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Tuesday, 14 July 2009


Cocamide DEA and skin cancer

There has been more scaremongering to cancer patients over on the What Now board, with a claim that Cocamide DEA in shampoos is a cause of skin cancer, based on a scientifically illiterate misinterpretation of a 1997 study by what appears to be a spammer. Here's the unedited post, which is all over the net under a number of names:

"Cocamide dea- a reson for skin cancer

Cocamide DEA is cocamide diethanolamine. It is used to thicken the shampoo, a body wash, or a facial cleanser and give it a nice goopy consistency.

It is made by reacting fatty acids in coconut oils with diethanolamine. It is a viscous liquid and is used as a foaming agent in bath products like shampoos and hand soaps, and in cosmetics as an emulsifying agent.

Product manufacturers believe that the thicker is the product, the more appealing it seems to the customers. Maybe they think the product is more “rich” or “nutritious” or “natural”. But there’s nothing natural about cocamide DEA.

DEA and its variants are suspected of increasing the risk of cancer. DEA can combine with amines present in cosmetic formulations to form nitrosamines (N-nitrosodiethanolamine), which are known to be highly carcinogenic."

1. The study does exist but tested mice and rats, not people. Of course mice and rats don't use shampoo, and are not the same as people. They are in fact not even that similar to each other- the rats showed no evidence of cancer in the study, whilst the mice did.

As is so often the case, the amounts of the substance tested would never be obtained by shampooing. If you liked that one, there's another which suggests that it causes problems with foetal development at concentrations only ten times those which would be obtained by shampooing.

The poster misunderstands and exaggerates the conclusions of the study in an unhelpful way.

The cancers found in the study were NOT skin cancers. DEA does not combine with amines as stated, it IS an amine. And so on...

If you are going to give what amounts to medical advice to your fellow cancer patients, please try to have some clue what you are talking about. How about....

It seems a bit like the saccharin thing. Concentrations wildly in excess of those that any user would ever see are harmful to mice, but of course all things are toxic-it is the dose which matters.

To put things into context, here's the safety datasheet for pure ethanolamine. At high concentrations it is a severe skin, eye and respiratory irritant, with a maximum recommended concentration in air of only 3 parts per million. Yet we put it on our heads several times a week without being hospitalised, because the dose is very low.

The US FDA's advice is here. Unfortunately by advising people how they can avoid the substance, they give credence to the poster's claims. As a result of the uncertainty, ethanolamine derivatives are far less frequently used nowadays than before the study, even though its conclusions have not been verified in over ten years.

2. The study never suggested any link between DEA and any human cancer. And of course even if they had, that something might contribute towards getting cancer in the first place is nothing to do with whether it promotes existing cancer. This scaremongering on a board frequented by people who already have cancer helps no-one.

3. There is a clear trend behind all of these claims of toxic toiletries-crusties are mounting a campaign against all forms of personal grooming. Vidal Sassoon have responded by producing a new shampoo especially for crusties. It's called "Go & Wash".

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