You’ve probably heard about the hormone being used to increase milk production in dairy cows. Its re­cent approval by the Food and Drug Administration has pro­voked intense opposition, with some consumer groups charging that it will poison cows as well as people. But the critics have it all wrong. Far from posing a threat, this hor­mone actually makes nature's most perfect food a little safer.

The hormone is bovine somatotropin (BST), which is pre­sent naturally in all cows and—in minute amounts—in all milk. BST is made by the cow's pituitary gland {the pituitary gland only makes very small amounts of hormones--jk} hormones to stimulate the animal to produce milk after giving birth. Injecting a cow with genetically engineered BST (sometimes referred to as recombinant bovine growth hormone, or rBGH) does not change the composition of the milk in any way. Even the amount of BST in the milk stays the same. The only differ­ence is that the cow produces 10% to 20% more milk than she did before. That's good for dairy farmers, who can get the same amount of milk with fewer cows, less feed and less ani­mal waste. But it's also good for milk drinkers—not because of what's in milk from BST-treated cows but because of what isn't, namely antibiotic residues.  {Secondly, cheaper milk means the greater consumption of all dairy products—jk}

The anti-BST argument was highlighted in a recent full-page ad in The New York Times paid for by an organization called the Pure Food Campaign, headed by anti-biotechnology activist Jeremy Rifkin: "Studies have shown that BST-injected cows suffer from in­creased udder infections," the ad­vertisement said, "so cows on BST are also likely to be shot up with larger doses of antibiotics [their italics], which may also find their way into your milk, butter, ice cream, cheese and yogurt, with un­known long-term effects."

Antibiotics in milk are a legiti­mate concern. Some people are al­lergic to certain antibiotics and could react to milk contain­ing them. More important, many experts worry that antibiotics are losing their effectiveness against infections. If a person drinks milk laced with antibiotics, the thinking goes, bacteria living in that individual could conceivably develop resistance to the antibiotic; such a person might even­tually need higher doses of that antibiotic, or different ones entirely, to fight off those resistant bacteria.

The second critical argument is that anything that results in more milk—better feed or improved breeding, as well as use of BST—will increase a cow's risk of an udder infection, or mastitis. Since her teat canal remains open longer due to greater milk outflow, there's a greater chance that bacteria can get inside and cause an infection.

Yet BST's role in causing mastitis is minimal compared with other things happening on a farm. The shift from winter to summer, for example, has nearly a tenfold greater impor­tance than BST as a mastitis risk fac­tor, because summer's warmth and dampness encourage bacteria growth. Parity—how many times a cow has given birth—has 6.5 times as great an impact as BST on mastitis risk (she's least vulnerable after her first calf). Even the type of bedding a cow uses—sand is best, sawdust worst—is three times as important as BST in causing mastitis.

Contrary to what opponents claim, BST's small contribution to mastitis risk should not increase antibiotic use. In fact, milk from BST-treated cows should contain lower antibiotic residues than milk from untreated cows.  Here's why: Without BST, milk output peaks about 30 days after a cow gives birth and gradually declines over the next nine months, for a lactation period totaling about 10 months. To keep the milk flowing, farmers see to it that their cows give birth about every 12 months. Use of BST significantly lengthens a cow's lactation: She'll give milk for 12 months after giving birth rather than 10. So farmers who use BST aren't in such a hurry to get their cows pregnant again, and they typically extend the calving interval from 12 to 14 months.  This becomes important when you consider that 75% of bovine health problems—including up to half of all cases of mastitis—occur in the first 60 days after a cow gives birth. In a BST-treated herd, with its longer calving in­terval, fewer cows will be in that vul­nerable 60-day period at any given time. So you'd expect fewer cases of mastitis in BST-treated herds—and that's ex­actly what you get.

