What is rBGH (Bovine Growth Hormone)?
Growth hormones exist naturally in a dairy cow and in the milk she produces. The hormone, called bovine growth hormone (rBGH), is a determining factor in how much milk the cattle can produce. In 1993, a synthetic growth hormone was approved for use. When injected in a cow, the synthetic hormone extends the cow's lactation period, increasing her milk production by at least 10 percent. Treated cows produce more milk with less feed and less animal waste, making an entire herd as efficient as the farmer's best cow.
The risks of drinking milk from injected cows are unsubstantiated.
A leading criticism is that rBGH increases an insulin-like hormone in cows and cow milk, and that increased levels of the same hormone in humans have been associated with cancer. Cornell University's Dale Bauman, former president of the American Society for Nutrition relates, "the amount of this hormone is insignificant compared to the amount already produced in our bodies every day. We swallow it in our saliva, and the amount we swallow daily is equal to the amount of this hormone in 95 quarts of milk. The amount produced in our whole body every day is equal to the amount in 3,000 quarts of milk."
Bauman further explains - and the American Cancer Society concurs - that there is no cause and effect chain linking rBGH, high levels of IGF-1, and cancer. "In fact, elevated levels are actually to be expected (when cancer is present) because IGF-1 is involved in the turnover and repair of cells, including tumor cells."
No one has been able to determine any differences in treated cows or in their milk.
"If one cow was treated with rBGH and you tested every cow in the herd, you could not determine any difference in the milk of the treated cow. There really is no difference that can be tested," says Bauman. He and a team of nutritional biochemists analyzed over 200 herds - and over 200,000 lactations - looking for rBGH-related problems and came up empty-handed.
"We compared the five years before and the five years after rBGH was used, analyzing herds that did and did not use it. We looked at all sorts of indexes for animal health, infection, health problems, reproduction. There just were no differences. The only distinction was that in herds that used rBGH, the cows gave more milk per day and were more efficient in their use of nutrients."