Uranium accumulates in infant bones. It interferes with skeletal development. It disrupts immune formation. Its toxicity may also increase the long-term cancer risks especially leukaemia and bone cancer.
Published Nov 25, 2025 | 6:00 AM ⚊ Updated Nov 25, 2025 | 6:00 AM
Synopsis: Uranium has been found in every breast milk sample tested from forty mothers across six districts in Bihar, with researchers linking the contamination directly to groundwater drawn daily from local handpumps. Although most infants in the study crossed the safety threshold for chemical exposure, scientists emphasise that breast milk still carries far lower uranium levels than formula prepared with the same contaminated water.
The handpump in six districts in Bihar delivers more than water. When a woman fills her vessel each morning from handpump water, unaware that uranium from rocks 30 metres below ground dissolves into the aquifer, rises through the pump, enters her body through daily drinking, and emerges in the milk she feeds her infant son.
The radioactive silvery-grey metal completes its journey from ancient geological formations to a six-month-old’s stomach in less than twenty-four hours.
Scientists have now mapped this pathway with precision. A three-year study, published in Scientific Reports, found uranium-238 in every breast milk sample collected from forty mothers across six Bihar districts.
The concentrations remain low, between 0.85 and 5.25 micrograms per litre, but the presence is universal and the route clear: contaminated groundwater becomes contaminated breast milk through the simple act of drinking and breastfeeding.
“The present study reports 100% lactating mothers having their breastmilk highly contaminated with uranium,” the authors state. Yet they insist mothers should continue breastfeeding. “It is also recommended to emphasize that breastfeeding is the optimal method for infant nutrition, and its discontinuation should only occur based on clinical indication.”
The contradiction dissolves when you trace uranium’s path from ground to infant.
Uranium exists in granite and sedimentary rocks across the Gangetic plains. Rainwater seeps down through soil and sediment layers. As water moves, it picks up dissolved substances including calcium, sodium and nitrates. And uranium.
But uranium does not dissolve easily. It needs specific chemical conditions. Bihar’s groundwater provides them all: high bicarbonate levels, alkaline pH above seven, low organic matter, oxygen-rich conditions and nitrates from agricultural runoff. The chemistry aligns. Uranium flows.
Then humans intervene. Farmers extract groundwater faster than the monsoon can replenish it. Water tables drop. Minerals concentrate. Phosphate fertilisers containing uranium spread across fields. Factories discharge effluents. Industrial waste adds to the load.
An earlier study by the same research team tested 273 groundwater samples across Bihar. Twenty samples exceeded 30 micrograms per litre, the World Health Organisation’s safety limit for drinking water. Another 150 contained uranium between one and 30 micrograms per litre.
“The maximum uranium concentration was reported as 82 µg/L in Supaul district, followed by 77 µg/L in Nalanda district and 66 µg/L in Vaishali district of Bihar,” the study notes.
Rural Bihar relies on handpumps and shallow wells. Water treatment remains scarce. Most households draw water directly from aquifers into cooking pots and drinking glasses. “The source of U238 contamination in the studied districts could be drinking water sources or the food source cultivated in the same location,” the researchers explain.
Swallow a glass of water containing uranium. The stomach and intestines absorb roughly one to five percent. The rest passes through and exits in faeces within days.
That small absorbed fraction enters the bloodstream. Uranium binds to proteins including albumin and transferrin. It circulates for hours, then the kidneys filter it. Within twenty-four to forty-eight hours, seventy to ninety percent leaves through urine.
But uranium behaves chemically like calcium. It binds to phosphate groups in bones with high affinity. It accumulates in kidneys. These become the main storage sites.
“Uranium binds to plasma proteins and preferentially accumulates in bones and kidneys due to its affinity for phosphates and carbonate groups, rather than in breast milk,” the study explains.
A small fraction drifts into other tissues and fluids. Mammary glands produce milk by drawing components from blood plasma. But uranium lacks specific transport mechanisms to cross from blood into milk. It shows low affinity for milk fats and proteins.
“Its low affinity for milk components (lipids, proteins, and water), combined with the absence of specific transport mechanisms, results in low uranium concentrations in breast milk,” the authors note.
This biological barrier explains why milk uranium levels remain far below water uranium levels. Mothers drink groundwater reaching 82 micrograms per litre. Their milk contains 0.85 to 5.25 micrograms per litre, roughly ten to fifteen times lower.
“The primary route of excretion is through urine which may lower the impact of uranium in the infant’s body,” the researchers add.
Researchers from Mahavir Cancer Sansthan & Research Centre in Patna collected samples between October 2021 and July 2024. They recruited forty women randomly across Bhojpur, Samastipur, Begusarai, Khagaria, Katihar and Nalanda. Ages ranged from seventeen to thirty-five years.
Scientists collected five millilitres of milk from each woman. Laboratory technicians mixed samples with nitric acid to break down organic matter. They heated, concentrated and filtered the solution. They analysed it using Inductively Coupled Plasma–Mass Spectrometry, a machine that atomises samples in 10,000-degree plasma and counts uranium atoms.
