As Slate’s Laura Helmuth pointed out in her series about longevity, contaminated milk used to be a major killer. Now a new study published in the journal Pediatrics shows that breast milk purchased on the Internet has “high overall bacterial growth and frequent contamination,” reflecting “poor collection, storage, or shipping practices.” Researchers compared samples bought over the Internet—which were sent to a rented mailbox in Ohio—to unpasteurized donated milk from a milk bank. Perhaps unsurprisingly, the milk from the Internet was often contaminated: 64 percent tested positive for staphylococcous, compared with a quarter of milk bank samples. Three of the Internet samples had salmonella. According to the New York Times article on the study, the amounts of salmonella “detected in some samples were sufficient to sicken a child.”
So who are these people sharing milk? The Times quotes a writer from Brooklyn named Rachel Holtzman, who was unable to breastfeed because she had a breast reduction. Her 4-and-a-half-month old son has received donor milk from about 30 different women. (What the Times didn’t note is that Holtzman helped to start a breast milk-sharing exchange with her friend Alicia Silverstone.) I reached out to Holtzman to ask her for more specifics about her milk donation experience, and the first thing she wanted to make clear is she would never, ever buy a stranger’s milk from the Internet—which is the kind of milk the Pediatrics study tested. “That’s just reckless,” Holtzman told me, for the reasons the Pediatrics study outlined: You have no idea how the milk was collected, stored or shipped. (More on that later.)
Because Holtzman’s son was not premature or otherwise ill, she knew she would have trouble getting milk from a milk bank—in general, milk banks reserve their supply for babies in need. And so Holtzman began approaching women she knew personally or through her social networks. “There was not one woman my husband or I did not meet face to face, and these were all actively breastfeeding mothers,” Holtzman said.
Holtzman told me that either she or her husband personally picked up the milk from the donors themselves, so they didn’t have to worry about it being shipped improperly. “I see them pluck it from the freezer,” she said. I’m sure that’s true, but before it gets to the freezer, a lactating woman needs to pump it with sterile parts and store it properly. (How many days can it stay in the fridge? How many hours can it be at room temperature? When’s the last time you boiled those breastshields?) Unless women move in with their donors, there’s no real way to ensure that the milk is being collected and stored according to guidelines.
Holtzman says she knows she’s taking a risk. The CDC and the FDA both advise against milk sharing because of the potential for disease transmission (though there also isn’t good recent data on whether donor milk has made babies sick). One thing that’s clear from the Pediatrics study is that the growth of bacteria is associated with the number of days the breastmilk spends in transit, so the fewer miles that milk has to travel, the better. The moral of the story—and of the Pediatrics study—seems to be that buying unregulated fluids from strangers on the Internet is a terrible idea. There is always formula.