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Controversial Ingredients: Setting the Record Straight
By: Ada Polla and Anne Pouillot
Posted: January 30, 2012, from the February 2012 issue of Skin Inc. magazine.
page 4 of 17
In regard to alternatives, an effective preservative must be nontoxic, nonirritating and have a broad spectrum of action while providing protection at a useful range of pH levels and temperatures. A hostile environment must be created for the growth of microorganisms, which requires optimization of the formulation and compatibility between preservatives.
“Preservative-free” formulas contain ingredients such as essential oils, which can have preservativelike qualities.7 However, essential oils are also considered allergens. Indeed, in Europe, 26 essential oils must be listed on a product label if the concentration is greater than 0.001% for nonrinsed products, and 0.01% for rinsed products, because of potential allergenicity (20–30% of intolerance reactions).
Preservation through packaging should also be discussed in this context.8 Indeed, brand owners may choose to move away from packaging, such as jars that are consistently exposed to air and high levels of hands-on contamination, and replace them with tubes or pumps that minimize the air channel and hand-to-product contact. This type of packaging allows for the use of less robust preservative systems, because microorganism exposure is reduced.
Ingredients with salts of sulfated ethoxylated fatty alcohols are primarily used in cleansing products—including bubble baths, soaps, detergents and shampoos. Among the alkyl ether sulfate ingredients, sodium laureth sulfate is most commonly used in cosmetics and personal care products. It has come to replace its family member, sodium lauryl sulfate, known to be very irritating to the skin. Sodium laureth sulfate did not yield adverse effects in a number of safety studies—including acute, subchronic and chronic oral exposure, reproductive and developmental toxicity, carcinogenicity and photosensitization studies.9
These ingredients have a bad reputation because trace amounts of 1,4-dioxane, a by-product of ethoxylation, may be found in the salts of sulfated ethoxylated fatty alcohols. The presence of 1,4-dioxane, even as a trace contaminant,10 is cause for concern because it accumulates in the body and is linked to liver and bladder cancer in animals.11 Moreover, in a 2003 study, German dermatologists found that patch testing sodium laureth sulfate increased transepidermal water loss (TEWL), or dehydration of the skin.12
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