Researchers have found that 10% of breast milk purchased online contained substantial amounts of cow DNA.

One in ten of the 102 samples that were DNA tested contained cow DNA, with further testing ruling out the possibility that it was a result of minor or incidental contamination. This was most likely due to the breast milk being mixed with cow-milk based baby formula. Lead researcher, Dr Sarah Keim, an epidemiologist at Nationwide Children’s Hospital in Columbus, Ohio said: “We confirmed that all of the samples did have human DNA in them, but they were not 100% human breast milk. One of our samples was almost half and half formula and milk.”

Cow DNA found in Human Breast Milk Bought Online

This could be particularly dangerous if the milk is being purchased by parents whose child has an intolerance to formula. According to the authors of the study, 21% of parents who seek breast milk over the internet are making the purchase for a child with a pre-existing medical condition. In addition, 16% of those looking to purchase breast milk say that their child is formula intolerant.

Although the Food and Drug Administration (FDA) and the American Academy of Pediatrics (AAP) have been clear that they do not believe buying milk via the internet is a good idea, it is a trend that continues to escalate. In 2011 the researchers estimated that there were over 12,000 people who made such purchases, with current estimates growing to over 50,000. Dr Keim said: “People feel a lot of pressure to breast-feed and guilt and disappointment if they are not successful. I think that is underlying a lot of the demand for milk online.”

Breast Milk Bought Online Poses Multiple Risks

In a previous study, the same research group found that 74% of human milk purchased over the internet was contaminated with Gram-negative bacteria, which can cause serious illness in infants with compromised immune systems. Dr Keim said: “Our series of studies clearly back up the warnings of the FDA and the AAP that acquiring milk for your baby in this way does pose multiple risks to your baby in terms of health and safety.”

Although the specific contents of the milk purchased by customers are unknown to them, some may be taking the risk due to pressure they feel to give their child breast milk when they are not able to provide it themselves. The AAP recommends breast milk for all infants as it provides immune factors and antibodies that pass through the baby, which may prevent infection early in life when their immune systems are developing.

It is not just whether or not the breast milk is mixed with formula that could pose a factor of risk. For example if a donor mother is a heavy smoker they could pass high levels of nicotine, or if they are an illicit drug user they could pass along the chemicals ingested as result. The team’s next aim is to look at some of the other risks the FDA warns against, using drug testing to check for illicit substances that could be contained within the milk.

DNA Fingerprinting Breast Milk

For those who feel they have no other choice and do take the risk and buy the milk online, there may not be any practical precautions they can take with such purchases. Dr Keim said: “I feel for women who desperately want to feed their babies breast milk, but they have no way to know it is safe.”

The only other safe alternative may be to use non-profit ‘milk banks’ where donor milk is pasteurised, tested for bacteria growth and shipped frozen overnight to hospitals and individual recipients. Other measures can be even more advanced, for example at Texas Children’s Hospital they use DNA fingerprinting to ensure their donor milk comes from their pool of screened mothers. However, this is a unique feature of the hospital and many people would argue that there are not enough non-profit milk banks, which is why people may wrongly turn to the internet as an alternative resource for obtaining breast milk for their child.