Women who purchase breast milk online likely have their baby's health in mind, which makes the findings of a study published today in Pediatrics so concerning. Researchers led by Nationwide Children's Hospital bought 102 samples of milk via milk-sharing websites and discovered that 10 of them "had a level of bovine DNA consistent with human milk mixed with at least 10% fluid cow's milk," they write in the study. That's a concentration high enough to indicate the cow milk was intentionally added, either straight from the carton or by way of baby formula. "This poses a risk to infants with an allergy or intolerance to cow's milk," says researcher Sarah Keim, in a press release. One milk bank director tells USA Today infants could experience bloody diarrhea or eczema as a result of ingesting it.