Ask the Doctors

Dear Doctor: Like millions of other women, I've always slathered myself with moisturizers and creams without paying any attention to the ingredients. But recently I read that the parabens found in these products have also been found in breast tissue. Should we rethink our use of these creams?

Dear Reader: That's a smart question to ask. Before we explore the data, let's take a look at what parabens are and what they do. These are chemicals used as preservatives in commercial moisturizers, shampoos, shaving gels, sunscreens and makeup. They were first used nearly 100 years ago to preserve drug products and are still used to preserve drugs applied to the skin, injected into veins and taken by mouth. Lastly, parabens are used as a preservative in multiple food products.

Parabens are good preservatives because they have antibacterial properties as well as activity against yeast and molds. They also don't allow water to enter or break down the product they are preserving. Parabens are relatively inexpensive to make and are considered generally safe for food consumption by the Food and Drug Administration and European Union.

The widespread use of parabens, however, leads to their deposit in unintended places. Parabens are found at various concentrations in indoor dust and air. The potential health effects are more concerning in children than in adults, because their ingestion rate of parabens from dust is five to 10 times higher. In addition, parabens can end up in wastewater, ultimately sending them into the water supply, agricultural soil and fish, which leads to higher paraben exposure through consumption of fish and food products. One good aspect of parabens is that they are quickly eliminated from the body, so it is less likely they will build up over time.

As for the health effects, the primary concern is about parabens' effect on sex hormones. Parabens can bind to estrogen receptors in the body, meaning they have an estrogenlike effect that could potentially raise breast cancer risk and impact fertility. They also can bind to testosterone receptors, potentially affecting male fertility as well. In rats, very high doses of parabens decrease levels of estrogen and testosterone and cause menstrual irregularities in females and alterations in sperm counts in male.

A study of 501 couples actively attempting pregnancy in Michigan and Texas supports concern over parabens. Researchers measured urinary levels of parabens in both men and women and found that women with the highest amounts of parabens in their urine had a 34 percent reduction in pregnancy compared to women with the lowest amounts in the urine.

Parabens have been found in both breast tumors and in the breast tissue adjacent to tumors. This doesn't mean that parabens cause breast cancer, but it also doesn't mean we should simply call them innocuous.

Also, in humans, higher levels of parabens in the urine have been associated with lower levels of thyroid hormones, although this potential link is clouded by the fact that women use more parabens than men and also have more thyroid problems. Lastly, parabens applied to the skin, in combination with UVB light, can increase the risk of skin damage and possibly skin cancer.

In short, parabens at current human exposure may not cause harm. But with greater use and with greater accumulation of parabens in our food and water supply, we should all ask questions about their future health effects.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

More like Ask the Doctors