An exponential growth in Australians donating or selling breast milk online is putting infants at risk of disease, a bioethicist says, calling for human milk to be defined as a “tissue” and regulated in the same way as blood.

There are Facebook groups facilitating the donation or sale of breast milk in every state and territory. The “about” section for one group states: “Please post milky requests, offers and milk-sharing questions … It can be helpful to include details such as the age of your baby and your location or how far you are willing to travel.”

The most active groups do not allow or support the sale of milk. However, there is an online black market where breast milk is bought by people including cancer patients under the mistaken belief that it will treat their disease, and by athletes and bodybuilders who believe breast milk enhances performance and muscle growth, despite no strong evidence for this.

A study led by an associate professor of law at Deakin University, Neera Bhatia, said because human milk is not legally defined as a tissue or a food in Australia, individuals that donate, share, or trade human milk “do so under a cloud of ambiguity”.

“Its donation, exchange, or sale is also unregulated,” the paper, published in the December issue of the Australian Feminist Law Journal, said. “This is a precarious situation, as unscreened and potentially unsafe human milk is being provided to the most vulnerable members of society – infants.”

But Dr Julie Smith, an honorary associate professor with the Australian National University’s College of Health and Medicine, said the risk of contamination from shared breast milk was low, and most women sharing milk did so without payment and with a genuine desire to help.

Bhatia, who is also a member of clinical ethics committees, said while there have been a number of government reviews and recommendations to address concerns about sharing breast milk, the practice remains unregulated, with inconsistencies between the states and territories.

“But there could be very grave results if something goes wrong, for example if an infant has an adverse reaction to unscreened milk that can potentially carry bacteria and diseases,” she said.

“From our research we have definitely seen an increase in the number of social media groups sharing and selling breast milk, and our paper is saying we need to do something about this now to plug the regulatory and legal gap.”

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While there are milk banks attached to hospitals, these provide donated breast milk to only premature and very sick infants. This milk is screened and pasteurised. The Australian charity Mother’s Milk Bank also has a process for registration and screening of donors.

Most of the milk sourced online does not undergo medical screening or testing for bacterial contamination, Bhatia said.

She said if breast milk was treated the same way as blood donations, relying on altruistic donations with clear clinical guidelines, screening and storage processes, then recipients would be protected from the risk that donors may conceal relevant information. She said regulation would also protect donors from potentially donating too much milk, which may compromise their health or that of their child.

A spokesperson for the federal health department said an expert working group finalised consistent guidelines for milk banks across Australia and New Zealand in early 2020 to address the ethical, safety and quality risks for the local and imported supply of human milk.

“The guidelines do not extend to the collection, storage and handling of breastmilk for a mother’s own infant, or to informal breastmilk sharing in the community,” he said.

Taking a more heavy-handed regulatory approach is not the way to ensure safe sharing, according to Smith .

Smith said regulation should focus on how to ensure babies get breast milk from donors during emergencies such as natural disasters that may lead to food insecurity and a lack of access to formula. The commercialisation of milk banks that may exploit low-income women must also be prevented, she said.

“There’s a strong ethic of care between women sharing milk and they develop friendships, they help each other,” Smith said. “The last thing you want is someone being too scared to share their milk in an emergency because of regulation.”

Smith called for a more sophisticated regulatory system where breast milk provided through hospital milk banks was considered a tissue and regulated accordingly, while informal milk sharing was treated as a food safety issue. People should be provided with guidelines, education and advice on how to store and share milk safely, she said.

“There are so many better frameworks to deal with the nuances of the different situations that may require someone to need breast milk and to get the best outcomes for babies,” she said.