Parabens are used to prevent the growth of microbes in cosmetics products and can be absorbed through skin, blood and the digestive system. Parabens have been found in biopsies from breast tumors at concentrations similar to those found in consumer products. Parabens may be found in a wide variety of products including facial cleansers, shampoos, lotions, deodorants, scrubs and eye makeup, and are found in nearly all urine samples from U.S. adults regardless of ethnic, socioeconomic or geographic backgrounds. Adolescents and adult females had higher levels of methylparaben and propylparaben in their urine than did males of similar ages.

Parabens are actually several distinct chemicals with a similar molecular structure. Four of these are used frequently in cosmetics: ethylparaben, butylparaben, methylparaben and propylparaben. Methylparaben and propylparaben are the most common of these. Parabens are most common in personal care products that contain significant amounts of water, such as shampoos, conditioners, lotions and facial and shower cleansers and scrubs, in order to discourage the growth of microbes. While Cosmetic Ingredient Review recommends concentration limits for single and total paraben concentration in a single product, these recommendations do not account for exposure to parabens from several products by a single individual.
A 2004 UK study detected traces of five parabens in the breast tumors of 19 out of 20 women studied. This small study does not prove a causal relationship between parabens and breast cancer, but it is important because it detected the presence of intact parabens—unaltered by the body’s metabolism—which is an indication of the chemical’s ability to penetrate skin and remain in breast tissue. A more recent study found higher levels of one paraben, n-propylparaben, in the axilla quadrant of the breast (the area nearest the underarm). This is the region in which the highest proportion of breast tumors are found.
Endocrine disruption: One of the greatest concern is that parabens are known to disrupt hormone function, an effect that is linked to increased risk of breast cancer and reproductive toxicity. Parabens mimic estrogen by binding to estrogen receptors on cells. They also increase the expression of genes usually regulated by estradiol (a natural form of estrogen); these genes cause human breast cancer cells to grow and multiply in cellular studies. Parabens are also linked to cancer, reproductive toxicity, immunotoxicity, neurotoxicity and skin irritation. Since parabens are used to kill bacteria in water-based solutions, they inherently have some toxicity to cells.

Look for products labeled “paraben-free” and read ingredient lists on labels to avoid products with parabens. Many natural and organic cosmetics manufacturers have found effective alternatives to parabens to prevent microbial growth in personal care products. Some companies have created preservative-free products that have shorter shelf lives than conventional products (six months to a year), but if used daily are likely to be used up before they expire. Read labels and protect your family from the accumulation of toxic chemicals.
What to look for on the label: Ethylparaben, butylparaben, methylparaben, propylparaben, other ingredients ending in –paraben
Health concerns: Endocrine disruption, developmental and reproductive toxicity, allergies and immunotoxicity

Excerpts taken from the Campaign for Safe Cosmetics website.