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Controversial Ingredients: One Brand’s Perspective
By: Ada Polla and Anne Pouillot
Posted: November 29, 2011, from the December 2011 issue of GCI Magazine.
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What is it? Propylene glycol, also known as 1,2-propanediol, is an organic alcohol. It attracts water, reduces flaking and restores the skin’s suppleness. Propylene glycol is also used to help stabilize formulas and is a solvent that dissolves natural extracts.
Why the bad reputation? Consumers associate propylene glycol with brake and hydraulic fluids and antifreeze, not understanding that there are different grades of this product. Moreover, its effect on the skin is drying, as it will partially dissolve the intercellular cement of the stratum corneum and decrease corneocyte cohesion, hence increasing TEWL.25 Indeed, high concentrations of propylene glycol in water kept in contact with human skin can cause irritation.26 No reaction was observed when tested in the open air on human subjects. One report indicates rare eczematous skin reactions and, even more rarely, an allergic reaction following exposure to propylene glycol.27
Should it be replaced? Probably. In the U.S. propylene glycol is listed as GRAS (Generally Recognized As Safe) for use in food and pharmaceuticals in the U.S. Food and Drug Administration document US—Pharmacopoeia (Ref21CFR). However, given its use in other industries, consumers are confused and are afraid of propylene glycol. Furthermore, given its drying effect, it is best to limit its use, e.g., in the case of a difficult dissolution of an active ingredient or the use of hydroglycolic plant extracts.
What are the alternatives? Butylene glycol or glycerin easily replace propylene glycol as a solvent to extract plants under the same conditions. Butylene glycol has been shown to have better skin tolerance.28 Oil extracts can also be used if one formulates with plants steeped in natural oils, synthetic triglycerides or synthetic fatty esters. Of course, this extraction process should be reserved for plants with liposoluble actives. Solid extracts, obtained by evaporating the solvent, can also be used. These solid extracts remain stable when introduced in the aqueous phase of formulas, yet can lead to the appearance of more- or less-visible particles. We recommend using a combination of glycerin, jojoba oil and solid plant extracts. Alchimie Forever has been working to replace propylene glycol with butylene glycol. Once again, it is primarily a question of the consumers’ perception, but as there is a perfectly adequate alternative, the question really becomes, “Why not? ”
Fragrances and Phthalates
What are they? Phthalates are composed of a benzene ring and two carboxylate groups in ortho position; the size of the alkyl chain can vary. Phthalates are commonly used to soften plastics. In cosmetics, a single phthalate is used in the U.S., Europe and Japan: diethyl phthalate (DEP). The use of DEP prolongs the scent of perfumes, and renders alcoholic products unfit for oral consumption. The use of DEP as an alcohol denaturant also continues to be approved by the U.S. Alcohol Tax & Trade Bureau.29 DEP is also used in nail polish so that the polish does not peel off. Another phthalate, dibutyl phthalate (DBP) is still sometimes used in nail polishes, but as it is prohibited in most countries, its use has been discontinued by many manufacturers.30 Why the bad reputation? Phthalates are accused of being endocrine disruptors that reduce fertility.