Study detects uranium in breast milk: Its findings, why experts have questioned its validity

Recent reports about the study have fuelled concern about the safety of breastfeeding. Dr Arun Gupta, founder of Breastfeeding Promotion Network of India (BPNI), told The Indian Express, “This is leading to unnecessary fears and may deter people from breastfeeding, which we have been working to promote for years because it is the best nutrition for the babies. It also protects the babies from infections.”

Experts have concluded that the levels detected are not significant, and no health impacts have been observed over the years. Also under scrutiny is the methodology followed by the researchers, as well as the aim of studying the levels in breast milk alone. Here is what to know.

Small amounts occur naturally

Dr Dinesh K Aswal, former group director of Bhabha Atomic Research Centre, allayed fears that breast milk may be harmful for children.

“Uranium is a natural element, which is invariably present in trace amounts in everything. There is some level of uranium in groundwater across the globe,” he said. “The good thing is that uranium is a heavy element and does not bind with the tissues of the body, so any uranium you consume will likely be flushed out in a very short time. People have to drink highly contaminated water for several years to have some impact on the kidneys. In fact, the levels in India — and what the authors of the study have found — is not very high.”

The World Health Organisation, in its 2001 guidance on uranium in drinking water, said that the human body, on average, contains about 90 µg of uranium derived from normal intakes of water, food and air — about 66% is found in the skeleton, 16% in the liver, 8% in the kidneys and 10% in other tissues.

Dr Aswal added: “While the WHO sets the limit of uranium in groundwater at 30 µg/L, Finland has naturally occurring high levels of uranium and therefore has a higher threshold of 100 µg/L. The levels in India are less than this. The people in Finland have been drinking the same water for generation after generation and haven’t faced significant health impacts.”

Inconsistencies noted in the study

1. 01

   Levels detected within permissible limits

   The highest concentration of 5.25 micrograms per litre was found in samples from Katihar, while the lowest concentration of 2.35 micrograms per litre in Nalanda. While the researchers began by saying that the uranium exposure through breast milk was at “hazardous levels”, they concluded thus: “…the reported concentrations are below the permissible limits hence, there could be least significant health threat from uranium exposure.”

   “The level of uranium was noticeable, but it did not appear to cause major health problems for either the mothers or their babies. Still, around 70% of the infants showed a possible risk for non-cancer-related health effects,” said Dr Ashok Sharma, coauthor of the study and Additional Professor in the Department of Biochemistry at AIIMS New Delhi.

2. 02

   Bioaccumulation not seen

   Notably, the researchers noted that the levels did not significantly increase with age, meaning there was no evidence to suggest that living in an area with high levels of uranium in groundwater over a longer period increased uranium levels. It also noted that “bioaccumulation of uranium in breast milk is minimal”.

3. 03

   Uranium content in local groundwater not correlated with breast milk

   For the study, the researchers also looked at the uranium levels in 273 groundwater samples. Interestingly, the second-highest level of 77 µg/L was found in Nalanda, where the concentration in breast milk was lowest.

4. 04

   Uranium in breast milk itself unlikely to be detected

   According to Dr Aswal, the possibility of finding uranium in breast milk is remote because it doesn’t bind well with the lactic acid or other components of milk.

   He added that there is also no rationale for choosing breast milk as the only sample for testing uranium levels, and that urine samples should also have been tested to see how much uranium gets flushed out.

5. 05

   No child health monitoring undertaken

   The children were also not monitored to see whether there was an impact on their health. “No child-health monitoring was done during the study because contamination was discovered only after data analysis,” said Dr Sharma.

6. 06

   Questionable degree of instrument calibration

   Dr Aswal also noted that the researchers have detected uranium at levels of around 5µg/L, which their equipment was not calibrated for.

   “They have used a very sensitive instrument, but the calibration has to be proper for detecting accurate levels. Their calibration was between 100µg/L and 2000µg/L — how did they detect 5µg/L then? It’s like going to the sweet shop and asking them to measure the weight of your jewellery,” said Dr Aswal.

   He added that the calibration was done using nitric acid and not breast milk, which might also affect the results.

7. 07

   Sample size statistically insignificant

   Importantly, Dr Aswal pointed out that with just 40 samples the researchers did not have a statistically significant sample to say which district had higher contamination and which did not. “For groundwater mapping, we had collected 55,000 samples, and I was still not happy.”