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Volume 15, Issue 17 ~ April 26 - May 2, 2007

Got an Environmental Question? Send it to: EARTH TALK, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881. Or submit your question at: Or e-mail us at: [email protected].

From the Editors of E/The Environmental Magazine

Got Milk?

Hormones pumped into cows can end up in our glasses

What’s the deal with 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 in their pituitary glands, and traces are secreted by the animals when milked. More popularly known as bovine growth hormone, bovine somatotropinin 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 recombinant bovine growth hormone. Monsanto obtained approval to market recombinant bovine growth hormone (known by the trade name Posilac) from the U.S. Food and Drug Administration in 1993 and began offering it to interested farmers. Today, about a third of American dairy cows are injected with recombinant bovine growth hormone, which boosts milk production by about 10 percent.

But the use of recombinant bovine growth hormone 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 recombinant bovine growth hormone 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 recombinant bovine growth hormone produce more insulin growth factor-1. The Organic Consumers Association says scientists have linked high levels of insulin growth factor-1 in humans who consume recombinant bovine growth milk with breast, prostate, colon and other cancers. This suggests that our natural defenses against early cancerous cells may be blocked by insulin growth factor-1.

Controversy also surrounds the fact that there are no labeling requirements in the U.S. for recombinant bovine growth hormone. In February 2007, Organic Consumers Association, 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 recombinant bovine growth hormone. They also asked the FDA to suspend recombinant bovine growth hormone approval due to “imminent hazard.” Analysts doubt the FDA will take the request seriously, despite not knowing what problems with recombinant bovine growth hormone 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 recombinant bovine growth-hormone-treated cows is safe for human consumption. However, many remain wary and, as a result, recombinant bovine growth hormone is banned in several nations, 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 recombinant bovine growth hormone. In January 2007 Safeway announced it would go recombinant bovine growth hormone-free at both its Portland and Seattle plants. Others following suit include Starbucks, Ben and Jerry’s and Chipotle Mexican Grills.

For more information:

• Center for Food Safety:

• Cancer Prevention Coalition:

• Organic Consumers Association:

• Family Farm Defenders:

Got an environmental question? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; submit it at or e-mail [email protected]. Read past columns at:

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