At various points during this series, I’ll post about issues surrounding food and agriculture to offer a more complete picture of the problems (and solutions) related to our current food system. Today, we’re going to talk about hormones.
We all have hormones – humans and all other animals. These chemicals are produced naturally in our bodies and circulate through our bloodstream to regulate and balance the work of our cells and organs. As far back as the 1930s, researchers noticed that cows injected with material from cow pituitary glands (a hormone-secreting organ) produced more milk. They also realized then that estrogen helped cattle and poultry grow faster. In the 1950s, a synthetic estrogen called DES was used to fatten cattle and chickens, then was phased out in the 1970s because it was found to cause cancer.
Today in the United States, cattle and dairy cows are still administered hormones to make them grow faster or produce more milk. In 2007, 34.3 million heads of cattle and 758,100 calves were slaughtered for beef in the United States, with approximately two-thirds having been regularly administered hormones either through an ear implant or in their feed. In addition, about one third of all dairy cows are routinely injected with rBGH, a genetically engineered hormone used to make cows produce more milk. Although the United States Department of Agriculture (USDA) and the Food and Drug Administration (FDA) state that these hormones are safe, there are continuing questions, growing concern and controversy about the routine use of added hormones in food animals.
There are six hormones administered to beef cattle (as well as sheep), three natural (estradiol, progesterone, and testosterone) and three synthetic (zeranol, trenbolone acetate, and melengestrol acetate). According to the European Union’s Scientific Committee on Veterinary Measures Relating to Public Health (SCVPH), when the naturally occurring hormones are given to cattle, their hormone levels increase 7 to 20 times. The SCVPH questioned whether hormone residues in meat from these animals can disrupt the hormone balance in humans, and concluded that “no acceptable daily intake could be established for any of these hormones.” They also concluded that people who eat meat with added hormones are at greater risk for certain cancers and some types of hormonal imbalances. As a result, the use of hormones to promote growth of farm animals has been prohibited by the European nations for more than two decades. Not so, however, in the United States.
Up to one third of all dairy cows in the U.S. are injected with a genetically engineered hormone called rBGH, or recombinant bovine growth hormone (also known as rBST or recombinant bovine somatotropin). (Some estimates have the figure down to about 17% now, in the face of widespread consumer protests.) rBGH is injected into dairy cows to make them produce more milk. The artificial hormone also makes cows more prone to illness, such as mastitis, a very painful udder infection that can lead to pus getting into milk, This increased risk of illness can lead to increased antibiotic use on cows treated with rBGH, resulting in more antibiotic residues in the milk we drink and dairy products we consume, potentially contributing to an increase of antibiotic-resistant bacteria.
rBGH was approved in the United States in 1993, but has been controversial ever since farmers started using it. The European Union, Japan, Australia and Canada have all outlawed its use.
