New York state dairy farmer John Bunting doesn't use an artificial bovine growth hormone on his cows for one key reason. He doesn't want them getting sick. "I care about my cows," he said, "I like my cows."

The growth hormone in question is made by the Monsanto Company. The current debate about Monsanto's hormone involves labels. The multinational agricultural biotech company seems to be getting nervous about the prospect of telling consumers what's in their milk - or rather, what's not in their milk.

A Monsanto-backed advocacy group is now going from state to state, fighting labels that declare dairy products free from the bovine growth hormone. Monsanto is the only producer of an artificial hormone, the Posilac brand recombinant bovine somatotropin (rBST or rBGH), that increases milk production in cows. Labels saying "rBST-free" could lead to financial losses for the corporation.

(Matt Mahurin) The growth hormone can mean more milk at cheaper prices. But Posilac has been linked to health problems in both cows and humans -- one reason the European Union and Canada both banned its use. Anti-labeling measures by Monsanto are facing a backlash from consumers who want to know what goes into their milk. Labeling would alert many to the fact that a large majority of American dairy products come from cows injected with the hormone. Many dairy processors are now using rBST-free alternative to meet these growing consumer concerns, for the hormone has been linked to cancer and other problems. Yet it doesn't look like the FDA-approved synthetic hormone will be pushed out of the market any time soon.

The advocacy group making the argument for Monsanto is American Farmers for the Advancement and Conservation of Technology (AFACT) -- an organization that gets at least some financial backing from Monsanto. AFACT was established in 2007 by the consultant Monty G. Miller of the Colorado firm International Performance Solutions, whose client list includes Monsanto. In launching AFACT, Miller received help from the public relations firm Osborn & Barr, whose CEO, Steve Barr, is a former Monsanto marketing executive.

AFACT has been pressuring state agriculture departments and state legislators to introduce bills that would restrict hormone labels. Bills restricting "rBST-free" labels have popped up in several state legislatures -- including Kansas, Utah, Indiana and Missouri. In Pennsylvania and New Jersey, similar pro-hormone bills have already been voted down.

Most of the nation's leading dairy processors use milk from cows treated with the bovine growth hormone in at least some products. Land O'Lakes, Good Humor-Breyers, Dreyers, Dannon, Yoplait and Sargento are some of the biggest buyers of milk from rBST-treated cows. Dean Foods and Kraft, the leading U.S. dairy producers, use rBST milk in many products, but not all. In June, Kraft will introduce a line of rBST-free 2-percent milk products.

Kraft spokesman Basil Maglaris says the company is responding to a growing consumer movement. "We do understand that some consumers -- not all -- are looking for products from cows not treated with [rBST]," said Maglaris. "So we are converting the line to give those consumers an option."

Converting the line will mean an increase in price for those 2-percent products. But Kraft says that rBST-free products will attract new customers.

Many of those customers are pointing to related health concerns -- for both cows and humans. According to Oregon Physicians for Social Responsibility, rBST increases the risk of cancer by elevating levels of another hormone, IGF-1. High levels of IGF-1 can promote breast cancer, prostate cancer and colon cancer.

"If you have even just subtle amounts of IGF-1, there's a link to breast, prostate and colon cancer," said Dr. Jenny Pompilio, an internist with Kaiser Permanente in Oregon. "It's been known for years that that particular hormone is linked with cancers [because of its] effects on the endocrine system. The endocrine system is so sensitive that subtle effects can [make a difference]."

The other health concern affects first cows and then humans, says the Oregon physicians group. People who consume these dairy products could become resistant to antibiotics -- making them prone to bacterial infections. The resistance is directly related to health problems of cows injected with the hormone. These cows have higher rates of udder infections, or mastitis. When they are treated with antibiotics, resistant bacteria can grow. People who later eat dairy products from these cows can also build up resistance. When antibiotics cease to be effective, the threat of infectious diseases increases.

Monsanto says its synthetic hormone does not create problems. "POSILAC is perfectly healthy for cows," said Monsanto spokesperson Lori Hoag, "bST is a naturally occurring hormone in every cow -- rbST is an additional supplement of that naturally occurring hormone."

Hoag says that there is no difference between milk from cows injected with rBGH/rBST and other milk. "[A]ll milk is the same. All milk has bST, all milk has hormones," she said. "Labels that claim "rbST-free" are misleading to consumers, making them believe there is a difference in the milk, when, in fact, there is none."

But New York dairy farmer Bunting disagrees. He says that rBST is a whole protein off from naturally occurring BST. "If you created a molecule one protein different, you could not honestly say there could be no difference [between the two]," said Bunting. "Monsanto and the FDA are asking farmers and consumers to take a risk for which there is no known benefit."

While there may be no benefits when it comes to human health, economic gains could be great for some. Cows injected with the hormone produce roughly a gallon more milk a day than untreated cows. (On average, untreated cows produce about eight gallons a day.) That means dairy farmers can produce more milk at lower costs, and dairy processors can make their products at lower costs. Big dairy farmers, big dairy processors and Monsato all get more money.

But Bunting says that rBST poses risks to smaller dairy farms, including his own. He says big farms that use rBST to produce more milk could lead to smaller farms going under. "More milk means fewer farmers," said Bunting, "It does not benefit the [whole] farm community."

It could benefit consumers, though. Using rBST brings milk prices down. Monsanto's product therefore provides an option for people who just want less expensive milk, cheese and ice cream.

Monsanto says that labeling could be unfair to certain corporations. "[B]ecause there is no difference [between BST and rBST]," said spokesperson Hoag, "there is no way to verify whether or not rbST was used as a supplement. So, even though some processors claim their milk to be 'rbST-free,' they cannot prove that to be true."

The ice cream company GoodHumor-Breyers has concerns about this. "We purchase our dairy ingredients from cooperatives, and are unable to guarantee that rBGH is not used," said GoodHumor-Breyers spokesperson Andon Tate, "Currently, there is no test available that can distinguish between the naturally-occurring BST and the rBGH growth hormone."

But even consumers who don't care about the growth hormone's health effects, says consumer advocate Jill Richardson of Recipe for America, are speaking out against Monsanto's efforts to restrict dairy labeling. "Some people even say that they don't personally mind the idea of milk with rBST," she said, "but the dishonesty of this [anti-labeling] tactic makes them furious."