New York, April 6 (IANS): Breast milk purchased on milk-sharing websites may do more harm than good to your baby as researchers have found it adulterated with cow milk in 10 percent of the tested samples.

A large number of babies receive the purchased breast milk due to medical conditions, the study published in the journal Pediatrics said.

"We found that one in every 10 samples of breast milk purchased over the internet had significant amount of cow's milk added, and this poses a risk to infants with an allergy or intolerance to cow's milk," said principal investigator Sarah Keim from The Research Institute at Nationwide Children's Hospital at Ohio, in the US.

"If a baby with cow's milk allergy were to drink this milk, it could be very harmful," Keim said.

Researchers believe that because money is exchanged in these transactions, there might be an incentive to boost milk volumes in order to make more money.

"Cow's milk and infant formula resemble human milk and could potentially be added to boost volumes without the recipient knowing," Keim said.

"Mothers who consider purchasing breast milk over the internet should beware -- when you obtain milk from an unfamiliar source, you cannot know for sure that what you are getting is safe for your baby," Keim said.

For the study, the researchers purchased and tested 102 samples of breast milk advertised on milk-sharing websites.

All purchased samples did contain human milk, but 11 also contained bovine DNA, 10 of which had results consistent with more than minor, accidental contamination with cow's milk.

Purchased breast milk also makes babies more vulnerable to the risk of infectious disease from bacterial and viral contamination of such milk, which was identified in a prior study by the same research team.