But a study being published Monday in the journal Pediatrics found that 72% of breast-milk samples purchased over the Internet contained infection-causing bacteria and 21% had potentially harmful viruses. Researchers' analysis of 100 samples of breast milk bought on a public milk-sharing website found three in four samples contained either high levels of bacterial growth overall or contained disease-causing bacteria, including fecal contamination. In 2011, there were more than 13,000 postings on the four leading milk-sharing Web sites, according to Sarah Keim, an assistant professor of pediatrics at Ohio State and a researcher at Nationwide Children’s Hospital in Columbus, Ohio. Twenty-five percent of the milk bank samples contained no detectable bacteria at all, compared with 9 percent of the samples from milk-sharing sites. Twelve such banks throughout the U.S. follow strict guidelines set by the Human Milk Banking Association of North America and provide pasteurized milk from carefully screened donors to fragile and premature infants, primarily in hospitals. But pasteurization also destroys some of the beneficial substances in breast milk. In all the samples analyzed, the Web-purchased milk had higher bacteria counts and were more likely to contain disease-related types of bacteria, even though the donated milk from the milk banks had yet to be pasteurized: 
 
 -- 72% had any detectable gram-negative bacteria, which are associated with bloodstream infections, wound or surgical site infections, meningitis and fecal contamination vs. 35% of milk bank samples 
 
 -- 63% tested positive for staphylococcus vs. 25% of milk bank samples 
 
 -- 36% tested positive for streptococcus vs. 20% of milk bank samples 
 
 -- 3% were contaminated with salmonella vs. none of the milk bank samples. The new study suggests that may prove hazardous. The Food and Drug Administration warns against feeding babies breast milk acquired directly from individuals or through the Internet, citing safety concerns; the American Academy of Pediatrics discourages feeding preterm infants human breast milk from unscreened donors.
– With the rise of sharing breast milk, a disturbing new study finds that 72% of samples bought online contained bacteria that could cause infections and 21% contained viruses. In 74% of the 101 samples purchased anonymously from two popular websites, the total bacteria count was significantly higher than the level generally considered safe. Bacteria found included E. coli, staphylococcus, streptococcus, and even salmonella, the Wall Street Journal reports. The FDA does not regulate the breast milk market, though it discourages sharing, the New York Times reports. Breast milk can be sold or donated on dozens of websites, and while some suppliers hand off the milk in person, others ship it. Problems during collection (improper hand-washing, dirty breast pumps or containers), improper storage (19% of the samples in the study were not cooled), and long shipping times (some of the samples took as long as six days to arrive) likely contributed to the health hazards. Another potential problem: Researchers say they are "a little suspicious of some of the milk," and are now working to determine if it's authentic breast milk, USA Today reports. In response to the study, at least one site that sells milk will stop allowing mothers to purchase from other mothers; donors will instead sell to a company that processes breast milk.