Isoamyl p-methoxycinnamate is a natural compound which is found in the roots of the Indian Galangal plant, a member of the Ginger family. Commercially, it is prepared from Cinnamic acid which is found in the leaves of the cinnamon tree, and is chemically identical to the naturally occurring molecule. We are not aware of any reported skin reactions to Isoamyl p-methoxycinnamate, and according to all the scientific evidence we have this molecule has not been found to possess any oestrogenic properties.
This is direct contrast to the similar sounding sunscreen ingredient called octyl-methoxycinnamate. This is a semi-synthetic compound, which has been shown to cause isolated skin reactions. More importantly, this compound does possess significant oestrogenic activity as was demonstrated in the study by Schlumpf et al from the Institute of Pharmacology and Toxicology, University of Zurich.
Whilst these compounds have similar names they are chemically quite different and possess very different properties. Our reason for using Isoamyl p-Methoxycinnamate is to give the lotions adequate protection against both UVA and UVB radiation. Titanium dioxide is more effective against UVA light, and to give adequate protection against UVB we would have to use so much Titanium dioxide that the lotions would be pure white when applied to the skin. As this would make them aesthetically unappealing and impractical to use, we need to add a secondary filter to boost the effectiveness of the Titanium dioxide - hence our use of Isoamyl p-Methoxycinnamate which is particularly effective against UVB radiation.