Mothers who want to feed their babies breast milk but are unable to produce enough on their own or have other issues with breastfeeding often rely on donated or purchased breast milk. But a new study looking into breast milk sold online for a few bucks an ounce says it could contain potentially dangerous bacteria including salmonella.

Researchers bought 101 breast milk samples sold by women on one site and found that three-fourths of those samples showed high amounts of bacteria. That’s not good for babies, who could become sick after ingesting many of those bacteria, researchers found. The study was published online today in the journal Pediatrics.

Over the weekend the site in question, onlythebreast.com, said it would make changes to its policies to try to prevent any harm to babies, reports the Associated Press.

The AP says an administrator for the site issued a statement that it will stop informal milk sharing and try to improve donor screening and pursue “professional milk processing.”

While the AP noted that the site was down this morning, as of right now the site appears to be working, albeit slowly.

One doctor not involved with the study says its findings are “pretty scary.”

“Just imagine if the donor happens to be a drug user. You don’t know,” a pediatrics chief told the AP.

While breast milk that comes from milk banks often have hospitals as clients and screen their donors before pasteurizing donated milk, Internet sites aren’t as foolproof, said the lead author and researcher of the study.

“You have very few ways to know for sure what you are getting is really breast milk and that it’s safe to feed your baby,” she explained of the online selling system. “Because the consequences can be serious, it is not a good idea to obtain breast milk in this way.”

In 2010 the Food and Drug Administration agreed.

“When human milk is obtained directly from individuals or through the Internet, the donor is unlikely to have been adequately screened for infectious disease or contamination risk,” the FDA says. “In addition, it is not likely that the human milk has been collected, processed, tested or stored in a way that reduces possible safety risks to the baby.”

Bacteria found in breast milk sold on Internet [Associated Press]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.