Homosalate is an organic compound used in some sunscreens. It is an ester formed from salicylic acid and 3,3,5-trimethylcyclohexanol, a derivative of cyclohexanol.
The salicylic acid portion of the molecule absorbs ultraviolet rays with a wavelength from 295 nm to 315 nm, protecting the skin from sun damage. The hydrophobic cyclohexanol portion provides greasiness that prevents it from dissolving in water.
Contained in 45% of US Sunscreens, It has limited skin penetration in vivo <1% (Was not detected in European mothers' milk (Sarveiya V, Risk S, Benson HAE. 2004. Liquid chromatographic assay for common sunscreen agents: application to in vivo assessment of skin penetration and systemic absorption in human volunteers. Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences. 803, (2), 225-231.) Limited evidence of hormone disruption.8, 19, 22, 28. Toxic metabolites 34 (Schreurs R, Sonneveld E, Jansen JHJ, Seinen W, van der Burg B. 2005. Interaction of polycyclic musks and UV filters with the estrogen receptor (ER), androgen receptor (AR), and progesterone receptor (PR) in reporter gene bioassays. Toxicological Sciences. 83, (2), 264-272., Wolff MS, Engel SM, Berkowitz GS, Ye X, Silva MJ, Zhu C, et al. 2008. Prenatal phenol and phthalate exposures and birth outcomes. Environmental health perspectives 116(8): 1092., et al.)