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Local communities living near oil sites in the Peruvian Amazon have high levels of mercury, cadmium and lead in their bodies. This is the conclusion of a study led by Cristina O’Callaghan Gordo, a researcher at the Barcelona Institute for Global Health (ISGlobal). She is also a professor at the Faculty of Health Sciences at the Universitat Oberta de Catalunya (UOC) and co-director of the Interuniversity Master’s Degree in Planetary Health (UOC, ISGlobal and Pompeu Fabra University).
The study, published in Environmental Health Perspectives, found high levels of these three metals in the urine of indigenous people living in four river basins in the northern Peruvian Amazon, where oil exploration began in the 1970s. It is currently one of the most polluted areas in the country. Previous research led by ISGlobal has already reported high levels of lead in the blood of the local population. New data have now been published on mercury, arsenic and cadmium, three metals that are toxic to humans.
Arsenic and cadmium are carcinogens. Arsenic exposure can cause lung, bladder, skin, liver and kidney cancer. And cadmium exposure can cause lung, prostate and kidney cancer. In addition, arsenic can have other serious health effects, such as skin lesions, liver and kidney damage, reductions in red and white blood cells, and developmental delays in children.
Cadmium, in turn, can cause breathing problems, kidney disease, brittle bones, reproductive problems and cardiovascular disease. Finally, long-term exposure to mercury can cause neurological damage and altered cognitive function, damage the nervous system of fetuses and children, and cause kidney and immune system disorders.
Active participation of local organizations
Between May and June 2016, the research team assessed urinary concentrations of mercury, arsenic and cadmium in 824 people (230 of whom were under the age of 12), all living in local communities near oil exploration sites in remote, non-industrialized areas. The team took into account the distance between their homes and the nearest oil facility and also conducted personal interviews to collect data on their risk factors and lifestyle.
The study is the result of an agreement between the local associations of the basins of the Corrientes, Pastaza, Tigre and Marañon rivers (ACODECOSPAT, FECONACOR, OPIKAFPE and FEDIQUEP, all of which belong to the Union of Indigenous Peoples of the Amazon United in Defense of their Territories, or PUINAMUDT) and the Government of Peru.
The purpose of the scientific study was to address local people’s concerns about the potential health effects of oil-related pollution. The research was supported by indigenous associations and the Peruvian National Institute of Health. “The active involvement of local organizations in the study is one of its strengths,” said Christina O’Callaghan. “The large sample size and the random sampling of families from different watersheds with different characteristics are also notable.”
Higher than average levels of mercury, arsenic and cadmium
Urinalysis showed that a significant proportion of children and adults in the study exceeded established reference levels for mercury, arsenic and cadmium. These high levels of metals are linked to the water they consumed and bathed in, especially in the case of mercury, which can be absorbed through the skin.
O’Callaghan said: “Crude oil can contain mercury and other metals and elevated levels have been reported in the environment and in aquatic organisms both around oil fields and in areas affected by spills.”
More mercury in people who bathe in river water
Twenty-five percent of children and 28% of adults had mercury levels above the reference value set by the Peruvian Ministry of Health (MINSA). Mercury levels were found to increase with age in adults and were higher in people living near the Marañón River, where fish consumption is higher than in other river basins. Elevated levels of mercury in fish from the Amazon basin have been linked to oil pollution.
However, previous studies in the same region suggest that the main route of mercury exposure in the area is through dermal absorption of mercury in water. This is consistent with the results of the now published study, as mercury concentrations were higher in children and adults who bathed in river water compared to those who bathed in wells, and also higher in adults who consume rainwater compared to those who drink water from public places. sources.
More arsenic in children drinking well water
Forty-eight percent of the child population and 23% of the adult population had arsenic levels above the reference value set by Peru’s Ministry of Health. Arsenic levels decline slightly with age in adults, tend to be higher in children who drink well water, and, like mercury, are highest in people living around Marañón.
Elevated levels of arsenic of geological origin have been reported in aquifers in western Amazonia, and relatively high concentrations have been reported in crude oil. However, the source of arsenic in the study area remains unknown.
More cadmium in homes and gardens near oil spills
Urinary cadmium levels above the reference value were found in 2% of children and 13% of adults. Cadmium concentrations increase with age in adults and are higher in women. The highest levels were found in people from the Achuar tribe and in people living around Corrientes and Tigre, the two most oil-active basins of the four studied.
Elevated cadmium levels have also been associated with the proximity of homes or gardens to oil spills. Consumption of contaminated vegetables is a known route of exposure to cadmium. Urinary cadmium levels were also associated with participation in cleaning up such spills in the six months prior to the study.
Drinking water and food security for indigenous peoples
The pattern of high concentrations for all metals observed in the study appears to be related to pollution from human activities, particularly oil extraction. According to Manolis Kogevinas, ISGlobal researcher and one of the authors of the study, “the finding of high levels of metals in a population living in a non-industrial environment is alarming because of the long-term health effects that exposure to metals can have.”
He said: “Preventing these exposures, regularly monitoring water quality, ensuring safe drinking water and ensuring food security are a priority for the local population living in these river basins.”
Levels of arsenic, cadmium and mercury in the urine of indigenous people living near oil production areas in the Peruvian Amazon. Environmental Health Perspectives (2023). doi.org/10.1289/EHP11932
Environmental Health Perspectives
Provided by the Open University of Catalonia