Duke University researchers have found hazardous levels of mercury hundreds of miles downstream from Peruvian gold mines.
Researchers have determined that the health risks taken on by artisanal, small-scale gold miners extend far beyond the miners themselves.
A small-scale gold mining operation docks along the Madre de Dios River in Peru. Small boats remove sediment from nearby riverbank where mercury is added to extract gold. Recently, the Peruvian Navy has begun to crackdown on mining operations directly on the river by bombing small boats such as this one.
Credit: Sarah Diringer, Duke University
Based on a study of gold-mining operations in Peru, the miners' practices not only contaminate local soil, sediment and water resources with mercury, they create hazardous levels of the neurotoxin in the food chain at least 350 miles downstream.
The study, led by Heileen Hsu-Kim, professor of civil and environmental engineering at Duke University, William Pan, professor of environmental science and policy and the Duke Global Health Institute, and Sarah Diringer, a Ph.D. candidate mentored by the pair, was recently published online in the journal Environmental Science: Processes & Impacts.
The Duke team looked at the wide-reaching effects of mercury contamination from gold-mining operations in Peru's southern Amazon region of Madre de Dios. However, the same mining practices are present throughout South America, as well as in Africa and Asia.
As the price of gold has soared during the past decade, thousands of Peruvians -- mostly from the Amazon and sierra region of Cusco -- have embraced artisanal small-scale gold mining to supplement their income. Mercury is used to bind loose flakes and bits of gold ore into hard chunks that can be more easily extracted from soil and sediment, and then burned off with blowtorches once the chunks are in hand.
The study found that the miners and their families are highly vulnerable to the impacts of mercury, with limited knowledge of mining's environmental or human health effects. Rarely do they have adequate safeguards to limit the release of mercury into the air, soil or water, the researchers said.
Once in river sediments, mercury is taken up by microorganisms that convert it to a highly neurotoxic form. As other animals consume the microorganisms, the levels of the neurotoxin accumulate in larger predators, such as carnivorous fish, according to the study.
"We've known that the use of mercury presents health risks to miners and their families, but it also releases a lot of contamination that ends up downstream," said Hsu-Kim. "Some of that mercury ends up in fish that other communities depend on as part of their diets, and that risk was not documented at all. We had heard anecdotal evidence, but this was the first scientific study to document the actual contamination."
In the study, Hsu-Kim, Pan and their colleagues took samples from river sediment, water and fish at 62 sites near 17 communities over a 350-mile stretch of the Madre de Dios River and its major tributaries. The results showed an increase in mercury concentrations in the mining areas as well as downstream, where concentrations in fish now exceed World Health Organization guidelines for safe consumption for children and women of maternal age.
"The calculations were made assuming that people ate two fish meals per week," Hsu-Kim said. "However, we have preliminary data from household health surveys indicating that fish consumption is actually much higher in many communities, which could increase the body burden and exceed safety limits even for healthy adults."
While mercury can be dangerous to adults, the primary concern is how it can impair neurological development in children, infants and fetuses. Because mercury can cross the placental barrier if it is ingested by the mother, the metal can affect the development of a baby's cardiovascular and nervous systems.
According to the Environmental Protection Agency, impacts on cognitive thinking, memory, attention, language and fine motor and visual spatial skills have been seen in children exposed to the neurotoxin in the womb.
The Madre de Dios region, home to some of the Amazon's largest remaining swaths of virgin rainforest, is thought to host among the highest number of mammal, bird and amphibian species in the world. Animal and plant life there is so diverse that Peruvian law proclaims it to be the world's "Capital of Biodiversity."
"We recognize that these gold mining practices are a beneficial economic activity for families and have the potential to be environmentally sustainable," Pan said. "To identify pathways toward sustainability, we have begun working with the Ministry of Health in Peru and local NGOs in Madre de Dios to raise awareness about the impacts of mining as well as engaging families, communities and other regional stakeholders to find mutually beneficial solutions for the humans and the environment."
This research was supported by the Inter-American Institute for Global Change Research (CRN3036).
CITATION: " River Transport of Mercury from Artisanal and Small-Scale Gold Mining and Risks for Dietary Mercury Exposure in Madre de Dios, Peru," Diringer, S. Feingold, B. Ortiz, EJ. Gallis, JA. Araujo-Flores, JM. Berky, A. Pan, WK. Hsu-Kim, H. Environmental Science: Processes & Impacts, Dec. 19, 2014.
Ken Kingery | EurekAlert!
Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences