Wednesday, October 20, 2010

Preservatives: Imidiazolidinyl and diazolidinyl urea

Imidiazolidinyl urea is one of the most common preservatives, found as Germall 115 (a powder). Created through a chemical reaction of allantoin and formaldehyde in the presence of a sodium hydroxide solution, it's then neutralized with hydrochloric acid and evaporated.

It's a good anti-bacterial preservative that isn't great with fungus, so it is generally combined with other preservatives that fight fungus better, like the parabens. In fact, using imidiazolidinyl urea with parabens potentiates or increases the effect of both preservatives! With a pH of 4 to 9, it's appropriate for pretty much any product we make, except for completely anhydrous products as it isn't soluble in oils. It's not heat stable, so it must be added to the cool down phase of our products.

Imidiazolidinyl urea is approved at up to 0.6% in the EU and 0.3% in Japan.

Diazolidinyl urea is a relative of imidiazolidinyl urea (found as Germall II) and is created in the same way with allantoin as a starting point. It is water soluble with low oil solubility, and is also a good anti-bacterial but weak fungal preservative, so it must also be combined with another preservative for broad spectrum protection. Its pH is also 4 to 9, so it's compatible with just about any product we make (except for anhydrous products as it's not oil soluble), and it should be added to the cool down phase of our products because it's not heat stable.

For a PDF on the toxicity of imidiazolidinyl urea, please click here.

Both ureas are considered low formaldehyde releasers. Diazolidinyl urea can be found in Liquid Germall Plus and Germaben II.


daniel said...

Can you please discuss PAPB aka polyaminopropyl biguinide? If no info, maybe look into researching and trying it? In my experience, it is acceptable to hardcore "natural/ organic" purists, as well as a great biocide. Not full spectrum, but seems great (again, in my experience with my formulations)coupled with k- sorbate. Full disclosure, I also tend to use essential oils at 1%, ethanol at 4%, and antioxidants. It's interesting. Non paraben or formaldehyde doning, but somewhat "complex". Its an oliger of biguinides, which are non- essential amino acid and DNA constituents. What do you think Swift?


p said...

Susan, what exactly does it mean that these molecules release formaldehyde? Do they break down over time into formaldehyde?

Hmm, I've got to say, I'm creeped out by the fact that these ingredients release formaldehyde. Formaldehyde is a known carcinogen, no? The toxicity info in the pdf suggests that acute toxicity isn't an issue at our usage rates, but it also states that there haven't been any long term carcinogenicity studies. This lack of evidence combined with the known carcinogenicity of formaldehyde concerns me. I personally choose to avoid these two ingredients (and products that contain them), but I understand other people choose differently!

Nedeia said...

Unfortunately, I have a friend who is allergic to Imidiazolidinyl urea. Good thing that she tested for allergies (she also has a contact dermatitis - I am not sure if this is the English term)

great post, I love posts about preservatives!

Nunung Warnida said...

Hi Susan, what a most helpful blog. I read a lot of information I couldn't find in textbook.
What do you think about Kemidant L-Plus (DMDM Hydantoin & Iodopropynyl Butylcarbamate), is it as effective as Germall in lotion and conditioner?

Susan Barclay-Nichols said...

I'm sorry, Nunung, but I've never used that preservative. Have you looked for a data bulletin or a forum where they might discuss this kind of thing? Sorry I can't be more helpful.