New research points to possible damaging effects of two chemicals, often used in cosmetics and sunscreen, on the DNA of cells with estrogen receptors, such as breast cells. The chemicals in question are benzophenone (BP-3) and prophylparaben (PP). The first is mostly used in sunscreen, cosmetics and lotions. PP is a preservative that prevents bacterial decay in food, cosmetics and other skincare products.
In the United States, PP is allowed in a maximum concentration of 0,1% in food, however, for care products, there is no specific limit. In Europe, PP is banned for use as a preservative in food and allowed for a maximum concentration of 0,4% in personal care products.
Previous studies on the influence of these chemicals on the development of cancers showed no risk of exposure to PP or BP-3 to the development or acceleration of cancers. PP and BP-3 had to be present in a very high concentration for it to be harmful. However, the research by dr. Majhi and colleagues showed that a low concentration of PP or BP-3 can already damage the DNA of cells with estrogen receptors, such as breast cells in the mammary gland.
In this study, the effects of PP and BP-3 were tested in mice, as well as cultured human breast cells. These received four days of either a low dose BP-3, PP or a control substance (such as an oil). The cells and mice who received BP-3 or PP developed more often mutations in the DNA of the breast cells than cells and mice who received the control substance.
These DNA mutations may cause a greater risk of developing breast cancer. However, this first needs to be confirmed with more research. The present study did not show a direct risk of using products with these chemicals on developing or accelerating breast cancer. Sunscreen is still an effective product to prevent melanoma, and is therefore important to keep using.
The researchers stated that there will probably a smaller subset of people who will have to start avoiding these chemicals. This group might consist of women with a high risk of developing breast cancer or those who have a history of estrogen receptor-positive breast cancer. It is also important to note that these effects of BP-3 and PP-3 have not have been tested directly in humans, only in cultured cells and mice. These results can therefore not be directly translated to the working in actual human being. Further research will have to show whether low concentrations of BP-3 and PP will actually pose a risk for developing or accelerating breast cancer for high-risk individuals.
Majhi PD, Sharma A, Roberts AL, et al. (2020). Effects of Benzophenone-3 and Propylparaben on Estrogen Receptor–Dependent R-Loops and DNA Damage in Breast Epithelial Cells and Mice. Environmental Health Perspectives, 128(1), 017002.