Diego Gomez drinks breast milk from a bottle during a newborn-care class on Feb. 23, 2010, in Aurora, Colo. John Moore/Getty Images
Human breast milk is sold on several online sites for a few dollars an ounce, but a new study says buyer beware: Testing showed the milk may contain potentially dangerous bacteria, including salmonella.
The warning comes from researchers at Nationwide Children's Hospital in Columbus, Ohio, who bought and tested 101 breast-milk samples sold on two popular sites. Three-fourths of the samples contained high amounts of bacteria that could sicken babies, the researchers found. They did not identify the website.
Breast milk is also provided through milk banks, whose clients include hospitals. Milk banks, which charge fees, screen donors and pasteurize donated milk to kill germs.
With Internet sites, "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," said Sarah Keim, the lead author of the study and a researcher at Nationwide. "Because the consequences can be serious, it is not a good idea to obtain breast milk in this way."
Keim said she and her colleagues had noticed milk-sharing websites popping up over the past few years.
For the new study, they responded to 495 ads placed on two of those sites and ended up purchasing and analyzing 101 batches of milk.
The researchers also looked at 20 milk samples that had been donated to a milk bank for comparison. Seven of those contained disease-causing bacteria, according to their findings.
The results of their study were published online Monday in the journal Pediatrics. The research follows previous medical studies that have cited several cases of infants getting sick from strangers' breast milk.
It is unknown exactly how common purchasing breast milk online is, but an earlier study cited 13,000 postings were placed on U.S. milk-sharing websites in 2011.
The Food and Drug Administration in 2010 warned against purchasing breast milk online.
"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."
The researchers believe theirs is the first study to test the safety of Internet-sold milk, although several others have documented bacteria in mothers' milk and in milk-bank donations. Not all bacteria may are harmful, but salmonella is among those that could pose a threat to infants.
Sources for bacteria found in the study aren't known but could include donors' skin, breast pumps used to extract milk and contamination due to improper shipping methods, Keim said.
Dr. Ekhard Ziegler said he believes it's too early to tell parents to avoid purchasing milk at all costs.
"Am I concerned about the recipients? Somewhat, yes," said Ziegler, director of the Fomon Infant Nutrition Unit at the University of Iowa in Iowa City.
But, he added, "what we need now is someone studying the recipients of Internet milk (to see) whether there is any indication that they have more illness."
Ziegler was not involved in the new research. He told Reuters Health he has seen a baby who developed sepsis from milk it received from its mother that was heavily contaminated with bacteria.
There are many milk-sharing sites online, including several that provide milk for free. Sellers and donors tend to be new mothers who produce more milk than their own babies can consume. Users include people with adopted infants and mothers who have difficulty breast-feeding and don't want to use formula.
Breanna Clemons of Dickinson, N.D., is a donor who found a local woman who needed breast milk through one of the online sites that offer free milk.
She is breast-feeding her 7-month-old and stores excess milk in her freezer. Every few weeks, she meets with a recipient with whom she has shared her medical history and gives her about 20 six-ounce bags containing. Clemons said the woman has a healthy 9-month-old who "loves my milk."
Bekki Hill is a co-founder of Modern Milksharing, an online support group that offers advice on milk donation. She said there's a difference between milk sellers and donors: Milk donors "don't stand to gain anything from donating, so they have no reason to lie about their health."
Hill, of Red Hook, N.Y., used a donor's milk for her first two children and plans to do so for her third, due in February, because she doesn't produce enough of her own.
"Breast milk is obviously the preferred food" for babies, she said.
Al Jazeera and wire services