The researchers believe theirs is the first study to test the safety of Internet-sold milk, although several others have documented bacteria in mothers’ own milk or in milk bank donations. Some bacteria may not be harmful, but salmonella is among germs that could pose a threat to infants, Boyer said.
Sources for bacteria found in the study aren’t known but could include donors’ skin, breast pumps used to extract milk, or contamination from improper shipping methods, Keim said.
The study was published online Monday in the journal Pediatrics.
The researchers attempted to buy milk from women on two websites but only tested milk obtained from women on one site, onlythebreast. An unidentified administrator for that site issued a statement saying the Incline Village, Nev.-based company is planning to stop informal milk sharing and will seek to improve donor screening and pursue “professional milk processing.” The website appeared to be down Monday morning.
There are many milk-sharing sites online, including several that provide milk for free. Sellers or donors tend to be new mothers who produce more milk than their own babies can consume. Users include mothers who have difficulty breast-feeding and don’t want to use formula and people with adopted infants.
Breanna Clemons of Dickinson, N.D., is a donor who found a local woman who needed breast milk through one of the online sites where milk is offered free.
“A lot of people are like, ‘Ewww, it’s weird,’ but they haven’t been in a situation where they didn’t want their child to have formula,” or couldn’t produce enough milk, Clemons said.