Saturday, August 15, 2009

Carcinogen in YOUR Shampoo? Yup. Pretty Much.

What if I told you that your shampoo almost assuredly has a "probable human carcinogen" in it, and that's likely true even if you use a "natural" or "organic" product? That's what I discovered quite by accident, when I landed at Green Reality Check [GRC], a blog by Debbi Mack. In a blogpost titled Green Reality Check: What the F*ck is This Stuff in My Organic Shampoo?, Mack talks about the substance, 1,4-dioxane - a cosmetic manufacturing by-product - that causes liver cancer in rats, and in humans is at a minimum a proven irritant. It has been identified by the EPA as a probable human carcinogen.
Here's the finding, from Agency for Toxic Substance & Disease Registry [ASTDR]

"The U.S. Department of Health and Human Services considers 1,4-dioxane as reasonably anticipated to be a human carcinogen.The limited number of studies available does not show whether 1,4-dioxane causes cancer in humans. However, laboratory rats and mice that drank water containing 1,4-dioxane during most of their lives developed liver cancer; the rats also developed cancer inside the nose. Scientists are debating the degree to which the findings in rats and mice apply to exposure situations commonly encountered by people.

"The U.S. Department of Health and Human Services considers 1,4-dioxane as reasonably anticipated to be a human carcinogen."

When you turn your own shampoo bottle around to see if you've been shampooing in a rat carcinogen along with body, volume and color-protectant, don't bother to look for 1,4-dioxane as a listed ingredient. The substance to look for is sodium laurel sulfate, something you've no doubt noticed as a primary ingredient on every shampoo, bubble bath, liquid soap and detergent label you've ever read because it's the ingredient that creates suds! Through a regulatory quirk, because 1,4-dioxane is a by-product of producing sodium laurel sulfate rather than an added ingredient in its own right, the FDA doesn't require it to be listed. Other damning watch words on the label are ingredients containing the clauses "PEG," "xynol," "ceteareth," and "oleth." These, too, indicate the probable presence of 1,4-dioxane.

I've barely scratched the surface of this topic, so I hope you'll go read the rest of Mack's article.

To make this more distressing, it turns out that many of the so-called "natural" products also have 1,4-dioxane. So how do you know which products contain 1,4-dioxane, and which are toxin-free? Well the Organic Consumer's Association released a study in 2008 listing several products it had tested, and their trace levels of the toxin, which are graded from a low of "not detectible" on up. Here's the list. Click on it, and it will get almost big enough to read. A link to the actual report, with a more legible chart, is below.

This list is over a year old, and it's possible that some of these manufacturers have found substitutes since the report issued. I've learned, for example, that Seventh Generation has plans to put out a 1,4-dioxane free dish detergent this fall, but I don't believe it's in the stores yet.

If you want to know more technical data about 1,4-dioxane, like information on human exposure pathways, and about animal research on the impacts of the toxin, there's a great resource page at the ATSDR right here,

Here is a link to the Organic Consumer's Association study, where you'll have a clearer picture of the chart, as well as additional explanatory information about 1,4-dioxane., and here is Seventh Generation's response to the OCA report, along with the Seventh Generation community's comments,

If you use a 1,4-dioxane free product, why not let us all know in the comments section?

Cute baby shampoo picture is lifted from, an article that says you don't need to shampoo your hair every day. Until you find a 1,4-dioxane substitute product, I think I'll be taking the Consumerist's advice.


  1. wouldn't you have to drink it for it to cause cancer?

  2. That's a good question, Joe! The answer, unfortunately, is "No." Pathways include inhalation, contact and ingestion. Actually at this point, we only know it causes cancer in rats. No cancer research has been undertaken in humans, but the EPA believes there is enough evidence from the rat research, coupled with evidence of other non-cancer effects to conclude that 1,4-dioxane is a "probable human carcinogen." We do know that inhalation, which apparently has been documented where 1,4-dioxane is present in conjunction with solvents (not cosmetics) has caused irritations of nose, lungs, eyes. From what I have read, you'd probably have to be exposed to fairly high levels to create cancer in a short-term research setting, but it's not clear what consistent, long-term exposure to lower levels might do. You can read what the EPA knows about it here:,4-Dioxane/cat/Overview/. I've seen a couple of scarier articles in the research journals, but I'm sure you can find those if your interest is truly piqued.

  3. "Almost assuredly is a probable human carcinagen" is, scientifically, a meaningless causal statement.

    Furthermore Rats drinking it for "most of their lives" is a real stretch to humans shampooing with it as an ingredient in shampoo as "probably" causal for cancer. Let's all get back to real science!

  4. I appreciate and share your desire for good science, but you misread my statement. What I said was that YOUR personal bottle of shampoo "almost assuredly" is one of those with 1,4-dioxane (since MOST brands show traces of it). What I did not say is that 1,4-dioxane "almost assuredly is a probable human carcinogen." (Had I said that, I would be objecting to my own wishy-washy grammar!).

    Because no actual human studies have been done to link the substance to human incidences of cancer (hey - who wants to be the guinea pig on that research??), the EPA identified 1,4-dioxane as "a probable human carcinogen" based on scientific extrapolations from what it does know of animal studies, coupled with other known effects of the substance. The quote I used (regarding the rats) is from an EPA summary, but the summaries are based on scientific data. While I often do go into the science journals myself, for this post I chose to use the EPA information as a short-cut.

    And, while it's probably true that limited exposure to 1,4-dioxane would be less likely to cause cancer, I also did not say that shampooing with shampoo having traces of it is probably a cause for cancer.

    The problem is that the carcinogen is present in trace amounts in almost every "sudsing" product you have in your home. Shampoo, liquid soap, dishsoap, laundry soap, bubble bath, face wash, etc. It is also present as a fume in many solvents we use, both industrially and residentially. And the scientific data says that it is toxic whether inhaled, ingested, or through skin contact. If we are exposed from infancy on, in all these ways, even only in trace amounts from any individual product, what might the long-term effects be? The EPA thinks it's dangerous enough that it has banned several solvent products that include it. And has labelled the product a "probable human carcinogen. But if you are skeptical, I encourage you to check for yourself the studies EPA relies upon. Go to the EPA link above, look for the research citations and find the articles online or in your library's medical journals. Then you can decide for yourself whether you trust EPA's judgment as "scientific." I do.