To quantify microbial contamination of human milk purchased via the Internet as an indicator of disease risk to recipient infants.
Cross-sectional sample of human milk purchased via a popular US milk-sharing Web site (2012). Individuals advertising milk were contacted to arrange purchase, and milk was shipped to a rented mailbox in Ohio. The Internet milk samples (n = 101) were compared with unpasteurized samples of milk donated to a milk bank (n = 20).
Most (74%) Internet milk samples were colonized with Gram-negative bacteria or had >104 colony-forming units/mL total aerobic count. They exhibited higher mean total aerobic, total Gram-negative, coliform, and Staphylococcus sp counts than milk bank samples. Growth of most species was positively associated with days in transit (total aerobic count [log10 colony-forming units/mL] β = 0.71 [95% confidence interval: 0.38–1.05]), and negatively associated with number of months since the milk was expressed (β = −0.36 [95% confidence interval: −0.55 to −0.16]), per simple linear regression. No samples were HIV type 1 RNA-positive; 21% of Internet samples were cytomegalovirus DNA-positive.
Human milk purchased via the Internet exhibited high overall bacterial growth and frequent contamination with pathogenic bacteria, reflecting poor collection, storage, or shipping practices. Infants consuming this milk are at risk for negative outcomes, particularly if born preterm or are medically compromised. Increased use of lactation support services may begin to address the milk supply gap for women who want to feed their child human milk but cannot meet his or her needs.
Comments
Differences Between Online Milk Sales and Peer-to-Peer Milk Sharing
In their study, "Microbial contamination of human milk purchased via the Internet," Keim and colleagues sought to "document the potential for human milk shared via the Internet to cause infectious disease." They measured bacterial contamination in breast milk purchased online, and found that a majority of samples contained high levels of bacteria. This study raises important questions about the potential for harm with milk sharing; however, the generalizability of the research is limited.
Ethical and methodological considerations constrained the researchers. Milk could only be acquired from websites that allowed anonymous exchange. The authors provided sellers with no detail about why milk was needed, communicated only by email, and excluded sellers who asked questions about recipient infants. Milk was shipped to a rented mailbox. Sellers were given no shipping instructions. These features - anonymous purchase, no questions asked, shipped without packaging requirements - mean that the researchers' method is unlikely to be representative of real parents seeking milk.
First, the authors used the only milk exchange site that allows milk selling. It is well recognized that payment increases risk with tissue donations, and the same is likely to apply to milk [1]. Thus, the overwhelming majority of parents seeking milk - 96% in one analysis [2] - eschew payment and instead use sites that only allow milk donation.
Second, by design, the authors did not screen milk sellers to minimize risk, whereas parents typically do. Milk recipients employ a variety of strategies, including asking questions about the donor's health, medications and reasons for donating, obtaining medical records, and getting to know the donor before accepting milk [3]. Understanding a donor's motivation and developing a relationship of trust are described as critical [3]. Parents also routinely reject donors who fail screening [3]. In contrast, Keim et al. did not apply any screening, except to exclude sellers who showed any interest in the recipient of the milk. Such disinterest would be viewed as a "red flag" by parents, meaning that the study selected suppliers whom parents would be least likely to choose.
Finally, milk gifting sites encourage local, in person, delivery. In a study of 138 milk sharing participants (unpublished, methods available [4]), less than 10% of milk was shipped. However, all milk samples in Keim et al. were shipped, increasing the risk of bacterial growth.
The results from Keim et al. thus reflect a worst-case scenario for milk sharing. When human milk is obtained through anonymous, paid, online exchanges from unscreened donors and shipped long distances, the risk of bacterial contamination is high.
These results underscore the need for further research on milk expression and storage. The majority of breastfeeding women express their milk [5]. However, the evidence base for safe expression and storage is limited, and little is known about knowledge of and compliance with guidelines. Research that evaluates the safety of peer-to-peer milk exchange as practiced by parents seeking milk for their infants is needed. Further research is also needed to determine the extent to which bacteria in expressed human milk might affect infant health.
