Cyclopentasiloxane

Montemayor, Beta P., et al. Chemosphere, 2013, 93(5), 735-740.

In personal care products, the three main product categories containing cyclopentasiloxane (D5, decamethylcyclopentasiloxane) include antiperspirants, skin care products, and hair care products. This work conducted a series of product application and rinse-off studies to measure the amount of D5 that can still be "leached" after typical use to assess the types of personal care products that may contribute to the overall aquatic D5 loading.
Assessment methods and results
· Antiperspirants and skin care products were applied to people, while hair care products were applied to human hair and then rinsed off after the specified time. The wash water was collected at different time points - 0, 8 and 24 hours for antiperspirants and hair care products, and additionally at 4 hours for skin care products. The samples were analyzed using isotope dilution headspace gas chromatography/mass spectrometry to measure the amount of D5 that could potentially be washed down the drain.
· Based on typical washing habits, less than 1% of the D5 used in products applied outside of shower or bath ends up in the drain. For products used before or after showering, the majority of D5 is released into the atmosphere rather than being washed down the drain. However, for products used during showering or bathing, around 40% or more of the D5 is expected to be washed down the drain. Although some D5 evaporates during this use, the balance between evaporation and drainage remains consistent.

Dudzina, Tatsiana, et al. Environment international, 2015, 84, 55-63.

A new method for measuring the chemical evaporation rate of cosmetics and personal care products (C&PCPs) under actual consumer exposure conditions is proposed, using the volatile cosmetic ingredient cyclopentasiloxane (D5) as a model.
Evaluation method and results
· The evaporation of D5 from both the neat substance and two commercial C&PCP formulations, such as deodorant/antiperspirant and moisturizing face cream, was studied by applying them to aluminum foil to investigate the impact of the product matrix on substance evaporation. Rate constants were accurately estimated by applying finite doses of neat D5 on aluminum and full-thickness porcine skin in vitro to determine condition-specific evaporation rates by measuring chemical mass loss per unit surface area at various time intervals within 1-1.25 hours post-dose.
· It was observed that D5 evaporated rapidly from the selected cosmetic products, with approximately half of the applied amount evaporating within one hour post-application. The release of D5 from exposed aluminum surfaces exhibited rapid evaporation rates, with mean rates of 0.029 mg cm-2 min-1 and 0.060 mg cm-2 min-1 at 23 °C and 32 °C, respectively. Statistical analysis of the experimental data confirmed a significant impact of cosmetic formulations on D5 evaporation, with the most pronounced effect (a 2-fold decrease in the evaporation rate) observed for the neat face cream pair at 32 °C.