Exploratory Use of Stable Mercury Isotopes to Distinguish Dietary Sources of Methylmercury and Their Relation to Neurodevelopment

项目摘要 对于大多数人来说，食用鱼类被认为是甲基汞的主要饮食来源，一种 强效神经毒素。鱼组织也是有益营养的丰富来源。大米是超过20亿美元的主食 30亿人。在大米是主食的地方，它也可以是甲基汞的重要饮食来源， 没有和鱼一样有益的营养物质。有证据表明，饮食可以改变甲基汞的毒性。 (大米对鱼)。由于饮食是接触甲基汞的主要途径，因此头发和皮肤中汞的分析 血液反映了饮食中的甲基汞暴露，然而，这些生物标志物并不区分 甲基汞来源。通常使用自我报告的食物频率来估计大米和鱼的消费量 问卷调查；然而，由于记忆偏差，食物频率往往不准确。要刻画 甲基汞与神经发育的关系(独立于营养的修饰)，它是 对确定甲基汞的饮食来源至关重要，测量误差较小。稳定汞 同位素已被用来追踪食物网中的饮食甲基汞来源，并可用于区分 在人类人口中，大米和鱼的甲基汞摄入量之间的差异。简而言之，水星由七种物质组成 同位素；所有七种同位素都受到质量相关分馏(MDF)的影响，而与质量无关 分馏(MIF)主要发生在两个奇同位素上。与MDF不同，MIF在营养过程中是保守的 转移和新陈代谢。我们测量了21个母亲头发样本中的稳定汞同位素 我们出生在中国农村，大多数母亲每天吃大米，超过40%的母亲 很少或从来不吃鱼。我们的发现表明，人类头发中的MIF可以用来区分 我们队列中从大米和鱼类中摄取的甲基汞。因此，头发MIF是一种很有前途的新型生物标志物 应该得到进一步的验证。我们建议对储存的晚期孕妇头发中的汞同位素进行分析。 这些参与者的样本，他们的孩子完成了为期12个月的神经发育评估 (n=264个头发样本)。我们提出以下目标：目标1.确定核素的同位素组成 在农村中国的孕妇中，母亲头发中的汞因饮食而异，在控制了 潜在的混杂因素(例如，产妇教育等)。目的2.在研究产前甲基汞的模型中 我们将探讨甲基汞暴露的来源是否与儿童的神经发育有关， 由母亲头发中的MIF确定，修正其对儿童神经发育结果的影响。在……里面 总结，使用头发MIF将通过解释修饰来提高我们对甲基汞毒性的理解 饮食影响的敏感性和精确度比以前更高。

Project Summary For most populations, fish consumption is considered the main dietary source for methylmercury, a potent neurotoxin. Fish tissue is also a rich source for beneficial nutrients. Rice is a staple food for more than three billion people. Where rice is a dietary staple, it can also be an important dietary source of methylmercury, without the same beneficial nutrients as fish. There is evidence that methylmercury toxicity is modified by diet (rice versus fish). As diet is the primary pathway for methylmercury exposure, analyses of mercury in hair and blood reflect dietary methylmercury exposure, however, these biomarkers do not differentiate between methylmercury sources. Rice and fish consumption are usually estimated using self-reported food frequency questionnaires; however food frequencies are often inaccurate due to recall bias. To characterize the relationship between methylmercury and neurodevelopment (independent of modification by nutrition), it is critical to characterize the dietary source of methylmercury, with less measurement error. Stable mercury isotopes have been used to track dietary methylmercury sources in food webs, and may be used to distinguish between rice and fish methylmercury intake in human populations. Briefly, mercury is comprised of seven isotopes; all seven isotopes are subject to mass dependent fractionation (MDF), while mass independent fractionation (MIF) occurs mainly for the two odd-isotopes. Unlike MDF, MIF is conserved during trophic transfer and metabolism. We measured stable mercury isotopes in a subset of 21 maternal hair samples from our birth cohort in rural China, where most mothers ingested rice daily, and more than 40% of the mothers rarely or never ingested fish. Our findings indicated that MIF in human hair can be used to distinguish methylmercury intake from rice versus fish in our cohort. Thus hair MIF is a promising novel biomarker, which should be further validated. We propose to analyze mercury isotopes in banked third trimester maternal hair samples for those participants, whose offspring completed the 12-month neurodevelopmental assessment (n=264 hair samples). We propose the following aims: Aim 1. Determine how the isotopic composition of mercury in maternal hair varies depending on diet, among pregnant mothers in rural China, after controlling for potential confounders (e.g., maternal education, etc.). Aim 2. In models investigating prenatal methylmercury exposure and children's neurodevelopment, we will explore whether the source of methylmercury exposure, determined from maternal hair MIF, modifies its effect on children's neurodevelopmental outcomes. In summary, use of hair MIF will improve our understanding of methylmercury toxicity by accounting for modifying effects of diet with better sensitivity and precision than has been possible previously.