Wednesday, November 10, 2010

Much-maligned ingredients: Ethoxylated ingredients & 1,4 dioxane

Many of the complaints about ethoxylated ingredients - those that have gone through the ethoxylation process, when ethylene oxide is added to fatty acid alcohols to give them detergent properties, to turn them into surfactants, like SLeS, our PEG esters, and things like ceteareth-20 - is that they contain 1,4 dioxane. A report put out by the Campaign for Safe Cosmetics, "Toxic Tub", notes this ingredient can be found in many children's products, and can be found in loads of other products that contain ethoxylated ingredients.

So what is 1,4 dioxane (or diethylene oxide)? From the Agency for Toxic Substances and Disease Registry (click here for the full PDF):

1,4-Dioxane is a clear liquid that easily dissolves in water. It is used primarily as a solvent in the manufacture of chemicals and as a laboratory reagent; 1,4-dioxane also has various other uses that take advantage of its solvent properties.1,4-Dioxane is a trace contaminant of some chemicals used in cosmetics, detergents, and shampoos. However, manufacturers now reduce 1,4-dioxane from these chemicals to low levels before these chemicals are made into products used in the home.

Make no mistake, 1,4 dioxane is not a pleasant chemical. The U.S. Department of Health and Human Services notes it is reasonably anticipated to be a human carcinogen. And the International Agency on Cancer considers it a group 2B carcinogen, which is defined as "The agent (mixture) is possibly carcinogenic to humans. The exposure circumstance entails exposures that are possibly carcinogenic to humans." It can also cause liver and kidney damage. This is one nasty chemical!

The FDA position on 1,4 dioxane can be found here, but I'll summarize it a little...The FDA doesn't have a limit for 1,4 dioxane and they are recommending manufacturers minimize the amount of 1,4 dioxane in products by vacuum stripping the ingredients after ethoxylation. Health Canada makes the same recommendations.

The limits are 10 ppm for polysorbates in our food, glycerides and triglycerides in supplements, and in a spermicide in a once popular contraceptive sponge. There aren't any cosmetic limits.

1,4 dioxane has no place in our products, and responsible manufacturers will go through the vacuum stripping process to ensure our safety. The amounts of 1,4 dioxane are incredibly low in most of the products tested in the Toxic Tub report, and very few products reach 10 ppm.

One of the things that really bothered me about the Toxic Tub report is this - "Some products tested for this report did not contain formaldehyde or 1,4-dioxane. However, that does not mean the products are safe." What does this mean? If you say these things are bad for us and you don't find them in the product, then shouldn't we breathe a sigh of relief? No. Because there might be other ingredients we should fear in the products. (Sorry, a bit of my opinion there, but I really do feel this last sentence of their report is fear-mongering.) 

So how worried should we be about using ethoxylated ingredients?

From Choose Organics:
Skin absorption studies demonstrated that dioxane readily penetrates animal and human skin during use of contaminated shampoos and other personal care products, although it is uncertain how much is available for absorption and how much evaporates instead of penetrating the skin.

From the Suzuki Foundation Report
Depending on manufacturing processes, PEGs may be contaminated with measurable amounts of 1,4- dioxane...1,4-dioxane can be removed from cosmetics during the manufacturing process by vacuum stripping, but there is no easy way for consumers to know whether products containing PEGs have undergone this process. In a study of personal care products marketed as “natural” or “organic” (uncertified), U.S. researchers found 1,4-dioxane as a contaminant in 46 of 100 products analyzed.

(This study of personal care products refers to this report from the Organic Consumers' Association. Unfortunately, the full report is "file not found" when I clicked on it, so I can't tell you at what levels the 1,4 dioxane was found, only the product lines that might have it.) 

From the FDA:
As a precaution, 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)

From Health Canada:
Dioxane exposure via cosmetic products was evaluated in Canada’s Chemical Management Plan (CMP) and found to be safe. Health Canada advises industry to follow the recommendations set out by the U.S. FDA. If a product was found to have unacceptable levels of this impurity, Health Canada would take action to remove the product from sale.

We have two facts here. The ethoxylation process can produce 1,4 dioxane. And 1,4 dioxane is considered carcinogenic. But they don't necessarily connect to make an argument against ethoxylated ingredients.

How much 1,4 dioxane is significant? If the limits are 10 ppm for food products, are results like 6 ppm or 0.65 ppm in an entire bottle of product significant? If 1,4 dioxane evaporates readily on our skin, how much of the 0.65 ppm is really penetrating our skin and is that significant?

I don't know the answers to these questions, but it seems like no one else does either. But now you know a little more about why ethoxylated ingredients are on the much maligned list.


p said...

Great post - thanks for covering this topic! I'm concerned about 1,4 dioxane in products.... I wonder how accurate the "safe levels" of exposure really are, whether we will assess risk very differently in 20 or 30 years when we have more data. From what I understand, it's difficult to design carcinogenicity studies that test the sort of long-term, low-dose exposure we experience in the real world. Acute toxicity is relatively easy to study, but how can you determine, in advance, the impact of 30 years of low-level exposure in humans? How good are our animal models, really? Anyway, musing....

A few weeks ago I bought some Polysorbate 80 from MMS. Not long after my purchase I read about the concerns over 1,4 dioxane in polysorbates, so I contacted MMS about 1,4 dioxane levels in their products. They were super helpful! Each lot of polysorbate 80 is tested for 1,4 dioxane (the specification is <10 ppm) - you can check with them on the specs of the exact lot you are buying. I hope all our suppliers are this on top of this issue!

Dot and Lil said...

Thanks so much for this post it's very timely for me. And to the commenter above, it's great to hear that MMS has that kind of information readily available! I do hope all of our suppliers follow suit. It would make it so, so much easier for us to reassure customers if they did.


Robert said...

OK, p, but how do you know a study of 30 yrs. of low level human exposure (if such a study could be done) wouldn't show that a given material PREVENTS cancers?

It is a very good bet that dioxane is a human carcinogen. I don't know if IARC still classifies carcinogenicity into strong, moderate, and weak, but I would have to guess that dioxane is a weak one -- just because the stronger ones were discovered first and now we're finding weaker and weaker ones. It's like we're mining a vein of a mineral, and needing more and more effort to find it as the low hanging fruit (to switch metaphors) got picked already.

It would be different if dioxane were a recently discovered substance, but it's had a long history of use as a solvent -- I remember using it in organic chem lab for extracting cholesterol from gall stones -- and so it's been studied for a while, and identified as a carcinogen just recently. So I've never been too concerned about this one.

But to the extent it is a legitimate concern, I wonder why the att'n was focused so much on toiletries like shampoo, when those same ethoxylation products are used in dish detergent, and we put spoons in our mouths.

Meanwhile I wonder whether the practice of sterilizing materials by ethylene oxide gas results in contamination of them with dioxane.

Anonymous said...

Your article is almost 5 years old, do you feel differently now? I always figure it's best to completely avoid possibly unsafe and carcinogenic ingredients because the long-term research just isn't out there.

Susan Barclay-Nichols said...

Hi Anonymous! Please put your name on your comment or I'll have to delete it.

No, I feel the same way. There are still no reputable studies showing that ethoxylated ingredients pose any risk to our health.