Impact of El Nino on Environmental Mercury and Human Exposure

 描述（由申请人提供）：从2015年11月开始，秘鲁将经历有记录以来最大的厄尔尼诺气候事件之一。科学家们历来专注于研究厄尔尼诺对沿海地区的影响，因为相对干燥的地区经历了大规模的洪水。研究在很大程度上忽视了厄尔尼诺现象在亚马逊地区的影响及其对人类健康的后果，而不仅仅是病媒传播的疾病风险。秘鲁亚马逊的马德雷德迪奥斯（MDD）地区预计将面临一个具有挑战性的厄尔尼诺季节，超过90%的人口将经历过度干旱和洪水。这些环境变化伴随着一个持续的社会挑战：手工小规模采金业（ASGM）由于跨洋公路的建设而迅速扩大。手工和小规模采金业将无机汞直接释放到附近的土壤和河流沉积物中，厌氧细菌将汞进行生物甲基化，形成在水生食物网中具有生物放大作用的强效神经毒物甲基汞。小规模手工开采金矿附近和下游的社区因食用受污染的鱼类而暴露于高浓度的甲基汞。我们的主要假设是，厄尔尼诺现象与人类甲基汞暴露增加有关，这是由于水生生态系统中汞生物甲基化率升高和鱼类消费增加。我们假设：（1）厄尔尼诺现象将破坏农业生产，导致人们更加依赖鱼蛋白;（2）由于厄尔尼诺现象引发的洪水导致沉积物中细菌活动增加，小规模手工开采金矿业释放到环境中的汞将更快地发生生物甲基化;（3）小规模手工开采金矿业下游被洪水淹没的河流中的鱼类以及市场上出售的鱼类将含有更高水平的甲基汞;（4）成人、儿童和发育中的胎儿的环境汞暴露将随着膳食暴露和营养脆弱性的增加而增加。我们将开发一个人体内甲基汞剂量的预测模型，以解释厄尔尼诺相关的环境变化。我们的团队在评估厄尔尼诺现象对亚马逊地区的影响方面具有独特的优势，他们利用MDD正在进行的研究，以及先前收集的环境和人类生物样本中汞含量的数据。此外，我们利用与社区领袖和卫生部的长期合作伙伴关系，协助实现我们的目标。为了检验我们的假设，我们将在厄尔尼诺期间和之后，在我们的团队先前采样的地区和人群中，通过测试鱼类、沉积物和人类生物样本中的汞和其他金属来收集更多的原始数据，在哨点家庭（先前采样）中进行每月食物频率调查，并启动出生队列（每月招募10名儿童）。这项拟议研究的结果将有助于确定厄尔尼诺洪水是否与甲基汞接触增加有关，确定接触源，并确定与生活在亚马逊地区的人的可观察到的健康影响有关的接触阈值。由于厄尔尼诺现象经常发生，而且预计今后还会加剧，该项目具有很大的潜力，可以为今后的备灾工作提供信息，并保护该区域脆弱人口的福祉。

 DESCRIPTION (provided by applicant): Beginning in November 2015, Peru will experience one of the largest El Niño climate events on record. Scientists have historically focused on studying impacts from El Niño in coastal areas due to relatively dry regions experiencing large-scale flooding. Research has largely overlooked the effects of El Niño in the Amazon and its consequences for human health beyond vector-borne disease risk. The Madre de Dios (MDD) region of the Peruvian Amazon is expected to face a challenging El Niño season with over 90% of the population experiencing both excessive drought and flooding. These environmental changes are coupled with an ongoing social challenge: artisanal small-scale gold mining (ASGM) that has rapidly expanded due to construction of the Interoceanic Highway. ASGM releases inorganic mercury (Hg) directly into proximate soil and river sediment, where anaerobic bacteria bio-methylate Hg to form the potent neurotoxicant methylmercury (MeHg) that biomagnifies in the aquatic food web. Communities near and far downstream from ASGM are exposed to high levels of MeHg via consumption of contaminated fish. Our primary hypothesis is that El Niño is associated with increased human MeHg exposure due to elevated rates of Hg bio-methylation in aquatic ecosystems and increased fish consumption. We hypothesize that: (1) El Niño will disrupt agricultural production, leading to increased reliance on fish protein; () Hg released into the environment by ASGM will undergo more rapid bio-methylation due to higher bacterial activity in sediment caused by El Niño- related flooding; (3) fish in flooded rivrs downstream from ASGM and sold in markets will contain higher levels of MeHg; and (4) environmental Hg exposures in adults, children, and developing fetuses will increase with higher dietary exposure and nutritional vulnerability. We will develop a predictive model for human internal MeHg dose that accounts for El Niño-related environmental changes. Our team is uniquely positioned to evaluate the impact of El Niño in the Amazon by leveraging ongoing research in MDD with prior data collected on Hg levels in environmental and human biological samples. In addition, we leverage our long-term collaborative partnerships with community leaders and the Ministry of Health to assist in implementation of our aims. To test our hypotheses, we will collect additional primary data by testing fish, sediment and human biological samples for Hg and other metals in areas and people previously sampled by our team during and following El Niño, conduct monthly food frequency surveys in sentinel households (previously sampled), and initiate a birth cohort (enrolling 10 children per month). Results from this proposed study will help establish whether El Niño flooding is associated with increased MeHg exposure, identify sources of exposures, and determine exposure thresholds associated with observable health effects among persons living in the Amazon. As El Niño events occur regularly and are projected to intensify in the future, this project has significant potential to inform future disaster preparedness and to protect the wellbeing of vulnerable regional populations.