Cows treated with rBGH show an increase in lameness (50%), udder infections (25%) and serious fertility problems. To counteract the udder infections, which raises the pus in the milk by 20%, farmers administer antibiotics to the cows.

The antibiotics are absorbed into the cow's blood and milk and also accumulate in the waste runoff that subsequently drains into nearby water systems. The runoff from feedlots then ends up in the local waterways near the farm and has had negative consequences for the local ecology.

Mutations in fish have become commonplace near dairy farms. For instance, biologists have found female fish with male characteristic mutations and male fish with female characteristic mutations. Scientists believe that the growth hormone may play a part in this development.

In terms of human consumption, when people consume the same antibiotics consistently it allows for antibiotic resistant bacteria to develop.

So, if one were to consume a certain level of antibiotics in their milk consistently over time, then that type of antibiotic would have less or no impact when needed to treat a human bacterial infection. This undermines the usefulness of antibiotics used to treat human bacterial infections.

One of the hot button issues surrounding dairy production is the increased levels of a hormone called "insulin-like growth factor-1" (IGF-1) found in cows treated with rBGH. IGF-1 has been proven to promote cell division, a necessary precursor to cancer. It has been traced in elevated amounts to cows that are treated with rBGH.

IGF-1 can survive the digestive process, meaning it can be transferred from the cow's milk to humans. It can survive stomach acids and then continue on through the intestines and be absorbed by the body into the bloodstream. IGF-1 has been a factor in terminal illnesses like breast, prostate and colon cancers.