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.


Ruth said...

Interesting. The deoderant link to breast cancer is so on again/off again. My mother, aunt, 1st cousin, and mother-in-law all have had breast cancer. My cousin is 2 years younger than me and is having chemo now. Any possible causes are worth considering seriously for myself and my 3 daughters. My m-i-l also had a malignant tumour on her eyelid, not related to her breast. The doctor told her it was related to cosmetic use. She was always made up gorgeously and also used permanent hair dye.

janeywan said...

I use a natural product, without going and looking I think it's called Crystal, basically it's a block of salt. Works great!

S said...

What i read from your post was new and informative. i never knew there was so much to a deodorant. Where do you get all these information from? What counts in these kind of posts is whether it will be useful to lay people or is it going to be only useful to doctors. Your posts are definitely useful to lay people in their day-to-day life. Keep it up - smalltowndoc

Mauigirl said...

Very interesting. While I expect there must be some other genetic co-factor involved (or else 90%+ of the deodorant-using population would be coming down with breast cancer) why take a chance if you don't have to? I may switch to Tom's of Maine. I always thought the deodorant-breast cancer link was just one of those urban myths but it sounds as if there may be a link.