Children who live near gold mine tailings facilities in Johannesburg, South Africa, have nearly twice as much as uranium in their hair as those who don’t live near tailings facilities, according to new research. Concentrations were especially high in young children not yet attending school.
Unlike other heavy metals, such as zinc or iron, uranium “has no known benefit or metabolic function in the human body.”
Uranium is present in most of the world’s soils in small amounts, so everyone is exposed to low levels of the metal. But exposure to higher levels of uranium and its decay products, such as radon, has been linked to kidney damage, neurological effects, and reduced lung function.
Unlike other heavy metals, such as zinc or iron, uranium “has no known benefit or metabolic function in the human body,” said Frank Winde, a geographer and environmental chemist at Wismut, a state-owned enterprise in Germany that is working to remediate uranium legacy sites. “[It] is only known to have adverse impacts on human health.”
Winde is a coauthor of a new paper on the findings, published in Environmental Geochemistry and Health.
Building Community Trust
The researchers worked with residents of three study sites within 3 kilometers of tailings facilities in Johannesburg: Riverlea, Tshepisong, and Snake Park, neighborhoods with a combined population of about 128,000 people. For reference sites, they worked with residents of Newlands East and Newlands West, two communities with a combined population of about 100,000 people located north of the city of Durban.
The team partnered with graduates from the University of Johannesburg and Mangosuthu University of Technology (located near Durban), as well as with local residents, to conduct fieldwork and hold a series of meetings with community members. They spent at least a month working to foster trust with the community, and hired at least one local resident for each fieldwork team.
Community representatives “had concerns about exposure to toxic substances from these mine tailings facilities, and some also expressed concerns about their health, and also their livestock,” said Busisiwe Shezi, a specialist scientist at the South African Medical Research Council (SAMRC) who studies exposure to environmental pollutants.
Some residents allowed the fieldwork team to sample soil from their yards, collect children’s hair samples of least 1 centimeter in length, and measure children’s height and weight. The residents also filled out questionnaires about the age, sex, and race of their children, as well as about how long they had lived in the area, whether they grew their own food at home, and other demographic data.
Researchers collected hair samples because hair can provide a record of an individual’s uranium exposure over 2–4 weeks, a period longer than that offered by blood or urine samples.
Michael Watts, a geochemist at the British Geological Survey, is the editor in chief of the journal in which the paper was published, but it was his co–editor in chief who reviewed the paper before publication. Watts told Eos that the researchers collected an appropriate amount of hair from each participant where possible (about 100 milligrams), which likely allowed the samples to be properly processed. He also noted that the researchers engaged with the community well and received appropriate commissions from the SAMRC Human Research Ethics Committee.
“It looks like a fantastic study,” Watts said. “It’s obviously gone through a lot of rigor in terms of planning and getting the permit.”
“Biomonitoring of vulnerable populations, particularly children, in regions impacted by legacy mining activities is a valuable and timely research focus,” said Matthew Omoniyi Isinkaye, an environmental scientist at Ekiti State University in Nigeria. However, he continued, “hair analysis for uranium exposure, while useful as a screening or indicative tool, is inherently subject to substantial uncertainties due to external contamination from dust and soil particles, which is very common, particularly in mine tailing environments.”
Smaller Bodies, Bigger Risks
The researchers sent 406 samples of hair (sealed in small, individual plastic bags) to Germany for testing. There, a team of scientists milled the hair, or ground it into a homogenized substance, explained Susanne Sachs, a chemist at the Institute of Resource Ecology–Helmholtz Zentrum Dresden Rossendorf who studies the environmental behavior of radionuclides.
“After that, this homogenized and milled hair was washed in order to remove any dust,” Sachs said. “This is in order to avoid any contaminations and to avoid overestimations of uranium concentrations.”
The team found that uranium concentrations were about twice as high in girls as in boys. This finding contrasts with previous studies that had found the opposite, signaling a need for more research into how biological sex influences the uptake and storage of toxins, the researchers said.
Hair from the 208 children from Johannesburg (the exposed group) had a median uranium concentration of 17.07 micrograms per kilogram, while hair from the 198 unexposed children from Durban had a concentration of 8.12 micrograms per kilogram. And the younger the children were, the higher the uranium concentrations in their hair: The geometric mean of uranium concentration was 0.99 times lower for each additional month of age.
“If you assume just identical volumes of uranium ingested with adults and kids, then having a much smaller body is already resulting in higher concentrations.”
The researchers weren’t surprised by this: Young children tend to touch their mouths more often, and some even eat soil. Not to mention, they’re simply smaller than their older counterparts.
“If you assume just identical volumes of uranium ingested with adults and kids, then having a much smaller body is already resulting in higher concentrations,” Winde said. However, he added, researchers don’t believe children are seeing the same exposure levels that adults are. “Actually, they have a higher uptake simply because they’re closer to where the stuff comes from. They play on the dumps. Some of them swim in the toe dams of tailings.”
Demographic data, including length of residence or water source, did not correlate significantly with detected levels of uranium.
Researchers did detect a difference in uranium concentrations in soil samples collected from exposed sites versus unexposed sites, but the difference was not as stark as the difference between hair samples. Shezi explained that a hair sample captures uranium taken up through multiple pathways, including by the inhalation of dust particles and the consumption of contaminated food or water.
“Whereas with soil, you’re just collecting a soil sample in one place at that one moment,” Shezi said.
Moving forward, the team hopes to return to the area, share their findings with the study participants, and conduct a longitudinal study of the risks of uranium exposure over time. Such research, the authors suggest, might contribute to stronger environmental protection and mitigation efforts around South Africa’s mining sites.
—Emily Gardner (@emfurd.bsky.social), Associate Editor
Citation: Gardner, E. (2026), Gold mines expose South African children to uranium, Eos, 107, https://doi.org/10.1029/2026EO260061. Published on 17 March 2026.
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