Livestock in the U.S. are given hormones to increase production. Although the USDA and FDA(1) claim that these hormones are safe, there is concern that hormone residues in meat might be harmful to human health and the environment .

    There are 6 hormones used in beef production three which are naturally occurring—Estradiol, Progesterone and Testosterone—and three which are synthetic—Zeranol, Trenbolone, and Melengestrol. Two of these, estradiol, a type of estrogen, and progesterone–are considered probable carcinogens by the Toxicology Program at the National Institutes of Health. Estrogen has been linked with breast cancer in women and testosterone with prostate cancer in men.

    The question is whether hormone residues in the meat of "growth enhanced" animals and can disrupt human hormone balance, causing developmental problems, interfering with the reproductive system, and even leading to the development of breast, prostate or colon cancer.

CBS Article - Hormones and cancer

    Children , pregnant women and the unborn are thought to be most susceptible to these negative health effects. Children have relatively low natural levels of the sex hormones in their bodies so even small increases are cause for concern. "The younger you are [when exposed], the greater the risks," says Samuel Epstein, M.D., professor of occupational and environmental medicine at the University of Illinois Medical Center and founder of Cancer Prevention Coalition. Hormone residues in beef have been implicated in the early onset of puberty in girls, (the average age of menarche is now 12.5 down from 17) which could put them at greater risk of developing breast and other forms of cancer. The incidence of breast cancer has tripled in the last 50 years and this cannot be due to genetics. 

    80 percent of all U.S. feedlot cattle are injected with hormones. Despite international scientific concern, the United States and Canada continue to allow growth promoting hormones in cattle. The European Union, however, does not allow the use of hormones in cattle production and has prohibited the import of hormone-treated beef since 1988, and has banned all beef imports from the US.

    Regardless of who you choose to believe on this issue, we know for sure there are no benefits to the consumer and the only benefit to the producer is profit. Not that they shouldn't make money, but why be greedy at the possible cost of the health of your customers. Also, not to get into freemarket politics here (that'll be later) but there's no need to regulate them either. If informed and concerned consumers simply stop purchasing from them, the practice will cease to be profitable and will naturally fall by the wayside.

(show me the money) maguire clip

    Then there's rBGH (recombinant bovine growth hormone ) which increases milk production up to 5x. RGBH was developed by Monsanto (1) and was approved by the FDA in spite of strong opposition from scientists  (and here ), farmers and consumers  (and here ). The FDA (2) relied solely on a study done by Monsanto (2) in which rBGH was tested for 90 days on 30 rats. The study was never published. Monsanto (3) has influenced U. S. product safety laws permitting the sale of unlabeled rBGH milk. (Monsanto would lose billions of dollars if rBGH were banned in America.) rBGH causes mastitis (swelling and infection of the udders causeing blood and puss to leak into the milk) and other health issues in the cows necessitating more antibiotics. European nations and Canada have banned rBGH to protect citizens from IGF-1 hazards, nasty stuff.

    The bottom line never changes. You can trust that the gubment has your back and consume acceptable levels of toxins or, choose not to poison yourself. Even without the documentation, common sense says these thing can't be good for you. Organic, organic.