I wrote a post about 1,4-dioxane in the much maligned ingredients series, but I'll write a little more today as I had a few thoughts I wanted to share. I will eventually answer these specific questions, but we need to know what 1,4-dioxane is, why we might find it in our products, and what evidence has been found about it before we can say if it's toxic or not.
What is 1,4-dioxane? From Wikipedia: "1,4-Dioxane...is a heterocyclic organic compound. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. It is classified as an ether."
As to its safety: Dioxane is classified by the IARC as a Group 2B carcinogen: possibly carcinogenic to humans because it is a known carcinogen in other animals. The U.S. Environmental Protection Agency classifies dioxane as a probable human carcinogen (having observed an increased incidence of cancer in controlled animal studies, but not in epidemiological studies of workers using the compound), and a known irritant (with a no-observed-adverse-effects level of 400 milligrams per cubic meter) at concentrations significantly higher than those found in commercial products. Under Proposition 65, dioxane is classified in the U.S. state of California to cause cancer. (Again, Wikipedia)
As for California classifying it as a cause of cancer, it seems like they classify everything as causing cancer! Check out this comic then this one from Romantically Apocalyptic! Armageddon plus Hello Kitty equals hilarity!
ethoxylation, which is done to increase the water solubility of our ingredients, like our emulsifiers. "Ethoxylation is an industrial process in which ethylene oxide is added to alcohols and phenols to give surfactants." In other words, without ethoxylation, emulsifying wax, Polawax, and other emulsifiers would just be fatty alcohols (like cetyl alcohol) that didn't mix with water. When something is ethoxylated, 1,4-dioxane can be produced as a side product.
When it comes to PEG type ingredients, they are ethoxylated to create a water soluble ester that might also work as an emulsifier. Ethylene oxide is added to a fatty acid or fatty acid alcohol, and in the end non-ionic surfactants are produced.
Let's pause for a second for an aside that will eventually make sense...There is an ad on TV I find really irritating lately. It says this: "Oat fibre has been shown to reduce cholesterol. Our product contains oat fibre." The unspoken third sentence is that this product will help me reduce my cholesterol. But will it? Coming to erroneous conclusions is called a logical fallacy, specifically the if-then fallacy. We've all seen this kind of reasoning - I like musicals. "Cats" is a musical. I must like "Cats"! (I really didn't!) Why do I mention this in a post on 1,4-dioxane? Because I think we are labouring under a logical fallacy. "Ethoxylation creates 1,4-dioxane. 1,4-dioxane is a bad thing. Therefore, any product with ethoxylated ingredients is bad or toxic." It seems like a logical fallacy to me because there isn't any evidence that a small amount of this contaminant will have an impact on our health
When you read this sentence about a commitment made by a company - (they will) reduce 1,4-dioxane in all of its baby products to less than 4 parts per million (ppm) - do you think this is an accurate accompanying headline? "Johnson & Johnson Promises to Remove Carcinogens from Baby Products."
The dose makes the poison. "It means that a substance can produce the harmful effect associated with its toxic properties only if it reaches a susceptible biological system within the body in a high enough concentration (dose)." Everything can kill you at a high enough dose. To be a poison, it has to be used in the amount that wil kill you. 7.6 grams per kilogram on the skin will kill a rabbit (EPA document). If we extrapolated this to a human being's size, it's the equivalent of 380 grams (0.84 pounds) applied to the skin of someone weighing 55 kg (121 pounds). Using 3 mg in a
I don't encourage extrapolation of this kind as 4 to 5 castor seeds can kill a human, whereas it takes 80 to kill a duck. There are huge differences between what can kill a mouse and a guinea pig as well. But it serves the purpose of illustrating how a few milligrams on our skin isn't the huge deal some perceive it to be....and that my conclusion that ducks are evil is solidified further.
From the EPA document: Dioxane has low acute toxicity. The liquid is painful and irritating to the eyes, irritating to the skin upon prolonged or repeated contact, and can be absorbed through the skin in toxic amounts...Death of a worker, probably attributable to one week’s inhalation exposure to about 1800 mg/m3 (500 ppm in air, which is roughly equivalent to 257 mg/kg over an 8-hour work day) has been reported. In that case, there was also the possibility of skin absorption since the dioxane was also used as a solvent to remove glue from hands (IARC 1976).
From the FDA (on cosmetics): FDA followed up with skin absorption studies, which showed that 1,4-dioxane can penetrate animal and human skin when applied in certain preparations, such as lotions. However, further research by FDA determined that 1,4-dioxane evaporates readily, further diminishing the already small amount available for skin absorption, even in products that remain on the skin for hours. (Robert L. Bronaugh, "Percutaneous Absorption of Cosmetic Ingredients," in Principles of Cosmetics for the Dermatologist, Philip Frost, M.D., and Steven Horwitz, M.D., Eds. St. Louis: The C.V. Mosby Company, 1982)
Again, you can see that there has to be quite a bit of 1,4-dioxane before we see some really awful results. A few milligrams found in a shampoo that you lather, rinse, and repeat is highly unlikely to have any effect on your health. Even ingredients left on your skin are unlikely to have any impact. (I say unlikely because I can't test this empirically. These conclusions are based upon the hours of research I've done on the topic reading well done studies and case reports by those more qualified than me.)
Please do not interpret this post as my encouragement to go out and slather yourself in 1,4-dioxane. It's a nasty customer that can do some serious damage to our health. My goal in this post is to get you to think about the conclusions to which we come and to give you another way to think about science, studies, claims, and our personal interpretation of those things.
I've said this before, but I think it bears repeating. I have used all the ingredients about which I write on the blog. I share these products with people I love - my family, my friends, co-workers, and kids in my youth program. Would I share anything with them that I thought might cause harm? Would I suggest anything that I thought might cause you harm?
If you want to comment on my post, play nicely. Use your name and avoid any attacks upon me or anyone else. Anything without a name will be deleted immediately. A friendly sign off is always welcomed.
Further suggested reading: