A densely-worded, 11-page assessment reaffirms the safety of BST use in dairy cows. The report, funded and sponsored by Elanco, was released this week at the American Dairy Science Association annual meeting in Montreal.
The assessment, conducted by four medical doctors and five Ph.D. scientists, cites some 66 research papers on BST, including work that was done both before and after BST was approved for use in U.S. lactating dairy cows in 1993. Dale Bauman, a Cornell University dairy scientist, and Steve Nickerson, a mastitis researcher at the University of Georgia, were part of the assessment team.
The assessment's conclusion: "Milk from rbST-supplemented cows has been a part of the U.S. food supply since receiving FDA approval over 15 years ago and its use has not been associated with any scientifically documented detrimental effects on human health.”
The safety assessment delves into common questions about rBST, including accusations that it is responsible for early on-set of puberty in girls, increased rates of breast cancer in women and increased levels of insulin-like growth factor-1 (IGF-1) in milk that lead to increased rates of cancer:
• On-set of early puberty: Researchers began noticing earlier onset of puberty in girls starting in 1940, showing a constant rate of decline of about two months per decade since that time. Results of more recent studies done since 2005 and after rBST was approved "do not show any change from the rate of decrease in the age of menarche when compared to the 50 years of studies that preceded this more recent analysis.
• Breast cancer: Breast cancer rates have actually declined since rBST was introduced, and 52 studies have concluded no association between dairy product consumption and the risk of breast cancer.
• IGF-1: The authors concede that IGF-1 levels in milk from rBST-supplemented cows is slightly higher than non-treated cows. But the authors say: "Even if the content of the IGF-1 in the milk is increased two-fold after rBST, the amount of IGF-1 contained in the daily recommended amount of milk would be less than 1% of the amount that is present in intestinal secretions and less than one ten-thousandth of the that produced by the human body.”
The authors also cited both environmental and economic savings with the use of rBST. They note that six cows supplemented with rBST can produce as much milk as seven unsupplemented cows, which means one less cow is consuming feed and water and producing manure. "If just 15% of the U.S. dairy herd was supplemented with rBST, the environmental gains of this reduction in the environmental impact would be equal to that produced on 540,000 acres of farmland, a reduction in enough fossil fuel to heat 15,000 homes and a reduction in water sufficient to supply 10,000 homes.”
Finally, the authors argue that the use of rBST offer economic benefits to consumers as well. Withdrawal of the product would increase milk prices 6¢ to 12¢/gal and cheese prices 7.5¢ to 15¢/lb. If only 20% of the nation's cows are supplemented with rBST, the annual savings to U.S. consumers would be approximately $400 million.