Updated research suggests that certain synthetic chemicals- known as parabens- may play a larger role in the development of breast cancer than was previously believed. Parabens are used as preservatives in personal care products and are found in a variety of types of products, including shampoos, cosmetics, lotions, and sunscreens. They are sometimes added to food as well. These preservatives came under fire in 2004, when a study published in the Journal of Applied Toxicology revealed that researchers had discovered parabens intact in breast cancer cells. However, critics of the study pointed out that the researchers did not look at paraben levels in healthy cells. So no baseline level for parabens in human tissues could be established.

Parabens generally continued to be considered safe for the next decade or so because they are added to products in small amounts. But updated research indicates that even low levels of parabens may cause harm when they are exposed to naturally-occurring compounds produced in the body.

The Link Between Parabens and Estrogen

Parabens are classified as xenoestrogens: synthetic compounds that imitate human estrogen by binding to and activating estrogen receptor sites in the body. That’s right- parabens may function like estrogen in the body. Estrogen is often of concern to persons with breast cancer (or a family history of it) because this hormone stimulates cells- including cancer cells- to multiply. Therefore, too much estrogen- or substances that act like it- can cause unwanted cells to proliferate.

The Relationship Between Parabens and Breast Cancer

I want to stress that a direct cause-effect relationship between parabens and breast cancer has not been established at this time. Things are rarely that simple. Until the past year or so, it was believed that parabens had only a weak estrogenic effect on cells and that they therefore did not contribute to breast cancer development. However, previous studies have only looked at how parabens interact with breast cancer cells in isolation. In contrast, 2015 study conducted at the University of California, Berkeley investigated how parabens behave around breast cancer cells when combined with other compounds that help regulate cell growth in the body. “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” stated lead investigator Dale Leitman (source).

To test this theory, Leitman and his colleagues activated human epidermal growth factor 2 receptors in breast cancer cells with heregulin (HRG), a growth factor found naturally in breast tissue, while at the same time exposing the breast cancer cells to a type of paraben called butylparaben (BP). Leitman and his colleagues found that the combination of BP and HRG together stimulated the proliferation of breast cancer cells compared to the effects of BP alone (source). In fact, the parabens that were combined with HRG were able to stimulate breast cancer cell growth at levels 100 times lower than in cells in which HRG was not introduced (source).

While all of these compounds may behave differently in the human body than they do in a laboratory, this study highlights an important fact: synthetic chemicals that are introduced into the body do not act in isolation. Rather, they interact with many of the naturally-occurring compounds produced in the body, including growth factors. This fact cannot be ignored when assessing the safety of any synthetic chemicals that are added to personal care products. As Leitman noted: “the real problem when you do studies in the laboratory is that you study one compound at a time, but in the body, that’s not the case. What you’re seeing in the body is really a combination” of the actions of a range of compounds (source).

Conclusion

It is important to remember that, although individual products may contain only small amounts of parabens, these preservatives are found in thousands of them. And most people- women especially- use several different personal care products everyday. So it is possible to be exposed to parabens from multiple products day after day. The 2004 study that found intact parabens in breast cancer cells may have had its flaws. But it did seem to indicate that parabens are not easily broken down in the body, which means it may be possible for them to accumulate in cells and tissues over time.

Further research is needed to better understand the relationship between parabens and breast cancer. But if you wish to avoid parabens, opt for products that are “paraben free,” and steer clear of products that list parabens as ingredients. They are easy to spot, as they usually contain the word “paraben” in them. Butylparaben and methylparaben are two examples. By staying away from parabens as much as possible, you can help yourself to avoid the potential risks associated with them as well.

Do you try to avoid parabens or any other synthetic ingredients? Tell us about it in the comments section.

Sources:

Leitman, Dale et al. “Parabens and Human Epidermal Growth Factor Receptor Ligand Cross-Talk in Breast Cancer Cells.” Environmental Health Perspectives. May 2016. Web. 26 September 2016.

http://ehp.niehs.nih.gov/14-09200/

Miller, Sarah G. “Chemicals in Personal Products May Stimulate Cancer More Than Thought.” Live Science. 27 October 2015. Web. 26 September 2016.

http://www.livescience.com/52593-parabens-breast-cancer-risk.html

Sanders, Robert. “Lotion Ingredient Paraben May be More Potent Carcinogen Than Thought.” Berkeley News. 27 October 2015. Web. 26 September 2016.

http://news.berkeley.edu/2015/10/27/lotion-ingredient-paraben-may-be-more-potent-carcinogen-than-thought/