Study on Mercury Pollution in The Amazonia, Brazil

1992年至1998年期间，作为与帕拉联邦大学热带医学中心的一个联合项目，在亚马逊河流域开展了汞污染对人类健康的不利影响研究。测定人发汞含量，评估人体健康风险，同时临床诊断甲基汞中毒症状。调查的主要区域是亚马逊河支流Tapajos河中游的三个渔村。对其他一些渔村、金矿矿区和城市进行了调查比较。通过对主调查区居民抽取的454份样本进行浓度分析和统计分析，估计发生感觉异常的概率约为4%。对57名年龄在20 ~ 30岁之间的妇女进行了调查，结果估计新生儿存在一定的行走迟缓现象。在此基础上，我们主要对头发汞含量超过2Oppm的居民和孕妇进行了更多的随访调查和医生的诊断。结果，我们发现3个人有慢性甲基汞中毒症状，5个人可能有同样的症状。由于居民头发中90%的汞是甲基汞，因此人们认为接触甲基汞是由于吃鱼。因此，对Tapajos河12种鱼类的20个样本进行了分析，发现3种大型食肉鱼的汞含量超过0.4ppm，这是日本咸水鱼类食用鱼类的健康标准，1种鱼的汞含量超过1ppm，这是淡水鱼食用鱼类的健康标准。小型食草鱼类的汞含量很低。由于发现了不同鱼类的汞含量差异，因此可以通过指导汞含量高的居民和孕妇食用哪种鱼类来降低风险。在3个采样点对渔村附近的河流沉积物进行了分析。加上去年6个点的样本，只有1个样本超过0。9个样品中汞的百万分之一汞含量。与日本和加拿大的汞污染相比，这是非常低的，这表明亚马逊河流域的自然特征。少

The adverse effect of mercury pollution on human health in the Amazon was carried out between 1992 and 1998 as a joint project with Nucleo de Medicina Tropical, Universidade Federal do Para. The mercury level of human hair was measured to estimate the risks of human health and the symptom of methylmercury poisoning was clinically diagnosed at same time. The main area for the investigation were the three fishing villages by the middle reaches of Tapajos river of a tributary in the Amazon. Some other fishing villages, the gold mining sites and cities were investigated for the comparison. From the concentration analysis and statistical analysis of 454 samples taken from residents in the main investigation area, the probability of the occurrences of paresthesia was estimated to be about 4%. It was estimated that there could be some occurrences of retarded walking for newborns from the result of the investigation of 57 women between 20 and 30 years old.Based on this result, we have done a f … More ollow up survey with the medical doctor's diagnosis mainly on the residents with over 2Oppm of mercury level in hair and the pregnant women. As a result, we have found 3 individuals with chronic methylmercury poisoning symptoms and 5 individuals who might have the same symptoms.Since 90% of the mercury in the residents' hair was methyl mercury, exposure is thought to be from eating fish. Hence, 20 samples of 12 kinds of fish in Tapajos river were analyzed, and 3 large carnivorous fish with over 0.4ppm mercury level, which is the health-standard for edible fish for saltwater fish in Japan and 1 kind of fish with over 1ppm mercury level, which is the health-standard for edible fish for freshwater fish was found. Small herbivore fish's mercury levels are low. Since the differences in the mercury level among fish kind were found out, the reduction or risks are possible by instructing the residents with high level of mercury and the pregnant women on which kind of fish to eat.Sediment of the river by the fishing villages was sampled at 3 points and was analyzed. Adding the samples of 6 points from last year, there were only 1 sample with over 0.lppm of mercury in 9 samples. This is very low comparing to the cases of mercury pollution in Japan and Canada, and shows the special characteristics of the nature in the Amazon. Less