Estrogen in my shampoo
I've been spending some time researching this to find out how widespread estrogen-mimicing ingredients are and to what extent they are harmful. You won't be surprised to hear that the hard evidence is patchy and sometimes contradictory.
The Sprecher Institute for Comparative Cancer Research at Cornell University lists the following cosmetic ingredients as possible sources of estrogen: parabens, placental extracts and benzophenones. Oddly, they don't mention petroleum-derived products such as mineral oil. But I'll come back to that, first let's look at The Sprecher's Insitute's list.
I have researched parabens (a family of preservatives with names like butylparaben or methylparaben) for earlier posts and my conclusion, at this stage, is that the evidence linking parabens to cancer because they act like estrogen is really very weak. The FDA has a good summation of the research and says:
"The FDA is aware that estrogenic activity in the body is associated with certain forms of breast cancer. Although parabens can act similarly to estrogen, they have been shown to have much less estrogenic activity than the body’s naturally occurring estrogen. For example, a 1998 study (Routledge et al.in Toxicology and Applied Pharmacology) found that the most potent paraben tested in the study, butylparaben, showed from 10,000- to 100,000-fold less activity than naturally occurring estradiol(a form of estrogen). Further, parabens are used at very low levels in cosmetics. In a review of the estrogenic activity of parabens, (Golden et al., in Critical Reviews in Toxicology, 2005) the author concluded that based on maximum daily exposure estimates, it was implausible that parabens could increase the risk associated with exposure to estrogenic chemicals."
Various proteins, lipids, or other extracts from human or animal placentas are described as cosmetic ingredients. Human-derived ingredients are prohibited in Europe because of concerns about transmission of HIV. Extract of umbilical cords are used without restriction in Japan and show up as hair and skin conditioners. Some common ingredients that might be derived from human or animal placentas include hyaluronic acid, collagen-elastin complex, and glucosaminoglycans.
There are some cosmetics that list placental extract as an ingredient in its own right. For example, I found a shampoo called PureStrength Close which uses placenta to "give life back to fine hair". A University of Texas study looked at four African-American girls aged 14 months to 93 months who developedbreast or pubic hair 2 to 24 months after starting the use ofestrogen or placenta-containing hair products. "Discontinuingthe use of the hair products resulted in regression of the breastor pubic hair."
Benzophenones are UVA sun filters. There have been more than 30 studies of estrogenicity in sunscreens and the majority tested positive as weak environment estrogens. Some studies have not been able to demonstrate that benzophenone-3 is estrogenic. However, when benzophenone-3 is exposed to sunlight, it changes into a more estrogenic form of the chemical. Two studies have demonstrated that avobenzone is not an environmental estrogen.
One petrochemical product, mineral oil, is used as a lubricant and emollient because it’s cheap and plentiful. It has been classified as a carcinogen according to the US Department of Health and Human Services 10th Report on Carcinogens (2002) and can be contaminated with xenoestrogenic polycyclic aromatic hydrocarbons (PAH). Studies show that PAHs cause tumors in laboratory animals through inhalation, via food, or following prolonged contact with skin. Some PAHs are known to activate estrogen receptors, and a 2004 study found that PAH stimulated proliferation of certain breast cancer cells.
These are surfactants that turn up in detergents and shampoos. They don't biodegrade easily so they also show up as contaminants in rivers. However, a University of Mississippi concluded that: "Given the reported environmental concentrations and bioconcentration factors of APE products, the potential for these compounds to produce estrogenic effects in the environment appears low."
I have read that two alkyphenols, nonylphenol and octylphenol, are particularly suspect. But here again, the evidence is contradictory and a study published in the Journal of Endochrinology declares that there is no link between octylphenol and estrogen production. On the other hand, the University of Ottowa does draw a link (with dire consequences for snapping turtles).
All in all, there does seem to a convincing estrogen link with most of these ingredients - with the exception of parabens. However, I would tend to avoid parabens in any case because they are a powerful environmental pollutant.