Impact of El Nino on Environmental Mercury and Human Exposure

 描述(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。历史上，科学家们一直专注于研究厄尔尼诺现象对沿海地区的影响，因为相对干旱的地区经历了大规模的洪水。除了病媒传播的疾病风险之外，研究在很大程度上忽视了亚马逊地区的厄尔尼诺现象及其对人类健康的影响。秘鲁亚马逊的Madre de Dios(MDD)地区预计将面临一个具有挑战性的厄尔尼诺现象季节，超过90%的人口将经历过度干旱和洪水。在这些环境变化的同时，还有一个持续不断的社会挑战：由于修建了大洋公路，手工小规模金矿开采迅速扩大。ASGM直接将无机汞(Hg)释放到邻近的土壤和河流沉积物中，在那里厌氧细菌将汞生物甲基化，形成有效的神经毒物甲基汞(MeHg)，在水生食物网中生物放大。通过食用受污染的鱼，ASGM附近和远离下游的社区暴露在高水平的甲基汞中。我们的主要假设是，厄尔尼诺现象与人类暴露在甲基汞中的增加有关，这是由于水生生态系统中汞生物甲基化速度的增加和鱼类消费的增加。我们假设：(1)厄尔尼诺现象将扰乱农业生产，导致更多人依赖鱼类蛋白质；(2)厄尔尼诺现象引发的洪灾导致沉积物中细菌活性增加，从而导致汞更迅速地被释放到环境中；(3)洪水泛滥的河里和市场上出售的鱼类将含有更高水平的甲基汞；(4)成人、儿童和发育中胎儿对环境汞的暴露将随着膳食暴露的增加和营养的脆弱性而增加。我们将开发一个人类体内甲基汞剂量的预测模型，以解释与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在亚马逊地区的影响方面具有得天独厚的优势，我们利用MDD正在进行的研究，利用之前收集的关于环境和人类生物样本中汞水平的数据。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。为了验证我们的假设，我们将收集额外的基本数据，方法是在厄尔尼诺现象期间和之后我们的团队先前抽样的地区和人群中测试鱼类、沉积物和人类生物样本中的汞和其他金属，在哨兵家庭(先前抽样)中进行每月食物频率调查，并启动出生队列(每月登记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暴露增加有关，确定暴露来源，并确定与亚马逊地区居民可观察到的健康影响相关的暴露阈值。由于厄尔尼诺现象经常发生，预计今后还会加剧，因此该项目在为未来备灾提供信息和保护脆弱区域人口的福祉方面具有很大潜力。

 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.