DECEMBER 2016 • Vol. 22 No. 10
New York Society of Cosmetic Chemists
www.nyscc.org
The Importance of Physicochemical Properties in the Safety Assessment of Skin Care Products
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by Nava Dayan
he first section on the guidelines for testing of chemicals— published in October of 2012 by The Organization for Economic Co-operation and Development (OECD)—outlines a list of relevant physicochemical properties.1 Identification of the composition of interest is the first step in any chemistry-body interaction assessment since it equips the assessor with tools for prediction and drafts a plan for valuation. Properties that do not change the chemical nature of matter are termed “physical” while those that alter the chemical nature of a substance are termed “chemical”. The more detailed the information obtained at the early stage of development, the better one can identify a substance and gain more knowledge of its characteristics. These properties can assist modeling the substance and understanding how it might behave under different conditions. The essence in safety evaluation of compounds we use on a daily basis, such as personal care and cosmetic products, lies in the interaction and impact of the composition on the body. The assessment is based on the postulation that at a given concentration, route of exposure, and intensity, the chemistry (composition applied) introduced to biology (skin) may be recognized by the body as foreign or harmful and, therefore, may generate an unfavorable reaction. The assessor should strive to outline the risks associated with predicted exposure and determine whether the predicted risk is acceptable and the benefit of use justifies the risk. The skin is the largest and most complicated immune organ in the human body. It fulfills multiple roles from acquiring signals from the environment—communicated via sophisticated signaling cascades—to other internal components of the body via circulation and vice versa. Its structure and composition provides a very sensitive responsive flow of stimuli inside and out. To add to this complexity, the skin hosts an abundance of biota—essential contributors to its maintenance—which prevent the proliferation and pathogenicity of opportunistic bacteria and fungi. Certain treatments and practices foster biota imbalance leading to impaired biological barrier, potential disease, and abnormal sensitivity. The first and most important step in safety assessment of skin care ingredients and compositions is the characterization of the compounds applied, including their chemistry, physical properties, stability, and overall nature. The collection of such information at the early stage of (Continued on page 2)
N Y S C C H O L I D A Y P A R T Y • D E C E M B E R 1 s t Maritime Parc, Jersey City, New Jersey (see page 5)