Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA.
Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA; Department of Epidemiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.
Environ Int. 2021 Jan;146:106201. doi: 10.1016/j.envint.2020.106201. Epub 2020 Oct 28.
Elevated blood pressure in childhood is an important risk factor for hypertension in adulthood. Environmental exposures have been associated with elevated blood pressure over the life course and exposure to mercury (Hg) has been linked to cardiovascular effects in adults. As subclinical vascular changes begin early in life, Hg may play a role in altered blood pressure in children. However, the evidence linking early life Hg exposure to altered blood pressure in childhood has been largely inconsistent. In the ongoing New Hampshire Birth Cohort Study, we investigated prenatal and childhood Hg exposure at multiple time points and associations with blood pressure measurements in 395 young children (mean age 5.5 years, SD 0.4). Hg exposure was measured in children's toenail clippings at age 3 and in urine at age 5-6 years, as well as in maternal toenail samples collected at ∼28 weeks gestation and 6 weeks postpartum, the latter two samples reflecting early prenatal and mid-gestation exposures, respectively. Five measurements of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were averaged for each child using a standardized technique. In covariate-adjusted linear regression analyses, we observed that a 0.1 μg/g increase in child toenail Hg at age 3 or a 0.1 μg/L urine Hg at age 5-6 were individually associated with greater DBP (toenail β: 0.53 mmHg; 95% CI: -0.02, 1.07; urine β: 0.48 mmHg; 95% CI: 0.10, 0.86) and MAP (toenail β: 0.67 mmHg; 95% CI: 0.002, 1.33; urine β: 0.55 mmHg; 95% CI: 0.10, 1.01). Neither early prenatal nor mid-gestation Hg exposure, as measured by maternal toenails, were related to any changes to child BP. Simultaneous inclusion of both child urine Hg and child toenail Hg in models suggested a potentially stronger relationship of urine Hg at age 5-6 with DBP and MAP, as compared to toenail Hg at age 3. Our findings suggest that Hg exposure during childhood is associated with alterations in BP. Childhood may be an important window of opportunity to reduce the impacts of Hg exposure on children's blood pressure, and in turn, long-term health.
儿童期血压升高是成年期高血压的一个重要危险因素。环境暴露与整个生命过程中的血压升高有关，而汞（Hg）暴露与成年人的心血管效应有关。由于亚临床血管变化在生命早期开始，Hg 可能在儿童血压改变中发挥作用。然而，将早期生活中的 Hg 暴露与儿童期血压改变联系起来的证据在很大程度上并不一致。在正在进行的新罕布什尔州出生队列研究中，我们在 395 名幼儿（平均年龄 5.5 岁，标准差 0.4）中调查了多个时间点的产前和儿童期 Hg 暴露情况，并将其与血压测量值相关联。在儿童 3 岁时，通过脚趾甲样本测量 Hg 暴露量，在 5-6 岁时，通过尿液样本测量 Hg 暴露量，还通过母亲在大约 28 周妊娠和 6 周产后时的脚趾甲样本测量 Hg 暴露量，后两者样本分别反映了早期产前和中期妊娠的暴露情况。通过标准化技术，为每个儿童平均了五次收缩压（SBP）、舒张压（DBP）和平均动脉压（MAP）的测量值。在调整协变量的线性回归分析中，我们观察到，儿童 3 岁时脚趾甲 Hg 增加 0.1μg/g 或 5-6 岁时尿液 Hg 增加 0.1μg/L，与 DBP（脚趾甲β：0.53mmHg；95%CI：-0.02，1.07；尿液β：0.48mmHg；95%CI：0.10，0.86）和 MAP（脚趾甲β：0.67mmHg；95%CI：0.002，1.33；尿液β：0.55mmHg；95%CI：0.10，1.01）的增加相关。通过母亲脚趾甲测量的早期产前和中期妊娠 Hg 暴露均与儿童 BP 的任何变化无关。在模型中同时纳入儿童尿液 Hg 和儿童脚趾甲 Hg 表明，与 3 岁时的脚趾甲 Hg 相比，5-6 岁时尿液 Hg 与 DBP 和 MAP 之间的关系可能更强。我们的研究结果表明，儿童期的 Hg 暴露与 BP 改变有关。儿童期可能是减少 Hg 暴露对儿童血压影响并进而影响长期健康的重要机会窗口。
