The most common group of chemical preservatives that are in cosmetics and deodorants has been found in human breast cancer tissue.
Although the discovery links breast tumors and this group of chemicals, called parabens, it is not clear what the relationship is and whether the use of these products might be hazardous.
The US Food and Drug Administration (FDA) has called parabens the most widely used preservatives in the United States. They are common in shampoos, foundations, facial masks, hair-grooming aids, nail creams and permanent-wave products.
Previous studies on animals and in the laboratory have shown that parabens can mimic the actions of the hormone estrogen. That has raised red flags because estrogen is known to fuel breast cancer.
The latest, apparently groundbreaking, research takes those findings one step further.
"We have always been assured that parabens could not get into the body. This study shows that they do. To my knowledge, no one else has done that," says Philippa D. Darbre, lead author of the study and cancer specialist at the University of Reading, England.
RESULTS CAN'T BE IGNORED
"It's preliminary but I think that it's a little worrisome. And I think there's definitely enough data here to suggest that more work needs to be done to look at this issue," adds Dr. Bert Petersen, a breast surgeon and former director of the Family Risk Program at Beth Israel Medical Center in New York City. "I don't think it can be dismissed."
Darbre has been studying breast cancer for 20 years, but could not get funding for a study on parabens.
"I was told that I wouldn't find anything," Darbre recalls. So, she galvanized friends and colleagues in the medical community, who helped her gain access to analytic machinery and to breast tissue.
Eventually, Darbre was able to analyze samples of 20 human breast tumors with high-pressure liquid chromatography followed by tandem mass spectrometry.
In four of the 20 tumors, the total concentration of parabens was more than twice the average level.
The form the chemicals were found in suggests that they entered the body topically, not orally, the researchers add.
DON'T TOSS YOUR DEODORANT..YET
Of particular concern to many people are underarm products, such as deodorants and antiperspirants, which are applied topically and absorbed through the skin.
But the Cosmetic, Toiletry and Fragrance Association defends the safety of parabens.
"There is no evidence of harm from the use of deodorants or antiperspirants. They are safe, and consumers should not be unnecessarily alarmed," according to the Association.
The study authors acknowledge that many issues need to be resolved before any definitive conclusions can be reached.
Researchers need to determine levels of parabens in normal breast tissue as well as in other parts of the body. Also, more samples should be examined.
"It would be interesting to see if women [who do not have breast cancer have very low levels of parabens," Petersen says. "Then you might start to believe maybe this isn't just an association. It might be cause and effect here."