Tests detect mercury in Yanomami indigenous hair samples

Research conducted by the Oswaldo Cruz Foundation (Fiocruz) indicates that mercury contamination is widespread among nearly all residents of nine Yanomami indigenous villages in the state of Roraima. The findings, released on Thursday (Apr. 4), were derived from the examination of hair samples collected in October 2022. According to the researchers, the study reveals a concerning scenario and enhances our understanding of the repercussions of illegal gold mining in the area.

“There are metals such as zinc, iron, and selenium that are important for the body as they are involved in human metabolism. For example, iron is crucial for the formation of hemoglobin. However, mercury plays no role in human metabolism, making it a chemical contaminant. Since the 1950s, science has been accumulating evidence of its harmful effects on health,” explains Paulo Basta, a researcher at Fiocruz.

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The study, titled “Impact of Mercury on Protected Areas and Forest Peoples in the Amazon: An Integrated Health-Environment Approach,” was supported by the non-governmental organization Instituto Socioambiental (ISA). It involved collaboration from two Fiocruz departments: the Sergio Arouca National School of Public Health and the Joaquim Venâncio Polytechnic School of Health. The villages included in the study are situated in the Upper Mucajaí River region and are home to Yanomamis from the Ninam subgroup.

A total of 287 hair samples were examined from individuals across different age groups, including children and the elderly. Among them, 84 percent showed mercury levels exceeding 2.0 micrograms of mercury per gram of hair (µg/g). For this age group, reporting cases to the Notifiable Diseases Information System (SINAN) is mandatory. This system produces official statistics that guide the measures to be adopted within the scope of Brazil’s public healthcare network, the SUS.

It is also noteworthy that, in 10.8 percent of the analyses, the levels exceeded 6.0 µg/g. This finding underscores the need for special attention to be given to this segment of the population. The researchers highlight that the highest exposure levels were observed in indigenous individuals residing in the villages nearest to the illegal mining sites.

The Yanomami indigenous land spans over 9 million hectares, stretching across the states of Roraima and Amazonas and standing as the largest indigenous reserve in Brazil. According to the 2022 Census data released by the Brazilian government´s statistic agency IBGE, this area is home to over 27,000 indigenous individuals.

Illegal mining has plagued this territory for decades. Mercury is employed to extract gold from sediments. Given its clandestine nature, environmental precautions are often ignored. This leads to the dumping of mercury into rivers and its subsequent entry into the food chain of fish and other animals. This contamination, coupled with the expansion of illegal mining, has contributed to health issues among the Yanomami population, including malnutrition and an increase in diseases, especially malaria.