Parabens in Shampoo and Body Lotions Linked to Breast Cancer

Researchers at the University of California, Berkeley, report that shampoo and body lotion ingredients known as parabens may be linked to breast cancer. Although previous studies had looked at the impact of parabens alone, it now appears these chemical preservatives interact with other bodily changes, which makes them more dangerous.

Parabens are commonly used in cosmetics and personal care items to protect against microbial growth and maintain the integrity of the products, according to the Food and Drug Administration. These substances are also classified as xenoestrogens, synthetic compounds that mimic the activity of estrogens by attaching themselves to and activating estrogen receptors, activity that has been associated with an increased risk of breast cancer.

It is common to see more than one paraben in a product, which is done to help guard against a variety of microorganisms. Some of the many forms of parabens you will see listed on personal care item ingredients panels (beyond shampoos and body lotions) include methylparaben, butylparaben, ethylparaben, and propylparaben.

Although the FDA is aware that parabens have estrogen-like activity, “they have been shown to have much less estrogenic activity than the body’s naturally occurring estrogen,” and the preservatives are used at very low levels in personal care products, according to the agency. This combination of low activity and low levels has served as the FDA’s reason not to be concerned about parabens in cosmetics and health care items.

New study of parabens and breast cancer
The new study, however, reveals that when parabens hook up with biochemical changes that occur in breast cancer cells, the impact is augmented and could result in more aggressive tumor growth and development of malignant breast cancer. To reach this conclusion, the researchers examined the effect of long-chain parabens plus the effects of naturally occurring molecules on breast cancer tumor cell receptors called HER2 (human epidermal growth factor receptor 2).

HER2-positive tumors usually grow and spread more vigorously than other types of breast cancer. About one-quarter of breast cancers make large quantities of HER2.

The scientists activated the HER2 receptors in breast cancer cells using heregulin, a growth factor made in breast cells, at the same time they exposed the cells to parabens. They discovered that the parabens had a significant impact—they triggered the estrogen receptors by switching on genes that then caused the cells to reproduce, and the concentration of parabens necessary to cause this activity was 100 times lower than in cells that were not exposed to heregulin.

The findings led the scientists to assume that HER receptors have the ability to boost the potency of butylparaben, which means low doses of this paraben are more hazardous than previously believed. Co-author and toxicologist Chris Vulpe noted that although the study focused on parabens, “it’s also possible that the potency of other estrogen mimics have been underestimated by current testing approaches,” which means there’s a lot more work to be done to uncover the effect of parabens and other chemicals lurking in shampoos, cosmetics, and other personal care items.

Sources
Food and Drug Administration. Parabens
Pan S et al. Parabens and human epidermal growth factor receptor ligands cross-talk in breast cancer cells. Environmental Health Perspectives 2015 Oct 27