Recombinant bovine somatotropin (rBST) is a synthetic version of the Bovine somatotropin (BST) hormone found in cattle. The hormone is used by many commercial dairies to increase milk production. It's been marketed under a number of names, but most consumers know it as rBST or BST. The use of rBST has met with some controversy from a variety of fronts, including the animal rights movement and some commercial dairy farmers. As a result, dairies that produce milk products without the use of rBST have begun indicating this on their labels. Though rBST has been banned in several countries, the Environmental Protection Agency in the United States has determined it to be safe to consume.
BST is a natural hormone that can be found in the pituitary glands of all cows. Researchers who studied BST in cows found that cows with elevated levels of the hormone produced more milk. They also discovered that BST extracted from one cow and injected into another would result in higher levels of milk production for the BST treated cow. Increased milk production per cow was attractive to some dairy farmers and as a result, synthesized BST was developed by recombining the DNA of bacteria to force them to produce the hormone. This synthetic BST, or rBST, was then tested in dairy cattle. In the US, the United States Department of Agriculture (USDA) determined that because rBST is a species-specific growth hormone, milk from rBST treated cows is identical to that of cows not injected with the hormone. As a result, rBST treated milk was approved for commercial sale.
Whether rBST is healthy for human consumption is disputed and because of this rBST-free labeling was initiated. In the US, this labeling was permitted only after some battling with the United States Department of Agriculture. In the end, dairies in the United States are allowed to use the rBST-free label as long as a disclaimer is included suggesting that no harmful human health effects have been linked with the hormone. This claim is contested by some scientists, who argue that further research on the hormone is needed before such a claim can be made. There is, however, some agreement within the commercial dairy industry on the use of rBST being harmful to the cows, forcing them to produce more milk than is normal and safe. They argue that the synthetic hormone can cause calcium deficiency and result in bone weakness in some cows.
Aside from the health-related controversy, some dairies are taking a more consumer-driven angle and marketing their milk production as "natural" and "humane" in order to grow a stronger, more loyal customer base — much in the same way as the egg market with "free range" and "organically-fed" chickens. These dairies figure that consumers can decide whether or not they want to consume rBST. The use of the rBST-free label has been bitterly fought by both pharmaceutical companies and mostly large-scale dairies, who would prefer that the label not be used at all. Some of them feel that the rBST-free label unnecessarily instills fear in consumers.
Many nations, including those in the European Union and Canada, have banned the use of rBST in their cattle. The European Union is more inclined to ban any use of hormones in their food supply, suggesting that they would prefer that consumers eat more naturally produced foods. Many advocates against the use of rBST point to this ban, suggesting that the United States should follow suit and disallow the use of the controversial hormone.