1. Wylie B. Which methods of donor recruitment give the safest donors? Malays J Pathol. 1993;15(2):99-103
2. Keim SA, McNamara KA, Jayadeva CM, Braun AC, Dillon CE, Geraghty SR. Breast milk sharing via the Internet: The practice and health and safety considerations. Matern Child Health J. 2013;doi:10.1007/s10995-013- 1387-6
3. Gribble K. Perception and management of risk in Internet-based peer-to-peer milk-sharing. Early Child Dev Care. 2013;184(1):84-98
4. Gribble K. Peer-to-peer milk donors' and recipients' experiences and perceptions of donor milk banks. J Obstet Gynecol Neonatal Nurs. 2013;42(4):451-461
5. Labiner-Wolfe J, Fein SB, Shealy KR, Wang C. Prevalence of breast milk expression and associated factors. Pediatrics. 2008;122 Suppl 2:S63- 68
Conflict of Interest:
None declared
What Next for Human Breast Milk Sharing Research?
In their provocative study, Keim and colleagues make an important contribution to our understanding of the growing practice of women donating and selling their breast milk to others.(1) However, generalizing the results of their highly selective and modestly-sized sample (101 Internet milk samples and 20 milk bank samples) to the wider population of informal human breast milk sharing should only be done with extraordinary caution. The reality is that a census of donated or purchased human breast milk could reveal that its microbial characteristics are better--or perhaps even worse--than what Keim and colleagues report. The same is true for their milk bank donor sample.
There are valuable lessons in their work, however, about the importance of good hygiene and rapid transport of shipped human breast milk, but the greater takeaway is that comparative effectiveness studies that focus on outcomes rather than intermediate measures--such as microbial burden--are needed.(2) Some parents (including this author) go to considerable lengths to provide their infants with human breast milk because of the body of evidence supporting its health benefits.(3) Prospective enrollment of parents with newborns would allow researchers to study health and even economic outcomes in babies fed with human breast milk donated or sold over the internet and through other venues, compared to babies who are breast- or formula-fed. Such studies would tell us much more about what parents can do to protect and support their children, and they would better inform the appropriate role--if any--of regulatory bodies like the FDA in the sharing of human breast milk. Well-designed decision-analysis models that integrate tradeoffs between health benefits and risks might also be highly informative.(4, 5)
On another note, I offer an explanation for the inverse relationship observed between the time since milk expression and bacterial counts. In addition to the possibility that this finding is the result of chance, which must be considered given the multiple comparisons that were performed and the study's modest sample size, it is also possible that hygienic practices wane over time. Studies in medical settings support the notion that some hygienic practices are often difficult to sustain.(6)
References
1. Keim SA, Hogan JS, McNamara KA, Gudimetla V, Dillon CE, Kwiek JJ, et al. Microbial Contamination of Human Milk Purchased Via the Internet. Pediatrics. 2013.
2. In: Velentgas P, Dreyer NA, Nourjah P, Smith SR, Torchia MM, eds. Developing a Protocol for Observational Comparative Effectiveness Research: A User's Guide. Rockville (MD); 2013.
3. Breastfeeding and the use of human milk. Pediatrics. 2012;129(3):e827-41.
4. Weinstein MC, Fineberg HV. Clinical decision analysis. Philadelphia: Saunders; 1980.
5. Ladapo JA, Neumann PJ, Keren R, Prosser LA. Valuing children's health: a comparison of cost-utility analyses for adult and paediatric health interventions in the US. Pharmacoeconomics. 2007;25(10):817-28.
6. White CM, Statile AM, Conway PH, Schoettker PJ, Solan LG, Unaka NI, et al. Utilizing improvement science methods to improve physician compliance with proper hand hygiene. Pediatrics. 2012;129(4):e1042-50.
Conflict of Interest:
None declared