Compared to an adult who drinks a large quantity of water, the total amount of uranium consumed by a baby through breast milk is extremely small.
| Photo Credit: N. Rajesh
The story so far: A recent study published from Bihar has revealed traces of uranium (U238) in the breast milk of lactating mothers across six districts of the State. This was followed by a period of panic, as shock set in over the presence of uranium, a known radioactive substance, in breast milk, being consumed by infants. However, a deeper reading of the study reveals that while the facts are concerning, and will have to be attended to forthwith, in this particular instance, the cancer scare associated with exposure to radioactive metals appears to be non-existent.
What did the study highlight?
In the paper titled ‘Discovery of uranium content in breast milk and assessment of associated health risks for mothers and infants in Bihar, India’, published on November 21, in Nature, Arun Kumar et al said samples of breast milk were taken from 40 mothers selected randomly from six districts of Bihar — Begusarai, Katihar, Nalanda, Samastipur, Kagharia and Bhojpur — between October 2021 and July 2024. The samples underwent a detailed uranium analysis at the Mahavir Cancer Sansthan & Research Centre in Patna. The results showed all breast milk samples had uranium concentrations between 0 microgram/L and 5.25 microgram/L. The highest U238 concentration was observed in Katihar district. The authors linked uranium in breast milk to uranium contamination of ground water, citing earlier groundwater studies to establish the link. There is currently no permissible limit or benchmark specified for uranium concentration in breast milk. However, the World Health Organization has set a provisional guideline limit of 30 microgram/L of uranium in drinking water.
What impact does it have on breast milk?
Scientists found the uranium isotope 238 (U238), said to be the most common isotope, making up over 99% of natural uranium in breast milk. It is a weakly radioactive, dense, and very heavy metal. It occurs naturally in the environment, and can be found in almost all rock, soil, and water, including the oceans, though in low concentrations. According to the United States Environmental Protection Agency (USEPA), “external exposure to uranium is not as dangerous as exposure to other radioactive elements because the skin will block the alpha particles [in the uranium]. However, ingestion of high concentrations of uranium can cause health effects, such as cancer of the bone or liver.” A person can be exposed to uranium by inhaling dust in air, or ingesting water and food contaminated with uranium. The general population is exposed to trace levels of uranium primarily through food and water, according to the USEPA.
The authors add: “In recent years, groundwater uranium [U238] poisoning has posed serious health hazards in the exposed population. In India, an estimated 151 districts and 18 States have reported groundwater uranium contamination, and about 1.7% of groundwater sources are affected in Bihar.”
Does it affect mothers and infants?
Ashok Sharma of AIIMS Delhi, one of the authors, told the media that uranium was found in all samples but remains under permissible limits, implying low expected health impact. The study concludes that the actual impact on infant health is likely low, and that most of the uranium absorbed by mothers is excreted primarily through urine, not concentrated in breast milk. Dr. Sharma added that 70% of the infants showed potential non-carcinogenic risk in the assessment but the levels observed are expected to have “minimal actual health impact” on mothers and infants, and breastfeeding should continue unless a clinical reason requires otherwise. If long-term exposure to uranium continues in infants, it may affect kidney development and cognitive and mental health outcomes (including low IQ and neurodevelopmental delay).
Senior consultant gastroenterologist and former President of Indian Medical Association Cochin, Rajeev Jayadevan, seeks to place this controversy in the right context. “The word uranium can cause panic among the general public because of its obvious radioactivity implication. In fact, uranium is only one among many elements naturally found in groundwater, not only in India but in numerous countries worldwide. Groundwater is commonly used for drinking; naturally, small amounts of these elements enter the human body and get safely excreted in the urine. Only a small fraction enters the breast milk — and the levels found in this study are about six times lower than WHO’s safe limit for drinking water. Thus, compared to an adult who drinks a large quantity of water, the total amount of uranium consumed by a baby through breast milk is extremely small.”
The actual immediate danger, he says, is that people might misunderstand or misinterpret the study, and stop breast-feeding in panic. Insufficient breast-feeding is a major cause of infant mortality, infections, and malnutrition, Dr. Jayadevan says. Therefore, while reporting the study, it must be emphasised that breast-feeding is safe.
Periodic groundwater studies must be conducted to ensure that concentrations of metals and other contaminants do not exceed ‘safe’ limits in the food chain. The paper calls for future studies with larger sample sizes and environmental uranium profiling (in water, soil, and diet). Isotope-specific measurements are warranted to better understand maternal-infant uranium kinetics in exposed populations. Further studies are being planned to study uranium contamination in breast milk in other States.
Published – November 30, 2025 02:35 am IST
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