Chemicals Commonly Found In Shampoos May Up Breast Cancer Risk: Study

Chemicals commonly found in personal care products including shampoos, body lotions, sunscreens and cosmetics may up breast cancer risk, a new study has warned.

According to a study conducted by researchers of the University of California, Berkeley, even low doses of the estrogen-mimicking chemical called parabens can be more harmful than previously thought.

Parabens activate the production of estrogen, mimicking the natural hormone estradiol. Both estradiol and estrogens have been linked to breast cancer and reproductive problems.

While it remains unclear as up to what extent parabens might be contributing to breast cancer risk, lead researcher Dale Leitman, a gynecologist and molecular biologist at University California, Berkeley, warned that the danger may lie in parabens interacting with other agents.

"Although parabens are known to mimic the growth effects of estrogens on breast cancer cells, some consider their effect too weak to cause harm, but this might not be true when parabens are combined with other agents that regulate cell growth," says Leitman.

Study co-author Chris Vulpe said "While this study focused on parabens, it's also possible that the potency of other oestrogen mimics have been underestimated by current testing approaches."

The research claims that current tests, which measure chemical effects on human cells, study parabens in isolation and fail to consider that the chemicals could interact with other signaling molecule types in cells to increase breast cancer risk.

During the course of the study, the researchers looked at breast cancer cells expressing two types of receptors - estrogen receptors and human epidermal growth factor receptor 2 (HER2). The researchers activated the HER2 receptors in breast cancer cells with a growth factor called heregulin that is naturally made in breast cells, while exposing the cells to parabens.

It was found that the parabens trigger the estrogen receptors by turning on genes that caused the cells to proliferate. The parabens in the HER2-activated cells were able to boost breast cancer cell growth at concentrations 100 times lower than in cells that were deprived of heregulin.

The findings appeared online in the journal Environmental Health Perspectives.