Accounting for intended use application in characterizing the contributions of cyclopentasiloxane (D5) to aquatic loadings following personal care product use: antiperspirants, skin care products and hair care products.

Decamethylcyclopentasiloxane, commonly known as D5 (cyclopentasiloxane) has a wide application of use across a multitude of personal care product categories. The relative volatility of D5 is one of the key properties attributed to this substance that provide for the derived performance benefits from the use of this raw material in personal care formulations. On this basis, rapid evaporative loss following use of many products comprising D5 is expected following typical use application and corresponding wear time. Studies were conducted on three key product categories containing D5 (antiperspirants, skin care products and hair care products) to characterize the amount of D5 that may be destined to 'go down the drain' following simulated typical personal care use scenarios. Marketed antiperspirants and skin care products were applied to human subjects and hair care products were applied to human hair tressesand subsequently rinsed off at designated time points representative of typical consumer cleansing and personal hygiene habits. Wash water was collected at 0, 8 and 24h (antiperspirant and hair care analysis) and additionally at 4h (skin care analysis) post product application and samples were analyzed by isotope dilution headspace gas chromatography/mass spectrometry (GC/MS) to quantify the concentration of D5 destined to be available to go down the drain in captured wash water. It is demonstrated that significant amounts of D5 in 'leave-on' application products evaporate during typical use and that the concentration of D5 available to go down the drain under such conditions of use is only a very small (negligible) fraction of that delivered immediately upon product application.