Estrogen-like chemical ups cancer risk in mice

NEW YORK (Reuters Health) – Exposure to the environmental
estrogen 4-nonylphenol increases the risk of breast cancer in
mice, a new study shows.

This research is another example demonstrating that
estrogen-like chemicals in the environment “have the ability to
cause cancer,” Dr. William S. Baldwin from University of Texas
at El Paso, El Paso, Texas told Reuters Health. “Whether they
really do or not is unknown.” The animals’ exposure in this
study was much higher than that encountered in the environment.

Breast cancer is the most commonly diagnosed cancer in
women and environmental factors appear to cause many of these
cases. Many of the environmental factors increase a woman’s
level of the female hormone estrogen, which is thought to be a
major contributing factor to the disease.

In the Journal of Applied Toxicology, Baldwin and
colleagues explain that 4-nonylphenol is released from cleaning
agents, textiles, paper, plastic, personal care products and
agricultural chemicals.

The team investigated the effects of 4-nonylphenol on the
incidence of breast cancer in mice susceptible to the disease.

All five mice treated with 4-nonylphenol formed breast
tumors, the researchers report, whereas one mouse in the
control group and no mice treated with the female hormone
estradiol formed breast tumors.

Treatment with 4-nonylphenol also shortened the latency
period before mammary tumor development and increased the
likelihood that breast tumors would spread to the lung.

Baldwin cautioned that the doses of 4-nonylphenol given to
the mice are “much greater than what humans are exposed to on a
daily basis.” He estimated the dose at 1000 times the level of
human exposure.

Baldwin and his colleagues plan to continue their
investigations by looking into the effects of developmental
exposures of nonylphenol on breast cancer.

SOURCE: Journal of Applied Toxicology July/August 2005.