A South Carolina doctor claims that consumption of dairy products can increase your risk of acquiring breast and prostate cancer. Dr. Robert Bibb of Myrtle Beach is working on a book, Death by Dairy, about the dangers of a dairy-consuming diet.

According to Bibb, a growing body of evidence supports his contention that the hormones found in dairy products increase the body's risk of cancer. "There's an association between dairy [consumption] and hormonally sensitive cancers," he said. "I looked, but I can't find any other factors that fit epidemiologically."

After 1948, Bibb says, rates of breast and prostate cancer in the United States began to rise sharply. Bibb attributes this to a change in the way that milk was enriched with vitamin D: From 1928 to 1948, milk was irradiated with ultraviolet rays in order to stimulate vitamin D production; after 1948, powdered vitamin D was added instead.

"My working hypothesis is that ultraviolet light incidentally inactivated the hormones and proteins in dairy - and we proved this at Clemson [University]," Bibb said.

He also notes that countries with low dairy consumption have much lower risks of the cancers in question.

Another potential culprit for the connection, according to Bibb, is recombinant bovine somatotropin (rBST), a genetically engineered version of a natural hormone that farmers inject into dairy cows to make them produce more. Studies have shown that in addition to containing the engineered hormone, milk from rBST-treated cows contains higher concentrations of insulin growth factor 1 (IGF-1).

Studies have found a correlation between elevated IGF-1 levels in humans and a higher risk of breast, colorectal and prostate cancer. In animal studies, elevated levels of the hormone have been associated with shorter lifespans and a higher risk of diabetes.

Bibb is only one of a number of scientists who are currently investigating a possible link between dairy products and cancer -- a link that has been suspected for more than 30 years. Dr. Sam Epstein, author of What's In Your Milk also covers the story on rBGH in great detail, revealing astonishing scientific facts about the health effects of milk produced with genetically modified hormones.