EarthTalk: Do Hormones Given to Cows Make Milk Unsafe?

Dear EarthTalk: What's the deal with rBGH, the hormone given to cows that makes them produce more milk? Why do some groups want it banned? -- David Gray, via e-mail

Cows naturally produce bovine somatotropin (BST) in their pituitary glands, and traces are secreted by the animals when they are milked. More popularly known as BGH, or bovine growth hormone, BST interacts with other hormones in cows' bodies to control the amount of milk they produce.

In order to increase milk production, scientists working for Monsanto spent years in the lab developing a genetically-engineered synthetic version of the hormone called rBGH, or recombinant bovine growth hormone. Monsanto obtained approval to market rBGH (known by the trade name Posilac) from the U.S. Food and Drug Administration (FDA) in 1993 and began offering it to interested farmers. Today, about a third of American dairy cows are injected with rBGH, which boosts milk production by about 10 percent.

But the use of rBGH is controversial, due to potential health hazards to both cows and humans. According to the Center for Food Safety (and supported by a 2003 study published in the Canadian Journal of Veterinary Research), cows treated with rBGH suffer a 50 percent greater incidence of lameness (leg and hoof problems), 25 percent more udder infections (mastitis), and serious reproductive problems including infertility, cystic ovaries, fetal loss and birth defects.

Such animal health issues can sometimes translate into human ones, as antibiotics used to fight infection can find their way into milk, affecting our disease-resistance. Also, animals given rBGH produce more insulin growth factor-1 (IGF-1). Studies, says the Organic Consumers Association (OCA), have linked high levels of IGF-1 in humans who consume rBGH milk with breast, prostate, colon and other cancers. This suggests that our natural defenses against early cancerous cells may be blocked by IGF-1.

Controversy also surrounds the fact that there are no labeling requirements in the U.S. for rBGH. In February 2007, OCA, along with the Cancer Prevention Coalition and the Family Farm Defenders, filed a joint petition asking the FDA to require cancer risk warning labels on all U.S. milk produced with rBGH. They also asked the FDA to suspend rBGH approval due to "imminent hazard." Analysts doubt the FDA will take the request seriously, despite not knowing what problems with rBGH might arise down the road.

Monsanto maintains that humans digest so little of the hormone that it has no direct effect on our health. The World Health Organization, the FDA and numerous medical associations concur that milk from rBGH treated cows is safe for human consumption. However, many remain wary and, as a result, several nations have banned rBGH, including all 25 European Union nations, Japan, Australia, New Zealand and Canada.

In the U.S., despite lack of federal concern, consumer pressure has led many companies to discontinue the use of rBGH. In January 2007 Safeway announced it would go rBGH-free at both its Portland (OR) and Seattle plants. Others following suit include Starbucks, Ben and Jerry's and Chipotle Mexican Grills.

CONTACTS: Center for Food Safety; Cancer Prevention Coalition; Organic Consumers Association; Family Farm Defenders.

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