Other concerns include health problems for the injected cattle, such as mastitis, udder inflammation and consequent lameness due to overenlarged udders. According to a Canadian committee report in 1998, use of rbST increased the risk of mastitis by up to 25%, of infertility by 18%, and of lameness by up to 50%. Humans who have too much growth hormone develop a disease called acromegaly (enlargement of hands, feet, and face), and some speculate that it is no more healthy for cows to have too much growth than it is for humans.

Monsanto, a corporation known for its promotion of genetically modified food, created the synthetic hormone which is a "recombinant bovine somatotropin" (rbST), and also goes by the brand name Posilac®. The FDA approved Posilac's use in 1993 in one of the most oft-criticized decisions in its history because agency employees with former ties to Monsanto were involved.

The product is now sold in all 50 states. According to Monsanto, approximately one third of dairy cattle in the U.S. are injected with Posilac — approximately 13,000 dairy producers use the product. It is now the top selling dairy cattle pharmaceutical product in the U.S. The FDA does not require special labels for products produced from cows given rbST.

According to Monsanto, milk and meat from cattle supplemented with rbST are safe. Monsanto also states that the only difference between milk from supplemented cattle and unsupplemented cattle is the amount of IGF1—and that there is not even a difference in the concentration of bST.

Recently, the Tillamook County Creamery Association, a large group of diary farmers in the U.S., voted to stop using the growth hormone in its diaries, due to pressure from its customers. But it was not without a legal battle with Monsanto — more details about this story can be found here.

[by Justin Thomas]