Low doses of chemical preservatives widely used in cosmetics, shampoos, skin lotions and other personal care products may be linked to breast cancer, according to a new study from researchers at the University of California, Berkeley.
The preservatives are parabens, found in more than a fifth of the products in EWG’s Skin Deep® Cosmetics Database. It's been known for more than a decade that parabens, which mimic the hormone estrogen, can disrupt lab animals' endocrine systems, but some scientists argue the concentrations in people are too low to worry about.
Now the UC Berkeley study, published online Oct. 27 in Environmental Health Perspectives, argues that previous research only looked at parabens' effects in isolation. The study shows that when parabens interact with other biochemical changes in breast cancer cells, the effect is much stronger and could lead to faster, more aggressive growth of tumors and formation of malignant cancer.
According to cancer scientists, two-thirds of breast cancer tumors have a cell receptor called estrogen receptor alpha. When estrogen interacts with this receptor, it activates genes that turn normal cells into tumor cells. Earlier studies showed that parabens can have a similar effect on this receptor, but the concentration of parabens needed to activate the genes was much higher than what was found in the human body.
Berkeley researchers examined the effect of low concentrations of so-called long-chain parabens when paired with the effects of naturally occurring molecules in the body on another type of receptors, called HER. Even at low doses, a type of paraben called butylparaben worked in conjunction with activation of the HER receptor to switch on cancer genes. Researchers surmise that HER receptors increase the potency of butylparaben, making low doses more dangerous.
A growing body of research finds evidence that preservatives commonly found in personal care products can harm health. Companies are allowed to use these risky ingredients because of the weak and outdated regulations governing the cosmetics industry.
Earlier this year, Sens. Dianne Feinstein (D-Calif.) and Susan Collins (R-Maine) introduced the Personal Care Products Safety Act that would give the Food and Drug Administration more oversight in cosmetics ingredient safety. The bill would require the FDA to review five potentially risky ingredients annually, and give it the authority to ban or restrict ingredients based on these assessments. One of the first ingredients on the list is propylparaben, a relative of butylparaben.
In the meantime, consumers should avoid long-chain parabens – butylparaben, propylparaben, isopropylparaben and isobutylparaben – by reading product labels and using EWG’s Skin Deep® to find products with safer ingredients.