OSU studies risk related to beef consumption.(Ohio State University)

2002 NOV 7 - (NewsRx.com & NewsRx.net) -- Scientists concerned that a growth promoter widely used in the U.S. cattle industry may increase the risk of breast cancer are launching the first-ever study comparing beef consumption with elevated levels of zeranol in women's blood, urine and breast tissue.

"We want our patients to know that we have no evidence suggesting that eating beef in any amount is dangerous," said Dr. William Farrar, a breast cancer specialist at the Arthur G. James Cancer Hospital and Richard J. Solove Research Institute and a coleader of the study. "But we are very interested in discovering any relationship between residual zeranol and enhanced estrogenic activity in the breast. There is a lot to sort out here; this is just the first step."

Zeranol is commonly used throughout the cattle, veal and lamb industry in the United States. It is produced from the mold of a fungus often found in cereal and animal feed, and manufactured as a pellet that can be implanted under the skin of an animal's ear. Cattle growers use zeranol to help fatten the animals more quickly, create a higher lean-to-fat ratio and to develop meat with more flavor. Although zeranol has been found to be biologically active in stimulating breast cancer cell growth, the U.S. Food and Drug Administration said it is safe to use in tiny amounts in young cattle and lambs.

It is a practice that concerns Dr. Young C. Lin, a veterinarian in the Ohio State University Comprehensive Cancer Center and a coleader of the study. Lin pointed out that zeranol, although a synthetic nonsteroidal agent, acts like estrogen in the body. He said early laboratory studies suggest that zeranol, like estrogen, stimulates estrogen-modulated genes that can affect the growth of human breast cancer cells.

"We think this may be important, because some studies suggest that the more unopposed estrogen a woman is exposed to over her lifetime, the greater her chances of developing breast cancer," said Lin.

Lin said the key question is, does long-term, low-level exposure to zeranol add to that risk, or not?

"We have examined the impact of zeranol on the breast tissue of rats - and on human breast cancer cells, as well," said Lin. "Our research shows that even in very small amounts - levels 30 times ...