Monday, October 08, 2007
The pit and the parabens
I just glanced at the ingredients on my deodorant's label, and it reads like the contents of a well-stocked biochemistry lab. Can this arsenal of armpit aromatizers contribute to breast cancer risk or is this just another urban myth? In case you need one more thing to worry about, read on for the evidence linking deodorant use to breast cancer.
Scientists from the UK noted that the majority of breast cancers are found in the upper, outer quadrant of the breast, nearest the armpit. They wondered if underarm hygiene habits, particularly the application of deodorant, contributed to this skewed tumor distribution. On sorting through 20 breast tumor samples, they found high concentrations of para-hydroxybenzoic acids (parabens) in 18 of the cancers.
Parabens are used as preservatives in cosmetics. Unfortunately, they are xeno-estrogens, meaning that they are molecules whose structure is similar enough to estrogen that they can occupy the estrogen receptor sites on cells. Korean scientists added butyl-parabens to mutant yeast cells (that had somehow been induced to express human estrogen receptors) and found that the parabens not only bound to the receptors, but also exhibited an additive estrogenic effect when administered along with estradiol. The yeast approved of their supple cell membranes and decreased hot flashes, but the investigators were concerned about the implications for human exposure to parabens.
Male rats, however, were not amused when their testosterone levels fell after they were exposed to parabens at levels equivalent to the "upper-limit acceptable daily intake of parabens in the European Community and Japan." Cultured breast cancer cells positive for estrogen-receptors increased their growth rate under the influence of parabens. But a population-based study in Seattle that randomly dialed for deodorant habits amongst breast cancer survivors and cancer-free controls found no association between armpit applications and breast tumors.
Molecular biologist Philippa Darbre was so appalled by her research results that she quit using cosmetic products some years ago. As I review the chemical stew in my Tom's of Maine deodorant, I can rejoice because it's parabens free. Likewise, the yummy-smelling stuff from Avalon Organics. Crocky or no, there's no reason to bother the breasts with the likes of parabens.