样品的大约一半）。结果我们观察到暴露于任何污染物和TAC之间没有显着关联。分析显示脐带血铅和汞与电生理视力之间呈负趋势（p值<0.1），而PCB和PBDE则无关联。当将母乳硒浓度添加到汞模型中时，这种关联性对于脐带浓度（β=-3.41，95％CI =-5.96，-0.86），而且对于妊娠的第一个和第三个妊娠期的血液水平也具有统计学意义（β= -3.29，95％CI =-5.69，-0.88）。但是，进一步的回归模型表明，估计值的这种变化可能不是由于硒的调整，而是由于研究样本的变化。结论我们的结果表明，在出生前暴露于低汞浓度的人群中，可以发现婴儿电生理视敏度的细微但可检测的变化。与行为视敏度测试相比，电生理评估在检测与产前汞暴露相关的视觉神经毒性方面可能更为敏感。