Dec. 20 (Bloomberg) -- Leah Garrapy produced so much breast milk for her baby Ella that she stuffed freezers with leftovers. She posted online that she's sell the surplus for $2 an ounce.

"I was running out of space,"said Garrapy, 25, who lives near Boynton Beach, Florida. "If I can sell some and make extra money, it would be great."

She has company. At websites such as Only the Breast, women may make as much as $2,000 a month selling milk to mothers who say it's the healthiest available diet. The unregulated transactions, including donations, are drawing a rebuke from doctors and U.S. health agencies who say drugs, disease and contamination may pass into the milk, endangering infants.

"It's playing Russian roulette," Ronald Cohen, director of intermediate and special care nurseries at Lucile S. Packard Children's Hospital in Palo Alto, California, said in an interview. "How do I know mom isn't selling her milk so she can go down to the street corner and buy some smack. "People wouldn't buy a kidney online, but people think milk is okay."

Breast milk is becoming a commodity. With more than $30 million in private funding, Prolacta Bioscience Inc. in Monrovia, California, uses donations to make a human milk fortifier costing as much as $10,000 per hospital stay for a premature infant. Nonprofit U.S. milk banks report they did as much as $9 million in sales last year.

These groups screen donors and test and treat the milk. About 3 percent of 1,019 potential milk bank donors screened positive for antibodies to diseases such as HIV, syphilis, and hepatitis, according to a 2010 study in the Archives of Disease in Childhood Fetal and Neonatal Edition.

Online sales don't ensure such safeguards, creating 'significant risks,' according to a call to action issued by Surgeon General Regina Benjamin that said the safety of human donor milk should be reviewed and clinical guidelines drafted for its use.

The U.S. Food and Drug Administration recommends against feeding babies breast milk sold online or acquired directly from individuals or through the Internet. The agency lacks the authority to regulate breast milk sales and donations, said Sandy Walsh, a spokesman for the agency, in an e-mail.

Activists disagree, saying breast milk leads to healthier babies and that there's no evidence infants are getting sick from shared milk.

Some women post on sites and Web pages that restrict ads to donations and directly wet nursing another infant. Others opt to sell. The website Only the Breast features ads such as "Mommy Ready to Share!" "College Professor with LOTS of Milk!" "00 Ounces for $675." The site also sells to men and includes a section for mothers offering to wet nurse, with such posted prices as $100 to $250 a week.

More than 9,000 mothers are sharing milk through the site, and about 80 percent seek compensation, according to Only the Breast.

Buyers include women who don't have enough of their own milk to breastfeed or people with medical issues, such as double mastectomy or breast-reduction surgery. The site is also used by adoptive and gay parents.

The demand is a sign that more parents are aware of nursing health benefits, according to some website founders. Advantages include babies with fewer instances of ear infections, pneumonia, obesity, and meningitis, according to the American Academy of Pediatrics, which recommends infants be breast fed exclusively for six months.

Breast milk acquired online may unwittingly expose babies to bacteria and diseases such as hepatitis, and HIV, said Richard Schanler, chairman of the American Academy of Pediatrics' breast feeding unit and a neonatologist at North Shore-Long Island Jewish Hospital System in New York.

"I can't understand why anyone would want milk that way. The women could be using illicit drugs, medications, or have some diseases," he said in an interview.

The 2010 journal study that found about 3 percent of potential donors screened positive for disease antibodies concluded that casual sharing may bring "significant risk" from unscreened donors.

Donors have been forthcoming, answering questions about their personal health and habits, said Piper Scott, 32, of Charles County, Maryland. Her milk supply never developed, so she went online and found donated milk for her five-month old daughter, Freya.

"I had reservations," Piper said in an interview. "I asked questions like how much do you drink  I felt very comfortable."

Safety warnings come from a patriarchal system that devalues women, said Emma Kwasnica, a breast feeding activist who founded Human Milk 4 Human Babies Global Network, which has 130 community pages on Facebook where mothers post offers to share milk for free. She said U.S. agencies should develop guidelines for safe sharing, not just issue warnings.

"There's a fear of women's bodies,"said Kwasnica, of Vancouver. "Communities of moms look out for each other. They're getting donations from moms who are breastfeeding their own babies."

The network doesn's accept liability for outcomes associated with sharing breast milk, according to its site.

Prolacta Bioscience's product derived from human breast milk is regulated by the U.S. because it's considered infant formula, said Scott Elster, chief executive officer, in an interview.

Prolacta has its own affiliated milk banks, including one named Milkin'Mamas, where mothers with excess supply donate. The surplus is turned into a human milk fortifier for premature infants in neonatal intensive care, with costs paid by the hospital or insurance.

Mothers are pre-screened for diseases and the milk is tested, said Elster. About 70 hospitals use the product and sales doubled from 2010 to 2011, he said.

The surgeon general report in January called for a study to examine models for U.S. regulation of milk banks. Such oversight would legitimize human milk sales and donations, said Pauline Sakamoto, executive director of Mothers?Milk Bank in San Jose, California, in an interview.

"It's going to take one child to die for someone to do something about this," she said.