Although BST was only recently ap­proved in the U.S., researchers have been testing it on selected herds in this country and in Europe for the past eight years. A study of more than 3,000 cows in the U.S. and Europe, published this July in the Journal of Dairy Science, looked at mastitis in both BST-treated and untreated cows. For every 1,000

quarts of milk produced, there were slightly fewer cases of mastitis in the higher-yielding BST-treated cows. Less mastitis obviously means a lower risk that antibiotics will end up in milk.  Moreover, BST could actually help eliminate mastitis—and the need for antibiotics—by motivating farmers to clean up their herds. "It's common knowledge among dairy farmers that BST will raise milk production only in cows that are healthy and free of masti­tis," says Dr. Dale Bauman, a nutri­tional biochemist at Cornell Univer­sity's College of Agriculture and Life Sciences in Ithaca, N.Y. If farmers want the economic benefits of using BST, he adds, "they'll first have to rid their herds of mastitis by improving their milking practices and the mam­mary health of their cows."

Last November the Clinton adminis­tration assembled a team of 40 special­ists from seven federal agencies to re­view the scientific evidence on BST. Its report, issued this January, found "no evidence that BST poses a health threat to humans or animals" and called BST "the most examined animal drug ever approved for use in the U.S."

The federal report also listed several benefits from BST's use, including:

• Improved water quality. Manure runoff from farms into waterways is a major source of water pollution. "With increased milk yield per cow," the re­port said, "the production of a given quantity of milk would require fewer cows, and hence generate less manure."

• Less methane pollution. Cows and their manure produce significant amounts of methane, a gas that con­tributes to global warming. Fewer cows and less manure due to BST will mean lower methane emissions.

• Cheaper milk. With use of BST, consumer costs for milk between 1994 and 1999 will decrease between $44 million and $770 million a year "due to higher quantities produced and de­creases in milk prices."

• More milk for food programs.   By reducing the retail cost of milk, BST will allow the federal Special Supplemental Food Program for Women, Infants and Children (WIC) to serve more people. BST will also lower the cost of milk and dairy products for other food programs.

• Benefits to small farmers.  BST's opponents claim that use of the hormone will favor large milk producers and put small ones out of business. But using BST requires no major capital outlays or equipment, which "should make it equally accessible to managers of small and large herds."

The activists trying to discredit BST may have a larger tar­get in their sights: the coming biotechnology revolution in agriculture. Get the public scared of BST, they may be rea­soning, and people will fear the many other products now approaching store shelves, such as the Flavr Savr tomato.

If you're really concerned about antibiotic residues in your milk—and about saving money, reducing pollution, feeding the needy and helping small farmers—you'll ignore those pro­liferating bst-free labels. Buying a quart of milk from BST-treated cows is not only an investment in good health but also a vote against the fearmongers. •

Larry Katzenstein is a Senior Editor at american health.

KEEPING ANTIBIOTICS IN PERSPECTIVE

Charges that use of BST will raise antibiotic lev­els in milk have obscured an important fact: Milk, the most rigorously inspected of all foods, is intensively monitored for antibiotic residues. Farm­ers who sell antibiotic-tainted milk soon find them­selves out of business.

Antibiotics are used sparingly on dairy cows. Strin­gent control measures begin on the farm, where any dairy cow being treated with antibiotics is taken out of circulation. Her milk won't be sold until the antibiotic is well out of her system.     When the tanker truck makes its rounds to pick up milk, the driver must remove a sample of each farm's milk before pumping it into his truck. Federal and state laws require that milk from every tanker truck be tested for the presence of antibiotics upon arrival at the milk-processing plant. Extremely sensitive tests can detect a broad range of antibiotics.  If the milk tests positive, the entire truckload is dis­carded and all samples are tested to identify which farm's milk contained the antibiotics. The offending farmer must pay for that truckload of milk—typically about $6,000. A farm guilty of three violations within a 12-month period loses its license to sell Grade A milk and is effectively out of the dairy business.

The monitoring program is clearly deterring antibiotic misuse. All milk in the major dairy state of New York, for example, was found free of antibiotic residues in 1992 and 1993. —L.K.