Bovine Growth Hormone

Bovine Growth Hormone

by Jack Kittredge

Insulin-like growth factor I (IGF-I) is a powerful naturally occurring growth hormone found in the blood of humans and some other animals. Dairy cows injected with genetically engineered bovine growth hormone (rBGH) give milk containing elevated levels of IGF-I, and the IGF-I in milk can pass into the bloodstream of milk consumers. Bovine IGF-I is chemically identical to that of humans. Ingested IGF-I would ordinarily be broken down in the stomach, but the presence of casein in milk prevents this.

The rBGH is injected into cows every few weeks to increase milk production. On average, production is increased by 8% to 15%. In addition, the length of the cow’s lactation is increased by a few months.

Because rBGH injections can cause numerous ill effects in cows, veterinarians in Germany have refused to administer it to cows on grounds that it violates their professional code of ethics, which forbids intentional harm to animals. U.S. veterinarians have not taken a similar stand.

A study by a scientist at the University of Illinois in Chicago in 1996 suggested that IGF-I in the milk of rBGH-treated cows may well promote cancer of the breast and colon in humans who drink such milk. The study pulled no punches: "In short, with the active complicity of the FDA, the entire nation is currently being subjected to an experiment involving large-scale adulteration of an age-old dietary staple by a poorly characterized and unlabeled biotechnology product."

A study of U.S. women reported on May 9, 1998, in the British medical journal Lancet found a sevenfold increased risk of breast cancer among premenopausal women younger than age 51 with high levels of IGF-I in their blood. A study reported in Science in January 1998 found a fourfold increase in risk of prostate cancer among men with the highest levels of IGF-I in their blood. IGF-I levels are now being artificially increased in much of the cow’s milk being sold throughout the United States. These new cancer studies raise serious questions about the wisdom of allowing IGF-I levels to be raised in milk.

It will be difficult for the U.S. Food and Drug Administration (FDA) to acknowledge that milk from rBGH-treated cows might be implicated as a cause of common cancers. Historically, the FDA has maintained a very close relationship with Monsanto, the chemical company that spent a billion dollars developing rBGH. The FDA approved the use of rBGH in cows in 1993 and issued regulations that made it appear to be illegal to label milk so as to distinguish milk that is produced with the use of rBGH from milk that is not. Some of the FDA officials who approved rBGH and who established the regulations discouraging labeling had previously worked for Monsanto.

In Vermont, the state legislature passed a law requiring the labeling of milk from cows treated with rBGH. The International Dairy Food Association, widely perceived to be backed by Monsanto, brought a lawsuit against the state of Vermont, alleging that this labeling law infringed on dairies’ freedom of speech insofar as it forced dairies to speak when they wished to remain silent. A U.S. district court ruled in favor of Vermont, but the Second Circuit Court of Appeals overturned this ruling. Deciding in favor of the International Dairy Food Association, the Second Circuit ruled that the manufacturers’ right to free speech was more important than the consumers’ right to know because rBGH is not considered an additive by the FDA. Vermont’s attorney-general declined to appeal this case to the U.S. Supreme Court. The Vermont legislature fell back on a voluntary labeling law that allows dairies that do not use rBGH to display this fact prominently.

While most Americans are not provided with labeling that would allow them to recognize milk produced with the use of rBGH, scientifically credible food safety concerns have led to the banning of rBGH in Canada, the European Union, Japan, and Australia. Eleven separate surveys have shown that Americans strongly prefer to have milk from rBGH-treated cows labeled as such. The use of rBGH is prohibited under organic milk production standards.