The spatial pattern emerged clearly. “The decreasing order of exposure to uranium [U238] contamination in the districts such as Katihar>Samastipur>Nalanda>Khagaria>Begusarai>Bhojpur,” the study reports.
Katihar recorded the highest single reading, 5.25 micrograms per litre. Khagaria showed the highest average, 4.035 micrograms per litre. Nalanda, despite high groundwater contamination in previous studies, showed the lowest breast milk average, 2.354 micrograms per litre.
The mismatch suggests other factors operate. Individual metabolism varies. Diet plays a role. Water sources differ even within districts.
“Correlation analysis indicated a weak positive association between uranium concentration and both the age of mothers and duration of residence, suggesting that longer exposure may slightly contribute to elevated uranium levels in breast milk, though not at statistically significant levels,” the authors observe.
The researchers used Monte Carlo simulations, running 10,000 iterations to estimate probability. They calculated Hazard Quotient, which compares exposure to a reference dose considered safe. A value below one suggests minimal risk, while a value above one indicates potential harm.
The study found a mean Hazard Quotient of 1.3745. The maximum reached 2.6287. Most infants exceeded the safety threshold.
“The results reveals that 70% of studied infant population have the potential to cause non-carcinogenic health effects,” the study states.
No carcinogenic risk appeared at the observed levels, but uranium damages organs in other ways.
“It causes serious health hazards to the infants to the vital parts of the body especially kidneys,” the authors warn. They list additional concerns including “neurodevelopment risks such as delayed cognitive development, impaired motor skills, reduced IQ levels.”
Uranium accumulates in infant bones. It interferes with skeletal development. It disrupts immune formation. “Its toxicity may also increase the long-term cancer risks especially leukaemia and bone cancer depending on the dose duration,” the authors wrote.
The metal crosses the blood-brain barrier. It enters brain tissue. Animal studies link uranium exposure to behavioural changes, learning deficits and anxiety.
Infants face disproportionate risk. Their kidneys continue developing through the first two years. They filter uranium less efficiently. Their body weight remains low, so the same dose delivers a higher concentration per kilogram. Their intestines absorb metals more readily. Their blood-brain barrier remains more permeable.
And they consume milk constantly. A breastfed infant drinks 750 millilitres per day, roughly ten to twelve percent of body weight. The exposure accumulates through the critical window when brains wire themselves, when bones grow fastest and when kidneys mature.
The findings sound alarming. Uranium in every sample. Seventy percent of infants at risk. Kidney damage. Developmental delays. The logical response seems obvious: stop breastfeeding.
The researchers argue the opposite. Formula preparation requires water. In Bihar’s villages, that water comes from the same contaminated handpumps. Formula mixed with 82-micrograms-per-litre groundwater delivers far more uranium than breast milk at 5 micrograms per litre. The infant’s exposure increases, not decreases.
Breast milk provides irreplaceable benefits. Antibodies protect against infections. Growth factors optimise brain development. The nutritional profile matches infant needs precisely. Dozens of studies link breastfeeding to higher IQ, stronger immunity and lower disease rates.
Stopping breastfeeding eliminates these benefits while increasing uranium exposure through contaminated formula.
“The evidence presented supports the statement that ‘all the samples had the uranium contents’; however, the reported concentrations are below the permissible limits hence, there could be least significant health threat from uranium exposure,” the authors note.
The real threat sits upstream. The problem is not breast milk. The problem is groundwater.
Eighteen Indian states report groundwater uranium contamination. An estimated 151 districts face the problem. About 1.7 percent of Bihar’s groundwater sources contain uranium, but systematic testing covers only a fraction of the state’s 45,000 villages.
The authors call for expanded action. “There is also a need for biomonitoring of U238 in these regions at a broader level.”
Their recommendations include testing soil, groundwater and human samples across all districts, mapping high-exposure zones, installing community water treatment units, promoting safe water sources for pregnant and breastfeeding women, regulating fertiliser uranium content and monitoring industrial discharges more strictly.
Technologies exist. Reverse osmosis filters out 95 to 99 percent of uranium. Ion exchange systems prove effective. The challenge lies in deployment, including cost, maintenance, electricity and trained operators.
Prevention offers a more sustainable path. Limit groundwater extraction. Shift irrigation to surface water. Test fertilisers before approval. Treat industrial waste before discharge. These measures address root causes rather than symptoms.
The study involved forty mothers, a small sample for a population exceeding 100 million. Bihar includes roughly 2.5 million women of reproductive age. The true scale of exposure remains unknown.
For now, women in Katihar, Khagaria, Nalanda, Bhojpur, Samastipur and Begusarai continue drawing water from handpumps. They continue breastfeeding their children, as they must, as researchers insist they should.
The uranium continues its journey from rocks formed millions of years ago, through aquifers filled over thousands of years, into pumps installed decades ago, into bodies that process it within days, into milk that sustains the next generation. The pathway remains open. The exposure continues. And the question shifts from discovery to action: who will close the circuit between contaminated ground and vulnerable infant?
