The main function of recombinant Bovine Growth Hormone (rBGH) is to artificially increase the milk yield of dairy cows by 10-15%. However, it has many harmful side effects.
Cows that receive rBGH injections experience higher rates of mastitis, a condition that requires antibiotic treatment.
A potent artificial hormone, rBGH has also been linked to conditions beyond mastitis, including malnourishment, hoof problems, increased pus in milk, heat stress, diarrhea and other gastrointestinal problems and disrupted fetal calf development.
Scientists have expressed concern over possible increased risks of cancer from rBGH milk.
rBGH elevates another powerful growth hormone called IGF-1, which is thought to increase breast, prostate, colon, lung and other cancers in humans. Scientific studies suggest that IGF-1 survives pasteurization and digestion, and enters the bloodstream in sufficient quantities to potentially trigger increased cancer rates.
Both Canada and the European Union have taken a precautionary approach and banned the use of rBGH in their dairy cows.
Note: The FDA has said no significant difference has been shown and no test can now distinguish between milk from rBGH treated and untreated cows.