Uranium in breastmilk? Bihar study finds U-238 in every sample, hazard marker raised for 70% infants

AIIMS co-author urges continued breastfeeding; NDMA scientist says no public health alarm.

A multi-institution study has detected uranium (U238) in breastmilk samples from lactating mothers in six districts of Bihar, raising questions about infant exposure to heavy metals through breastfeeding. The study analysed breastmilk from 40 randomly selected mothers aged 17 to 35 years in Bhojpur, Samastipur, Begusarai, Khagaria, Katihar and Nalanda, with collection carried out between October 2021 and July 2024.

According to the study, every sample tested contained uranium. The researchers quantified U238 levels in the range of 0 to 5.25 micrograms per litre (µg/L), with the highest individual concentration recorded in Katihar district at 5.25 µg/L. The study described Katihar’s samples as showing “hazardous levels” compared with other districts, even as overall concentrations remained below permissible benchmarks for uranium in water.

District-wise exposure pattern

The study’s district-wise contamination order was reported as:
Katihar > Samastipur > Nalanda > Khagaria > Begusarai > Bhojpur.

Researchers also noted that the highest average contamination was observed in Khagaria, while Katihar had the highest individual value.

What the risk assessment showed for infants

Health risk assessment in the study indicated that infants are more vulnerable to uranium exposure because they have limited ability to eliminate the metal from their bodies. The study reported hazard quotient (HQ) values greater than 1 for about 70 percent of infants, which indicates possible non-carcinogenic health risks from uranium exposure through breastmilk.

The potential effects listed for long-term exposure include impacts on kidney development, neurological development, and cognitive outcomes such as reduced IQ and neurodevelopmental delay. The study also said uranium exposure could be linked to cognitive and behavioural issues and may increase cancer risk later in life.

Why the study still says impact is likely low

Speaking to ANI, Dr Ashok Sharma of AIIMS Delhi, a co-author of the study, said uranium was found in all samples but under permissible limits, implying low expected health impact. He said 70 percent of 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.

Dr Sharma told ANI that most uranium absorbed by mothers is excreted primarily through urine rather than concentrated in breastmilk, which lowers expected exposure to infants.

No benchmark for uranium in breastmilk

The study noted that there is no specified permissible limit for uranium concentration in breast milk. It compared findings with drinking water standards, highlighting that the World Health Organisation (WHO) sets a provisional limit of 30 µg/L for uranium in drinking water, while some countries such as Germany follow tighter limits of 10 µg/L.

Possible sources: groundwater and food chain

The research linked breastmilk contamination to uranium presence in groundwater and possibly the local food chain. The study said mothers’ exposure could come from drinking water sources or food cultivated in the same locations.

It reported high uranium concentrations in Bihar groundwater, including a maximum value of 82 µg/L in Supaul, followed by 77 µg/L in Nalanda and 66 µg/L in Vaishali. The study added that extensive groundwater use for drinking and irrigation, industrial effluents entering rivers, and agricultural chemicals such as fertilisers and pesticides may contribute to pollutant build-up in soil and water.

Co-author Dr Ashok Sharma, quoted by The Times of India, said the exact source remains unclear and that the Geological Survey of India is also examining the issue.

NDMA scientist says levels pose no public health concern

NDTV reported that nuclear scientist Dr Dinesh K Aswal, a member of the National Disaster Management Authority (NDMA) and former group director at Bhabha Atomic Research Center, said the uranium detected is far below WHO’s permissible threshold for drinking water and does not pose a public health concern.

Dr Aswal told NDTV that WHO’s safety limit is nearly six times higher than the uranium levels observed in the Bihar breastmilk samples. He reiterated that there is no reason for mothers to discontinue breastfeeding.

What researchers plan next

Dr Ashok Sharma told ANI that similar biomonitoring studies will be conducted in other states to examine heavy metals in breastmilk. He said future work will also look at environmental pollutants including pesticides, building on earlier research that found arsenic, lead, and mercury in breastmilk samples.

Wider context on uranium exposure

The study noted that uranium is a naturally occurring radioactive element found in rocks such as granite, and can enter groundwater through natural processes and human activities including mining, coal burning, nuclear industry emissions, and phosphate fertilisers.

The study also cited prior reports that uranium contamination has been identified in about 151 districts across 18 Indian states, with 1.7 percent of groundwater sources affected in Bihar. Globally, elevated uranium levels have been reported in countries including Canada, the United States, Finland, Sweden, Switzerland, the United Kingdom, Bangladesh, China, Korea, Mongolia, Pakistan, and the lower Mekong Delta region.

While earlier global studies have not consistently linked uranium exposure to clear clinical symptoms in exposed populations, the Bihar findings underscore the need for continued monitoring of U238 in breastmilk and groundwater to track infant exposure risk.