An antibacterial chemical commonly used in soaps, toothpaste, and other consumer goods has been linked to breast cancer, in new laboratory research.
 

The study is the latest to raise concerns about the antimicrobial agent triclosan, which some manufacturers have stopped using amid growing scientific evidence that it may pose health risks.
 

The new research, published in the American Chemical Society journal Chemical Research in Toxicology, found that triclosan, as well as another commercial substance called octylphenol, promoted the growth of human breast cancer cells in lab dishes and breast cancer tumors in mice.
 

Lead researcher Kyung-Chul Choi and colleagues noted hormonal imbalances seem to play a role in the development of breast cancer and endocrine-disrupting chemicals – such as triclosan – might spur cancer cell growth. Triclosan and octylphenol – used in some paints, pesticides, and plastics – have accumulated in the environment. In addition, triclosan is reportedly in the urine of an estimated 75 percent of Americans.
 

In tests on human breast cancer cells and mice, the scientists found that both agents interfered with genes involved with breast cancer cell growth, resulting in more cancer cells.
 

"Although the doses of EDCs were somewhat high, we did this to simulate their effects of daily exposure, as well as body accumulation due to long-term exposure, simultaneously in animal experiments," said Choi. "Thus, exposure to EDCs may significantly increase the risk of breast cancer development and adversely affect human health," the researchers state in the paper.