Natural glycol replacement for hair and skin care

Once they have identified a new ingredient, evaluation of its safety, efficacy and performance attributes is critical prior to adoption in new formulations. Certification agencies such as ECOCERT, COSMOS, BDIH, Natrue and the Natural Products Association (NPA) have been evaluating and approving ingredients as being safe and/or natural. Products that are on the “do not use” lists from these agencies as well as information on the internet are driving various “free from” marketing claims. Paraben-free, phthalate-free and sulfate-free are some examples that you will see on the retail shelves today. In May 2004, DuPont and Tate & Lyle formed a joint venture – DuPont Tate & Lyle Bio Products, LLC – and invested in one of the largest bio-materials processing facilities in the world at Loudon, Tennessee. The proprietary fermentation process converts glucose or corn sugar, a rapidly renewable feedstock, to 100% bio-based 1,3-propanediol. Originally intended to be an ingredient in DuPont Sorona polymer, a renewably sourced polytrimethylene terepthalate (PTT), a cosmetics grade of this material has been available since 2006 under the registered trade name, Zemea. Zemea bio-derived 1,3-propanediol (now referred to as ‘the glycol replacement’) can replace petroleumbased glycols such as propylene glycol (PG), butylene glycol (BG) or glycerin. It can be used as a humectant, emollient, natural solvent, viscosity enhancer, handfeel modifier and for botanical extraction and dilution. It is also being used as a carrier for active ingredients, as an ingredient in natural preservative systems and for developing natural esters. Various technical and consumer tests have been conducted to evaluate the performance of the glycol replacement as compared to traditional glycols and glycerin. This paper will highlight the key test results.

Skin irritation and sensitisation

Two independently conducted human skin patch studies were completed using the glycol replacement. A modified Draize Repeated Insult Patch Test (RIPT) method was used for the first test where solutions containing 5%, 25%, and 50% of the glycol replacement and water were applied to the skin of approximately 100 volunteers. Patches remained on the skin for 24 hours for each of nine applications in the induction phase. Following a two-week rest period, volunteers were challenged with one final application. The glycol replacement was shown not to be a skin irritant, fatiguing agent or sensitising agent in the first study. In the second RIPT study, a single-blind comparison of the glycol replacement and PG (25%, 50%, and 75% the glycol replacement, 25%, 50%, and 75% PG) was conducted on approximately 200 volunteers. Test conditions in the second study were similar to those in the first study. In the second study, there was no clinically significant dermal irritation or allergic contact sensitisation reactions following exposure up to 75% the glycol replacement at three different pH levels. These results were in contrast to the skin irritation observed at all three PG concentrations with 22.7% of the test population indicating positive irritation results at 75% concentration (Fig. 1). The results from these human studies show that the glycol replacement has low potential to irritate and sensitise human skin.