Organic Sunscreens - infant exposure via breastfeeding

Xenobiotic secretion into breast milk is a concern because it exposes infants to unwanted, potentially harmful compounds. Studying plasma-to-milk transport is challenging due to ethical and technical constraints.

Organic sunscreens are used worldwide to protect skin from the harmful effects of excessive UV exposure. Unfortunately, some of these compounds are absorbed through the skin into the user's blood circulation. This study focused on the ability of organic sunscreens to be released into milk when administered to breastfeeding females.

Initially, a one-class classification methodology was employed. 202 compounds (mostly pesticides, drugs, aromatic hydrocarbons, and cosmetic raw materials) [1] with experimentally demonstrated ability to be secreted into human breast milk were used as reference compounds. Sixteen sunscreens from different chemical families were analyzed, and the key physicochemical properties of the reference compounds and sunscreens were subjected to Principal Component Analysis.

The properties of reference compounds (easily secreted into breast milk) were plotted in the PC2 vs. PC1 coordinate system to form a single cluster. All the studied sunscreens, except for two, fall within the chemical space of 99% of the reference compounds.

We demonstrated that all the sunscreens studied, except for bulky 1,3,5-triazine derivatives, have physicochemical properties that should enable their passage into human breast milk. This conclusion was corroborated by binary classification results obtained using the Classification Tree and Artificial Neural Network methodologies, based on a set of 122 reference compounds [2], which vary in their ability to enter breast milk. Since most of the sunscreens investigated in this study can be absorbed through the skin, infant exposure via the mother's milk seems a possible scenario.

1. Vijayaraghavan, S.et al. ACS Omega 2024, 9, 13006-13016
2. Maeshima, T. et al.Pharmaceutical Research 2023, 40, 711–719.