A synthetic preservative and moisture-binding agent belonging to a class of agents known as higher molecular glycols. It is considered non-sensitizing.
References for this information:
International Journal of Toxicology, September-October 2012, pages 147S-168S
International Journal of Cosmetic Science, October 2011, pages 421-425
Cutaneous and Ocular Toxicology, Volume 28, 2009, pages 23-24